THE I N F L U E N C E OF

C ER T A IN EN VIR ON ME N TA L F A C T O R S ON

THE PRO DU C T IO N AND QUALITY OF P O T A T O E S F O R
THE P O T A T O CHIP INDUSTRY

By
D A T T A J E E R A O KO N D JEE RA O SALUNKHE

A. THESIS
S u b m i t t e d to the School of G r a d u a t e Studies of M i c h ig a n
State C o lle ge of A g r i c u l t u r e and A pp lie d S cienc e
in p a r t i a l f u l f i l l m e n t of the r e q u i r e m e n t s
f o r the d e g r e e of

DOCTOR O F PHILOSOPHY

D e p a r t m e n t of F a r m

1953

Crops

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To

F a r m e r s — w ith

whose

friendly

a s s o c i a t i o n s the a u t h o r fin ds r e c r e a t i o n ,
e d u c a t io n ,
are

and

herew ith

i n s p i r a t i o n — the
affectionately

ii

results

dedicated.

ACKNOWLEDGMENTS

The

s tudy w as u n d e r t a k e n u n d e r the i n s p i r i n g ,

f a i li ng g u id a n c e , and t h o u g h t - s t i m u l a t i n g
D e x t e r , P r o f e s s o r of F a r m
A ssociate P ro fe s s o r
M i c h i g a n State
to e x p r e s s

of F a r m

m y deep

Dr.

and M r . E.

Crops;

s e n s e of g r a t i t u d e

T.

I take t h is o p p o r t u n i t y

to th e m .

C. M. H a r r i s o n , P r o f e s s o r of F a r m

of B o t a n y a nd P l a n t P a t h o l o g y ;

S.

J. W h e e l e r , f o r m e r l y

r e n d e r e d to the m e m b e r s

M eg ee , A s s i s t a n t Dean of A g r i c u l t u r e ;

of Dr.

c u r r e n t l y chief of m i s s i o n of

C ollege to Ryukyu I s l a n d s .

A p p re ciatio n is
mittee:

Crops,

suggestions

a b le , n e v e r -

of m y g u id a nc e c o m ­
Crops;

D r . J. H. Muncie,

a nd Dr. G. P .

Dr.

C. R.

Professor

Steinbauer, A ssociate

P r o f e s s o r of B o t a n y and P l a n t P a th o l o g y .
My w a r m e s t t h a n k s a r e
P r o f e s s o r of F a r m

due to M r . H. M. B ro wn , A s s i s t a n t

C r o p s , f o r h i s willing c o o p e r a t i o n and h i s g u i ­

d ance in p r e s e n t a t i o n of s t a t i s t i c a l data.
H erew ith I also

a ck no w le dg e the c o o p e r a t i o n of the m a n a g e ­

m e n t of the K u e h m a n n ’s P o t a t o
E r a Potato

Chip Co mpany,

Toledo, Ohio; New

Chip C om pa ny , D e t r o i t , Michigan; A d a m s P o t a t o

Company, Lansing,

Mic higan ;

Chip

and P o t a t o E x p e r i m e n t S tation, L a k e

City, M i c h ig a n .
iii

H e a rtfelt thanks a re
a nd to h e r h u s b a n d ,

e x t e n d e d to m y s i s t e r ,

K ir tim a lin i Raje,

R a j k u m a r A j i t s i n h Raje D a p h a l e , f o r t h e i r p r e ­

cious enc o u rag em en ts.
G r a t i t u d e i s a l s o e x p r e s s e d to the A g r i c u l t u r a l E x p e r i m e n t
Station,

M i c h ig a n State

C o l l e ge , f o r m a k i n g a v a i l a b l e

lo w s hi p , w hic h e n a b l e d m e to u n d e r t a k e

iv

these

a research fel­

investigations.

D a t t a j e e r a o K o n d j e e r a o Salunkhe
c a n d i d a t e f o r the d e g r e e

of

D o c t o r of P h i l o s o p h y

F inal examination,
R o o m 307.

A u g u st 4,

1953,

10:00 a . m . , A g r i c u l t u r a l Hall,

D issertatio n:
The in f lu e n c e of c e r t a i n e n v i r o n m e n t a l f a c t o r s on the
p r o d u c t i o n and qu a lity of p o t a t o e s f o r the po tato chip i n d u s t r y .
Outline of s t u d i e s :
M ajo r
Minor

s ub je ct:
sub ject:

F a r m Crops.
B ota ny and P l a n t P a t h o l o g y .

B iographical Items:
B o r n , N o v e m b e r 7,

1925, K o l h a p u r , India.

U n d e r g r a d u a t e studies,. B.Sc. (Agri.) H o n ou r s , 1949.
R a j a r a m C olle ge K o lh a p u r , B o m b a y U n i v e r s i t y , 1945-46.
A g r i c u l t u r a l College P o o n a , P o o n a U n i v e r s i t y , 1946-49G r a d u a t e s t u d i e s , M ic h ig a n State Co lle ge , E a s t L a n s i n g ,
i gan, 1950-53.

M ich­

M a s t e r of s c i e n c e , 1950.
M a j o r su bje c t:
F a r m Crops.
Minor subjects:
Soil Sc ie nc e a nd B ota ny and P l a n t
Pathology.
Experience:
I n s t r u c t o r in P l a n t P a t h o l o g y , A g r i c u l t u r a l C o l ­
l e ge P o o n a , 1949; G r a d u a t e R e s e a r c h A s s i s t a n t , M i c h ­
iga n State Co lle ge , 1951-53.
M e m b e r of S o c ie t y of the S i g m a Xi.

v

PREFACE

’’M o r e t h a n half the p e op le of the w o r l d go to b e d h u n g r y
e v e r y night.

This n e e d n o t be

so if the known m e t h o d s

of i m p r o v e d

a g r i c u l t u r a l p r o d u c t i o n and n u t r i t i o n a l p r a c t i c e s w e r e w i d e ly adopted;
food p r o d u c t i o n c ould be g r e a t l y i n c r e a s e d and f a m i l y l e v e l s of l i v ­
ing m a t e r i a l l y

raised.

. . .

[ N o r r i s E. Dodd (23), D i r e c t o r G e n e r a l ,

F o o d and A g r i c u l t u r a l O r g a n i z a t i o n ,

United N a t i o n s ] . 11

In c o n s i d e r a t i o n of th is thought, a t h o r o u g h d i a g n o s i s of the
v i t a l q u e s t i o n of s i m p l e

su stenance is needed.

This d i a g n o s i s

should

be b a s e d p r i m a r i l y on an i n v e s t i g a t i o n of the i s s u e of getting enough
to e a t and s hould be f o llo w e d by an a p p l ic a t i o n d e s i g n e d t o w a r d f u r ­
t h e r i n g not only food p r o d u c t i o n b u t a l s o a d e q u a te d i s t r i b u t i o n .
problem s deserve

T h e se

a c u t e a t t e n ti o n f r o m t hose who r e s p e c t h u m a n i t y

and who have it s w e l f a r e a nd p r o g r e s s

at heart.

The c u r r e n t and u r g e n t l y i m p o r t a n t p r o b l e m of h u n g e r in
many p arts

of the w o r l d ,

e s p e c i a l l y in A si a , is twofold:

firs t, that

of i m p r o v i n g the food s i t u a t i o n by i n c r e a s i n g p e r c a p i t a c o n s u m p t i o n
t h r o u g h i n c r e a s i n g quantity;

sec ond,

t h a t of e n r i c h i n g the f a u l t y and

u n b a l a n c e d d i e ts of t h e s e p o o r l y fe d p eo p le b y p r o v i d i n g a g r e a t e r
v a r i e t y of f ood m a t e r i a l s

of b e t t e r quality.

The a u t h o r ,

therefore,

thought t h a t he could do s e r v i c e , not

only to h i s M o t h e r India, b u t a ls o to the f r e e
h i m s e l f with,

and deve lo p in g i n t e r e s t in,

w orld,

by a c q u a i n t i n g

s o m e of the c u r r e n t t e c h ­

n i q u e s in c r o p p r o d u c t i o n and food p r o d u c t i o n .

D. K. Salunkhe

vii

T A B L E O F CO NTE NTS

Page
I N T R O D U C T I O N .................................................................................................................

1

REVIEW OF L I T E R A T U R E

..................................................................................

3

of P l a n t i n g .....................................................................................................

3

....................................................................................................................

5

........................................................................................................................

6

V a r i e t i e s ............................................................................................................................

7

S p ec ific G r a v i t y

8

D a te s

F ertilizers
Irrigation

Storage

.

..........................................................................................

...............................................................................................................................

C h e m i s t r y of the C o l o r of P o t a t o

Chips

.........................................

10
1Z

Chip C o l o r R a t i n g s ..........................................................................................

15

M A TE RI A L S AND M E T H O D S ...............................................................................

16

Cultural

............................................................................................................................

16

Spec ific G r a v i t y .........................................................................................................

18

S t o r a g e ...............................................................................................................................

18

P icric

.....................................................................................................

19

.................................................................................................................

20

Acid T e s t

Chip Making

Chip C o l o r R ating

..................................................................................................

viii

21

Page

C o m p u t a t i o n s .......................................................................................... .....................
RESULTS

................................................................................................................................

ZZ
Z4

Lake

City,

1950 C r o p ..........................................................................................

Z4

Lake

City,

1951 C r o p .........................................................................................

Z5

E a s t Lansing,

1951 C r o p ..................................................................................

Spec ific g r a v i t y of t u b e r s

................................................................

Z9
31

Chip c o l o r r a t i n g s :
c hippe d i m m e d i a t e l y
a f t e r cold s t o r a g e of t u b e r s f o r two m o n th s
......................................................................................
and f o r five m o n t h s

36

Chip c o l o r r a t i n g s :
c hippe d a f t e r conditioning f o r
t h i r t y d a y s following two m o n t h s cold s t o r a g e ...............

39

Chip c o l o r r a t i n g s :
c h ip pe d a f t e r c onditioning f o r
t h i r t y d ays following five m o n t h s c old s t o r a g e ...............

45

Lake

City,

Spec ific

195Z C r o p - - E x p e r i m e n t A

City,

48

......................................................................

5Z

..........................................................................................

57

g r a v i t y of t u b e r s

Chip c o l o r r a t i n g s
L ak e

..................................................

..................................................

6l

......................................................................

61

..........................................................................................

64

DISCUSSION O F R E S U L T S ......................................................................................

78

Specific

195Z C r o p - - E x p e r i m e n t B
g r a v i t y of t u b e r s

Chip c o l o r

ratings

Spec ific G r a v i t y of T u b e r s

...........................................................................

ix

78

Page

F r e q u e n c y d i s t r i b u t i o n of t u b e r s into
specific-gravity c lasses
...........................................................................

78

Average

......................................

80

C o l o r of P o t a t o C h i p s ...............................................................................

89

s p e c i f i c g r a v i t y of t u b e r s

SUMMARY AND CONCLUSIONS

...................................................................

10 4

L IS T O F L I T E R A T U R E

.......................................................................

108

APPENDIX

CITED

....................................................................................................................

x

115

L IS T OF

TABLES

Table
1.

2.

3.

4.

5.

6.

7.

8.

Pave
A v e r a g e p i c r i c a c i d t e s t r a t i n g s and a v e r a g e
chip c o l o r r a t i n g s f o r t h r e e v a r i e t i e s f r o m
t h r e e d a t e s of p l a n ti n g , L ak e City, 1950

26

Av e r a g e s p e c i f i c g r a v i t y f o r e a c h v a r i e t y
f r o m e a c h da te of p la ntin g , La ke City, 1951

28

A v e r a g e chip c o l o r r a t i n g s f o r e a c h v a r i e t y
f r o m e a c h d a te of p la ntin g , La ke City, 1951

30

A v e r a g e s p e c i f ic g r a v i t y f o r e a c h v a r i e t y
f r o m e a c h date of p l a n t i n g on e a c h t r e a t ­
m e n t , E a s t L a n s i n g , 1951

32

T w o - w a y table f o r v a r i e t i e s and t r e a t m e n t s ,
f o r a v e r a g e s p e c if ic g r a v i t y of t u b e r s , E a s t
L a n s i n g , 1951

54

table f o r d a t e s of pla ntin g and
t r e a t m e n t s , f o r a v e ra g e specific grav ity
of t u b e r s , E a s t L a n s i n g , 1951

55

A v e r a g e chip c o l o r r a t i n g s i m m e d i a t e l y
fo llow ing c old s t o r a g e (41° F.) f o r two
m o n t h s f o r e a c h v a r i e t y , date of pla n tin g ,
a nd t r e a t m e n t , E a s t L a n s i n g , 1951

37

A v e r a g e chip c o l o r r a t i n g s i m m e d i a t e l y
following c o ld s t o r a g e (41° F.) f o r five
m o n t h s f o r e a c h v a r i e t y , date of pla n tin g,
and t r e a t m e n t , E a s t L a n s i n g , 1951

38

T w o-w ay

xi

Table

9.

10.

11.

12.

13.

14.

15.

Page

T w o - w a y t ab le f o r v a r i e t i e s and t r e a t ­
m e n t s , f o r chip c o l o r r a t i n g s i m m e d i a t e l y
a f t e r cold s t o r a g e a t 41° F . of t u b e r s f o r
two m o n t h s , E a s t L a n s i n g , 1951 .
.........................................

40

T w o - w a y t ab le f o r v a r i e t i e s and t r e a t ­
m e n t s , f o r chip c o l o r r a t i n g s i m m e d i a t e l y
a f t e r cold s t o r a g e a t 41° F . of t u b e r s f o r
five m o n t h s , E a s t L a n s i n g , 1951

41

T w o - w a y t ab le f o r d a t e s of p la ntin g and
t r e a t m e n t s , f o r chip c o l o r r a t i n g s i m m e ­
d i a t e l y a f t e r c old s t o r a g e a t 41° F . of
t u b e r s f o r two m o n t h s , E a s t L a n s i n g ,
1 9 5 1 .....................

42

t a bl e f o r d a t e s of p la ntin g and
t r e a t m e n t s , f o r chip c o l o r r a t i n g s i m m e ­
d i a t e l y a f t e r c o ld s t o r a g e a t 41° F . of
t u b e r s f o r five m o n t h s , E a s t L a n s i n g , 1 9 5 1 ......................

43

A v e r a g e chip c o l o r r a t i n g s a f t e r c o n d i t i on ­
ing of p o t a t o e s at 78° F . f o r t h i r t y days
following two m o n t h s c o ld s t o r a g e at 41°
F . f o r e a c h v a r i e t y , f r o m e a c h date of
p l a n ti ng , and t r e a t m e n t , E a s t L a n s i n g ,
1951

44

T w o - w a y table f o r v a r i e t i e s and t r e a t ­
m e n t s , f o r chip c o l o r r a t i n g s a f t e r t h i r t y
d ays c o n d itio n in g of t u b e r s a t 78° F. s u b ­
s e q u e n t to cold s t o r a g e a t 41° F . f o r two
m o n t h s , E a s t L a n s i n g , 1 9 5 1 .................................

46

T w o - w a y table f o r d a t e s of pla nting and
t r e a t m e n t s , f o r chip c o l o r r a t i n g s a f t e r
t h i r t y d ays conditioning of t u b e r s a t 78°
F . s u b s e q u e n t to cold s t o r a g e at 41° F .
f o r two m o n t h s , E a s t L a n s i n g , 1951

47

T w o-w ay

xii

Table

16.

17.

18.

19-

Paoe
o

A v e r a g e chip c o l o r r a t i n g s a f t e r c o n d i ti o n ­
ing of p o t a t o e s a t 78° F . f o r t h i r t y days,
fo llow ing five m o n t h s co ld s t o r a g e a t 41°
F . f o r e a c h v a r i e t y , f r o m e a c h date of
p l a n t i n g a nd t r e a t m e n t , E a s t L a n s i n g , 1951
T w o - w a y ta ble f o r v a r i e t i e s and t r e a t ­
m e n t s , f o r chip c o l o r r a t i n g s a f t e r t h i r t y
da ys cond itio n in g of t u b e r s at 78° F. s u b ­
s e q u e n t to cold s t o r a g e a t 41° F . f o r five
m o n t h s , E a s t L a n s i n g , 1 9 5 1 ......................................................................

50

T w o - w a y table f o r d a t e s of pla n tin g and
t r e a t m e n t s , f o r chip c o l o r r a t i n g s a f t e r
t h i r t y d a y s conditioning of t u b e r s a t 7 8°
F . s u b s e q u e n t to cold s t o r a g e at 41° F.
f o r five m o n t h s , E a s t L a n s i n g , 1 9 5 1 ................................................

51

Average specific gravity for each variety,
from each date of planting, and irrigation
l e v e l in E x p e r i m e n t A, L ak e City,

20.

49

1952

T w o - w a y ta ble f o r v a r i e t i e s and i r r i g a t i o n
l e v e l s , f o r a v e r a g e s p e c if ic g r a v i t y of
t u b e r s , E x p e r i m e n t A, L a k e City, 1952 ........................................

5 4

55

21.

T w o - w a y table f o r d a te s of plan tin g and
i r r i g a t i o n l e v e l s , f o r a v e r a g e s p e c if ic
g r a v i t y of t u b e r s , E x p e r i m e n t A, Lake
City, 1952

22.

A v e r a g e chip c o l o r r a t i n g s f o r e a c h v a r i e t y ,
f r o m e a c h d a te of pla n tin g , and i r r i g a t i o n
l e v e l , in E x p e r i m e n t A, L a k e City, 1952 ...................................

58

T w o - w a y t a b l e f o r v a r i e t i e s a nd i r r i g a t i o n
l e v e l s , f o r chip c o l o r r a t i n g s , E x p e r i m e n t
A, L a k e City, 1952 ...........................................................................................

59

2 3.

xiii

T ab 16
24.

25.

26.

27.

28.

29.

30.

31.

P a ve
T w o - w a y table f o r d a t e s of p l a n ti n g and
i r r i g a t i o n l e v e l s , f o r chip c o l o r r a t i n g s ,
E x p e r i m e n t A, L a k e City, 1952

60

A verage specific gravity fo r each variety,
f r o m e a c h date of p la n ti ng , i r r i g a t i o n l e v e l ,
f e r t i l i z e r a n a l y s i s in E x p e r i m e n t B, L ak e
City, 1952

62

T wo - w a y ta ble f o r v a r i e t i e s and i r r i g a t i o n
l e v e l s , f o r a v e r a g e s p e c if ic g r a v i t y of
t u b e r s , E x p e r i m e n t B, L a k e City, 1952 .....................................

65

T w o - w a y tab le f o r v a r i e t i e s and f e r t i l i z e r
t r e a t m e n t s , fo r a v e r a g e specific g ra v ity
of t u b e r s , E x p e r i m e n t B, L a k e City, 1952 ..............................

66

T w o - w a y tab le f o r i r r i g a t i o n l e v e l s and
f e r t i l i z e r t r e a t m e n t s , f o r a v e r a g e s p e c if i c
g r a v i t y of t u b e r s , E x p e r i m e n t B, L a k e
City,
1952

67

T w o - w a y ta ble f o r d a t e s of p la nt in g and
f e r t i l i z e r t r e a t m e n t s , f o r a v e r a g e s p e c if ic
g r a v i t y of t u b e r s , E x p e r i m e n t B, Lake
City,
1952

68

T w o - w a y ta ble f o r d a t e s of pla ntin g and
i r r i g a t i o n l e v e l s , f o r a v e r a g e sp e c if ic
g r a v i t y of t u b e r s , E x p e r i m e n t B, Lake
City,
1952

69

A v e r a g e chip c o l o r r a t i n g s f o r e a c h v a r i e t y ,
f r o m e a c h date of p l a n ti n g , i r r i g a t i o n l e v e l,
f e r t i l i z e r a n a l y s i s in E x p e r i m e n t B, L ak e
City,
1952

70

xiv

Table

32.

33.

34.

35.

36.

Page

Two-way table fo r v a r i e t i e s and i r r i g a t i o n
l e v e l s , f o r chip c o l o r r a t i n g s , E x p e r i m e n t
B, L a k e City, 1 9 5 2 .............................................................................................

7 3

T w o - w a y t a b le f o r v a r i e t i e s a nd f e r t i l i z e r
t r e a t m e n t s , f o r chip c o l o r r a t i n g s , E x p e r i ­
m e n t B, L a k e City,
1952 .................................................................

74

T w o - w a y t a b le f o r d a t e s of p l a n ti n g and
i r r i g a t i o n l e v e l s , f o r chip c o l o r r a t i n g s ,
E x p e r i m e n t B. L a k e City, 1952

75

T w o - w a y t ab le f o r d a t e s of p la ntin g and
f e r t i l i z e r t r e a t m e n t s , f o r chip c o l o r
r a t i n g s , E x p e r i m e n t B, L a k e City, 1952

76

T w o - w a y t a b le f o r i r r i g a t i o n l e v e l s and
f e r t i l i z e r t r e a t m e n t s , f o r chip c o l o r
r a t i n g s , E x p e r i m e n t B, L a k e City, 195 2

77

App endix
Table
I.

II.

The p e r c e n t a g e of t u b e r s in e a c h
g r a v i t y c l a s s and the a v e r a g e s of
c o l o r r a t i n g s of the t u b e r s of s ix
and t h r e e d a t e s of p la nt i n g , La ke

specificthe chip
varieties
City, 1951

The p e r c e n t a g e of t u b e r s in e a c h s p e c i f i c g r a v i t y c l a s s and the a v e r a g e s of the chip
c o l o r r a t i n g s of o n e - h a l f of e a c h t u b e r
a f t e r c old s t o r a g e at 41° F . f o r two m o n t h s
and of the r e m a i n i n g h a l v e s , following
t h i r t y d ay s of conditioning a t 78° F . , f o r
five v a r i e t i e s , on t h r e e d a t e s of pla n tin g
and four i r r ig a tio n - f e r tiliz e r tre a tm e n ts,
E a s t L a n s i n g , 1 9 5 1 ......................................................................................

xv

116

118

A pp en d ix
Table
III.

The a v e r a g e chip c o l o r r a t i n g s of o n e - h a l f
of e a c h t u b e r a f t e r the cold s t o r a g e a t 41°
F . f o r five m o n t h s and of the r e m a i n i n g
h a l v e s f ollowing t h i r t y days of conditioning
a t 78° F . f o r two v a r i e t i e s on t h r e e d a t e s
of p l a n t i n g , and f o u r i r r i g a t i o n - f e r t i l i z e r
t r e a t m e n t s , E a s t L a n s i n g , 1951 ..........................

IV.

The p e r c e n t a g e of t u b e r s in e a c h s p e c i f i c g r a v i t y c l a s s and a v e r a g e of the chip
c o l o r r a t i n g s of the t u b e r s of e i g h t v a r i e t i e
f o u r d a t e s of p l a n ti ng , a nd t h r e e l e v e l s of
i r r i g a t i o n , E x p e r i m e n t A., L a k e City, 1952

V.

The p e r c e n t a g e of t u b e r s in e a c h s p e c i f i c g r a v i t y c l a s s a nd the a v e r a g e s of chip
c o l o r r a t i n g s of the t u b e r s of two v a r i e t i e s ,
t h r e e d a t e s of p l a n t i n g , t h r e e l e v e l s of
i r r i g a t i o n , and f o u r f e r t i l i z e r a n a l y s e s ,
E x p e r i m e n t B, L a k e City, 1952...............................

xvi

L IS T OF FIG URES

Figure
1.

2.

3.

4.

Page
P e r c e n t a g e d i s t r i b u t i o n of t u b e r s
five s p e c i f i c - g r a v i t y c l a s s e s f r o m
f i r s t (May 2,1)., s e c o n d (June 13),
t h i r d (June 25) d a t e s of p l a n t i n g

6.

7.

8.

82

P e r c e n t a g e d i s t r i b u t i o n of t u b e r s into
five s p e c i f i c - g r a v i t y c l a s s e s f r o m the
f i r s t (May 4), s e c o n d (May 2 3), and
t h i r d (June 4) d a t e s of p la nt i n g
.............................................

84

P e r c e n t a g e d i s t r i b u t i o n of t u b e r s into
five s p e c i f i c - g r a v i t y c l a s s e s f r o m the
f i r s t (May 1), s e c o n d (May 16), t h i r d
(June 2), and f o u r t h (June 16) d a t e s of
p l a n t i n g ...........................................................................

86

A v e r a g e chip c o l o r r a t i n g s f o r the
Ma y 21, J u n e ' 13, and June 25 d a t e s
of p l a n ti ng in five s p e c i f i c - g r a v i t y

cla sses
5.

into
the
and
....................................................

............................................................................................... .

91

A v e r a g e chip c o l o r r a t i n g s f o r the
M ay 1, May 16, June 2, and J un e 16
d a t e s of p l a n ti n g i n five s p e c i f i c ......................................................................................
g ravity c la s s e s

93

Appe a r a n c e of pota to chips:
C o b b l e r v a r i e t y , L a k e City,

99

A p p e a r a n c e of p o ta to c hips:
Rural variety, E a s t Lansing,

Irish
1951
Russet
1951

A p p e a r a n c e of p o t a to chips:
Katahdin
v a r i e t y , E a s t L a n s i n g , 1 9 5 1 .................................................
xvii

101

103

IN TRODUCTION

H o r t i c u l t u r a l q u a li ty of a p o ta to c r o p
clim atic, biotic,
teristics
itation,

as

a nd e d a p h ic f a c t o r s :

g e n e t i c —the v a r i e t a l c h a r a c ­

d ete rm in e d by its h e r e d ita r y m ake-up;

tem perature,

o th e r plants,

d e pe n d s upon g e n e t i c ,

and d u r a t i o n of s u n s h in e ; b i o t i c - - m a n ,

a nd the c r o p i t s e l f in r e l a t i o n to i ts

edaphic--physical,

clim atic - - p r e c i p ­

chem ical,

anim als,

environment;

a nd b i o l o g i c a l p r o p e r t i e s

of the

soil

i n f lu e n c in g the c a p a c i t y to su p p ly the c r o p w ith n e c e s s a r y n u t r i e n t s
and w a t e r .

The s u c c e s s f u l

p r o d u c t i o n of p o t a t o e s of

high q ua l i t y is

f u n d a m e n t a l l y i n f l u e n c e d by

the in di vi d u a l a s well a s

the

e f f e c t of t h e s e f o u r f a c t o r s .
t o r s , th e ir effects

a r e well r e c o g n i z e d f a c ­

on q u a lity n e e d f u r t h e r e x p l o r a t i o n and definition.

The p u r p o s e

of the i n v e s t i g a t i o n p r e s e n t e d h e r e i n

p l o r e the e f f e c t s of c e r t a i n
several varieties

Though t h e s e

cumulative

e n v i r o n m e n t a l f a c t o r s on the

was

q u ality of

of p o t a t o e s u s e d by the po ta to chip i n d u s t r y .

p a r t i c u l a r agronom ic f a c to rs

i n vo lv e d in t h is

planting,

d i f f e r e n t l e v e l s of I r r i g a t i o n ,

m ineral fe rtiliz ers,

d i f f e r e n t l o c a t i o n s in Michiga n; n a m e l y , L a ke
1952,

a nd E a s t L a n s i n g in 1951.

to e x ­

study w e r e :

City in 1950,

The

d a t e s of
a nd two
1951, and

The s tu d y a ls o i n c l u d e d the i nf lu e nc e

1

of d u r a t i o n a nd t e m p e r a t u r e
of the t u b e r , p i c r i c
the t u b e r ,

of t u b e r s t o r a g e .

the in fl u en c e of a g r o n o m i c

were

be of value to the p o ta to g r o w e r s

sugars

in

the q u a li t y f a c t o r

and s t o r a g e p r a c t i c e s .

I t is the a u t h o r ’s s i n c e r e hope t h a t t h e s e

ufacturer s .

specific g ra v ity

a c i d t e s t f o r the c o n t e n t of r e d u c i n g

a n d the c o l o r of the p o t a to c h ip s,

u s e d to e v a l u a t e

The

investigations

a s well a s to the p o t a to

will

chip m a n

REVIEW OF LITERATURE

More than five hundred papers on the quality study of potatoes
and potato chips were examined, but only those directly concerned
with this study are reviewed here.

Dates of Planting

S m i t h a n d N a s h (49) m e n t i o n e d t h a t p o t a t o e s o b t a i n e d f r o m
e a r l y planting w e r e m o r e m a t u r e than w e re

t h o s e f r o m l a t e p la nt i n g.

Pyke and Johnson (42) reported that late planting gave more
immature tubers at harvesting and that this immaturity resulted in
a greater tendency to develop dark chip color on frying.
Mikuljskil (36) emphasized that the ripening of the tubers of
potato is characterized by an increase in the content of dry matter,
starch, and total nitrogen, and by an increase in the ratio of soluble
nitrogen to protein nitrogen and a decrease in the ratio of sucrose
to reducing sugars.
Appleman and M iller (4) noted that in general immature po­
tatoes contained le s s starch, more total sugar, le s s protein, and more
reducing sugars than did mature tubers.

Reducing sugars were always

4

h ig h i n i m m a t u r e p o t a t o e s e v e n at the t i m e of h a r v e s t ,
a fte r a r e s t period.

M oisture

S w e e t m a n (54)
in c o l d s t o r a g e

c o n t e n t in i m m a t u r e

as well a s

tubers

was high.

c o n c l u d e d t h a t i m m a t u r e p o t a t o e s which w e r e

responded l e s s

slowly to w a r m t h d u r i n g a cond itio nin g

p e r i o d th an m a t u r e p o t a t o e s a n d t h a t c h i p s m a d e f r o m i m m a t u r e p o ­
t a t o e s w e r e u n e v e n in c o l o r .

F o r high-q u ality chips,

t u r e p o t a t o e s h igh in s t a r c h c o n t e n t was

the u s e of m a ­

recommended.

M c L e a n (34) o b s e r v e d t h a t the b e s t date of p la ntin g p o t a t o e s
v a r i e s w i t h the l o c a l i t y .
W h e e l e r a nd Salunkhe

(64)

t a t o e s p l a n t e d on M ay 18, Ju ne
determ ine

6, and J u n e

21,

1951, w e r e u s e d to

the e f f e c t of date of p l a n t i n g a nd s p e c i f ic g r a v i t y on c o l o r

of p o t a t o c h ip s .
specific

r e p o r t e d t h a t the R u s s e t R u r a l p o ­

The t h r e e

dates w ere

s e p a r a t e d into five

g r o u p s of

g r a v i t y r a n g i n g f r o m a low of 1.062 to a high of 1.090.

p o t a t o e s of h igh s p e c i f i c g r a v i t y of the May 18 p la ntin g m a d e
lent chips.

The c h ip s f r o m

g r a v i t y gave a d a r k c o l o r .
giving a high s p e c i f i c
s p e c ific -g ra v ity group.

the J u n e

excel­

21 p l a n ti n g of high s p e c i f i c

The May 18 p la n ti n g p r o d u c e d t u b e r s

gravity.

A few t u b e r s g r a d e d into the l o w e r

Chips f r o m the high s p e c i f i c - g r a v i t y t u b e r s

w e r e w hite , a nd p r o g r e s s e d d a r k e r a s the
tu b e rs lowered.

The

s p e c if ic g r a v i t y of the

5

Fe rtilize r s

It is a w e l l - r e c o g n i z e d f a c t t h a t v a r i o u s f e r t i l i z e r s , whe n a dd ed
to the

s oi l ,

a t l e a s t to t h o s e

s o i l s t h a t have b e e n u n d e r c u l t i v a t i o n

f o r a c o n s i d e r a b l e p e r i o d of y e a r s ,
of m a t u r i t y ,

and s o m e t i m e s

S m i t h a nd N a s h (48)
percentage

r e p o r t e d t h a t the s p e c i f i c g r a v i t y and the

3-12-12 w ere in c r e a s e d fro m

average

rate

the q u ality of the c r o p s grown.

of d r y m a t t e r of p o t a t o e s

Dunn and Nylund (24)

will m a t e r i a l l y in f l u e n c e the

d e c r e a s e d as a p p l i c a t i o n s of

1,000 p o u n d s to

3,000 p ou nd s p e r a c r e .

s t a t e d t h a t the g r e a t e s t d i f f e r e n c e s

s p e c i f i c g r a v i t y w e r e found b e t w e e n l o c a t i o n s .

in

The u s e of

n i t r o g e n a lone d e l a y e d the m a t u r i t y b ut ha d no a p p a r e n t e f f e c t on
specific gravity.

P o t a s h f e r t i l i z e r conta ining c h l o r i d e

caused m arked

r e d u c t i o n in s p e c i f i c g r a v i t y and the h i g h e r the a p p l i c a t i o n of p o t a s h
the g r e a t e r the d e p r e s s i o n in s p e c i f i c g r a v i t y v a l u e s .
rule

P o ta s h as a

s e e m e d to d e l a y m a t u r i t y .
S m i t h and N a s h (49) found t h a t t u b e r s f r o m u n f e r t i l i z e d p l o ts

a nd f r o m

the p l o t s f e r t i l i z e d with 5 - 1 0 - 0 ha d a h i g h e r

ity tha n t u b e r s f r o m p l o t s f e r t i l i z e d w ith 5 - 1 0 - 5 ,
10-10-10,
p e r acre).
gravity.

5-0-10,

5-20-10,

and 5 - 1 0 - 1 0

specific g r a v ­

5-10-10,

0-10-10,

(on the b a s i s of 1,000 pounds

The t u b e r s f r o m the 5 - 0 - 1 0 p l o t w e r e l o w e s t in s p e c if i c

Term an (55) experimented with muriate, chloride, and sulphate
of potash, and found that sulphate of potash consistently resulted in
higher starch content of the tubers, and in higher yields of starch
per acre than did the chloride, indicating that the chloride ion may
be responsible for decreasing the starch content of the potato.

It has

been repeatedly reported that potash fer tilize r containing chloride
lowered the dry-m atter content (8, 9, 13, 25, 27, 30, 56, 57).
Nail and Whittemore (39) noted that potash had very little ef­
fe c t on the quality of chips.

Irrigation

High quality of potatoes can be obtained by frequent irrigation
and by maintaining the m oisture content midway between the field
capacity and the permanent wilting point (14, 15).
Wagar (62 ) pointed out that wet seasons result in potatoes
with a low dry-m atter content which varies somewhat from season
to season.
According to Edmundson (26), early irrigation produced an
ea rlier set and more rapid development of tubers than did an initial
irrigation later in the season.

Varieties

V arieties of potatoes differ in genetic characters that influence
the quality of potatoes and potato chips.
M etzger e t a l. (35) demonstrated statistically significant dif­
feren ces in the composition of potato v arieties.

They also noted

that potatoes from one locality differed in starch and dry matter
from those of another locality.
Vanasse et ad. (61) noted that variety has a significant effect
on the specific gravity-dry matter relationship.
Page (40) reported that the different characteristics of potato
va rieties are important in selecting the right one for '^ r is p 11^ mak­
ing.
Wright and Whiteman (68) and Wright et a l. (66) stated that
the quality of potato chips depends largely on the variety of potatoes
used.

Some of the varieties preferred by the manufacturers were

Russet Rural, Russet Burbank, Irish Cobbler, and Kennebec.

Some

varieties were unsuitable for chipping, even when conditioned at 70°
F. (21° C.), such as Green Mountain, Pontiac, and Triumph.

In England, ^ c r isp 11 is synonymous with ,,chip.,,

S t u a r t (52) a n d Denny and T h o r n to n (18) found t h a t the

supe­

r i o r i t y of the R u r a l g r o u p f o r the p r o d u c t i o n of p o ta to c hip s of good
color was

clearly

ducing-sugars

shown,

and t h a t t h e s e v a r i e t i e s w e r e

low in r e ­

c o n t e nt .

Specific G r a v i t y

The
m easure

s p e c i f i c g r a v i t y of p o t a t o e s h a s long b e e n u s e d a s a r a p i d

of the c o n t e n t of d r y m a t t e r .

Y anscheels

a nd h i s

A c c o r d i n g to B u r t o n (10),

c o -w o rk e rs p re se n te d their

p l e s , in cl u d in g a n u m b e r of v a r i e t i e s ,

r e s u l t s on 560

sam ­

a nd found highly s i g n i f i c a n t

c o r r e l a t i o n s b e t w e e n s p e c i f i c g r a v i t y and d r y m a t t e r and s t a r c h c on ­
t e n t of p o t a t o e s .
The
the

s p e c i f i c g r a v i t y is

t u b e r in a i r

a n d in w a t e r .

^
,
S pecific G r a v i t y

C l a r k e t a l . (11)
use

d e t e r m i n e d a c c u r a t e l y by weighting

Weight in A i r
= “ GT7 .
*.
77G7 ^ ; 777
Weight m A i r - Weight m W a t e r
suggested a new method that consists

of s a l t s o l u t i o n s of known d e n s i t i e s f o r the

t e r m i n a t i o n of p o t a t o e s .
rapid,

a nd s i m p l e .

of the

specific-gravity de­

This m e t h o d i s c o m p a r a t i v e l y a c c u r a t e ,

9

Vanasse

e t a l . (6l)

o b s e r v e d t h a t the l o c a t i o n of p r o d u c t i o n

and the v a r i e t y of p o ta to h a s
specific

gravity-dry m atter
C o c h r a n e t al.

(12)

a s t a t i s t i c a l l y s i g n i f i c a n t e f f e c t on the

relationship.
s a i d t h a t the

f ou nd to v a r y i n v e r s e l y w ith s p e c i f i c
Sparks

reducing

s u g a r content was

gravity.

(51) found t h a t t h e r e m i g h t be a c o n c e n t r a t i o n of s o m e

m a t e r i a l in the s t e m e n d of po ta to t u b e r s whic h c ould be r e a d i l y
d e t e c t e d by m i c e

o r rats.

T his

s u b s t a n c e w as c o r r e l a t e d with high

s t a r c h c o n t e n t a n d m u s t be e i t h e r

r e l i s h e d by t h e m o r n e c e s s a r y f o r

t h e i r g ro w th .
T h i e s s e n (5 8) r e p o r t e d t h a t t h e r e w a s a h i g h e r p e r c e n t a g e
w a t e r and c r u d e f i b e r w ith a l o w e r p e r c e n t a g e
a s c o m p a r e d w ith the
h i g h e r in the

s t e m end of the t u b e r .

of s t a r c h in the bud
P r o t e i n was

s li g h t l y

s t e m end of the t u b e r .

A l e x a n d e r e t a l . (1)

s t a t e d t h a t the p o t a t o e s

g r a v i t y d e s u g a r e d e a r l i e r than th o s e of l o w e r
W r i g h t and W h i t e m a n (6 9 ) r e p o r t e d
best

of

appearance

of h i g h e r s p e c i f ic

s p e c if ic g r a v i t y .

t h a t the potato c h i p s

of

and q u a li t y a r e p r o c e s s e d f r o m the t u b e r s having

a

r e l a t i v e l y high specific gravity.
St u tz a nd B u r r i s
ture

(5 3) r e p o r t e d t h a t

the t u b e r s w ith l e a s t m o i s ­

c o n t e n t u s u a l l y t a ke up l e a s t oil in f r y i n g .

10
K u nk le e t a l . (33) f ound t h a t h i g h - s p e c i f i c - g r a v i t y
tato es

averaged alm ost

3.5 p e r c e n t m o r e

salable chips p e r bushel

t h a n t h e l o w - s p e c i f i c - g r a v i t y (1.0777) p o t a t o e s ,
potato

and t h a t the c o l o r of

c hi ps f r o m the hig he r - s p e c i f i c - g r a v i t y p o t a t o e s was l i g h t e r

t h a n t h a t of c h ip s m a d e f r o m
was

(1.0916) p o ­

the l o w - s p e c i f i c - g r a v i t y g ro u p.

It

a l s o found t h a t the c h i p s m a d e f r o m the t u b e r s low in s p e c if ic

g r a v i t y a b s o r b e d on an a v e r a g e
chips made f r o m

4.4 p e r c e n t m o r e f a t than did the

the t u b e r s h igh in s p e c if ic

gravity.

Storage

B e c a u s e of the v e r y n a t u r e
taken in its

storage.

of the p o ta t o t u b e r , c a r e

m u s t be

The s t o r a g e t e m p e r a t u r e p l a y s an i m p o r t a n t

r o l e in the p h y s i c o - c h e m i c a l b e h a v i o r of p o ta to t u b e r s .

Too low

t e m p e r a t u r e s , f r e e z i n g o r l o w e r ^ will p e r m a n e n t l y d a m a g e the t i s ­
sues

due to t h e i r high w a t e r c ontent.

o t h e r hand, w ill p r o m o t e

High t e m p e r a t u r e s ,

on the

desiccation and deterioratio n.

M u l l e r - T h u r g a u (38) d i s c o v e r e d t h a t cooling of p o t a t o e s
s u l t e d in s u g a r f o r m a t i o n a t 32° to 42°
later

F.

c o n f i r m e d by Wolff (65) a nd R o g e r s
Barker

(0° to 6°

C.).

re­

Thi s wa s

e t a l . (45).

(6) c l a i m e d t h a t s u g a r c o n te n t g r a d u a l l y i n c r e a s e d in

p o t a t o e s w h e n t he y w e r e

t r a n s f e r r e d to low t e m p e r a t u r e s .

The

11
m axim al

c o n c e n t r a t i o n w a s a t t a i n e d a t the l o w e s t t e m p e r a t u r e .

however,

potatoes,

r e n d e r e d s w e e t by a p r o l o n g e d p e r i o d of s t o r a g e

a t low t e m p e r a t u r e ,
t r a n s f e r r e d to 59°

If,

or partially
F.

(15°

C.),

s w e e t by a s h o r t p e r i o d , w e r e then
a rapid desweetening o ccu rred .

A p p l e m a n (2 , 3) e x p l a i n e d t h a t the c a r b o h y d r a t e t r a n s f o r m a ­
tions

are

d e p e n d e n t e n t i r e l y upon changing the s t o r a g e t e m p e r a t u r e s

of p o t a t o e s .
tures,

When the p o t a t o e s w e r e

g e n e r a l l y b e l o w 38° F .

s t o r e d a t the c o o l e r t e m p e r a ­

{1 . 6 ° C.), the r a t e of s u g a r t r a n s f o r m a ­

tion w a s m o s t r a p i d b e t w e e n 3Z° F .

(0°

A c c o r d i n g to A r r e g u i n - L o z a n o
sucrose

c o n v e r s i o n is

C.), and 29° F .

(-1.6°

and B o n n e r (5), the

F.,

0°

8 6 ° F.,

starch-to-

a c c o m p l i s h e d by the e n z y m e p h o s p h o r y l a s e ,

an e n z y m e of the c a r b o h y d r a t e m e t a b o l i s m of the p l a n t .
attacks

C.).

This e n z y m e

s t a r c h w i t h the p r o d u c t i o n of gluco se - 1-pho sp h a te a t low (32°
C.)

storage

20°

phorylase

to

30°

tem perature.

C.), though the p o t a t o e s p o s s e s s

as p o t a t o e s

s t o r e d at low t e m p e r a t u r e , the

u n a t t a c k e d by pho spho r y l a s e .
phosphorylase

But a t high t e m p e r a t u r e s

(6 8 ° to

as much phosstarch rem ains

T h is m i g h t be due to a n i n h i b i t o r of

a c t i v i t y a t high t e m p e r a t u r e s ,

which m i g h t be a b s e n t

a t low t e m p e r a t u r e s .
H arris

(28)

sh o w e d t h a t the s u g a r c o n t e n t i n c r e a s e d d i r e c t l y

w ith l e n g t h of s t o r a g e a t 40°

F.

(4.4°

C.).

The

r a t e of i n c r e a s e

of

1Z

s u g a r c o n t e n t w a s i n v e r s e l y r e l a t e d to the
results

sh o w e d t h a t 40°

tem perature.
d i f f i c u l t to

F.

(4.4°

If the t e m p e r a t u r e

"condition"

C.)

sto rage te m p e r a t u re s .

is a m inim um

g o e s b e lo w 40°

safe

F.

His

storage

(4.4°

C.), i t i s

the p o t a t o e s f o r chipping (6 7 ).

C h e m i s t r y of the C o l o r of P o t a t o

Chips

S e v e r a l i n v e s t i g a t o r s have p r o v e d t h a t p o t a t o e s high in s u g a r
content a r e p a r tic u la rly
c o l o r in p o t a to c h i p s
Thornton

(59)

s u s c e p t i b l e to the f o r m a t i o n of a d a r k b r o w n

(17,

18, 54).

r e p o r t e d t h a t only the r e d u c i n g

sugars

are

re­

s p o n s i b l e f o r b r o w n c o l o r of c hips a nd t ha t s u c r o s e i s n o t involved.
Denny and T h o r n t o n (17) found a d i r e c t c o r r e l a t i o n b e t w e e n
the a m o u n t of r e d u c i n g
e x t e n t of b r o w n i n g
D e x t e r a nd
reducing

sugars

s u g a r in the j u ic e of potato t u b e r s

when c hips w e r e m a d e

from

Salunkhe

showed t h a t the

seems

(Z0, Zl,

a m o u n t of

c h ip s.

s t a t e d t h a t the c o nte nt of r e d u c i n g s u g a r s

m i n e s the c o l o r of
K irkpatrick

t h em .

to be one of the c a u s e s f o r the f o r m a t i o n of

the d a r k b r o w n c o l o r of p o t a to
S m i t h (47)

ZZ)

and the

deter­

p ota to c hip s and h e n c e the q u a li ty of c h ip s .
(31)

s u g a r s in r a w s a m p l e s

c o n c l u d e d t h a t the c o n c e n t r a t i o n of r e d u c i n g
is n e g a t i v e l y c o r r e l a t e d with p a l a t a b i l i t y ,

sco re fo r colo r, c ris p n e s s ,

and f l a v o r of f r e n c h f r i e s .

i

R o g e r s e t a l . (43)

:

o b s e r v e d t h a t the d a r k b r o w n o b j e c t i o n a b l e

c o l o r of p o ta to c h i p s d e v e l o p s in r e l a t i v e l y h ig h t e m p e r a t u r e s
d u r i n g the f r y i n g p r o c e s s .

used

L o w e r i n g the i m m e r s i o n t e m p e r a t u r e

a nd l e n g t h e n i n g the f r y i n g t i m e

a s s i s t e d in p r o d u c i n g c h ip s of a c c e p t ­

a ble c o l o r .
The d e v e l o p m e n t of c o l o r of p o ta to c hips w as g e n e r a l l y thought
to be a c a r a m e l i z a t i o n of s u g a r s
hydroxym ethyl fu rfu ra l

(70)

D an eh y and P i g m a n
in c h i p s i s

(7,

17,

18,

19), and the f o r m i n g of

at h i g h e r f r y i n g t e m p e r a t u r e s .
(16) r e p o r t e d t h a t the c o l o r d e v e l o p m e n t

due to the c a t a l y t i c e f f e c t of n i t r o g e n on the p r o c e s s

of

caram elization.
P a tt o n and Pyke

(41) p r e s e n t e d e v i d e n c e t h a t the M a i l l a r d

R e a c t i o n is r e s p o n s i b l e f o r the c o l o r of po ta to c h i p s,

and t h a t the

b r o w n i n g of chips i s c a u s e d b y the c o m b i n e d e f f e c t of r e d u c i n g
ars

a n d a m i n o a c i d s in the pota to

e n c e of r e d u c i n g

s l i c e s and n o t s o l e l y by the p r e s ­

sugars.

In s u p p o r t of t h is t h e o r y ,
on the n a t u r e

sug­

S h a l l i n b e r g e r (45)

re p o rte d studies

of the M a i l l a r d r e a c t i o n a t the t e m p e r a t u r e u s e d to

f r y p o ta to c h ip s

(370.4°

F.,

188°

C.).

Using f i l t e r - p a p e r d i s c s

com­

p a r a b l e to p o ta t o c h ip s , he d e m o n s t r a t e d t ha t the c o n d e n s a t i o n b e t w e e n
the

so lu b l e n i t r o g e n o u s

and c a r b o h y d r a t e f r a c t i o n s

gave a b r o w n

14

colo ration.

G l u c o s e m a y c o n d e n s e with, the a m in o a c i d gly c in e in a

M ole/M ole

ratio, but m o r e

each mole

of s u c r o s e .

g l y c in e

s y s t e m is

potato

H o w e v e r , the c o l o r p r o d u c e d by a sue r o s e -

consistently less

c o n c e n t r a t i o n of g l u c o s e
t h a t the b r o w n i n g

than one m o l e of g ly c in e c o n d e n s e s w ith

d a r k t h a n t h a t given with an e qual

and g ly c in e .

S h a l l i n b e r g e r (46) a l s o

r e a c t i o n t h a t m a y o c c u r in the m a n u f a c t u r e of

c hip s i s due to c o n d e n s a t i o n of s u c r o s e

w it h the a m i n o a c id , g l yc i n e .
reducing

sugars

som etim es

a nd a s c o r b i c

a c id

B e c a u s e p o t a t o e s t h a t t e s t low f o r

r e s u l t in u n d e s i r a b l y c o l o r e d c h ip s ,

w as th o u g h t t h a t r e a c t i o n s involving s u c r o s e
be

stated

it

and a s c o r b i c a c i d m i g h t

responsible.

p o ta to

D e x t e r an d Salunkhe

(22 ) r e p o r t e d t h a t the d i s c o l o r a t i o n of

c h i p s w a s of v a r i o u s

types.

R educ ing s u g a r s gave one type

of d a r k b r o w n c o l o r and the i n t e n s i f i c a t i o n of t h a t c o l o r w a s m a n i ­
f e s t e d in the c o m b i n e d r e a c t i o n of r e d u c i n g s u g a r s w it h s o m e o t h e r
insoluble

c o n s t i t u e n t o r c o n s t i t u e n t s of the po ta to .

of the c o l o r d e v e l o p m e n t of p ot at o c hips n e e d s
tion,

s in c e t h e r e

The m e c h a n i s m

system atic fo rm u la­

a p p e a r to be d i f f e r e n t ty pe s of d i s c o l o r a t i o n s .

15

Chip C o l o r R a t i n g s

D e x t e r a nd Salunkhe
m e t h o d to s c o r e
= l i g h t yellow;

the c o l o r of p ota to chips:

7.5 to

(most desirable).

(21) and Salunkhe e t a l . (44)

10 = a c c e p t a b l e ;

described a

1 = e x tre m ely dark;

10

and 8.5 to 9 = golden y ello w

MATERIALS AND METHODS

In 1950, 1951, and 1952, several varieties of potatoes were
grown in various ways at two locations in Michigan.

After harvest,

sp ecific-gravity determinations were made on a random sample of
potatoes from each of the treatm ents.

Following the determination

of the specific gravity, the potatoes were subjected to various stor­
age treatm ents.

The potatoes were removed from storage, processed

into chips, and scored for chip color.

Cultural

Potatoes were grown at Lake City in 1950, 1951, and 1952,
and at East Lansing in 1951.

The soil was a productive Hillsdale

sandy loam at both locations.

Balbo rye was drilled for green

manuring in the month of August at a rate of approximately one
bushel per acre.

The rye was turned under the following April to

help in the control of scab (63).

The potatoes were planted in rows

36 inches apart with seed p ieces at 12-inch intervals.

The method

of planting was sim ilar in all three years and at both locations.
randomized block design with four replications was used.

16

A

17
The plots in all the experim ents were planted at three or four
different dates of planting from May 1 to June 25.
The several analyses of fe r tiliz e r s used were applied at the
rate of 1,000 piounds per acre by the band method at Lake City and
by hand-spreading at East Lansing.

Thejkind of fer tilize rs used

varied from year to year and are mentioned in detail under each
experiment.
The plots were divided as to water supply, some receiving
only rainfall, and others, supplemental irrigation.
irrigation was at two rates:

This supplemental

normal, in which irrigations were made

for a period of two hours at each time; and twice normal, in which
the sprinklers ran for four hours.
The plots were sprayed with standard fungicides and in secticides.

1

Potatoes in all the plots were harvested in the latter part of
September.

After harvest, a random sample of ten to forty U. S.

No. 1 tubers from each replicate of each treatment of each variety
was taken for subsequent analyses.

^ Under the kind supervision of Dr. J. H. Muncie, pathologist.
Bordeaux mixture and D.D.T. were used.

18
Spe cific Gravity

Tlie sp ecific-gravity determinations were made on the individ­
ual tubers by the brine-flotation method described by Clark et a l. (11).
In this method, salt solutions of 1.064, 1.070, 1.076, and 1.088 spe­
cific gravity were prepared in four different containers and arranged
in an ascending order of specific gravity.

The specific gravity of

each tuber was marked by a rating of 1, 2, 3, 4, or 5 by means of
a saturated solution of potassium permanganate.
Rating
1.

2.

3.

4.

5.

Specif ic-G ravity Class

M id-Class Value

L ess than 1.064 (the potato floats in
1.064)

1.062

Between 1.064 and 1.070 (the potato
sinks in 1.064 but floats in 1.070) . . . .

1.067

Between
sinks in

1.070 and 1.076 (the potato
1.070 but floats in 1.0 76) . . . .

1.073

Between
sinks in

1.076 and 1.088 (the potato
1.076 but floats in 1.0 88) . . . .

1.082

Over 1.088 (the potato sinks in 1.088) . .

1.090

Each random sample was placed in a numbered Kraft paper bag.

Storage

(1) Lake City:

The potatoes from the experiments of 1950

and 1951 were subjected to cold storage at 41° F. (5° C.) for the

19

period of two months, then conditioned at a room temperature of
78° F. (25.5° C.) for thirty days.
atures was ±2° F.

The range of all storage tem per­

The potatoes from the 1952 crop were never sub­

jected to cold storage but were stored at 60° F. (15.5° C.) for four
months and then conditioned at 78° F. (25.5° C.) for thirty days.
This conditioning period is essential for the possible development
of desirable and com m ercially acceptable chip color (19, 54, 60, 67).
The conditioned potatoes were processed into chips and scored for
color of the chips.
(2) East Lansing:

The potatoes were grown only in 1951 at

East Lansing, and were subjected to cold storage at 41° F. (5° C.)
for two months or five months.

Immediately after two or five months

cold storage at 41° F. (5° C.), each tuber was cut into longitudinal
halves.

A representative slice from one-half of each tuber was made

into chips at once and scored.

The other half was conditioned at

78° F. (25.5° C.) for thirty days and then processed into chips and
scored for color.

P icric Acid Test

The picric acid test (37) for estimating the amount of reduc­
ing sugars in the potato tuber was made on the crop grown in 1950

20
at Lake City.

The test consisted of pipetting 2 c.c. of saturated

aqueous solution of picric acid and 1 c .c . of 20 percent anhydrous
sodium carbonate solution into each test tube.

The middle half

section of a 3 / 12-inch-diam eter round core obtained from the center
of a potato with a cork borer was inserted
tube was then

in a test tube.

The test

loo sely stoppered and heated in a boiling-water bath

for thirty minutes.

The test tube and contents were cooled and the

core section removed.

The liquid in the test tube was matched with

a set of color standards (32) which ranged from

dark red to yellow,

and was given a color rating as follows:
Hating

Color

1

Dark red (high amount of reducing sugars)

2

Red

3

Light red

4

Orange

5

Yellow (low amount of reducing sugars)

Chip Making

Each tuber was sliced longitudinally; i.e ., parallel to the axis
from apex to basal end.

The sixth to eighth slice from the outside,

with a uniform thickness of 3/64 inch to 4/64 inch, was retained for

21
frying.

F o r identification, e ith e r c e rta in p a tte rn s

p u n c h e d in the

slices

approxim ately 200
move

adhering

F.

{196°

g r a m s w e r e w a s h e d u n d e r ru nn in g tap w a t e r to r e ­

a t an

C.).

or

" in itia l" or

The t e m p e r a t u r e

"rem oval"

w a t e r in f r y i n g oil,

"im m ersion"

tem perature.

a t th is

(177°

tem perature

of

stage w a s

r e a d as an

the t e m p e r a t u r e of the oil f ell r a p i d l y , b u t n e a r

ing t i m e s w e r e p r o l o n g e d .
F.

the n t he y w e r e

D uring the r a p i d e v a p o r a t i o n of

the end of the cooking the t e m p e r a t u r e

350°

slices;

F r y i n g w a s ju dg e d to be c o m p l e t e d when bubbling

in the oil sto pp ed .
"exit"

s l i c e s w e r e t h r e a d e d t o g e t h e r and l a b e l e d ;

s t a r c h a nd to s e p a r a t e the

f r i e d in P r i m e x
385°

o r the

of h o l e s w e r e

C.) f o r the

H o w e v e r,

som etim es

r o s e , w he n c o o k ­

the e x i t t e m p e r a t u r e w as about

s t a n d a r d 200 g r a m

sam ples fo r a uniform

v o l u m e of f r y i n g oil.

Chip C o l o r Rating

The f r i e d s a m p l e s w e r e
f o r chip c o l o r r a t i n g .

E a c h chip wa s then m a t c h e d to a s e t of c h ip s

showing te n d i f f e r e n t c o l o r a t i o n s
a s s i g n e d to t h e s e

s e p a r a t e d and a r r a n g e d on the table

colors.

and r a t e d a c c o r d i n g to the n u m b e r s

The following a r e the c o l o r s

P r o c t o r a nd G a m b l e p r o d u c t ,

C i nc in n a ti , Ohio.

and r a t i n g s :

22
Colo r

R a ti n g

Black, c h a r r e d

1

V ery d ark brown

2

Dark brown

3

Brown

4

Slig htly l i g h t e r b r o w n

5

Light brown

6

L i g h t b r o w n i s h yellow

7

Y e ll ow t i n g e d w ith b r o w n

8

G o ld en y e l l o w - - n o b r o w n tinge

9
10

V e r y l ig h t yellow, a l m o s t white

In the c a s e s w h e r e the c o r t i c a l a r e a and the p it h a r e a w e r e
n o t g ive n the

same

c o l o r ra ti ng ,

an un we ig hte d a r i t h m e t i c

of the two r a t i n g s w as g iven to the chip.
co n sid e re d acceptable

average

R a t i n g s of 7.5 to

and of 8.5 to 9 m o s t d e s i r a b l e

(21,

10 w e r e

44).

C o m p u t a t io n s

The

s p e c i f i c g r a v i t y of e a c h t u b e r f r o m e a c h r e p l i c a t i o n of

e a c h t r e a t m e n t w a s o b t a in e d , but,
cific-gravity classes

were

due to the f a c t that n o t all

spe­

r e p r e s e n t e d by the t u b e r s f r o m one plot,

the d e t e r m i n a t i o n s f r o m f o u r

replications were

combined.

A w e i g h te d

23

average

s p e c i f i c g r a v i t y p e r t r e a t m e n t wa s then o b t a i n e d by m u l t i ­

p ly in g the

specific gravity m id - c la s s

c e n t a g e of t u b e r s

in t h a t s p e c i f i c - g r a v i t y c l a s s .

E a c h chip f r o m
Chip c o l o r

v alu e by the c o r r e s p o n d i n g p e r ­

e a c h sound t u b e r w a s

r a t i n g s of t u b e r s

a ll

and s econd , b e c a u s e

The c l a s s
class

some

av­

R e p l i c a t i o n s then w e r e

first, because,

specific-gravity c la sse s were

plot;

color.

in e a c h s p e c i f i c g r a v i t y c l a s s w e r e

e r a g e d to o b ta i n a s c o r e f o r t h a t c l a s s .
c o m b i n e d f o r two r e a s o n s :

r a t e d f o r i ts

as m e n t i o n e d above, not

r e p r e s e n t e d by the t u b e r s
of the t u b e r s

of one

ro tte d during sto ra g e .

r a t i n g s w e r e w e i g h t e d by the p e r c e n t a g e

of t u b e r s in e a c h

to o bt a in the p l o t r a t in g .
The d a t a o b t a i n e d in t h e s e i n v e s t i g a t i o n s w e r e a n a l y z e d f o r

statistical

significance

{50).

RESULTS

Lake City, 1950 Crop

Russet Rural, Irish Cobbler, and Pontiac potatoes were planted
on May 1, May 25, and June 16.

At each date of planting, 3-12-12

fer tilize r at the rate of 1,000 pounds per acre was applied to the
row by the band method.

During the growing period the field r e ­

ceived five normal supplemental irrigations.
After harvest, sp ecific-gravity determinations were made on
the potatoes.

From each of the three dates of planting ten tubers

having a specific gravity of 1.0 76 to 1.0 88 from the Russet Rural
variety and from Irish Cobbler variety, and of 1.0 64 to 1.0 70 from
the Pontiac variety were involved in the investigation.

These ranges

were chosen because prelim inary observations had shown that they
were the modal c la s se s for these varieties.

Following the sp ecific-

grayity determinations, the potatoes were stored for a period of two
months at 41° F. (5° C.), and then conditioned at 78° F. (25.5° C.)
for thirty days.

The picric acid test (37) was made for estimating

the content of reducing sugars in each potato.

24

Slices from each

25
potato were made into chips and were rated for color.

The results

of this trial are shown in Table 1.
Potatoes from the early planting (May 1) of the varieties
R usset Rural and Irish Cobbler had higher average picric acid test
ratings than those from the late planting (June 16); while the potatoes
of Pontiac variety from the early date of planting had the same av­
erage ratings as those from the late planting.

Russet Rural gave

the highest picric acid test ratings on each of the three dates, and
Pontiac, the low est.

Irish Cobbler was clo ser to Russet Rural than

to Pontiac in its picric acid reaction.
The early-planted Russet Rural and Irish Cobbler yielded
ligh ter-colored and mo re-acceptable chips than did the late-planted.
Chips made from Pontiac potatoes were com m ercially unacceptable
regardless of the dates of planting.
There was a direct relation between the picric acid test
ratings and the chip color ratings.

This means, the le s s the reduc­

ing sugars in potatoes, the lighter the color of chips.

Lake City, 1951 Crop

In this 1951 crop, the cultural and storage practices were the
same as in 1950.

26

T ab le

1.

A v e r a g e p i c r i c a c i d t e s t r a t i n g s and a v e r a g e chip c o l o r
r a t i n g s f o r t h r e e v a r i e t i e s f r o m t h r e e d a t e s of p la n ti ng ,
L ak e City, 1950.

D a te s of P l a n t i n g
Varietie s

SpecificG ravity
Cl a s s

Ave r a g e
May

1

May 25

J une

16

P. A. 1 c . c . 2 p .a .

C.C.

P . A.

C.C.

P . A.

C.C.

Russet
Rural

1.0 76 - 1 .0 8 8

3.4

8.8

3.2

7.9

2.9

7.6

3.2

8. 1

Irish
Cobbler

1 .0 7 6 - 1 . 0 8 8

3.1

8.6

2.8

7.0

2.7

6.7

2.9

7.4

Pontiac

1 .064- 1.070

1. 2

3.1

1.1

3.0

1. 2

3.2

1. 2

3.1

Picric

acid te s t ratings

Chip c o l o r r a t i n g s

(1 = d a r k red;

(1 = v e r y d a r k ;

5 = yellow).

10 = a l m o s t white).

27

A p p r o x i m a t e l y f i f t e e n to tw enty t u b e r s f r o m
replications
June

of e a c h of t h r e e

4), f r o m

Kennebec,
specific

d a t e s of p l a n t i n g (May 4, M a y 2 3, a n d

e a c h of s ix v a r i e t i e s

R u s s e t Rural,

e a c h of the f o u r

(Chippewa, I r i s h C o b b l e r , K a t a hd in ,

and Sebago) w e r e

taken for

analyses

as to

g r a v i t y and the c o l o r of c hi ps .
The p e r c e n t a g e

d i s t r i b u t i o n of the t u b e r s

and the a v e r a g e

chip

color

r a t i n g s by v a r i e t y and date of p l a n t i n g in e a c h s p e c i f i c - g r a v i t y

class

a r e g i v e n in A pp e nd ix Table I.
V a r i e t y w as found to have a c o n s i d e r a b l e

s p e c i f i c g r a v i t y of th e p o t a t o e s
I r is h Cobbler,

( Tab le 2).

e f f ec t on the a v e r a g e

R u s s e t R ura l, Kennebec,

a nd Sebago w e r e in the high r a n g e of 1.076 o r above.

K a t a h d i n m i g h t be c l a s s e d a s a b o r d e r l i n e v a r i e t y , while Chippe wa
h a d a d e c i d e d l y low a v e r a g e

s p e c i f ic

gravity.

D ate of p l a n t i n g h ad a m a r k e d in f l u en c e on the a v e r a g e
c if ic

spe­

g r a v i t y of p o t a t o e s bu t n o t to the e x t e n t t h a t v a r i e t y had.
The a v e r a g e

f o r Ma y 23,

1.076;

s p e c i f i c g r a v i t y f o r the May 4 p l a n t i n g w a s
a nd f o r J un e

Within a v a r i e t y ,
had h igher average

in g e n e r a l ,

1.071.
the t u b e r s f r o m t he f i r s t p la ntin g

s p e c i f i c g r a v i t y than the t u b e r s of the s e c o n d

and the t h i r d d a t e s of p l a n t i n g .
two e x c e p t i o n s .

4,

1.079;

K e n n e b e c and K a ta h di n w e r e the

28

T a b le 2.

A verage specific gravity for each v a rie ty fro m
of p l a n t i n g , L a k e City, 1951.

e a c h date

V arietie s

Date s
of
Plant­
ing

Rus­
set
Rural

Ken­
nebec

Irish
Cob­
bler

Se­
bago

Ka­
t a hd in

C h ip ­
pewa

M ay 4

1.083

1. 0 80

1. 0 80

1.080

1.079

1.071

1.079

May 2 3

1.080

1.075

1.077

1.077

1.079

1.066

1.076

June

1.076

1.080

1.073

1.070

1.065

1.062

1.071

1. 0 80

1.078

1.077

1.076

1.074

1.066

1.075

Avg.

4

Avg.

A n a l y s i s of v a r i a n c e i n d i c a t e s highly s i g n i f i c a n t d i f f e r e n c e s
b e t w e e n v a r i e t i e s and b e t w e e n d a t e s.
L e a s t significant difference between varieties:
0 .0 0 6 ; 1% l e v e l , 0.008.

0.004;

L e a s t significant difference between
1% l e v e l , 0.006.

d ates:

5% l e ve l,

5% l e v e l ,

29

The a v e r a g e

chip c o l o r

ratings

R u s s e t R u r a l and I r i s h C o b b l e r w e r e
the c o n s u m e r s .

(Ta ble

3) f o r the v a r i e t i e s

g r a d e d a s the m o s t d e s i r e d by

The chip c o l o r of K a t a h d in and K e n n e b e c w e r e

s l i g h t l y above a nd Sebago and C h ip p e w a d e c i d e d l y b e l o w the line of
acceptance.
C hips w e r e of a c c e p t a b l e

c o l o r f r o m the May 4 a nd May 2 3

p l a n t i n g s , with the e x c e p t i o n of C h ip p e w a on the M a y 2 3 date .
a n d u n s a l a b l e c h i p s w e r e o b t a i n e d f r o m the J un e

Dark

4 p l a n t i n g , with the

e x c e p t i o n of R u s s e t R u r a l and K e n n e b e c .
In e a c h of the v a r i e t i e s
increase

the l a t e p l a n ti ng ,

June

4, w as found to

the d e v e l o p m e n t of the d a r k c o l o r of c h i p s in c o m p a r i s o n

w ith the f i r s t date of p la n ti n g .

E a s t Lansing,

1951 C r o p

I r i s h C o b b l e r , K a t a h d in , K e n n e b e c , R u s s e t R u r a l ,
varieties
were

w e r e p l a n t e d on May 21, J u n e

13, and J une

and Sebago

25.

The p l o ts

s u b j e c t e d to the following i r r i g a t i o n and f e r t i l i z e r t r e a t m e n t s :
1.

No s u p p l e m e n t a l i r r i g a t i o n with 3 -1 2 - 1 2 f e r t i l i z e r .

2.

Supplemental irrig a tio n

and no f e r t i l i z e r .

3.

Supplemental irrig a tio n

w ith 0 - 0 - 1 8 f e r t i l i z e r .

4.

Supplemental irrig a tio n

w ith 3 - 1 2 - 1 2 f e r t i l i z e r .

30

T a b le

3.

A v e r a g e chip c o l o r r a t i n g s f o r e a c h v a r i e t y f r o m e a c h
date of p l a n t i n g , L a k e City, 1951.

V arietie s

Dates
of
Plant­
ing

Rus­
set
Rural

Irish
Cob­
bler

Ka­
t a h di n

Ken­
nebec

Se­
bago

C h ip ­
pewa

M ay 4

9.6

9.3

9.6

8.7

8. 0

7.5

8.8

May 2 3

9.3

8.9

9.0

7.5

8. 0

6.7

8.2

June

8.7

7.4

5.8

7.5

5.6

5.3

6.7

9.2

8.5

8. 1

7.9

7.0

6.5

7.9

4

Avg.

Avg.

A n a l y s i s of v a r i a n c e i n d i c a t e s hig hly s i g n i f i c a n t d i f f e r e n c e s
b e t w e e n v a r i e t i e s and b e t w e e n d a t e s .
L e a s t significa nt difference between v a rie tie s :
1% l e v e l , 1 . 2 .
Least
level,

1.7.

s i g n i f i c a n t d i f f e r e n c e b e t w e e n d ate s:

5% l e v e l ,

5% l e v e l ,

1.2;

0.8;

1%

31
The f e r t i l i z e r s
r e c e i v e d five n o r m a l

were

s p r e a d b y hand.

The i r r i g a t e d p l o ts

supplem ental irrig a tio n s

in a d ditio n to

ra in .

The p l o t s w e r e h a r v e s t e d in the l a t t e r p a r t of S e p t e m b e r .
Following h a r v e s t ,
random

sample

four replicates

specific-gravity determ inations were

c o n s i s t i n g of tw enty to t h i r t y t u b e r s f r o m e a c h of the
of e a c h of the t r e a t m e n t s

e a c h of the p l a n t i n g d a t e s .
Each

m a d e on a

of e a c h of v a r i e t i e s f r o m

E ach sample was

divided into two s e t s .

s e t c o n s i s t e d of t e n to f i f t e e n t u b e r s .
One s e t of s a m p l e s of all the v a r i e t i e s w a s

m o n t h s a t 41°

F.

(5°

C.)

s t o r e d f o r two

and a n o t h e r s e t of only two v a r i e t i e s ,

s e t R u r a l a nd K a t a h d in , w as

s t o r e d f o r five m o n t h s

a t the

Rus­

same te m ­

perature .
C hips w e r e m a d e
im m ediately after

storage

ing f o r t h i r t y d ays a t 78°

and s c o r e d f o r c o l o r f r o m half of e a c h t u b e r
a t 41°
F.

F.

(25.5°

(5°

C.)

C.).

and a ga in a f t e r c o n d i ti o n ­

The r e m a i n i n g h a l v e s w e r e

c h ip p e d and s c o r e d .
The p e r c e n t a g e

d i s t r i b u t i o n of t u b e r s

c o l o r r a t i n g s by v a r i e t y ,
specific-gravity class

are

date of p l a n ti n g ,

chip

and t r e a t m e n t in e a c h

g iven in A p p en dix T a b l e s II and III.

S p e ci f ic g r a v i t y of t u b e r s .
p otato es

and the a v e r a g e

The a v e r a g e

s p e c i f i c g r a v i t y of

( T a b l e 4) of the K e n n e b e c v a r i e t y (1.077)

was

significantly

32

4.

Date s
of
P lant­
ing

A v e r a g e s p e c i f i c g r a v i t y f o r e a c h v a r i e t y f r o m e a c h date
of p l a n t i n g on e a c h t r e a t m e n t , E a s t E a n s i n g , 1951.

Se,
bago

Ka­
t ahdin

1.079
1.077
1.074
1.077

1.077
1.078
1.078
1.073
1.077

1.076
1.077
1.072
1.075
1.075

1.074
1.074
1.074
1.072
1.074

1.071
1.074
1.072
1.071
1.072

1.075
1.076
1.075
1.073
1.075

1.079
1.079
1.076
1.079
1.078

1.073
1.076
1.072
1.076
1.074

1.069
1.077
1.071
1.070
1.072

1.070
1.070
1.067
1.067
1.069

1.068
1.070
1.068
1.067
1.068

1.0 72
1.074
1.071
1.072
1.072

1.076
1.078
1.076
1.072
1.076

1.071
1.071
1.071
1.073
1.072

1.074
1.073
1.074
1.070
1.073

1.072
1.076
1.076
1.072
1.0 74

1.069
1.069
1. 0 6 6
1.065
1.067

1.072
1.073
1.073
1.070
1.072

1.077

1.074

1.073

1.072

1.069

1.073

No
Ye s
Ye s
Ye s
Avg.

3-12-12

1.077

o
i
o
i
o

Ken­
nebec

1

CO

I—1

1

0
1
0

o

3-12-12

M ay 2 3 No
Y es
Y es
Y es
Avg.

3-12-12
CO

I

r— 1

o
1
o

o
!

0
1

O

3-12-12

No
Yes
Ye s
Y es
Avg.

co

3-12-12
0
1
0
1

4

Irish
Cobble r

F er­
tilize r

3-12-12

G rand average

s

Rus­
set
Rural

Irri­
g a t io n

I— *

May 4

Ju n e

V arietie

T reatm ents

0
1
0

T a b le

Avg.

A n a l y s i s of v a r i a n c e i n d i c a t e s highly s i g n i f i c a n t d i f f e r e n c e s
b e t w e e n v a r i e t i e s , b e t w e e n d a t e s , and b e t w e e n t r e a t m e n t s .
L e a s t significant difference between v a rie tie s :
0 .0 0 2 ; 1% l e v e l , 0 .0 0 2 .
Least
1% l e v e l ,

s i g n i f i c a n t d i f f e r e n c e b e t w e e n d at e s:

5% l e v e l ,

5% l e v e l , 0.001;

0 .0 0 2 .

L e a s t sig nificant difference between tr e a tm e n ts :
0 .0 0 1 ; 1% l e v e l ,

0 .0 0 2 .

5% l e v e l,

h i g h e r t h a n t h a t of R u s s e t R u r a l (1.074), I r i s h C o b b l e r
bago

(1.0 72), and K a t a h d i n (1.0 6 9 ).

b e t w e e n the

specific

(1.073), Se-

The r e w a s no m a r k e d d i f f e r e n c e

g r a v i t y of R u s s e t R u r a l and I r i s h C o b b l e r p o ta to e

b u t R u s s e t R u r a l p o t a t o e s had s i g n i f i c a n t l y g r e a t e r

s p e c if ic g r a v i t y

th a n did S eba go.
The a v e r a g e
planting

s p e c i f i c g r a v i t y of the p o t a t o e s f r o m

(1.075) w a s

of M ay 2 3 p l a n ti n g

statistically g re a ter
(1.072),

than t ha t

(1.072).

K e n n e b e c, R u s s e t R u r a l ,

had p r o g r e s s iv e ly low er average
was delayed.

(1 p e r c e n t level)

and of J u n e 4 p la ntin g

T h r e e of the v a r i e t i e s ,

the May 4

and Katahdin,

s p e c i f i c g r a v i t y a s the p l a n ti ng date

Such w a s n o t t r u e of I r i s h C o b b l e r and Sebago

(Table

4).

The a v e r a g e

specific gravity,

1.075, of the p o t a t o e s f r o m the

t r e a t m e n t w h ic h w as i r r i g a t e d b ut h a d no f e r t i l i z e r was
g r e a t e r than t h o s e of the o t h e r t r e a t m e n t s :
w ith 3 - 1 2 - 1 2 ,

1.0 73 f o r no i r r i g a t i o n

1.073 f o r i r r i g a t i o n w ith 3 - 1 2 - 1 2 , a nd 1.072 f o r i r r i g a ­

t io n w i th 0 - 0 - 1 8 .
from

s i g n if ic a n t ly

The l a t t e r t h r e e w e r e not s t a t i s t i c a l l y d i f f e r e n t

each other.
V arieties

t e n d e d to give

m ents

( Tab le

( T a b le

6) on a v e r a g e

sim ilar

responses

5), b u t d a t e s a nd t r e a t m e n t s
specific gravity.

to the v a r i o u s t r e a t ­

showed no de finite t r e n d s

34

T a b le

5.

T w o - w a y t ab le f o r v a r i e t i e s a nd t r e a t m e n t s , f o r a v e r a g e
s p e c i f i c g r a v i t y of t u b e r s , E a s t L a n s i n g , 1951.

Treatm ents
Irri­
ga tio n,
No F e r ­
tilize r

Varietie s

Kennebec

...................

No I r ­
rigation
3 - 12 - 1 2

Irri­
ga tio n
3 -1 2 - 1 2

Irri­
g a t io n
0-0-18

Av g .

1.079

1.077

1.076

1.075

1.077

R usset Rural

. . .

1.075

1.074

1.074

1.074

1.074

Irish

. . .

1.076

1.073

1.072

1.072

1.073

1.073

1.072

1.072

1.070

1.072

Cobbler

Sebago

...................

Katahdin

...................

1.071

1.069

1.067

1.068

1.069

Average

...................

1.075

1.073

1.072

1.072

1.0 7 3

35

Table

6.

T w o - w a y t a b le f o r d a t e s of p l a n ti n g and t r e a t m e n t s , f o r
a v e r a g e s p e c i f i c g r a v i t y of t u b e r s , E a s t L a n s i n g , 1951.

Treatm ents
D a t e s of Plauiting

No
F er­
t il i z e r

No I r ­
rigation
3 - 12 -1 2

Irrig atio n
3 -1 2 - 1 2

Irri­
g at i on
0-0-18

Avg.

M ay 4 ................... . . . .

1.076

1.075

1.075

1.073

1.075

May 2 3 ............... . . . .

1.074

1.072

1.071

1.072

1.072

1.073

1.072

1.073

1.070

1.072

1.075

1.07

1.072

1.072

1.073

June

4

Average

............... . . . .

36

Chip c o l o r r a t i n g s :

chipped im m ed iate ly afte r

of t u b e r s f o r two m o n t h s a nd f o r five m o n t h s .
(T a b le

were

The c o l o r of c h ip s

7) m a d e f r o m the t u b e r s of the R u s s e t R u r a l

C o b b l e r (5.2)

varieties

c old s t o r a g e

(5.5) a nd I r i s h

w h ic h h a d b e e n in c o l d s t o r a g e f o r two m o n t h s

c o m p a r a t i v e l y l i g h t e r t ha n t h a t of Sebago (4.7), K e n n e b e c

(4.7),

a n d K a t a h d i n (4.2).
Two v a r i e t i e s ,

R u s s e t R u r a l and K atahd in , w e r e h e l d f o r

a d d i t i o n a l t h r e e m o n t h s in c old s t o r a g e .
(T ab le

The chip c o l o r of t u b e r s

8) w a s d a r k e r than t h o s e o b t a i n e d f r o m t u b e r s

two m o n t h s , but t h e i r

r a t i n g s w e r e i n the

tubers

s h o r t e r period.

s t o r e d f o r the

an

s t o r e d f o r only

s a m e o r d e r as t h o s e f r o m

D a t e s of p l a n t i n g a p p e a r e d to h ave only a s l i g h t e f f e c t on chip
r a t i n g s of the t u b e r s p r o c e s s e d i m m e d i a t e l y a f t e r r e m o v a l f r o m two
m o n t h s of c o ld s t o r a g e .

Less

e f f e c t w as o b s e r v e d on t h o se t u b e r s

h e l d f o r five m o n t h s t h a n f o r two m o n t h s
The v a r i e t i e s
dates

( T a b l e s 7 a nd 8).

did not r e a c t in the s a m e m a n n e r to the d i f f e r e n t

of p l a n t i n g a s j u d g e d by the chip c o l o r r a t i n g s o b t a in e d i m m e ­

diately a f te r rem oval fro m

s t o r a g e w h e t h e r they w e r e

stored for

two m o n t h s o r five m o n t h s .
It i s v e r y a p p a r e n t f r o m
of t u b e r s f r o m v a r i o u s

Tables

7 a nd 8 t h a t the chip c o l o r

ir r ig a t i o n - f e r t i l i z e r tre a tm e n ts was d a r k e r

37

T a b le

7.

D ate s
of
P lant­
ing

A v e r a g e chip c o l o r r a t i n g s i m m e d i a t e l y f ollowing c old
s t o r a g e (41° F.) f o r two m o n t h s f o r e a c h v a r i e t y , date of
p l a n t i n g , a nd t r e a t m e n t , E a s t L a n s i n g , 1951*

Va r i e t i e s

T reatm ents
Rus­
set
Rural

Irish
Cob­
bler

3-12-12
0-0-0
3-12-12
0-0-18

5.8
5.6
5.2
5.2
5.5

M a y 2 3 No
Ye s
Yes
Ye s
Avg.

3-12-12
0-0-0
3-12-12
0-0-18

June

3-12-12
0-0-0
3-12-12
0-0-18

Ma y 4

4

Ir ri
g a ti on

Fer­
tilizer

No
Yes
Yes
Ye s
Avg.

No
Ye s
Ye s
Yes
Avg.

Grand average

Avg.

S ebago

Kennebec

Ka­
tahdin

6.3
3.3
5.4
5.3
5.6

4. 6
4.4
4.8

5.1
4.6

4.9
4.7

4.9
5.5
5.0

4.6
4.5
4.3
4.2
4.4

4.9
4.9
5.0
5.0 '

5.8
5.6
5.3
5.7
5.6

5.1
4.7
4.6
4.7
4.8

5.0
4.2
3.5
4.8
4.3

5.0
4.7
4.7
4.5
4.7

4.3
4.2
3.8
4.2
4.1

5.0
4.7
4.4
4.8
4.7

6.0
5.6
5.3
5.4
5.6

4.9
5.4
5.4

4.9
5.6

4.9
4.1

4.9
5.2

4.9
4.9
5.1

3.9
4.4
4.3

4.8
4.3
3.2
3.5
3.9

5.1
5.0
4.5
4. 6
4.8

5.5

5.2

4.7

4.7

4.2

4.8

5.3

A n a l y s i s of v a r i a n c e i n d i c a t e s highly s i g n i f i c a n t d i f f e r e n c e s
( 1% level) b e t w e e n v a r i e t i e s a nd b e t w e e n t r e a t m e n t s , but only s i g ­
n i f i c a n t d i f f e r e n c e s (5% level) b e t w e e n d a t e s .
L e a s t significant difference between varieties:
5% l e v e l , 0.3;
1% l e v e l , 0.4.
L e a s t s i g n i f i c a n t d i f f e r e n c e b e t w e e n da te s:
level,
0.3;

5% l e v e l , 0.Z;

0.3.
L e a s t significant difference between treatm e n ts:

1% l e v e l , 0.4.

5% l e v e l ,

1%

38

8.

A v e r a g e chip c o l o r r a t i n g s i mrn e d i a t e l y f ollo wing c old
s t o r a g e (41° F.) f o r five m o n t h s f o r e a c h v a r i e t y , date of
p l a n t i n g , and t r e a t m e n t , E a s t L a n s i n g , 1951.

T reatm ents

Rus s e t
Rural

No
Yes
Yes
Yes
Avg.

3-12-12

5.2
4.2

3-12-12
0-0-18

3.9
3.8
4.3

2-9
3.0

3-12-12

5.2
4.2
4.2
4.8
4.7

2.7
2.7
2.3
2.5
2.6

4.1
3.7
3.3
3.7
3.6

5.1
4.8
4.9
5.6
5.1

2.5
3.4
1.7
1.9
2.4

3.8
4.1
3.8

4.7

2.6

3.6

3 - 12 - 1 2
0-0-18

Ayg •
J une

4

Grand average

3 -1 2 - 1 2
o
i
o
f
o

No
Y es
Ye s
Yes
Av*oa .

K a ta h d i n

4.5
3.1
3.6
3.4
3.6

o
i
o
1
o

No
Y es
Ye s
Yes

Ave r a g e

CO

May 2 3

Fertilizer

00

May 4

Irri­
g at i on

0
1
0
1
o

D a t e s of
Planting

Yarietie s

3 -1 2 - 1 2
0-0-18

1.9
3.3

00

T ab le

3.7

A n a l y s i s of v a r i a n c e i n d i c a t e s highly s i g n i f i c a n t d i f f e r e n c e s
b e t w e e n v a r i e t i e s b ut n ot b e t w e e n t r e a t m e n t s n o r b e t w e e n d a t e s .
L e a s t significant difference fo r varie ties:
level,

1.0.

5% le v e l , 0.6;

1%

39

after five months storage than after two months.

In both cases no

irrigation with 3-12-12 fer tilize r produced, lighter-colored chips than
any other treatment.
V arieties did not respond the same to irrigation -fertilizer
treatm ents, as judged by their chip color ratings after two months
of cold storage.

The two varieties kept in storage for a five-months

period did show sim ilar responses to the several treatments (Tables
9 and 10).

Chip color ratings:

chipped after conditioning for thirty days

following two months cold storage.

The average chip color ratings,

Table 13 (after conditioning the potatoes at 78° F. [25.5° C.] subse­
quent to cold storage at 41° F. [5° C.] for the period of two months),
of R usset Rural (8.8) and Kennebec (8.5) were in the grade most de\

sired by consum ers, and those of Irish Cobbler (8.2) and Katahdin
(7.8) were in the grade of acceptable, while that of Sebago (7.4) was
in the unacceptable grade.
Chip color from the May 4 planting (8.7) was significantly
lighter than those of May 23 (8.2) and of June 6 (7.5).

Also, the

chip color from the May 23 planting was significantly lighter than
that of the June 6 planting.

40
Table

9-

Two-way table for v ar i e t i es
ratings
for

and t r e at m en t s ,

immediately after cold storage

two months,

E a s t Lansing,

at

for chip color

41°

F.

of tubers

1951.

Treatm ents

V a r i e t ie s

No I r ­
rigation
3-12-12

Irri­
ga tion
No F e r ­
ti l i z e r

Irri­
g at i on
0-0-18

Irri­
ga t i on
3- 12-12

Avg.

R usset Rural

. .

5.8

5.6

5.4

C

C

5.5

Irish

. . . .

5.4

5.1

5.0

5.1

5.2

...................

4.9

4.7

4.9

4.4

4.7

Kennebec

...............

5.0

4.5

4.8

4.5

4.7

Katahdin

...............

4.6

4.3

4.0

3.7

4.2

5.1

4.9

4.8

4.6

4.8

Cobbler

Sebago

Aye r a g e

41
Table

10.

Two-way table for v a r i e t i e s
ratings

and tr e atmen ts ,

immediately after cold storage

f or five months,

E a s t Lansing,

at

for chip color

41°

F.

of tubers

1951.

Treatm ents
V arieties

Irri­
ga tio n
0-0-18

Irri­
g a tion
No F e r ­
tilizer

5.3

4.7

4.4

4.3

4.7
2.6

No I r ­
rigation
3 - 12 - 1 2

R usset Rural

. . . .

Irri­
ga tion
3 -1 2-1 2

...............

3.0

2.4

2.7

2.4

Average

...............

4.1

3. 6

3.6

3. 4

1

Katahdin

Avg.

^
eh
|

42
Table

11.

Two-way table for dates
chip color
F.

ratings

of planting and tr e atmen ts ,

immediately af t er cold storage

of tubers for two months,

Ea s t Lansing,

for

at 41°

1951.

Treatm ents
D a t e s of
Planting

No I r ­
rigation
3 - 12 - 1 2

Irri­
g a tio n
No F e r ­
tilizer

Irri­
ga tion
0-0-18

Irri­
g a t io n
3 -1 2-1 2

A y co'.
_>

M ay 4 .......................

5.3

4.9

5.0

4.9

5.0

J une

...................

5.1

5.0

4.6

4.5

4.8

...................

5.0

4.7

4.8

4.4

4.7

4.9

4.8

4.6

4.8

4

Ma y 2 3

Average

43
Table

1Z.

Two-way table for dates
chip color
F.

ratings

of planting and t r e at m en t s, for

immediately af t er cold storage

of tubers for five months,

E a s t Lansing,

at 41°

1951.

Treatm ents
D a t e s of
Planting

Irri­
ga
C
O tion
0-0-18

Irri­
g a t i on
No F e r ­
tilize r

3.8

3.8

4.1

3.3

3.7

May 4 ...................

4.5

3.4

3.1

3.6

3.6

Ma y Z 3

...................

4.1

3.7

3.7

3.3

3.6

Average

...............

4.1

3.6

3.6

3.4

3.6

June

4

...................

No I r ­
rigation
3- 12-1Z

Irri­
ga tion
3-1Z-1Z

Avg.

44

13.

Ma y 4

Va r i e t i e

T reatm ents
Irri­
g a ti on

F e rtilizer

No
Yes
Ye s
Y es
A.vg.

3 - 1 2 - 12
1
o

Dates
of
Plant­
ing

A v e r a g e chip c o l o r r a t i n g s a f t e r c on ditio nin g of p o t a t o e s
a t 78° F . f o r t h i r t y d ays following two m o n t h s c old s t o r ­
age a t 41° F . f o r e a c h v a r i e t y , f r o m e a c h date of p l a n t ­
ing, a nd t r e a t m e n t , E a s t L a n s i n g , 1951.

0
1
0

Table

3-12-12
1—1

00

I
o
t
o

3-12-12
0-0-0
3-12-12

Ju n e

3-12-12

No
Yes
Yes
Ye s
Avg.

0
1

0
1
o
s
o

6

o
(
00

M ay Z 3 No
Ye s
Yes
Ye s
Avg.

3-12-12
0-0-18

Grand ayerage

Rus­
set
Rural

Kenn
nebec

9.4

Irish
^ ,
Cob.
bier

Ka ­
ta hd in

Se­
bago

9.6
9.2
9.0
9.0
9.2

8.3
0.4
8.2
8.2
8.3

7.7
7.7
8.0
8.2
7.9

8.5
7.2
7.7
7.2
7.6

7.3
7.0
7.1
7.5
7.2

7.9
8.1
8.2
8.2

Avto/ .

9-7
8.7
9-4
9.3
9.3

9.1
8.6
9.2
9.1

9.7
8.8

9.1
8.4

8.9
9-2
9.2

8.9
8.4
8.7

8.6
8.1
7.8
8.8
8.3

8.8
7.7
8.5
7.4
8.1

8.8
8.0
7.0
7.4
7.8

7.2
7.2
6.8
7.0
7.1

8.5
8.0
6.3
7.1
7.5

7.8
7.3
6.5
7.2
7.2

8.2
7.6
7.0
7.2
7.5

8.8

8.5

8.2

7.8

7.4

8.2

8.9
8.6
8.6
8.8
8.7
8.6

A n a l y s i s of v a r i a n c e i n d i c a t e s highly s i g n i f i c a n t d i f f e r e n c e s
b e t w e e n v a r i e t i e s , d a t e s , and t r e a t m e n t s .
L e a s t significant difference between varie ties:
5% l e v e l , 0.4;
1% l e v e l , 0.5.
L e a s t s i g n i f i c a n t d i f f e r e n c e b e t w e e n da tes:

5% l e v e l , 0.3;

l e v e l , 0.4.
L e a s t significant difference between tre atm en ts:
0.3;

1% l e v e l , 0.5.

5% l e v e l ,

1%

45

W ithin a v a r i e t y ,
the

c o l o r of p o t a t o

the date of p l a n ti n g had s t r i k i n g e f f e c t on

c hi p s ,

that is,

d a r k e r the c o l o r of c h i p s .
Kennebec,

the l a t e r the p la n ti n g date, the

This w a s e s p e c i a l l y t r u e of R u s s e t R u r a l ,

a nd I r i s h C o b b l e r .

No i r r i g a t i o n w ith 3 - 1 2 - 1 2 f e r t i l i z e r p r o d u c e d s ig n i f ic a n t l y
lighter

c o l o r c h ip s

w i th no f e r t i l i z e r

(8.6) t h a n i r r i g a t i o n with 0 - 0 - 1 3
(8.1), and i r r i g a t i o n with

3 - 12 -1 2

(8.1), i r r i g a t i o n
(7.9),

Table

13.

The d i f f e r e n c e s b e t w e e n the a v e r a g e chip c o l o r r a t i n g s of the l a t t e r
t h r e e w e r e not significant.
It is v e r y a p p a re n t f r o m
react

T able

s i m i l a r l y to the t r e a t m e n t s

14 t h a t the v a r i e t i e s did not

a s i n d i c a t e d by the c o l o r of c h ip s .

The f i r s t and s e c o n d d a t e s of plan tin g gave s i m i l a r t r e n d s
in a v e r a g e

chip c o l o r

r a t i n g f r o m one t r e a t m e n t to a n o t h e r (Table

15), b u t the t h i r d d a te of p l a n t i n g d e v ia t e d f r o m
a g iv e n t r e a t m e n t the chip c o l o r b e c a m e
layed.

These

w e r e in the

Within

d a r k e r as p la n t i n g was d e ­

d i f f e r e n c e s in r a t i n g w e r e n o t e x a c t l y e qu a l , b u t t h e y

sam e direction.

Chip c o l o r

ratings:

ch ip pe d a f t e r conditioning f o r t h i r t y d ays

f o ll o w ing five m o n t h s c old s t o r a g e .
of t h i r t y d ay s a t 78°
(5°

this p a t t e r n .

F.

C.) f o r five m o n t h s ,

(25.5°

A f t e r c onditioning f o r a p e r i o d

C.) following c old s t o r a g e a t 41°

the a v e r a g e chip c o l o r o v e r all d a t e s

F.

and

46

Ta ble

14.

T w o - w a y t a b l e f o r v a r i e t i e s a nd t r e a t m e n t s , f o r chip
c o l o r r a t i n g s a f t e r t h i r t y days c onditioning of t u b e r s at
78° F . s u b s e q u e n t to c o ld s t o r a g e a t 41° F . f o r two
m o n t h s , E a s t L a n s i n g , 1951.

Treatm ents

Varietie s

Irish

Sebago

Average

Irri­
ga tion
No F e r ­
tilize r

Irri­
g a ti on
3 -1 2-1 2

Avg.

9.4

8.6

8.4

8.9

8,8

...............

9.1

8.3

8.5

8.2

8.5

. .

8.5

8. 3

8.2

7.9

8.2

...............

8.4

7.5

7.9

7.4

7.8

...................

7.6

7.6

7.3

7.2

7.4

...............

8.6

8.1

8.0

7.9

8.2

Cobbler

Katahdin

Irri­
ga tion
0-0-18

. .

R usset Rural
Kennebec

No I r ­
rigation
3-12-12

47

Ta ble

15.

T w o - w a y ta ble f o r d a t e s of p l a n ti n g and t r e a t m e n t s , f o r
chip c o l o r r a t i n g s a f t e r t h i r t y d ays c on ditio nin g of t u b e r s
a t 7 8 F . s u b s e q u e n t to c old s t o r a g e a t 41° F . f o r two
m o n t h s , E a s t L a n s i n g , 1951.
°

Treatm ents
D a t e s of
Planting

No I r ­
rigation
3-12-12

Ir riga tion
0-0-18

Irri­
gation
No F e r ­
tilize r

Irri­
g a tio n
3 -1 2-1 2

Avg.

May 4 .......................

8.9

8.8

8.6

8.6

8.7

Ma y 2 3

...................

8.6

8.2

7.9

8.1

8.2

J une

...................

8.2

7.2

7.6

7.0

7.5

...............

8.6

8.1

8.0

7.9

8.2

4

A verage

48
treatm ents (Table 16) of Russet Rural was golden yellow (9.0).
rating was in the m ost desirable range as to chip color.

This

That of

Katahdin was dark brown (7.4), which was dark for comm ercial a c­
ceptance.
The planting dates had no significant effect on the color of
chips of either variety (Table 16).
No irrigation with 3-12-12 fer tilize r (8.9) and irrigation with
0 -0 -1 8 fe r tiliz e r (8.4) yielded the chips of lighter color than those
of irrigation with 3-12-12 (7.9) and of irrigation with no fertilizer
(7.5) (Tables 17 and 18).

The responses of the two varieties to

treatment were sim ilar (Table 17), in that the no irrigation with
3-12-12 had the best chip color, while the irrigation with no fer­
tilizer produced the poorest chip color.
The responses shown between dates of planting and treatments
were rather sim ilar to each other (Table 18).

Lake City, 1952 Crop--Experiment A

The preplanting and the planting methods practiced were the
same as in 1950 and 1951.

Chippewa, Irish Cobbler, Katahdin, Ken­

nebec, Pontiac, Russet Rural, and Sebago varieties, and a seedling,
505-3, were planted on May 1, May 16, June 2, and June 16.

At

49
Table 16.

Average chip color ratings after conditioning of potatoes
at 78° F. for thirty' days, following five months cold
storage at 41° F. for each variety, from each date of
planting and treatment, East Lansing, 1951.
Treatments

Dates of
Planting

Varieties
Avg.

Irri­
gation

F er ­
tilizer

Russet
Rural

Katahdin

May 4

No
Yes
Yes
Yes
Avg.

3-12-12
0-0-0
3-12-12
0-0-1 8

9-4
8.9
9-1
9-8
9.3

8.2
6.4
7.4
7.6
7.4

8.8
7.7
8.3
8.7
8.4

May 2 3

No
Yes
Yes
Yes
Avg.

3-12-12
0-0-0
3-12-12
0-0-1 8

9.4
8.7
9-0
9.4
9.1

8.3
6.4
7.4
7.5
7.4

8.8
7.6
8.2
8.5
8.3

June 6

No
Yes
Yes
Yes
Avg.

8-12-12
0 -0 -0
3-12-12
0 -0 -1 8

9.4
8.4
7.3
9.3
8.6

8.8
6.3
7.4
7.2
7.4

9-1
7.4
7.4
8.3
8.0

9.0

7.4

8.2

Grand average

Analysis of variance indicates highly significant differences
between varieties and between treatments, but no significant differ
ences between dates of planting.
L east significant difference for varieties:
level, 0.5.
Least significant difference for treatment:
1% lev el, 0.7.

5% level, 0.3; 1%

5% level, 0.4;

50

Ta ble

17.

T w o - w a y ta ble f o r v a r i e t i e s and t r e a t m e n t s , f o r chip
c o l o r r a t i n g s a f t e r t h i r t y d a ys conditioning of t u b e r s at
7 8° F . s u b s e q u e n t to c old s t o r a g e at 41° F . f o r five
m o n t h s , E a s t L a n s i n g , 1951.

Treatm ents

No I r ­
rigation
3 - 1 2 - 1Z

Irri­
gation
C
O
0-0-18

Irri­
g a t i on
3 -1 2- 12

Irri­
ga tion
No F e r ­
tilize r

. .

9.4

9.5

8.4

vO
00

9.0

Katahdin

...............

8.4

7.4

7.4

6.4

7.4

Average

...............

8.9

8.4

7.9

7.5

8.2

Varietie s

R u sset Rural

Avg.

51
Table

18.

T w o - w a y t a b le f o r d a t e s of p l a n ti ng and t r e a t m e n t s , f o r
chip c o l o r r a t i n g s a f t e r t h i r t y days cond itio nin g of t u b e r s
a t 78° F . s u b s e q u e n t to co ld s t o r a g e a t 41° F. f o r five
m o n t h s , E a s t L a n s i n g , 1951.

T re a t m e n t s
D a t e s of
P l a n t i n go

M ay 4 ..........................

No I r ­
rigation
3-12-12

Irri­
g a t io n
0-0-18

Irri­
g a t i on
3 -1 2 - 1 2

Irri­
ga tion
No F e r ­
tilize r

A wo .

8.8

8.7

8.3

7.7

6.4

May 2 3

...................

8.8

8.5

8.2

7.6

8.3

June

...................

9.1

8.3

7.4

7.4

8.0

...............

8.9

8.4

7.9

7.5

8.2

4

Average

52

e a c h of the p l a n t i n g t i m e s the r o w s
the b a s i s
were

received

3 - 1 2 - 1 2 f e r t i l i z e r on

of 1,000 p ou nd s p e r ' a c r e by the b a n d m e t h o d .

s u b j e c t e d to t h r e e l e v e l s of i r r i g a t i o n :

irrigation;

(2) n o r m a l

the n o r m a l

(1) no s u p p l e m e n t a l

supplemental irrig atio n ;

supplem ental irrig atio n .

The p l o ts

and (3) h e a v y o r twice

(See m e t h o d s f o r m o r e d e t a i l e d

description.)
The p l o t s w e r e h a r v e s t e d in the l a s t w e ek of S e p t e m b e r and
a random

s a m p l e of te n t u b e r s was t a k e n f r o m e a c h plot.

S p e c if ic -

g r a v i t y d e t e r m i n a t i o n s w e r e m a d e on e a c h t u b e r of e a c h r a n d o m

sam ­

ple .
The s a m p l e s w e r e
of f o u r m o n t h s
month

before

s t o r e d a t 60°

F.

(15.5°

and t h en c o n d i t i o n e d a t 78°
t h ey

F.

C.) f o r the p e r i o d

(25.5°

C.) f o r one

w e r e p r o c e s s e d into chips a nd s c o r e d f o r

chip

color.
The p e r c e n t a g e d i s t r i b u t i o n of t u b e r s
c o l o r r a t i n g s by v a r i e t y ,

and the a v e r a g e

chip

date of p l a n ti n g , and i r r i g a t i o n l e v e l, in

each specific-gravity class

a r e g iven in Appendix Table IV.

S pec ific g r a v i t y of t u b e r s .

Average

w a s found to v a r y c o n s i d e r a b l y with v a r i e t y .
g r a v i t y f o r e a c h v a r i e t y w as

as follow s:

s pe c if ic g r a v i t y of t u b e r s
The a v e r a g e

R usset Rural

s p e c if ic

(1.086),

53

Sebago (1.083), K e n n e b e c
(1.081), P o n t i a c

(1.082), K a t a h d in (1.081), I r i s h C o b b l e r

(1.074), 5 0 5 - 3 (1.074), and C h ip p ew a (1.071)

(Table

19).
The date of p l a n t i n g h a d a m a r k e d in flu en ce on the a v e r a g e
s p e c i f i c g r a v i t y of p o t a t o e s , with the l a t e r d a t e s
the h i g h e r

specific g ra v itie s.

vious e x p e rim en ts.

T his is i n m a r k e d c o n t r a s t w it h p r e ­

The a v e r a g e

s p e c i f i c g r a v i t y of the t u b e r s in

o r d e r of m a g n i t u d e f o r the t h i r d date of p la n ti n g ,
f o r the f o u r t h da te , J u n e
1.078;

16,

1.076.

sam e

The s u c c e s s i v e d i f f e r ­

Table

19 t h a t the v a r i e t i e s

reacted approx­

s p e c i f i c g r a v i t y of the p o t a t o e s f r o m the no

p l e m e n t a l i r r i g a t i o n , the n o r m a l s u p p l e m e n t a l i r r i g a t i o n ,
i

s u p p l e m e n t a l i r r i g a t i o n w a s a p p r o x i m a t e l y the s a m e

(Tables

20 a nd 21).
The t h r e e l e v e l s of m o i s t u r e
s p e c i f i c g r a v i t y of the

discrepancies

sup­

and the twice

norm al

m a y be

16,

to the d i f f e r e n c e s in p la n t i ng d a t e s .

The a v e r a g e

on the

1.0 82;

significant.

It is evident f r o m
i m a t e l y the

J un e 2, w a s

1.0 80; f o r the s e c o n d da te, May

and f o r the f i r s t d a t e , Ma y 1,

ences were

of p l a n ti ng giving

(1.0 79)

supply a p p a r e n t l y had no e f fe c t

several varieties.

(T able 20), b u t t h e s e w e r e

T here were

of m i n o r va lue.

slight

The s a m e

s a i d w ith r e g a r d to the r e l a t i o n s h i p b e t w e e n date of p l a n ti n g

a nd l e v e l s of i r r i g a t i o n

(T ab le 21).

54
Table

19-

Average

specific gravity for each variety, f rom

of planting,
City,

Date s
of
RusPlant­
set
ing
Rural

and i r rig ati on level

each date

in Experiment A,

Lake

1952.

Va r i e t i e s

Seba<7o
O

Ken­
nebec

Irish
Cob­
bler

Ka­
ta hd in

Pon­
tiac

505-3

C h ip ­
pewa

Avg.

Twice N o r m a l S u p p l e m e n t a l I r r i g ation
5 /1
5/16
6/2
6/16
Avg.

1.0 80
1.087
1.087
1.088
1.086

1.080
1.082
1.0 86
1.085
1.083

1.079
1.081
1.0 83
1.083
1.082

1.078
1.079
1.082
1.083
1.081

1.077
1.079
1.084
1.081
1.080

1.070
1.069
1.078
1.076
1.073

1.070
1.078
1.077
1.073
1.0 75

1.070
1.072
1.069
1.069
1.070

1.075
1.078
1.081
1.0 80
1.079

No r m a l S u p p l e m e n ta l I r r i g a t i o n
5/1
5/16
6/2
6/16
Avg.

1.084
1.0 86
1.089
1.088
1.087

1.079
1.082
1.087
1.085
1.083

1.0 80
1.081
1.083
1.084
1.082

1.078
1.079
1.084
1.083
1.081

1.078
1.0 80
1.083
1.081
1.080

1.073
1.068
1.080
1.076
1.074

1.070
1.073
1.076
1.074
1.073

1.069
1.073
1.078
1.073
1.073

1.076
1.078
1.083
1.081

1.068
1.0 7 3

1.076
1.078
1.083
1.081
1.080
1.079

1.079

No S u p p l e m e n t a l I r r i g a t i o n
5/1
5/16
6/2
6/16
Avg.
Grand

1.083
1.085
1.090
1.089
1.087

1.075
1.083
1.087
1.086
1.083

1.077
1.083
1.085
1.084
1.082

1.079
1.080
1.082
1.082
1.081

1.081
1.084
1.084
1.081
1.083

1.073
1.073
1.080
1.077
1.076

1.079
1.077
1.074

1.071
1.064
1.076
1.073
1.071

1.086

1.083

1.082

1.081

1.081

1.074

1.074

1.071

4 yk A n a l y s i s of v a r i a n c e i n d i c a t e s highly s i g n i f i c a n t d i f f e r e n c e s
b e t w e e n v a r i e t i e s and b e t w e e n d a t e s , but no s i g n if ic a n t d i f f e r e n c e s
in i r r i g a t i o n l e v e l s .
L e a s t significant difference between v arieties:
5% l e v e l,
0.002;

1% l e v e l , 0.002.
L e a s t s i g n i f i c a n t d i f f e r e n c e b e tw e e n dates:

1% l e v e l , 0.002.

5% l e v e l , 0.001;

55
Ta.ble 20.

Two-way table for v a r i e t i e s
average
City,

specific

and i r r igati on levels,

gravity of tubers,

Experiment

A,

for
Lake

1952.

Irrig a tio n Levels
V arieties

Avg.
None

N orm al

Heavy

Russet R u r a l

1.087

1.087

1.086

1.086

Sebago

1.083

1.083

1.0C3

1.083

Kennebec

1.082

1.082

1.082

1.082

Katahdin

1.083

1.080

1.080

1.081

Irish C o b b l e r

1.081

1.081

1.081

1.081

Pontiac

1.076

1.074

1.073

1.074

5 0 5 -3

1.074

1.073

1.075

1.074

C hippew a

1.071

1.073

1.070

1.071

Average

1.079

1.079

1.079

1.079

56
Table

21.

Two-way table f or dates of planting
for

average

Lake

City,

and irrigation levels,

specific gravity of tubers,

Experiment A,

1952.

Irrig a tio n Levels
D a te s

of P l a n t i n g

Avg.
None

Normal

He avy

J une

2

.................................................

1.083

1.0 8 3

1.081

1.082

June

1 6 .................................................

1.081

1.081

1.080

1.080

May 1 6 ................................................

1.078

1.078

1.078

1.078

1 .......................................................

1.076

1.076

1.075

1.076

1.079

1.079

1.079

1.079

May

Aye r a ge

...............................................

57

Chip c o l o r r a t i n g s .

The a v e r a g e

the v a r i e t i e s w a s a s follows:

chip c o l o r

R u s s e t R u r a l (9.5), K e n n e be c

I r i s h C o b b l e r (8.6), K a t a h d i n (8.6), Sebago (8.4),
(7.3), a nd P o n t i a c

(6.9).

c o l o r of R u s s e t R u r a l ,

I t is e v i d e n t f r o m

5 0 5 - 3 a nd P o n t i a c ,

5 05-3

22 t h a t the chip

and K a t a h d in w e r e

Sebago and Chippewa,

"acceptable";

and

"co m m ercially unsalable."

The a v e r a g e

chip c o l o r r a t i n g s of the p o t a t o e s f r o m the J une

16 p l a n t i n g (8.6) w a s

s i g n i f i c a n t l y g r e a t e r t h a n t h o s e f r o m J un e 2

(8.3), M a y 16 (8.3), a nd May
tistically

(9.4),

Chippew a (8.0),

Ta ble

Kennebec, I r is h Cobbler,

in the g r a d e of " e x c e l l e n t " ;

r a t i n g f o r e a c h of

1 (8.2)

(T able 24).

T h e r e wa s no s t a ­

s i g n i f i c a n t d i f f e r e n c e in the chip c o l o r f r o m J u n e 2, May

16, a nd May

1 plantings.

I r r i g a t i o n w a s found to have c o n s i d e r a b l e
No i r r i g a t i o n
irrig atio n

(8.8), n o r m a l i r r i g a t i o n

(8.1).

e f f e c t on chip c ol o r :

(8.2), and tw ice the n o r m a l

T h e r e w a s no s i g n i f i c a n t d i f f e r e n c e b e t w e e n the

l a t t e r two.
T able 22 i n d i c a t e s t h a t the v a r i e t i e s

r e s p o n d e d s i m i l a r l y to

the d a t e s of p l a n t i n g .
Within a v a r i e t y ,

supplemental irrig a tio n

h a r m f u l e f f e c t on the c o l o r qua lity of c h i p s,

s e e m e d to have a

t h a t i s , no s u p p l e m e n t a l

i r r i g a t i o n p r o d u c e d c o m p a r a t i v e l y l i g h t e r - c o l o r e d c hips t h a n t h o s e
of n o r m a l and tw i c e n o r m a l i r r i g a t i o n

(Table

2 3).

Table

ZZ.

Average

chip color

date of planting,
Lake

Date s
of
Rus­
Plant­
set
ing
Rural

City,

ratings f or each variety, from each

and ir r i g at i on level,

in Experiment A,

195Z.

Va r i e t i e s

K en ­
nebec

Irish
Cob­
bler

Kata hd in

Sebago

Chippewa

505- 3

Pon­
t ia c

Aw.

Twice N o r m a l S u p p l e m e n ta l I r r i g a t i o n
5/1
5/16
6/Z
6/16
Avg.

9.6
9.6

9.4
9.4

9.1
9.Z
9.4

9.2
9-3
9.3

8.3
7.9
8.7
8.6
8.4

8.7
7.6
7.9
8.7
8. Z

8.1
8.1
7.8
8.1
8.0

7.8
7.6
7.9
8.Z
7.9

6.6
7.8
6.f
7.3
7.1

6.3
6.7
5.9
6.7
6.4

6.9
7.4
6.4
7.5
7.1

6.4
6.1

8.1
8.1
7.9
8.3
8.1

N o r m a l S u p p l e m e n ta l I r r i g a t i o n
9.5
9.6
9.0
9. Z
9.3

5/1
5/16
6/Z
6/16
Avg.

9.6
9.1
8.9
9.3
9.2

8.0
8.4
8.4
9.0
8.5

8.0
8.4
8.7
8. Z
8.3

8.Z
8.Z
8.4
8.3
8.3

7.7
7.9
8.1
8.3
8.0

6.9
7.6
6.8

8.0 '
8.1
8/1
8.4
8. Z

No S u p p l e m e n t a l I r r i g a ti on

Grand

9.1

9.3
9-6
9.4
9.3
9.4

9.0
8.6
8.7
9-0
8.8

8.3
7.3
8.1
8.6
8.1

7.0
7.1
8.3
8.1
7.6

7.9
8.0
7.6

8.6
8.6
8.8
9-0
8.8

8.6

8.6

8.4

8.0

7.3

6.9

8.3

9.9
9.8
9.6

9.7
9.9
9.6
9.8
9.8

9.2
9.0
8.8
9-4

9.5

9.4

9.Z
9.8

5 /1
5/16
6/Z
6/16
Avg.

6.9
7.4

AXg_:
A n a l y s i s of v a r i a n c e i n d i c a t e s h ig h l y s i g n i f i c a n t d i f f e r e n c e s
b e t w e e n v a r i e t i e s , b e t w e e n t r e a t m e n t s , and b e t w e e n d a t e s .
L e a s t s i g n i f i c a n t d i f f e r e n c e b e tw e e n v a r i e t i e s :
5% l e v e l , 0.3;
1% l e v e l , 0.4.
L e a s t s i g n i f i c a n t d i f f e r e n c e b e tw e e n t r e a t m e n t s :
O.Z;

1% l e v e l , O.Z.
L e a s t s i g n i f i c a n t d i f f e r e n c e b e t w e e n dates:

l e v e l , 0.3.

5% le v e l ,

5% l e v e l , O.Z;

1%

59
Table

23.

Two-way table for v ar i e t i es
chip color

ratings,

and i rr igati on levels,

Experiment A,

Lahe

City,

for

1952.

Irrig a tio n Levels
V arieties

Av v
None

Norm al

He av y

R u s s e t R u r a l ......................................

9.6

9.3

9-4

9.5

K e n n e b e c .................................................

9.6

9.2

9-3

9.4

Irish C o b b l e r

9-1

8.5

8.4

8.6

Katahdin

.................................................

9.4

8.3

8.2

8.6

.....................................................

8.8

8.3

8.0

8.4

C hippew a

8.0

8.0

7.9

8.0

505-3

7.6

7.1

7.1

7.3

P o n t i a c ......................

7.6

6.8

6.4

6.9

8.8

8.2

8.1

8.3

Sebago

A verage

.................................................

60
Table

24.

Two-way table for dates of planting and i r r igati on levels,
for chip color

ratings,

Experiment A, Lake City,

1952.

Irrig a tio n Level s
Dates

of P l a n t i n g

Av ov .
None

Norm al

Heavy

June

16 .................................................

9-0

8.4

8.3

8.6

June

2

.................................................

0.8

8.1

7.9

O ,

M ay

1 6 .................................................

8.6

8.1

8.1

8.3

May

1 .....................................................

8.6

8.0

8.1

8.2

8.8

8.2

8. 1

Average

O■
?

61
Dates of planting reacted sim ilarly to the lev els of irrigation
with no irrigation giving the highest chip color rating on every date
and heavy irrigation low est or near the low est on each date (Table
24).

Lake City, 1952 Crop--Experim ent B

Potatoes of Russet Rural and Irish Cobbler varieties were
planted on May 1, May 16, and June 16.

Cultural techniques such

as irrigation and harvesting, and sampling methods, specific-gravity
determinations, storage practices^ chip making, and chip rating were
the same as described in Experiment A.

In addition to the above,

the plots were subdivided for four fertilizer treatments; namely, no
fer tilize r, 3-12-12, 3-0-0, and 0-0-12.

The fertilizers were applied

at the rate of 1,000 pounds per acre.
The percentage distribution of tubers, the average chip color
ratings by variety, by date of planting, by irrigation level, and by
fer tilize r analysis in each specific-gravity class are given in Appen­
dix Table V.

Specific gravity of tubers.

The average specific gravity of

the tubers of Russet Rural (1.087) was significantly greater than that
of Irish Gobbler (1.082) (Table 25).

62
Table

25.

Average

specific gravity for

date of planting,
E x p e r i m e n t B,

each v ar ie ty,

i r r i g a t i o n level,

Lake

City,

fertilizer

from

each

anal ysis

in

1952.

Irrig a tio n Levels
F ertilizer
T reatm ents

I r i s h C obbler
Heavy

N orm al

N one

Avg.

3- 12*12
3-0-0
0-0-12
Avg.

1.0 84
1.078
1.079
1.081
1.081

1.082
1.078
1.0 80
1.079
1.0 80

1.087
1.079
1.086
1.0 80
1.083

1.084
1.078
1.082
1.0 80
1.081

1.084

1.0 84

1.079
1.083
1.078
1.081

1.079
1.0 80
1.082
1.081

1.081
1.0 80
1.080
1.0 80
1.080

1.083
1.079
1.081
1.080
1.081

1.084
1.083
1.086
1.079
1.083

1.083
1.083
1.087
1.081
1.084

1.0 84
1.082
1.086
1.082
1.0 84

1.084
1.083
1.086
1.081
1.084

1.082

1.082

1.082

1.0 82

1 6 ...................

°

?

o

May

0
1

M a y 1 ...............................

0
1

i

of P l a n t i n g

o
t

Dates

3-12-12
o
i
o

1

0-0-12
Avg.
16 ...........................

o
i
o
1
o

June

Avg.

Grand average

. . .

tv

0
1
1—•

1

0

3-12-12
5-0-0

A n a l y s i s of v a r i a n c e i n d i c a t e s h i g h l y s i g n i f i c a n t d i f f e r e n c e s
betw een v a r i e t i e s , b etw een d a te s, and betw een f e r t i l i z e r s , but not
between irrig a tio n s .
L e a s t significant difference betw een v a r ie tie s :
5% l e v e l ,
0.001; 1% l e v e l , 0 .0 01 .
L e a s t sig nificant difference b etw een dates:
5% l e v e l , 0.001;
1% l e v e l , 0.0 0 1 .
L e a s t sig nificant differen c e b etw een f e r t i l i z e r s :
5% l e v e l ,
0.001; 1% l e v e l , 0 . 0 0 2 .

63
Table 25 (continued)

Irrigation Levels
Russet Rural
Heavy

Normal

None

Ave rage
A yv
*o .

He avy

Normal

Grand

None
.

. A y g*.

1.087
1.0 80
1.088
1.0 84
1.085

1.084
1.084
1.087
1.085
1.085

1.087
1.0.83
1.088
1.088
1.087

1.086
1.082
1.088
1.086
1.086

1.086
1.079
1.0 84
1.083
1.083

1.083
1.081
1.084
1.082
1.083

1.087
1.081
1.087
1.082
1.0 84

1.085
1.0 80
1.085
1.082
1.083

1.089
1.087
1.085
1.0 84
1.086

1.0 89
1.086
1.089
1.087
1.088

1.090
1.085
1.0 84
1.089
1.087

1.0 89
1.086
1.086
1.087
1.087

1.087
1.083
1.0 84
1.081
1.084

1.087
1.083
1.085
1.085
1.085

1.0 86
1.083
1.0 82
1.085
1.084

1.087
1.083
1.084
1.0 84
1.084

1.0 87
1.088
1.090
1.088
1.0 88

1.090
1.088
1.090
1.087
1.089

1.088
1.089
1.090
1.088
1.089

1.088
1.088
1.090
1.088
1.089

1.086
1.086
1.088
1.0 84
1.086

1.087
1.086
1.089
1.0 84
1.086

1.086
1.086
1.088
1.085
1.086

1.086
1.086
1.088
1.0 84
1.086

1.086

1.087

1.087

1.087

1.084

1.084

1.085

1.084

64

The a v e r a g e
ing

(1.0 86) w a s

s p e c i f i c g r a v i t y of t u b e r s f r o m the J u n e

s i g n i f i c a n t l y h i g h e r than t h a t of the May 16 p la nt i n g

(1.0 84), and of the Ma y 1 p la ntin g
May

16 p l a n t ­

(1.083).

The s p e c i f i c g r a v i t y f o r

16 p l a n ti n g w a s only s i g n i f i c a n t l y g r e a t e r a t the 5 p e r c e n t l e v e l

t h a n t h a t of the May

1 p la n ti n g .

The a p p l i c a t i o n of a d d it io n a l a m o u n t s

of w a t e r by s u p p l e m e n t a l

i r r i g a t i o n e i t h e r n o r m a l o r twice n o r m a l a p p e a r e d to have but s lig ht
e f f e c t on the a v e r a g e
No f e r t i l i z e r
significantly higher
3-12-12

(1.083)
From

s p e c if i c g r a v i t y (Table 26).
(1.086)

s p e c if i c

and 3 - 0 - 0

(1.085) p r o d u c e d p o t a t o e s of

g r a v i t y t h an t h o s e of 0 - 0 - 1 2

(1.083)

and

(T able 27).

Tables

25, 27, a nd 28 i t c a n be s e e n t h a t v a r i e t i e s

r e s p o n d e d in a s i m i l a r m a n n e r to d a t e s of pla nting and to f e r t i l i z e r
treatm ents,

a nd t h a t the d i f f e r e n t l e v e l s

r e a c t i o n s to the v a r i o u s f e r t i l i z e r s .

of i r r i g a t i o n gave

sim ilar

This was n o t t r u e f o r d a te s

of p l a n t i n g v/ith f e r t i l i z e r s

(Table 29), and f o r d a t e s of p la ntin g with

l e v e l s of i r r i g a t i o n

30).

( T ab le

Chip c o l o r r a t i n g s .

The a v e r a g e chip c o l o r

v a r i e t y R u s s e t R u r a l (9-4) w e r e
I r i s h Cobbler

r a t i n g s f o r the

s i g n i f i c a n t l y g r e a t e r t h a n t h a t of

(8.5); in f a c t , in e v e r y t r e a t m e n t R u s s e t R u r a l gave a

h i g h e r chip c o l o r

r a t i n g than did I r i s h

C o b b l e r (Table

31).

65
Table

26.

Two-way table for v a r i e t i e s
average
City,

specific

and irr igati on levels,

gravity of tubers,

for

Experiment 13, Lake

1952.

I r r iv a tion L e v e l s
Varieties

Avr/ .
None

Normal

Heavy

R u s s e t R u r a l ...........................

1.087

1.087

1.086

1.0 87

I r i s h C o b b l e r ..........................

1.0 82

1.082

1.082

1.0 82

1.085

1.084

1.084

1.084

Average

.................................................

66

Table

27.

T w o - w a y ta b le f o r v a r i e t i e s and f e r t i l i z e r t r e a t m e n t s ,
f o r a v e r a g e s p e c i f i c g r a v i t y of t u b e r s , E x p e r i m e n t B,
L a k e City, 1952.

Fertilizer
V arieties

Treatm ents
Avo'.

No F e r tilize r

3 -0 -0

0-0-12

3 -1 2 -1 2

R usset Rural

. . . .

1.088

1.088

1.087

1.086

1.0 87

I r i s h Cobbler

. . . .

1.084

1.083

1.080

1.080

1.082

1.086

1.085

1.083

1.083

1.084

Ave r a g e

67
Table

2 8.

Two-way table for i r rig ati on levels
ments,
B,

f or average

Lake

City,

and f e r t i l i z e r t r e a t ­

specific gravity of tubers,

Experiment

1952.

F ertilizer

Treatm ents

1

Irrig atio n Levels

Ayg.
o
i
O
1
00

No F e r ­
tilize r

0-0-12

3 -1 2- 1 2

I

i

!
!
I

!

N o n e ..................................

1.086

1.086

1.084

1.083

1.085

N o r m a l ...........................

1.085

1.085

1.083

1.083

1.084

He a v y ..............................

1.086

1.085

1.082

1.082

1.084

Average

1.086

1.085

1.08^

1.083

1.084

.........................

68
Table

2 9.

Two-way table for dates
ments,
B,

f or average

Lake

City,

of planting

treat­

Experiment

1952.

Fertilizer
D a t e s of P l a n t i n g

and f e r t i l i z e r

specific gravity of tubers,

Treatm ents
Av O
e.

No F e r ­
tilizer

3-0-0

0-0-12

3 - 1 2 -1 2

16 ...........................

1.086

1.088

1.084

1.086

1.086

M ay 1 6 ...........................

1.087

1.084

1.084

1.083

1.084

M ay 1 ..............................

1.085

1.085

1.082

1.080

1.083

Average

1.086

1.085

1.083

1.083

1.084

J une

69

Table

30.

T w o - w a y ta b le f o r d a t e s of p l a n t i n g and i r r i g a t i o n l e v e l s ,
f o r a v e r a g e s p e c i f i c g r a v i t y of t u b e r s , E x p e r i m e n t B,
L a k e City, 1952.

Irrig a tio n Levels
Dates

of P l a n t i n g

Avo
v.
None

No r m a l

He avy

June

1 6 .................................................

1.086

1.086

1.086

1.086

M ay

1 6 .................................................

1.084

1.085

1.084

1.084

May 1 .....................................................

1.084

1.083

1.083

1.083

Average

1.085

1.084

1.084

1.084

.............................................

70
Table

31.

Average

chip

color

date of planting,
Ex p e r i m e n t B,

r atings

f o r each v a r i e t y ,

i r r i g a t i o n level,

Lake

City,

fertilizer

from

each

analysis

in

1952.

Irrig a tio n Levels

o

i
0
1

U>

3-12-12

June

16 ...........................

None

Avg.

8.7
8.3
8.0
8.3
8.3

8.4
8.0
7.8
8.0
8.1

9.8
9.2
9.4
8.9
9.3

8.9
8.5
8.4
8.4
8.6

7.5
8.4
7.7
8.6
8.1

8. 3
9-0
8.8
9-0
8.8

7.9
8.4
8.1
8.7
8.3
8.4
9-0
8.8
8.3

8.0

3-12-12
3-0-0
0-0-12
Avg.

7.9
8.0
8.5
8.1
8.0
8.6
8.4
8.2
8.3

7.9
9.0
8.6

9.3
9.4
9-4

7.9
8.4

8.9
9.3

8.2

8.2

9.1

o

1 6 ...............

N orm al

o
i
o
I
o

May

Heavy

0
1
0
1

0-0-12
Avg.

I r is h Cobbler

i
I

3-12-12
3-0-0
0-0-12
Avg.

> ON

1 ...............................

o
i
o
i
o

May

E e rtilize r
Treatm ents

0 0

D a t e s of P l a n t i n g

G rand average

. . .

8.5

A n a l y s i s of v a r i a n c e i n d i c a t e s h i g h l y s i g n i f i c a n t d i f f e r e n c e s
b e t w e e n v a r i e t i e s a nd b e t w e e n i r r i g a t i o n s , b u t no s i g n i f i c a n t d i f f e r ­
en ces betw een dates n o r betw een f e r t i l i z e r t r e a t m e n t s .
L e a s t significant difference betw een v a r ie tie s :
5% l e v e l , 0.2;
1% l e v e l , 0.2.
L e a s t significant differen ce b etw een ir r ig a tio n s :
5% l e v e l ,
0.2; 1% l e v e l , 0.3.

71
Table

31 (continued)

Irrigation Levels
Russet Rural

Ave rage
None

Grand
Avg.

8.6
8.6
8.6
8.9
8.7

9.7
9.2
9-7
9.4
9.5

9.1
8.9
8.9
9.0
9.0

8.8
8.8
8.5
8.9
8.7

8.6
9.1
8.4
9.0
8.8

9.1
9.4
9.1
9.5
9.3

8.8
9.1
8.7
9.1
8.9

9.2
9.6
8.8
9-5
9.3

8.3
8.9
8.6
8.9
8.7

8.9
9.4
8.7
8.7
8.9

9.4
9.6
9.1
9-2
9.3

8.8
9.3
8.8
8.9
9.0

9.4

8.7

8.8

9-4

9.0

Heavy

Normal

None

Avg.

Heavy

9.5
9.6
8.9
9.3
9.3

8.8
9.2
9.3
9.7
9.3

9.6
9.2
9-9
9.9
9.7

9.3
9.3
9.3
9.6
9.4

9.1
8.9
8.5
8.8
8.8

9.5
9.6
8.9
9.3
9.3

9.7
9.8
9.2
9.4
9.5

9.9
9.8
9.3
10.0
9.8

9.7
9.7
9.1
9.5
9.5

8.6
9-2
8.8
9.6
9-1

9.8
9.8
8.8
9.5
9.5

9.4
9.8
8.8
9.4
9.4

9.2

9.4

9.6

Normal

72

No s i g n i f i c a n t d i f f e r e n c e s w e r e o b s e r v e d b e t w e e n chip c o l o r
r a t i n g s of M ay

1, Ma y 16, a nd J u n e

The a v e r a g e
(9.4) w e r e
tion (8.8)

chip c o l o r r a t i n g s f r o m the no i r r i g a t i o n p lo ts

s i g n i f i c a n t l y h i g h e r t ha n t h o s e f r o m the n o r m a l i r r i g a ­
an d the tw ic e n o r m a l i r r i g a t i o n

The a v e r a g e
treatm ents were
izer

16 p l a n t i n g s .

(8.9), and

chip c o l o r

a s f ollows:

3-0-0

(8.8)

(8.7) p l o t s

(Table

32).

r a t i n g s f o r e a c h of the f e r t i l i z e r
3-12-12

(Table

33),

(9.0), 0 - 0 - 1 2
There

(9.0), no f e r t i l ­

was no s t a t i s t i c a l l y

s i g n i f i c a n t d i f f e r e n c e b e t w e e n th e m .
R u s s e t R u r a l a nd I r i s h C o b b l e r did n ot r e s p o n d s i m i l a r l y
f r o m one d a te of p l a n t i n g to a n o t h e r (Ta ble
levels

of i r r i g a t i o n

tilizers

(Table

31), n o r to the t h r e e

32), b u t t he y did r e a c t s i m i l a r l y to f e r ­

w ith the one e x c e p t i o n of R u s s e t R u r a l to 0 - 0 - 1 2
D a te s

of p l a n t in g did not give

(Table

said f o r dates

33}.

s i m i l a r r e s p o n s e s to l e v e l s of

i r r i g a t i o n , b u t the i n t e r a c t i o n w a s n o t s i g n i f i c a n t (Table
s a m e m a y be

(Table

of p l a n ti n g with the

34).

The

several fe rtilizers

35).
The r e s p o n s e s

of i r r i g a t i o n ( Ta b l e

g iven b y the

several fertilizers

to the l e v e l s

36) t e n d e d to be s i m i l a r as f a r as no i r r i g a t i o n

c o m p a r e d with i r r i g a t i o n w a s c o n c e r n e d , with the no i r r i g a t i o n t r e a t ­
m e n t giving the h i g h e r chip c o l o r r a t i n g s .
sponses

to f e r t i l i z e r s

Within i r r i g a t i o n s

sh ow ed no d ef in ite t r e n d s .

the

re­

73

Table

32.

T w o - w a y t a b l e f o r v a r i e t i e s and i r r i g a t i o n l e v e l s , f o r
chip c o l o r r a t i n g s , E x p e r i m e n t B, La ke City, 1952.

Irrig a tio n Levels
Va r i e t i e s

Avg.
None

No r m a l

Heavy

R u s s e t R u r a l .......................... . . .

9.6

9.4

9.2

9-4

I r i s h C o b b l e r ........................... . . .

9.1

8.2

8.2

8.5

Average

9.4

8.8

8.7

9.0

......................................

74
T able

33.

T w o - w a y ta ble f o r v a r i e t i e s a nd f e r t i l i z e r t r e a t m e n t s , f o r
chip c o l o r r a t i n g s , E x p e r i m e n t B, L a k e City, 1952.

F ertilizer
V arieties

Treatm ents

3- 12- 12

0-0-12

Ho F e r ­
tilize r

Avg.
3 -0 -0

R usset Rural

. . . .

9.5

9.6

9.4

9.1

9.4

I r i s h Cobbler

. . . .

8. 6

8.4

8.4

8.5

8.5

9.1

9.0

8.9

8.8

9.0

Average

.......................

75
Table

34.

Two-way table for dates
for

chip color

ratings,

of planting and irrigation levels,

Experiment B,

Lake

City,

1952.

Irrig atio n Levels
D a t e s of P l a n t i n g

Avg.
None

Normal

H eavy

May

1 .......................................................

9-5

8.7

8.8

9.0

J une

1 6 .................................................

9.3

8.9

8.7

9.0

May

1 6 .................................................

9.3

8.8

8.7

8.9

9.4

8.8

8.7

9.0

Average

76
Table

35.

Two-way table for
ments,
1952.

for

dates

chip color

of planting and f e r t i l i z e r

ratings,

F e rtilize r
Dates

of P l a n t i n g
3 -1 2 - 1 2

0-0-12

Experiment B,

Lake

treat­
City,

T reatm ents
No F e r ­
ti l i z e r

Avg.
3- 0-0

Ma y 1 ..............................

8.9

9.0

9.1

8.9

9.0

16 ...........................

9.3

8.9

8.8

8.8

9.0

May 1 6 ..........................

9.1

9.1

8.8

8.7

8.9

Average

9-1

9-0

8.9

8.8

9.0

June

.......................

77
Table

36.

Two-way table for i r r igati on levels
ments, f or
1952.

chip color

ratings,

and f e r t i l i z e r t r e a t ­

Experiment B,

Bake

City,

F ertilize r Treatm ents
Irrig a tio n L evels

Avg.

3 -1 2- 12

0-0-12

No F e r ­
tilizer

N o n e ..................................

9.4

9.4

9.4

9.3

9.4

N o r m a l .......................

9.0

8.9

8.7

8.6

8.8

8.9

8.7

8.5

8.7

9.0

8.9

8.8

9.0

Average

.......................

!

i

!

v O

He a v y ..............................

3 -0 - 0

9-1

DISCUSSION OF RESULTS

S p e cif ic G r a v i t y of P o t a t o e s

F r e q u e n c y d i s t r i b u t i o n of t u b e r s into s p e c i f i c - g r a v i t y c l a s s e s .
In A ppe ndix

T a b l e s I, II, IV, a nd V rnay b e s e e n the p e r c e n t a g e d i s ­

t r i b u t i o n of the t u b e r s into the five

specific-gravity classes.

was considerable v ariatio n between v a rie tie s ,
g a ti on t r e a t m e n t s , f e r t i l i z e r

d a t e s of p la ntin g , i r r i ­

a p p l i c a t i o n s , l o c a t i o n , and s e a s o n s .

The R u s s e t R u r a l and K e n n e b e c v a r i e t i e s
h igh p e r c e n t a g e
classes.

of t u b e r s

a lways p r o d u c e d a

in the h i g h - s p e c i f i c - g r a v i t y (4 and 5)

I r i s h C o b b l e r a n d Sebago p o t a t o e s w e r e

s p e c i f i c g r a v i t y w ith m o s t of the t u b e r s in C l a s s
tiac,

There

r a t e d m id w a y in
3.

Ka ta hd in , P o n ­

Ch ipp ew a, a nd S eedling 50 5 -3 ha d a high p e r c e n t a g e of t u b e r s

in l o w - s p e c i f i c - g r a v i t y

(1 and 2) c l a s s e s .

I t i s i n t e r e s t i n g to note t h a t in 1951 the date of p l a n ti n g a ls o
a f f e c t e d the d i s t r i b u t i o n of t u b e r s in v a r i o u s
The l a r g e p e r c e n t a g e

specific-gravity classes.

of t u b e r s f r o m e a r l y - p l a n t e d p l o t s w as in the

high-specific-gravity classes,

and t hi s p e r c e n t a g e d e c l i n e d p r o g r e s ­

s i v e l y with l a t e r d a t e s of p l a n ti n g .

H o w e v e r , o b s e r v a t i o n s of the

e x p e r i m e n t s of 1952, a t L a k e City, p r e s e n t c o n t r a d i c t o r y

78

results

to

79

t h o s e of 1951.

That is,

h ad a h i g h e r p e r c e n t a g e

l a t e - p l a n t e d (June
of t u b e r s

than t h o s e p l a n t e d e a r l i e r
p l a n a t i o n of t h e s e
year

(May

contradicting

2 and J u n e

16) p o t a t o e s

in high- s p e c if ic - g r a v i t y c l a s s e s

1 and May
results

1952 w a s not n o r m a l f o r L ak e

16).

The p r o b a b l e e x ­

m a y be as follows:

City b e c a u s e h ea vy r a i n s

The
in the

l a t t e r p a r t of J u l y h a m p e r e d the g r o w t h of e a r l y - p l a n t e d p o t a t o e s ;
t h e r e w a s e no u g h s u n s h i n e and w a r m t h and an a b s e n c e of f r o s t to
a llow the l a t e - p l a n t e d p o t a t o e s
w eath er changes w ere
previo us

to m a t u r e .

H ence, t h e s e

responsib le for re su lts

seasonal

so d i f f e r e n t f r o m the

season.

D a t a of 1951, a t E a s t L a n s i n g ,

s u g g e s t t h a t i r r i g a t i o n with no

f e r t i l i z e r t r e a t m e n t t e n d e d to y i e l d a h i g h e r p r o p o r t i o n of highs p e c i f i c - g r a v i t y t u b e r s t h a n any o t h e r t r e a t m e n t .
3-12-12

No i r r i g a t i o n with

and i r r i g a t i o n w ith 3 - 1 2 - 1 2 p l o t s p r o d u c e d high p e r c e n t a g e s

in m e d i u m - s p e c i f i c - g r a v i t y c l a s s e s

and the p l o ts w h ic h r e c e i v e d

i r r i g a t i o n w i th 0 - 0 - 1 8 y i e l d e d the l a r g e s t p e r c e n t a g e

of p o t a t o e s in

low -specific-gravity classes.
The e x t e n s i v e

s tu dy of the

1952 c r o p f r o m La ke

t h a t t h e r e w as no m a r k e d e f f e c t of v a r i o u s l e v e l s
d i s t r i b u t i o n of p o t a t o e s

into

City i n d i c a t e s

of i r r i g a t i o n on the

specific-gravity classes.

The p o t a t o e s

f r o m the u n f e r t i l i z e d p l o t s h a d a l a r g e p e r c e n t a g e of t u b e r s in the

80

high-specific-gravity classes.
produced many tubers
w e r e f e r t i l i z e d with
specific g ra v ity .

The p l o t s

r e c e i v i n g 0 - 0 - 1Z f e r t i l i z e r

of low s p e c i f i c g r a v i t y ,

3-0-0

and

and the p l o t s which

3-12-12 yielded potatoes

of m e d i u m

This i s p a r a l l e l to the f in d in g s of 1951 f r o m E a s t

Lansing.
Figures

1, 2, a nd 3 p oin t out t h a t the l o c a t i o n w h e r e p o t a t o e s

w e r e g r o w n m a d e a g r e a t d i f f e r e n c e in the d i s t r i b u t i o n of t u b e r s
into v a r i o u s
from

specific-gravity classes.

E a s t Lansing,

(Class

1, p r e s e n t i n g the d a ta

1951, i n d i c a t e s t h a t t h e r e w as a d i s t i n c t d i v i s io n

3) b e t w e e n l o w -

gests that th ere

Figure

and h i g h - s p e c i f i c - g r a v i t y c l a s s e s .

This

sug­

m a y have b e e n two d i f f e r e n t t u b e r s e t ti n g s in the

life of the p ot at o c r o p , w hic h could h av e b e e n e n c o u r a g e d by the e n ­
vironm ental influences.

The p a t t e r n of d i s t r i b u t i o n of t u b e r s

s p e c i f i c - g r a v i t y c l a s s e s f r o m the c r o p s
1952 w e r e to a l a r g e
were

some

e x t e n t the s a m e

a t Lake

in

City in 1951 and

( F i g u r e 2 and 3), e x c e p t t h e r e

s l i g h t s e a s o n a l v a r i a t i o n s , with 1952 t u b e r s a v e r a g i n g

h i g h e r in s p e c i f i c g r a v i t y .

Average

s p e c i f i c g r a v i t y of t u b e r s .

The a v e r a g e

s pe cif ic

g r a v i t y of t u b e r s fo llo w e d the s a m e p a t t e r n as d i s c u s s e d p r e v i o u s l y .
That i s ,

R u s s e t R u r a l a nd K e n n e b e c p o t a t o e s h a d high, I r i s h C o b b l e r

and Sebago h a d m e d i u m ,

and Chippewa, P o n t i a c ,

and Seedling 5 05- 3

81

Figure

1.

Percentage

d i s t r i b u t i o n of t u b e r s

classes from
third

(J un e

average
with

the f i r s t

25)

dates

of p l a n t i n g .

of f i v e v a r i e t i e s ,

3-12-12 f e r t i l i z e r ,

L ansin g,

(May 21),,

1951.

into f i v e

specific-gravity

s e c o n d (June
The

curves

13), a n d
sh o w the

grown u n d e r n o r m a l ir r ig a tio n

1,000 p o u n d s p e r

acre,

East

82

60
May 2 1
June

13

June 25

Percentage

Distribution

40

20

Specific-G ravity C lasse s

83

Figure

2.

Percentage
classes
third

from

( June

average

d i s t r i b u t i o n of t u b e r s
the f i r s t (May 4),

4) d a t e s

of p l a n t i n g .

of s i x v a r i e t i e s ,

with 3-1 2 -1 2 f e r t i l i z e r ,
1951.

into f i v e
second

sp e c i f i c - g r a v i t y

(May 2 3), a n d

The c u r v e s

sh ow the

grown u n d e r n o r m a l
1,000 p o u n d s p e r

acre,

irrigation
Lake

City,

84

60

• May

X June

Percentage

Distribution

40

20

Specific-Gravity C lasses

85

Figure

3.

Percentage

d i s t r i b u t i o n of t u b e r s

classes from
( J u n e 2),
curves

the f i r s t

a nd f o u r t h

(June

sh o w the a v e r a g e

n o r m a l i r r i g a t i o n w i th
per

(May

a c re , Lake

C it y ,

1),

into f i v e

specific-gravity

s e c o n d (May

16) d a t e s

16 ), t h i r d

of p l a n t i n g .

The

of e i g h t v a r i e t i e s , g r o w n u n d e r

3-12-12 f e r tiliz e r ,
1952.

1,000 p o u n ds

60

May
May
June
June

Percentage

Distribution

40

Z0

Specific-Gravity C lasses

87

h ad low a v e r a g e

specific gravity.

t u b e r s of low s p e c i f i c
specific

g r a v i t y in 1951 a t E a s t L a n s i n g , b u t of m e d i u m

g r a v i t y f o r b ot h y e a r s ,

confirm s

The K a t a h di n v a r i e t y p r o d u c e d

the o b s e r v a t i o n s

1951 and 1952,

at L a k e City.

T hi s

of V a n a s s e e t a l . (6l), who r e p o r t e d t h a t

v a r i e t y h a d a s i g n i f i c a n t e f fe c t on the s p e c i f i c g r a v i t y , a nd of M e t z £e r

a l - (35)

and Dunn and Nylund (24), who s t a t e d t h a t p o t a t o e s

f r o m one l o c a l i t y d i f f e r e d in d r y - m a t t e r c o n te nt f r o m th o se of a n o t h e r .
The t u b e r s f r o m e a r l y p l a n ti n g had c o n s p i c u o u s l y h i g h e r s p e ­
cific g r a v i t y t h an t h o se f r o m l a t e p l a n t i n g s in the y e a r
E a s t L a n s i n g and L a k e City.
contrasting

results.

B ut in 1952, the L a k e City c r o p gave

T h a t i s , la te p l a n t i n g s ( t h i r d and f o u r t h dates)

y i e l d e d p o t a t o e s of s li g h t l y h i g h e r
plantings

1951 f r o m

s p e c i f ic g r a v i t y t ha n the e a r l y

( f i r s t a nd s e c o n d d a t e s ).

(The p r o b a b l e e x p l a n a t i o n of s e a ­

sonal v a r i a t i o n i s d i s c u s s e d above).
In 1951, E a s t L a n s i n g d a t a show t h a t i r r i g a t i o n with no f e r ­
t i l i z e r gave t u b e r s w ith a n a v e r a g e h i g h s pe c if ic g r a v i t y .
tio n with 3 - 1 2 - 1 2 , i r r i g a t i o n w it h 3 - 1 2 - 1 2 ,
treatm ents
indicates
tubers.
City.

No i r r i g a ­

and i r r i g a t i o n with 0 - 0 - 1 8

t e n d e d to p r o d u c e l o w - s p e c i f i c - g r a v i t y p o t a t o e s .

This

t h a t i r r i g a t i o n did not in flu en ce the s p e c i f i c g r a v i t y of
T his w a s l a t e r c o n f i r m e d f r o m the r e s u l t s of 1952, L a k e

88

In 1952, the highest average specific-gravity ratings were
given to tubers from the unfertilized plots, followed by those which
r e c e iv e d -3-0-0 and 3-12-12, while the low est ratings were found in
treatments 0 -0 -1 8 or 0 -0 -1 2 .

This higher specific gravity of tubers

from unfertilized plots contrasted with those from plots fertilized
with different types of fer tilize rs is in agreement with the findings
of Smith and Nash ( 49).
It can be seen from Appendix Tables I and II that the average
specific gravity of the tubers of a given variety from Lake City was
comparatively higher than those from East Lansing.

A sim ilar ef­

fect due to locational differences was given by Vanasse et a l. (6l).
Furtherm ore, the specific gravity of any variety was higher in 1952
than in 1951, which confirms the findings of Wager (62) on seasonal
influences on specific gravity of tubers.

89

C o l o r of P o t a t o

In the t h r e e

years

Chips

of o b s e r v a t i o n ,

R u sse t Rural,

and I r i s h C o b b l e r v a r i e t i e s p r o d u c e d m a r k e t a b l e ,
a p p e a l i n g g ol de n y ello w c h i p s .
the g r a d e of a c c e p t a b l e ;
c o m m e rc ia lly unsalable

K e n n e be c ,

delectable,

and e y e -

Chips f r o m K a t a h d i n t u b e r s w e r e in

Chippe wa , P o n t i a c , Sebago, and 505-3 m a d e
c h ip s

(68).

The da te of p l a n ti n g had s o m e i nf lu en c e on c o l o r qua lity of
p o t a to c h i p s.

The r e s u l t s of 1950 and 1951 f r o m L a k e City a nd of

1951 f r o m E a s t L a n s i n g i n d i c a t e t h a t the c h ip s f r o m the e a r l y - p l a n t e d
potatoes w ere
results
1951.

of a l i g h t e r c o l o r t h a n t h o s e of l a t e - p l a n t e d (64).

of 1952 f r o m L a k e City c o n t r a d i c t e d the r e s u l t s
T h a t i s , the l a t e - p l a n t e d p o t a t o e s m a d e

c h ip s t ha n t h o s e f r o m the e a r l y - p l a n t e d
a ll w e r e

The

of 1950 and

s lightly l i g h t e r - c o l o r e d

(Figures

4 and 5), a lthough

a c c e p t a b l e in the b e t t e r v a r i e t i e s .

It c a n be

s e e n f r o m Appendix T a b le s IV and V t h a t t h e r e

s e e m e d to be a m o r e
c if ic g r a v i t y of t u b e r s
f ro m them.

T h a t is ,

or less

d i r e c t r e l a t i o n s h i p b e t w e e n the s p e ­

and the c o l o r of the chips (33) p r o c e s s e d
the h i g h e r the s p e c if ic g r a v i t y , the l i g h t e r the

chip c o l o r when the date of p l a n ti n g e f f e c t s a r e

a ls o c o n s i d e r e d .

It

is o b s e r v e d t h a t, w hile , within the l a t e date of p la n ti n g , the h i g h e r s p e c i f i c - g r a v i t y t u b e r s p r o d u c e d l i g h t e r - c o l o r e d chips than the

90

Figure

4.

A v e r a g e chip
June

color

r a t i n g s f o r the May 21, J u n e

2,5 d a t e s of p l a n t i n g in f iv e

The c u r v e s

show the a v e r a g e

i r r ig a tio n with
E a s t Lansin g,

1951.

spe c i f i c - g r a v i t y c l a s s e s .

of five v a r i e t i e s ,

3-12-12 f e r t i l i z e r ,

1,000 p o u n d s

The l a r g e s t p o r t i o n

the M a y 21 p l a n t i n g w a s

1 3, and

acceptable.

norm al
per

acre,

of c h i p s f r o m

91

Specific-Gravity

on

Classes

vO

o

00

Chip Color Ratings

92

F ' i g u re

5.

A verage

chip c o l o r

2, a n d J u n e
classes.

r a t i n g s f o r the M a y

16 d a t e s

The c u r v e s

1, M a y

of p l a n t i n g in f iv e
show th e a v e r a g e

specific-gravity
of e i g h t v a r i e t i e s ,

n o r m a l i r r i g a t i o n w ith 3 - 1 2 - 1 2 f e r t i l i z e r ,
per
from

acre,

Lake

the J u n e

C ity ,

1952.

16, J un e

1,000 p o u n d s

The l a r g e s t p o r t i o n of chips

16 p l a n t i n g w a s

acceptable.

93

oo

o

oo
Chip Color Ratings

Specific-Gravity

Classes

in

94

lo w e r - s p e c if ic - g r a v ity tu b ers,

yet these

those fro m

specific-gravity class from

p l a n ti n g

the c o r r e s p o n d i n g

c hip s w e r e not as l ig h t as
the e a r l y

(64).
T a b le

1 shows t h a t the a m o u n t of r e d u c i n g s u g a r s

and the

c o l o r of c h ip s v a r i e d n o t only f r o m v a r i e t y to v a r i e t y , b u t a ls o
within a v a r i e t y ,

a n d within the

same

specific-gravity class from

one d a t e of p l a n t i n g to a n o t h e r .
The e x p e r i m e n t s
Lake

of 1951 f r o m

E a s t L a n s i n g and of 1952 f r o m

City sh o w t h a t t u b e r s f r o m n o - i r r i g a t i o n p l o t s p r o d u c e d l i g h t e r -

c o l o r e d c h i p s than t h o s e f r o m i r r i g a t e d , in sp ite of the f a c t th at
t h e r e w a s no d i f f e r e n c e in s p e c i f i c g r a v i t y .

It m a y f u r t h e r be ob ­

s e r v e d f r o m the e x p e r i m e n t a t E a s t L a n s i n g ,
B, a t L a k e

City,

3 - 1 2 - 1 2 a t the

1952, t h a t the p l ot s which w e r e f e r t i l i z e d with

r a t e of 1,000 pounds p e r

m ore-acceptable
tilize r analyses.

It is

a cre made com paratively

c h i p s than the p o t a t o e s f r o m p l o t s with o t h e r f e r ­
It i s i n t e r e s t i n g to note t h a t p o t a s h (KC1) f e r t i l i z e r

( 0 - 0 - 1 8 and 0 - 0 - 1 2 )
t h a t of 3 - 1 2 - 1 2 .

1951, and E x p e r i m e n t

d e c r e a s e d the a v e r a g e

s p e c i f ic g r a v i t y below

T h is w a s p r o b a b l y due to the c h l o r i d e ion (55).

s u g g e s t e d t h a t the c h l o r i d e m i g h t be playing

enzyme

system o r carbohydrate

some

s y s t e m of the p o ta to .

r o l e in the
T u b e r s of

any g iv en s p e c i f i c g r a v i t y f r o m p l o t s f e r t i l i z e d with 3—12-12, 0 - 0 - 1 8 ,

95

o r 0 - 0 - 1 2 p r o d u c e d l i g h t e r - c o l o r e d c h i p s than did t u b e r s
s p e c if ic g r a v i t y f r o m u n f e r t i l i z e d o r
plots produced tu b e rs

3 -0 - 0 p l o t s .

w ith h i g h e r a v e r a g e

of the

sam e

B u t the l a t t e r two

specific g r a v itie s

than

any of the o t h e r p l o t s .
C o n s i d e r i n g b o t h s p e c i f i c g r a v i t y and chip c o l o r ,
b a l a n c e d in p o t a s h and p h o s p h o r u s
Potatoes

seems

g r o w n a t L a k e City (1950,

a fertilizer

advisable.
1951, and 195 2) m a de

l i g h t e r - c o l o r e d c h ip s tha n t h o se t h a t w e r e g r ow n a t E a s t L a n s i n g
(1951).

This m i g h t be due to h i g h e r t e m p e r a t u r e , n o n u n i f o r m soil

(lo w-ly in g a r e a s ) ,
E ast Lansing

a h igh p o p u l a ti o n of w e e d s and d i s e a s e d p l a n t s

at

(60).

The y e a r

1952 s e e m e d to be a m o r e f a v o r a b l e y e a r f o r g r o w ­

ing p o t a t o e s f o r the m a n u f a c t u r i n g of p ota to chips t ha n did 1950 and
1951.
f o r the

The c o l o r of c hip s in 1952 w as l i g h t e r tha n in 1950 and 1951,
same variety,

and the s a m e

s p e c i f i c - g r a v i t y c l a s s ; no m a t t e r

w h a t da te of p l a n t i n g o r t r e a t m e n t .
In 1951, e x p e r i m e n t s w e r e
the e f f e c t s of s t o r a g e
chips.

tem perature

c o n d u c te d a t E a s t L a n s i n g to study
and d u r a t i o n on the c o l o r of po tato

R u s s e t R u r a l y i e l d e d c o m p a r a t i v e l y l i g h t e r - c o l o r e d c hip s than

did K at ah d i n ,

a f t e r two, a s we ll a s fiv e, m o n t h s c old s t o r a g e

Chip c o l o r a f t e r five m o n t h s

(41°

F.).

s t o r a g e w as d a r k e r than a f t e r two m o n t h s

96

storage,

s u g g e s t i n g the t r a n s f o r m a t i o n and a c c u m u l a t i o n of l a r g e p e r ­

centages

of r e d u c i n g

s u g a r s in the t u b e r s .

The d a t a on h i g h - t e m p e r a t u r e
quent to two m o n t h s

c o ld s t o r a g e

conditioning of p o t a t o e s

c old s t o r a g e , R u s s e t R u r a l m a d e l i g h t e r - c o l o r e d

c h i p s th an a f t e r two m o n t h s .
was true:

and t h a t K a t a hd in co nd itio n e d

A fter h ig h -te m p e r a tu re

following five m o n t h s

subse­

s u g g e s t t h a t t u b e r s of K en ne be c

c o n d it io n e d f a s t e r t h a n I r i s h C o b b l e r ,
f a s t e r t h a n Sebago.

con d itio nin g of p o t a t o e s

With the K a t a h di n v a r i e t y ,

the op po site

d a r k e r c h i p s w e r e p r o d u c e d a f t e r five m o n t h s than a f t e r

two m o n t h s

cold s t o r a g e .

Date of p l a n ti n g a p p e a r e d to h ave only a s li g h t e ff ec t on c o l o r
q ua lity of c h i p s p r o c e s s e d i m m e d i a t e l y a f t e r the r e m o v a l f r o m cold
storage.

All c h ip s w e r e too d a r k f o r c o m m e r c i a l a c c e p t a n c e .

The o r d e r of r a n k i n g as to c o l o r w a s a l m o s t i d e n t i c a l f o r
c h ip s p r o c e s s e d f r o m t u b e r s
the chips f r o m the
perature.

The

d i r e c t l y out of cold s t o r a g e

and f o r

s a m e t u b e r s a f t e r c onditioning a t a h i g h e r t e m ­

s a m e w a s t r u e w h e t h e r o r not the t u b e r s had b e e n

p r e v i o u s l y s t o r e d f o r two o r five m o n t h s in c old s t o r a g e .
P o t a t o e s f r o m no i r r i g a t i o n w ith 3 -1 2- 1 2 p l o t s p r o d u c e d
l i g h t e r c h i p s t h r o u g h o u t ( a f t e r two as well as five m o n t h s
storage

and a f t e r conditioning)

than i r r i g a t e d

cold

3-12-12 plots.

It is

97

suggested th at i r r i g a t i o n is
enzyme, p h o s p h o ry la s e .

the c o n t r o l l i n g f a c t o r in a c t i v a t i o n of the

I r r i g a t i o n with 0 - 0 - 1 8 m a r k e d l y i n f l u e n c e d

R u s s e t R u r a l p o t a t o e s to m a k e l i g h t e r - c o l o r e d chips than K a ta h d i n
potatoes.

Some

6, 7, and 8.

anatom ical observatio ns

(29)

are

shown in F i g u r e s

98

Figure

6.

A ppearance
City, 1951.
F rom

of p o t a t o c h i p s :

th e t u b e r s

Irish

C obbler variety,

of s p e c i f i c - g r a v i t y

class

Lake

3 (1.067 - 1.073).

TOP:
C h i p s of the t u b e r s f r o m M a y 4 p l a n t i n g ,
a p p e a r a n c e i s l ig h t , p i t h r a y s a r e d a r k .

general

B O T T OM :
C h i p s of t h e t u b e r s f r o m J u n e 4 p l a n t i n g .
e r a l a p p e a r a n c e is d a rk ; c o r t e x is l i g h t e r than pith.
In b o t h t h e c a s e s , f i b r o v a s c u l a r

ring

Gen­

is p r o m in e n tly dark.

99

A p p e a r a n c e of p o t a t o
L a n s i n g , 1951.

chips:

R usset Rural variety,

East

TOP:
F r o m t h e t u b e r s of h i g h s p e c i f i c g r a v i t y , g e n e r a l
a p p e a r a n c e i s light; c o r t i c a l a n d p i t h r e g i o n s a r e e q u a l l y
li g h t , b a s a l p a r t of chip i s d a r k e r t h a n a p i c a l .
Fibrov a s c u la r ring is p ro m in e n tly dark.
BOTTOM:
F r o m the t u b e r s of l o w s p e c i f i c g r a v i t y , g e n ­
e r a l a p p e a r a n c e i s d a r k ; c o r t i c a l a r e a i s l i g h t e r t h a n the
c e n tr a l pith.
F i b r o v a s c u l a r ring is p r o m i n e n t l y d ark .

101

10Z

F ig u r e

8

Appearance
s i n g , 1951.

of p o t a t o

F ibrovascular

chips:

K atahdin v a r ie ty ,

rin g is not p r o m i n e n t l y d a rk .

E ast Lan­

103

SUMMARY AND CONCLUSIONS

The e x p e r i m e n t s w e r e d e s i g n e d to e v a l u a t e the e f f e c t of c e r ­
t a in a g r o n o m i c a l p r a c t i c e s ,
of i r r i g a t i o n ,

s u c h as d a t e s of p la ntin g, d i f f e r e n t l e v e l s

and m i n e r a l f e r t i l i z e r s on the s p e c i f i c g r a v i t y of t u b e r s

and the c o l o r of c h i p s of s e v e r a l v a r i e t i e s of p o ta t o , which w e r e
g ro w n a t two d i f f e r e n t l o c a t i o n s in M i c h i g a n - - L a k e
and 1952) a n d E a s t L a n s i n g

(1951).

City (1950,

1951,

The s tudy a l s o i n c lu d e d the i n ­

fl ue n c e of t e m p e r a t u r e s a n d d u r a t i o n of s t o r a g e of the t u b e r s on the
c o l o r q u a l i t y of p o t a to c h i p s .
A pproxim ately

15,000 t u b e r s w e r e a n a l y z e d in t h e s e i n v e s t i ­

g a ti on s .

V ariety.

R u s s e t R u r a l and Kenne be c v a r i e t i e s p r o d u c e d

t u b e r s of h i g h s p e c i f i c g r a v i t y .
t u b e r s of m e d i u m

specific gravity;

ling 5 05 -3 , of low a v e r a g e
yielded tu b e rs
of m e d i u m

I r i s h C o b b l e r and Sebago p r o d u c e d
a nd Chippewa, P o n t i a c ,

specific gravity.

and S e e d ­

The K a ta hd in v a r i e t y

of l o w s p e c i f i c g r a v i t y a t E a s t L a n s i n g (1951), b ut

s p e c i f i c g r a v i t y a t L a k e City (1951 and 1952).

R u sse t R ural, Kennebec,
golden y e ll o w c o l o r e d c h i p s .

and I r i s h C o b b l e r v a r i e t i e s p r o c e s s e d

C hips of K a ta h d i n t u b e r s w e r e in the

104

105

grade

of c o m m e r c i a l l y a c c e p t a b l e ;

while Chippe wa , P o n t i a c ,

Sebago,

a n d 50 5 - 3 m a d e u n s a l a b l e c h ip s .

2.

Date of p l a n t i n g .

Tubers from

e a rly plantings had higher

s p e c i f i c g r a v i t y t h an t h o s e f r o m l a t e p l a n t i n g s a t b o t h E a s t L a n s i n g
and L a k e
these

C ity in 1951.

B u t the L a k e

results.
R esults f r o m Lake

sing (1951)

City (1950 and 1951)

and f r o m E a s t L a n ­

show t h a t e a r l y - p l a n t e d p o t a t o e s m a d e l i g h t e r - c o l o r e d

c h i p s t h a n t h o s e of l a t e - p l a n t e d .
potatoes m ade
T he se

City c r o p of 1952 c o n t r a d i c t e d

B u t the L a k e

City (1952) l a t e - p l a n t e d

s l i g h t l y l i g h t e r - c o l o r e d c h i p s t ha n t h o s e of e a r l y - p l a n t e d .

c o n t r a d i c t o r y r e s u l t s on s p e c i f i c g r a v i t y and c o l o r of c h i p s

a r e p r o b a b l y due to s e a s o n a l v a r i a t i o n s .
In 1951, t u b e r s

of a g iven s p e c i f i c - g r a v i t y c l a s s f r o m

an e a r l y

date of p l a n ti n g p r o d u c e d l i g h t e r - c o l o r e d c h i p s t ha n t h o s e f r o m the
same

s p e c i f i c - g r a v i t y c l a s s of l a t e p l a n t i n g .

3.
the a v e r a g e
p l o ts

Irrigation.

V a r i o u s l e v e l s of i r r i g a t i o n did n o t i n flu e nc e

s p e c i f i c g r a v i t y of t u b e r s ,

but the t u b e r s f r o m n o n i r r i g a t e d

y i e l d e d s i g n i f i c a n t l y l i g h t e r - c o l o r e d c hips

gated plots.

than t h o s e f r o m

irri­

106

4.
average

F ertilizer.

T u b e r s f r o m the u n f e r t i l i z e d p l o t s h a d h i g h e s t

specific g ra v ity , followed by those which r e c e iv e d

3-12-12 f e r t i l i z e r s

(at the r a t e

3-0-0

a nd

of 1,000 p ou n d s p e r a c r e ) , w h ile the

l o w e s t r a t i n g s w e r e f ou n d in t r e a t m e n t s

of 0 - 0 - 1 8 o r 0 - 0 - 1 2 f e r ­

tilizers.
Tubers fro m

3-12-12 fe r tiliz e d plots yielded m o re -a c c e p ta b le

chips than th ose f r o m plots with o th e r f e r t i l i z e r a n aly ses.
p o t a s h f e r t i l i z e r l o w e r e d the

specific gravity,

Though

it l i g h t e n e d the c o l o r

of c h i p s .

5*

Location.

Average

s p e c i f i c g r a v i t y of the t u b e r s of a

g iv e n v a r i e t y w a s h i g h e r a nd c o l o r of c h i p s w as l i g h t e r f r o m L a k e
City than f r o m E a s t Lansing.

6.
ratings

Season.

C onsidering v a rie ta l av erag es,

specific-gravity

and chip c o l o r r a t i n g s w e r e h i g h e r ip. 1952 t h a n t h o s e f r o m

1950 a n d 1951.

7.

R e d u c in g s u g a r s .

The c o n t e n t of r e d u c i n g s u g a r s

and

c o l o r of p o t a t o c h i p s v a r i e d n o t o n ly f r o m v a r i e t y to v a r i e t y , b u t
a l s o w i th i n a v a r i e t y a nd w ith in t h e
f r o m one d a te of p l a n t i n g to a n o t h e r .

same

specific-gravity class

107

8.

Storage.

a.

Chip c o l o r i m m e d i a t e l y a f t e r five m o n t h s

c old s t o r a g e

(41°

F.)

w a s d a r k e r t h a n a f t e r two m o n t h s .

B u t a f t e r c o n d itio n in g

(78°

F.)

of p o t a t o e s f o llo w in g five m o n t h s c o l d s t o r a g e ,

Russet

R u r a l m a d e l i g h t e r - c o l o r e d c hips t h a n a f t e r two m o n t h s , b u t K a t a h d i n
p r o c e s s e d d a r k e r c h i p s a f t e r five m o n t h s t h a n a f t e r two m o n t h s .
b.

S u b s e q u e n t to two m o n t h s c old s t o r a g e , t u b e r s of K e n n e ­

b e c c o n d i t i o n e d f a s t e r t ha n I r i s h C o b b le r, and K a ta hd in f a s t e r than
Sebago.
c.

The o r d e r of r a n k i n g a s to c o l o r w a s i d e n t i c a l f o r c hips

p r o c e s s e d d i r e c t l y out of c o ld s t o r a g e (two o r five months)
c h ip s f r o m the
d.

same tubers

as f o r

a f t e r c onditioning.

D ate of p l a n t i n g h a d only a s l i g h t e f f e c t on c o l o r q u a li ty

of c h i p s m a d e i m m e d i a t e l y a f t e r two a s we ll a s five m o n t h s cold
storage.

The s t r i k i n g e f f e c t of date of p l a n t i n g showed up in p o t a t o e s

c o n d i t i o n e d a f t e r two m o n t h s c o ld s t o r a g e .
gave

The f i r s t date of p la nt in g

s i g n i f i c a n t l y l i g h t e r - c o l o r e d c hips t h an the l a t e r p l a n t i n g s .

H o w e v e r , t h e r e w e r e no a p p a r e n t d i f f e r e n c e s b e t w e e n the d a t e s of
p l a n t i n g a s j u d g e d b y the c o l o r of c h i p s of the t u b e r s
a f t e r fiv e m o n t h s in c old s t o r a g e .

9.

Some a n a t o m i c a l a s p e c t s

are

shown.

conditioned

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p otato es.
A m e r . Che m. Soc., Div. A g r . and F o o d Chem.
A bs. of p a p e r s 110th M e e tin g , P . 10A., 1946.

42.

Pyke,

43.

Rogers,

44.

Sa lunkhe , D. K.,
ter.
The
Hydrazide
q u a l i t y of
1953.

45.

S h a l l e n b e r g e r , R.
S., and O. S m i t h. The m e c h a n i s m f o r
the
d e v e l o p m e n t of c o l o r in p o ta to c hi p s.
A m e r . Soc. H o r t .
Sc. 49th M e etin g. Abs. of p a p e r s .
P . 3, 1952.

46.

S h a l l e n b e r g e r , R. S., and O. Sm ith .
C o n s t i t u e n t s o t h e r than
r e d u c i n g s u g a r s t h a t c a u s e c o l o r in potato c h ip s.
Potato
A s s o c . A m e r . M e e tin g . Abs. of p a p e r .
P . 4, 1952.

47.

Sm ith, O.
R e s e a r c h n e e d s of the potato chip i n d u s t r y .
P o t a t o J o u r . 2 7 : 1 18 - 12 2, 1950.

48.

S m ith , O., and E .
B. N a s h . P o t a t o
qu ality III:
R e la tio n of soil
r e a c t i o n , i r r i g a t i o n , and m i n e r a l n u t r i t i o n to cooking
qua lity.
A m e r . Soc. H o r t . Sci. P r o c . 38:507-512, 1940.

49.

S m i t h, O., a nd L.
B. N a s h . P o t a t o
Qu ality V.
R e l a t i o n of tim e
of p l a n t i n g , t i m e of h a r v e s t , and f e r t i l i z e r t r e a t m e n t to
c o m p o s i t i o n and cooking q uality.
Am. Soc. A g r o. J o u r .
3 4:4 37 -4 5 1 , 1942.

W. E . , a nd G. J o h n so n .
Several discoveries, resu lt from
S t a n t o n ' s i n v e s t i g a t i o n of cooking q u ality of p o t a t o e s .
Col.
F a r m . B u l l. 3 ( Co lo r ad o Sta.), No. 2 :1 5 - 1 9 , 1941.
M. C., C. F . R o g e r s , and A. M. C h ild s .
The m a ki ng
of p o ta to c hips in r e l a t i o n of s o m e c h e m i c a l p r o p e r t i e s
of p o t a t o e s .
A m e r . P o t a t o J o u r . 14:269-290, 1937.
S. H. W it t w e r , E. J. W h e e l e r , and S. T. D e x ­
in fl u e nc e of a p r e h a r v e s t f o l i a r s p r a y of M a le ic
on the s p e c if ic g r a v i t y of p o t a t o e s a nd the
p o t a to c h i p s.
F o o d R e s . 18, No. 2:191 -196,

Am.

113
50.

S n e d e c o r , G. W.
S t a t i s t i c a l M e th o ds .
P r e s s , A m e s , Iowa, 1948.

The Iowa State

College

51.

S p a r k s , W. C.
The f e e d in g h a b i t s of m i c e as c o r r e l a t e d with
the s p e c i f i c g r a v i t y of the s t e m and bud e n d s of p ot a to .
P r o c . A m . Soc. H o r t . Sc. 5 8 :288- 290, 1951.

52.

Stuart,

Wm.
cation;

The pota to:
i t s c u l t u r e , u s e s , h i s t o r y , and c l a s s i f i ­
518 pp.
J. B. L i p p i n c o t t Co., P h i l a d e l p h i a , 19^3.

53.

Stutz,

R. E . , a n d R. H. B u r n s .
F a c t o r s i n f lue ncing oil c o n te n t
of p o t a t o c h ip s .
F o o d Indu s. 20:1 146-114 9, 1243-1246,
1948.

5 4.

S w e e t m a n , M. D.
C o l o r of p ota to c h i p s as i n f l u e n c ed by s t o r a g e
t e m p e r a t u r e s of the t u b e r s and o t h e r f a c t o r s .
Jour.
A g r. R e s . 4 1:479- 490, 1930.

55.

T e r m a n , G. L.
E f f e c t of s o u r c e of p o t a s h in the f e r t i l i z e r on
the y i e l d a nd on the s t a r c h c o n t e n t of p o t a t o e s .
Amer.
P o t a t o J o u r . 26:291- 299, 1949.

56.

T e r m a n , G. E .
E f f e c t of r a t e and s o u r c e of p o t a s h on y ie ld
a nd s t a r c h c o n t e n t of p o t a t o e s .
Maine A gr. Exp. Bull.
4 8 1 :1 -2 4 , 1950.

57.

T e r m a n , G. L . , P . N. C a r p e n t e r , and S. C. J u n k i n s .
Nutrient
c o n t e n t of p o ta to p l a n t a s a f f e c t e d by f e r t i l i z e r t r e a t m e n t
a nd o t h e r f a c t o r s .
Soil Sci. Soc. A m e r . P r o c . 14:137142, 1950.

5 8.

T h i e s s e n , E. J .
C u l i n a r y q u a l i t i e s and n u t r i t i v e v a l u e s of p o ­
t a t o e s g r o w n upon d r y a nd i r r i g a t i o n land.
Wyo. A g r .
Exp. Bull. 2 80:1-31 , 1947.

59.

T h o r n t o n , N. C.
C a r b o n dioxide s t o r a g e VIII:
c h e m ic al changes
in p o ta to t u b e r s r e s u l t i n g f r o m e x p o s u r e to c a r b o n dioxide
contrib.
Boyce T h o m p s o n I n s t . , 7 :113- 118, 1935.

60.

U n p u b l i s h e d d at a, D e p a r t m e n t of F a r m
C o l l e g e , 1951, 1952, and 1953.

Crops,

M i c h i g an State

114
V a n a s s e , 14. A ., I. D. J o n e s , and H. L, L u c a s .
Specific g r a v i t y d r y m a t t e r r e l a t i o n s h i p in p o t a t o e s .
Am er. Potato Jour.
2 8 :7 8 1 -7 9 1, 1951.
62.

W a g e r , H. G.
Q u a l i t y of p o t a t o e s in r e l a t i o n to soil a nd s e a s o n .
J o u r . A g r . Sc.
36:207-213, 1946.

63.

W h e e l e r , E. J .
R e s i d u a l e f f e c t of c r o p r o t a t i o n s on po ta to yield
a nd p r e s e n c e of p o ta to sc a b .
M i c h. A g r . Exp. Q u a rt .
Bull. 2 8 : 3 2 6 -3 3 2, 1946.

64.

W h e e l e r , E. J . , a nd D. K. Salunkhe.
Spe cif ic g r a v i t y and date
of p l a n t i n g a s it i n f l u e n c e s the c o l o r of potato c h i p s .
P o t a t o A s s o . A m e r . M ee ting Abs. of p a p e r s .
P . 3, 1952.

65.

Wolff, C. J. DE.
Die S a c c h a r o s e - b i l d u n g in K a r t o f f e l n W a h r e n d
de s T r o c k n e n s .
B i o c h e m . Z e i t s . 176:225-245, 1936.

66.

W r i g h t , R. C., M. E. D a v i s , and C. H ende l.
Making of pota to
chips.
U. S. A g r. Y e a r Book.
188-189, 1951.

67.

W r i g h t , R. C ., W. M. P e a c o c k , T. M. W h item an , and E. F .
W h i te m a n .
The cooking q ua lity, p a l a t a b i l i t y , and c a r b o ­
h y d r a t e c o m p o s i t i o n of p o t a t o e s as i n fl u e nc e d by s t o r a g e
tem perature.
USDA T ech . Bull. 507, 1936.

68.

Wright,

R. C., and T. M. W h ite m an.
P r o g r e s s r e p o r t on the
ch ip p in g q u a li t y of t h i r t y t h r e e potato v a r i e t i e s .
Am er.
P o t a t o J o u r . 2 6 :117- 120, 1949.

69.

W r i g h t,

R. C., a nd T. M. W h i te m a n .
p o t a t o e s f o r chip m a n u f a c t u r e .
1951.

70.

X a n d e r , P . A.
P r o b l e m s of the potato chip i n d u s t r y .
C h i p p e r . Vol. 8, No. 7, 1949.

V a r i e t i e s and handling of
P o t a t o C h i p p e r 10:50,

Potato

APPENDIX

115

116
A p p e n d i x T a b le I.
Tbe p e r c e n t a g e of t u b e r s in e a c h s p e c i f i c - g r a v i t y
c l a s s a n d the a v e r a g e s of the c hip c o l o r r a t i n g s ^ of the t u b e r s
of s i x v a r i e t i e s a n d t h r e e d a t e s of p l a n t i n g , L a k e C i ty , 1951.

Date s
of
P lant­
ing

May 4

May 2 3

June

4

Chippewa

Irish

C obbler

% of
Tu ­
bers

Chip
Color

•Ketahdin

Sp.~

G r.2
Clas s

% of
Tu­
bers

Chip
Color ^

1
2
3
4
5
Avg. ^
Tubers

21.8
23.6
24.5
20.1
-

1
2
3
4
5
Avg.
Tube r s

44.0
32.0
17.3
6.7
1.066
75

6.5
6.5
7.1
7.8
6.7

1
2
3
4
5
Avg.
Tube r s

96.2
3.8
1.062
52

5.3
6.5

1.071
55

7.0
7.0
7.4
9.0
7.5

-

-

5.3

.

2.9

10.0
82.8
4.3
1.0 80
70

7.0
8.5
9.5
10.0
9.3

—

-

12.4
34.8
49.4
3.4
1.077
89
10.4
26.9
2 3.8
38.9
1.073
67

8.4
8.5
9.2
10.0

1 = belo w
5 = 1.088
2 = 1.067;

7.7
11.5
5.8
71.2
3.8
1.079
52
2.9
2.9
20.6
69.2
4.4

8.9

1.079
68

5.9
6.5
8.0
8.2
7.4

62.7
20.8
16.5
—
1.065

Chip
Co lo r

6.6
9.0
9.4
10.0
10.0
9.6

5.7
6.0
9.0
9.3
10.0
9.0

5.5
5.6
7.0
5.8

67

1 = e x t r e m e l y d a r k ; 10 = l i g h t yellow ;
y e l l o w ( m o s t d e s i r a b l e ) ; 7.5 to 10 = a c c e p t a b l e .
S pecific-gravity classes:
1.070 to 1.076; 4 = 1.076 to 1.088;
f o r weighted a v e ra g e s :
1 = 1.064;
5 = 1.090.

% of
Tu­
be r s

8.5 to 9 - g o l d e n

1.064; 2 = 1.064; 3 =
and o v e r. C la s s values
3 - 1.073; 4 = 1.082;

117
Appendix

Kennebec
% of
Tu­
bers

Chip
Color

7.5
8.0
9.8
8.7

15.9
38.6
45.5
-

1.0 80
44

6.0
6.5
7.2
8.3

10.5
23.7
15.8
50.0
-

-

Table I (Continued)

Rus s e t R u r a l
% of
Tu­
bers

3.9
9.8
56.9
29.4
1.083
51
-

Chip
Colo r

6.3
9-2
9-7
10.0
9-6

-

2.6
12.8
79.4
5.2
1.0 80
78

8.0
9-0
9.4
9-5
9-3

1.075
38

7.5

1.8
1.8
9.4
87.0

3.8
6. 3
7.6
7.7

10.0
2.0
34.0
54.0

8.0
8.2
8.6
9-0

1.080
54

7.5

1.076
50

8.7

3

Ave r ag e

Sebago
% of
Tu­
bers

Chip
C olor

9.8

5.5

-

-

9.8
65.9
14.5
1.0 80
41

5.8
8.3
9.5
8.0

1.4
11.4
34.3
50.0

5.2
6.5
8.2
8.5
8.8
8.0

2.9
1.077
70
36.2
13.1
30.4
20.3
1.070
69

% of
Tu­
bers

6.6
9.6
18.1
57.1
8.6
1.078
313
9.8
14.2
22.6
50.8
2.6
1.076
418

Chip
Color

6. 4
7.4
8.2
914
9.9
8.8

5.9
6.9
8.1
8.7
9-5
8.0

5.0
5.4
5.5
7.2

36.2
11.4
19- 0
33.4

5.5
6.4
7.3
8.0

5.6

1.071
359

6.8

A v e r a g e s of the chip c o l o r r a t i n g fo r the t u b e r s in t h a t
specific- gravity class.
4
T h e s e a v e r a g e v a l u e s a r e w e i g h t e d a c c o r d i n g to the p e r c e n t a g e of t u b e r s in the s e v e r a l s p e c i f i c - g r a v i t y c l a s s e s .
The f i r s t
v a l u e of e a c h p a i r i s the w e ig h t e d a v e r a g e s p ec if ic g r a v i t y .
The
s e c o n d v a l u e i s the w e i g h t e d a v e r a g e of the chip c o l o r r a t i n g s f o r
the s e v e r a l s p e c i f i c - g r a v i t y c l a s s e s .

118
A p p e n d i x T a b l e II.
The p e r c e n t a g e of t u b e r s in e a c h s p e c i f i c - g r a v i t y
c l a s s a n d the a v e r a g e s of the c hip c o l o r r a t i n g s ^ - of o n e - h a l f
of e a c h t u b e r a f t e r c o l d s t o r a g e a t 41° F . f o r two m o n t h s
a nd of the r e m a i n i n g h a l v e s , f o l l o w i n g t h i r t y d a y s of c o n d i ­
t i o n i n g a t 78° F . , f o r f iv e v a r i e t i e s , on t h r e e d a t e s of p l a n t i n g
a n d f o u r i r r i g a t i o n - f e r t i l i z e r t r e a t m e n t s , E a s t L a n s i n g , 1951.

I r i s h C ob b le r
Sp.Gr.
C lass

D a t e s of P l a n t i n g

No I r r i g a t i o n ,
M a y ZI

...........................

.

.

1
2
3
4
5 4
Avg.
Tube r s

June

13 ...........................

.

.

1
2
3
4
5
Avg.
Tubers

June

25 ...........................

.

.

1
2
3
4
5
Avg.
T ub e r s

% of
Tu ­
bers

Chip 3
Color
05

305

Katahdin

rri
r
%
m of
Tu­
bers

Chip
c*~\
C olor
0

30

r
4.3
5.0
5.1

r
8.0
8.5
8.9

-

-

1.071
60

4.6

8.3

23.3
63.3
3.3
10.1

4.3
4.3
4.5
r

8.3
8.6
8.8
r

-

-

w i t h 3-• 12-12
-

~

5.8
26.7
33.3
6.4
33.3
6.5
6.7
r
1.076 6.3
60

-

9*3
9.6
9.9
r
9.6

—

80.0
6.7
13.3
-

5.0
5.1
5.3

8.5
8.9
9*3

-

-

1.069 5.1
30
-

37.9
2 4.3
34.4
3.4
1.074
60

—

4.0
5.0
5.8
6.0
4.9

8.6

—

6.0
7.8
8.0
8.5
7.2

3.3
56.6
18.3
21.7
-

-

1.068 4.3
60

8.5

3.3
5 9-0
18.0
19*7

r
4.6
5.0
5.7

r
8.2
9-0
9*2

-

-

4.8

8.5

-

1.069
60

Appendix Table II (Continued)

Kennebec

% of

Tu­
bers

R usset Rural

Chip
Color
0

30

% of

Tu­
bers

Chip
C olor
0

30

Sebago

% of

Tu­
bers

Aye r a g e

Chip
Color
0

30

% of

Tu­
bers

Chip
Color
0

30

2.8
31.8
22.2
41.4
1.8
1.075
300

3.5
4.8
5.3
5.8
6.0
5.3

8.0
8.4

4.4
4.8
5.0
5.5
5.6

No I r r i g a t i o n , w it h 3- 12-12
10.8

3.5
5.0
9.9
17.2
5.3
5.3
60.0
2.1
6.0
1.077 5.1
60

8.0
9.0
9.5
9.6
9.6
9.4

_

10.1
13.3
71.6
5.1

3.5
5.0
5.2
5.6
l".079 5.0
60

5.3
17.8
28.6
48.3
..

3.8
4.8
5.0
5.1
—

1,076 4.9
60

-

20.7
24.1
55.2
-

-

_

5.3
5.8
6.0

9.2
9.8
9.9

-

-

1.077 5.8
60
—

9.7

_

_

6.1
5.6
6.0

9.7
9.8
9.9

-

-

_

_

45.0
18.3
36.7
1.0 74
60

3.7
4.2
6.0
4.6

6.5
7.2
9.3
7.7

20.0
35.0
31.0
13.3

4.5
5.0
5.1
5.6

6.7
7.2
7.7
8.0
7.3

8.7
44.7
19.3
26.3
1.0
1.072
270

3.5
4.2
5.5
6.1

6.7
7.5
8.2
8.8

-

-

4.1
4.7
5.3
5.7
29.9
6.0
0.7
1.0 71 5.1
295

7.0
8.2
9.6
9.8

35.0
41.7
23.3

9.1

1.073 5.8
60

9.7

1.070 5.0
60

7.0
8.8
9.0
9.0

4.9
41.0
33.5
18.6

5.0
6.0
6.1
6.2
—
1.071 6.0
60

6.5
8.6
9.0
9.6

18.3
30.1
23.3
28.3

—

8.8

-

-

8.8

-

-

-

1.072 4.9
60

7.8

6.5
37.2
25.6

4.9

8.9
9.5
9.6
9.0

7.5
8.2
8.7
9.2
9.8
8.5

6.7
7.8
8.6
8.9
8.5
8.3

1Z0
Appendix

Table II

(Continued)

Irish

Dates

Sp.Gr.
Cl a s s

of P l a n t i n g

Irrigation,
M ay Z 1

.........................................................................

% of
Tu­
be r s

Chip
C olo r
0

30

Katahdin

% of
Tu­
be r s

Chip
C olor
0

30

4.0
4.1
4.5
4. 6

7.0
8.0
8.5
8.5

w i t h 3- 1Z- 1Z
5.8
47.1
Zl. 3
Z5.8

1
Z
3
4

C o b b le r

4.3
50.2
15.4
30.1

4.5
5.0
5.7
6.1

8.0
8.6
9.5
9.8

1.07Z 5.4
116

9.0

1.072
117

4.3

8.Z

3.Z
3.7
4.0
5.5

6.3
8.0
8.6
9.0

3.8

7.7

3.0
3.3
3.0
3.0

5.6
6.5
7.0
7.0

3.Z

6.3

3.8
4.Z
4.5
5.0
44.9
3.3
r
1.074 4.5
116

7.7
7.9
8.1
9.0
r
8.4

C

D

Avg.
Tube r s
June

13

.........................................................................

1
Z
3
4

3.3
51.Z
Z0.8
Z4.7

4.0
4.5
4.8
5.0

6.5
7.4
8.Z
8.5

25.9
49. 3

1.071
1Z0

4.6

7.8

1.068
1Z0

-

-

4.8
5.5
6.0

7.1
6.5
7.0

1.074 5.4
91

6.8

14.9
9-9

c

D

Avg.
Tube r s
J une

Z5

.........................................................................

1
Z
3
4

-

36.7
30.0
33.3

2Z.6
67.2
6.8
3.4

C
D

Avg.
Tube r s
Irrigation,
M a y Z1

.........................................................................

1.066
120

w i t h No F e r t i l i z e r

1
Z
3
4
5
Avg.
Tubers

1.9
Z3.4
16.1
49.7
8.9
1.077
1Z0

4.0
5.0
5.3
5.4
6.0
5.3

7.0
8.8
9.6
9.2
9.8
9.2

16.9
21.3
13.5

121
Appendix Table II (Continued)

Kennebec

% of
T u­
bers

R usset Rural

Chip
Colo r
0

30

% of
Tu­
bers

Chip
Color
0

30

Ay e r a g e

Sebago

% of
Tu­
bers

Chip
Color
0

30

% of
Tu­
bers

Chip
Colo r
0

30

7.2

I r r i g a t i on, with 3 - 12 - 12
1.7
18.4
22.7
49-4
7.7
1.077

3.5
4.2
5.5
5.0
5.0
4.9

r
7.5
8.5
9.1
9-2
8.6

24.1
3.3
70.3
2.3
1.078

5.0
5.3
5.4
r
5.2

8.5
8.8
9-8
r
9.4

3.5
4.8
5.7
30.9
24.3
6.1
1.072 5.3
67

6.5
8.7
9.1
9.6
-

9.7
4.5
47.7
4.9
5.5
19.4
23.2
6.5
1.071 5.3
75

7.4
8.5
8.7
8.8
8.5

69

119
4,0
4.0
25.9
4.3
14.9
5.1
51.5
5.5
5.9
1.076 4.7
120

r
8.5
8.8

3.0
4.0
4.3
4.0
5.0

4.0
5.0
8.0
8.1
9.0
7.0

1.8

5.5
25.9
11.3
55.6
1.7
1.076

-

3.9

9.1
9*6
8.9

119

3.3
41.5

8.9

10.0
36.7
8.3
41.7
8.3
1.074
60

3.3
4.2
5.2
5.6
r
4.8

6.5
7.2
8.7
9.0
r
8.0

4.4
34.2
14.2
43.5
3.7
1.074
481

3.7
4.5
5.2
5.3
5.0
4.9

20.9
65.2
5.3
8.6
1.067
120

3.1
3.5
4.3
5.0
3.5

6.0
7.2
7.6
8.8
7.1

11.0
46.6
17.4
23.8
1.2
1.071
547

3.6
4.1
4.6
5.3
5.5
4.4

7.9
8.5
9.0
9.6
8.1

r
5.8
1
7.1
7.5
6.5

8.2
39.7
18.5
32.4
1.2
1.072
525

3.5
4.2
4.6
4.7
5.3
4.3

5.7
6.6
7.3
7.6
8.3
7.0

7.4
23.5
14.4
44.0
10.7
1.077
446

3.7
4.3
4.8
5.3
5.8

6.4
8.3
8.7
9.4

3.3
r
4.0
21.0
25.0 4. 8 6.
5.3
46.7
4.0
5.5
1.076 4.9
120

7.9
8.8
9-2
9*2
8.6

6.3

I r r i g a t i o n , w ith No F e r t i l i z e r
1.6
20.0

3.0
3,5
4.5
8.9
4.9
54.9
5.0
14.6
1.079 4.6
120

5.0
8.0
9*0
9.7
r
9-1

_
8.7
8.7
53.5
10.1
1.078
60

5.5
5.5
6.0
6.5
5.6

9.0
9.0
9.6
10.0
8.7

16.7
25.0
25.0
16.8
16.7
1.074
30

4.0
4.1
4.5
5.0
r
4.4

6.0
7.5
8.0
9.5
r
7.7

4.9

9.9
8.9

122
Appendix

Table II (Continued)

I r is h Cobbler
S p .G r.
Clas s

D a t e s of P l a n t i n g

Irrigation,
June

June

13 . .

25

. .

1
2
3
4
5
Avg.
Tubers
Irrigation,

M ay 21

Chip
Color

% of
Tu­
bers

0

w i t h No F e r t i l i z e r
1
2
3
4
5
Avg.
Tubers

1
2
3
4

% of
Tu­
be r s

30

Chip
Colo r
0

30

(Continued)

5.0
1.6
23.5
4.5
16.1
4.5
49.2
5.0
9.6
r
1.077 4.7
120
1.6
13.2
30.6
5 1.3
3.3
1.073
90

Katahdin

4.0
5.1
6.0
5.3
6.0
5.4

7.0
7.5
7.6
8.6
r
8.1

6.0
7.8
7.8
6.8
7.0
7.2

11.7
58.3
10.0
20.0

3.5
4.1
4.5
4.7
1.0 70 4.2
120
25.9
42.5
11.5
21.6
-

1.069
120

6.0
7.0
8.0
8.1
-

7.2

3.4
4.4
4.4
5.3

7.8
7.9
7.2
9.0

-

-

4.3

8.0

3.7
4.2
4.4
4.5

7.7
8.1
8.5
8.5

4.2

8.2

4.1
4.3
4.2
r

7.0
7.0
8.5
r

4.2

7.2

w i t h 0-0 --18
3.3
33.3
18.3
45.1

4.0
4.8
5.5
5.8

7.1
8.5
9.3
9.4

5.3

9.0

33.5
27.1
14.1
2 5.3

r
4.3
5.0
5.0

r
8.2
9.6
9.2

1.070
98

4.7

8.8

10.0
5 6.6
20.0
13.3

c

D

Avg.
Tube r s
June

13 . .

1
2
3
4

1.075
120

1.071
120
27.0
57.9
10.8
4.2

c

D

Avg.
Tubers

1.067
120

123

A p p en d ix T a b le II (Continued)
Kennebec
% of
Tu­
bers

Russet Rural

Chip
Color
0

30

% of
Tu­
bers

Chip
Color
0

30

Sebago
% of
Tu­
bers

Average

Chip
Color
0

30

% of
Tu­
bers

Chip
Color
0

30

Irrigation, with No Fertilizer (Continued)
1.7
13.6
19-6
48.3
16.8
1.079
120

2.9
4.3
4.5
5.0
5.0
4.7

r
7.0
8.3
8.6
9-5
8.4

1-9
18.6
28.6
50.9

2.0
17.6
15.6
63.1
1.7
1.078
117

3.0
3.3
4.5
4.4
r
4.1

7.0
7.7
7.3
8.3
r
8.0

23.9
33.6
10.9
31.6

-

r
r
5.2 8.0
5.3 8.5
6.1 9.4
-

1.076 5.6
91

-

-

8.8

5.2 6.5
5.5 7.5
5.8 8.1
6.0 8.9
-

-

1.071 5.6 7.7
117

9-1
60.3
11.5
19-1

4.5
4.1
4.5
r

7.0
6.8
8.1
r

-

-

-

1.070 4.2
90

7.0

6.6
36.7
35.0
21.7

4.0
5.2
6.0
6.5

6.0
7.0
8.0
8.6

-

-

-

1.076 5.6 7.3
60

5.2
34.9
17.2
37.5
5.2
1.075
541

3.9 6.6
4.4 7.2
4.7 8.1
5.2 8.6
5.0 9.6
4.6 8.0

12.0
28.6
20.6
37.8
1.0
1.073
504

3.9 6.6
4.7 7.5
5.3 7.6
5.5 8.3
6.0 7.0
5.0 7.7

6.1
43.9
19.8
29.2
1.0
1.072
510

4.2
4.8
5.0
5.6
r
5.0

7.4
8.5
8.9
9.2
r
8.7

20.1
33.0
13.4
31.7
1.8
1.071
538

3.9

6.5
7.5
8.7

Irrigation, with 0-0 -18
5.6
37.3
22.7
29.5
5.0
1.074
120

r
5.0
5.0
6.6
r
5.5

3.2
12.9
11.3
63.7
9.0
1.079
120

3.5 5.5
4.0 6.8
4.5 8.1
4.7 9-6
4.6 9.6
4.5 8.4

r
9-0
9.0
9.5
r
9.2

3.2
44.2
21.4
31.2

5.0
5.1
5.3
5.5

7.3
9-0
9-7
9.8

8.3
48.3
16.7
26.7

4.0
4,7
5.0
5.6

7.5
8.0
8.3
8.6

-

-

-

-

-

-

1.073 5.2
90
_

28.8
14.4
56.8
-

-

9.3
-

4.6 8.4
6.0 9.0
6.2 9-7
-

1.076 5.7
80

-

9-2

1.072 4.9
60
36.6
38.3
16.6
8.5

4.0 7.0
5.1 7.4
5.7 8.3
6.0 9.0

1.067 4.8

-

120

8.2

-

7.5

4.4

5.1
5.5
4.6
4.7

9-3

9.6
8.1

124
A p p e n d ix T a b le II (C o n tin u ed )
Irish Cobbler
Date s of Planting

Sp.Gr.
Clas s

% of
Tu­
bers

Chip
Color
0

30

Katahdin
% of
Tu­
bers

Chip
Color
0

30

3.3
3.7
4.0
-

6.1
7.6
8.0
-

1.065 3.5
118

7.1

Irrigation, with 0 - 0 - 1 8 (Continued)
June 25 ....................................

1
2
3
4
c
D
Avg.
Tube rs

4.0
4.9
5.4
5.3

5.5
6.7
7.5
8.3

1.070 4.9
90

7.0

11.5
52.4
13.9
24.2

34.6
5 6.8
8.6
-

1 = extremely dark; 10 = light yellow; 8.5 to 9 = golden
(most desirable); 7.5 to 10 =acceptable.

yellow
2

Specific-gravity classes;
1 —below 1.064; 2 = 1.064 to
1.076;3 = 1.070 to 1.076; 4 - 1.076
to 1.088; 5 =1.088 and over.
Class
values for weighted averages; 1 = 1.0 62; 2
= 1.067; 3 =
1.073; 4 = 1.082; 5 = 1.090.
3
Averages of the chip color ratings for the several specificgravity c l a s s e s .
4
These average values are in sets of three and are obtained
by weighting according to the percentage of tubers in the several
specific-gravity c l a s s e s .
The firs t value of each set is the weighted
average specific gravity.
The second and third values are the
weighted averages of the chip color ratings.
5
Potatoes were stored at 41° P. for two months; one—
half of
each potato was chipped immediately following 41° F. (0) and the
remaining halves were conditioned at 78° F. for 30 days and then
chipped (30).
r
Indicates potatoes had become rotten in storage.

125
A p p e n d ix T ab le II (C ontinued)
Kennebec
% of
Tu­
bers

Russet Rural

Chip
Color
0

30

% of
Tu­
bers

Chip
Color
0

30

Average

Sebago
% of
Tu­
bers

Chip
Color
0

30

% of
Tu­
bers

Chip
Color
0

30

3.7
4.5
5.1
5.3
r
4.6

5.5
7.0
7.8
8.4
r
7.2

Irrigatio n, ’with 0 -0-18 (Continued)
10.0
35.0
23.3
31.7
-

3.0
4.0
5.0
5.0
-

1.072 4.4
120

3.5
6.5
8.3
9.0
7.4

5.2
42.3
16.8
30.6
5.1
1.073
57

5.0 7.0
5.3 7.2
5.8 8.0
r
r
r
r
5.4 7.4

12.9
38.1
16.5
32.5
1.072
90

3.6
4.8
5.4
5.5
4.9

5.5
7.2
7.5
7.8
7.2

14.9
44.9
15.6
23.6
1.0
1.070
475

126

1

A p p e n d i x T a b le III.
The a v e r a g e c hip c o l o r r a t i n g s
of o n e - h a l f of
e a c h t u b e r a f t e r the c o l d s t o r a g e a t 41° F . f o r f i v e m o m t h s
a n d of the r e m a i n i n g h a l v e s f o l lo w i n g t h i r t y d a y s of c o n d i ­
ti o n i n g a t 7 8° F . f o r two v a r i e t i e s on t h r e e d a t e s of p l a n t i n g ,
a n d f o u r i r r i g a t i o n - f e r t i l i z e r t r e a t m e n t s , E a s t L a n s i n g , 1951.

Nc►Irrigation
3- 12-12
Sp.Dates of Planting

Gr' 2
Clas s

Russet
Rural
Chip ^
Color
o5 30

May 2 1 .....................

Katahdin
Chip
Color
0

30

Rus set
Rural
Chip
Color
0

Katahdin
Chip
Color

30

0

30

-

-

3.0

8.0

-

-

2.0

5.9

2

4.0

8.0

3.5

8.0

3.0

8.0

2.0

6.8

3

5.0

9.8

3.0

8.0

3.5

8.5

1.5

r

4

5.8

9-9

5.5

9.3

5.0

9.5

-

-

-

-

-

-

r

r

-

-

5.2

9.4

3.8

8.2

4.2

8.9

1.9

6.4

1

-

-

2.0

8.1

r

r

1.8

5.0

2

5.8

9.2

2.9

8.4

5.0

r

2.4

6.2

3

5.6

9.6

3.9

r

3.5

8.0

2.6

7.1

4

5.1

9.8

r

r

4.2

9.2

4.4

8.0

5.5

9.4

2.7

8.3

4.2

8.7

2.7

6.4

1

5
Avg.
June 13 .....................

5

Ir rig ation,
0 -0-0

4

£

D

Avg.

127
A p p e n d ix T ab le III (C ontinued)

Irrigation,
0 -0-18
Russet
Rural
Chip
Color

Irrigation,
3-12-12

Katahdin
Chip
Color

0

30

-

—

-

—

7.1

4.0

8.5

3.5

3.0

8.4

3.5

8.5

4.5

9.1

4.0

9.3

r

r

30

0

30

4.2

8.0

2.0

7.7

3.6 9.8

2.6

4.0

9.9

4.0

9.9

0

Katahdin
Chip
Color

30

0

3.8 9.8

Russet
Rural
Chip
Color

Average
Russet
Rural
Chip
Color

Katahdin
Chip
Color

Avg.
Chip
Color
0

30

0

30

0

30

4.2

8.0

2.0

6.7

3.1

7.4

6.9

3.6 8.8

3.1

7.3

3.4

8.0

3.6

7.8

4.3 9.5

2.9

8.0

3.6 8.7

3.0

8.5

4.7

9.6

4.1

8.9

4.4 9.2

3.8 8.6

2.9

7.6

3.9 9.1

3.3 7.4

4.3 9.3

3.2 7.8

—

—

2.0

7.2

3.0

r

1.6

6.8

3.0

r

1.9

7.0

2.4

7.0

5.2

9.0

2.5

7.6

3.9

8.6

2.5

7.7

4.9

8.9

2.5

7.5

3.7

8.2

6.0 10.0

3.0

7.7

4.0

9.0

2.6

7.7

4.8 9.1

2.8

7.5

3.8 8.3

4.2

9.5

3.5

8.9

5.1

9.6

r

r

4.5 9.5

4.2

8.1

4.4

-

-

-

-

-

-

-

-

-

-

-

2.5

7.5

4.2

9.0

2.3

7.4

2.6

7.4

3.7

4.8 9.4

-

-

4.6 9.1

8.8

8.2

1Z8
A p p e n d ix T a b le III (C on tin u ed )
No1 Irrigation,
3-12-12
Sp.Gr.
Class

Dates of Planting

June 25 .....................

Rus set
Rural
Chip
Color

Irrigation
0-0-0

Katahdin
Chip
Color

Russet
Rural
Chip
Color

Katahdin
Chip
Color

0

30

0

30

0

30

0

30

1

5.0

r

r

r

4.8

8.6

3.3

6.0

2

4.7

9.0

2.1

8.4

5.6

8.7

3.5

6.0

3

5.3

9.8

2.0

9.5

5.0

8.5

3.5

7.0

4

5.5

9.8

4.1

9.5

4.0

8.0

3.6

7.1

5.1

9.4

2.5

8.8

4.8

8.4

3.4

6.3

zc>
Avg.

1 = extremely dark; 10 = light yellow; 8.5 to 9 — golden
yellow (most desirable); 7.5 to 10 = acceptable.
Specific
1.070; 3 = 1.070
Class values for
1.073; 4 = 1.082;

gravity classes:
1 = below 1.064; 2 = 1.064 to
to 1.076; 4 = 1.076 to 1.088; 5 = 1.088 and over.
weighted averages:
1 = 1.0 62; 2 = 1.067; 3 =
5 = 1.090.

3

Averages of the chip color rating for the tubers in that
specific-gravity c la ss.
4

These average values are weighted according
age of tubers in the several specific-gravity c l a s s e s .
of each pair is the weighted average specific gravity.
and third values are the weighted averages of the chip

to the percent­
The f i r s t value
The second
color ratings.

129
A p p e n d ix T ab le III (Continued)
Irrigation,
0 -0 -1 8

Irrigation,
3-12-12

Katahdin
Chip
Color

Russet
Rural
Chip
Color

Russet
Rural
Chip
Color

Average

Katahdin
Chip
Color

Russet
Rural
Chip
Color

Katahdin
Chip
Color

Avg.
Chip
Color
0

30

0

30

0

30

0

30

0

30

0

30

0

30

r

r

1.9

6.0

3.0

6.5

1.2

6.7

4.4

8.0

2.2

6.2

3.3 7.1

5.2

8.9

1.8 7.7

4.8 7.0

1.7

7.8

5.0

8.3

2.2

7.5

3.6 7.9

3.5

5.0

7.7

3.0

r

5.4 9.1

2.8

8.5

4.1

8.8

6.0

8.0

3.0

7.9

5.0

3.7

8.2

4.4

8.3

6.7 10.0
r

r

r

r

8.6

-

8.5

-

5.6 9.3

1.9 7.2

4.9

7.3

1.7

7.4

5.0

8.4

2.5

7.4

5

3.8 8.1

Potatoes were stored at 41° F. for five months; one-half
of each potato was chipped immediately following 41° F. (0) and the
remaining halves were conditioned at 78° F. for thirty days and
then chipped (30).
Indicates potatoes had become rotten m storage.

130
Appendix Table IV,
The percentage of tubers in each specificgravity class and average of the chip color ratings ^ of the
tubers of eight varieties, four dates of planting, and three
l evels of irrigation, Experiment A, Lake City, 1952.
Irrigation Levels
_ ,
Dates of
Planting

Sp.*
r' 2
Class

Heavy
J
% of
_
Tu.
bers

Normal
___________

Chip
« ,
3
Color

% of
m
Tubers

None
___________

Chip
_ n*
Color

% of
m
Tu,
bers

Chip
_ , ^
Color

6.7
7.4
8.4
9.5

25.0
5.0
55.0
15.0

7.1
8.0
8.6
9.5

Chippewa
May 1

1
2
3
4
5 4
Avg.

May 16

June 2

June 16

1
2
3
4
c
5
Avg.
1
2
3
4
5
Avg.
1
2
3
4
5 .
Avg.

25.0
22.5
45.0
7.5
1.070
7.5
32.5
42.5
17.5
1.072
5.0
55.0
40.0
—

6.7
7.9
8.1
9.5
7.8
5.3
7.0
7.8
9-4
7.6
7.5
7.5
8.4
-

1.0 69

7.9

_

-

17.5
52.5
30.0

7.3
8.2
8.8

17.5
47.5
25.0
10.0
1.069
10.0
20.0
50.0
20.0
1.073
2.5
35.0
62.5
-

7.7
6.2
7.5
8.2
8.5
7.9
7.8
8.3
8.1

5.0
25.0
45.0
25.0

70.0
25.0
5.0
-

1.0 64
15.0
40.0
45.0
-

-

1.078

1.071

8.1
7.0
7.7
8.3
9.2

1.076
5.0
15.0
65.0
15.0

-

-

-

-

-

1.069

8.2

1.073

8.3

1.073

8.3
6.3
9.6
10.0
7.3
7.5
7.6
8.8
8.1
r
8.3
9.0
10.0
8.6

131
A p p e n d ix T able IV (C ontinued)
Irrig a tio n L e v e ls
Dates of
Planting

Sp.-

Heavy

No rmal

None

Gr.

Clas s

% of
Tu­
bers

Chip
Color

% of
Tu­
bers

Chip
Color

% of
Tu­
bers

Chip
Color

5.0
15.0
10.0
60.0
10.0
1.079

7.0
9.0
9-0
9.3
10.0
9-2

Irish Cobbler
May 1

1
2
3
4
5
Avg.

17.5
25.0
52.5
5.0
1.078

*
8.0
7.5
8.8
9.0
8.3

5.0
37.5
57.5
1.078

5.0
7.5
8.6
8.0

May 16

1
2
3
4
5
Avg.

2.5
2.5
35.0
50.0
10.0
1.079

7.0
7.0
7.4
8.2
9.0
7.9

2.5
5.0
17.5
70.0
5.0
1.079

r
8.0
8.2
8.7
10.0
8.4

June 2

June 16

1
2
3
4
5
Avg.

10.0
82.5
7.5
1.082
_

_

6.7
73.3
20.0
1.083

8.3
8.7
9.7
8.7
*

7.0
8.3
o vO
o 00
r-H

1
2
3
4
5
Avg.

-

10.0
53.3
36.7
1.084
_
2.5
82.5
15.0
1.083

8.0
8.4
8.6
8.4
—

6.0
9.1
9.4
9-0

-

15.0
15.0
45.0
25.0
1.0 80
-

6.0
8.0
9.7
10.0
9.0
-

5.0
85.0
10.0
1.082

8.0
8.9
9.1
8.8

5.0
85.0
10.0
1.082

9-0
9.4
10.0
9-4

132

A p p e n d ix T a b le IY (Continued)
Irrig a tio n L e v e ls
Date s of
Planting

Sp.Gr.
Class

He av y
% of
Tu­
bers

Normal

Chip
Color

% of
Tu­
bers

Chip
Colo r

None
% of
Tu­
bers

Chip
Color

K a ta h d i n
Ma y 1

M ay 16

Ju n e

2

1
2
3
4
5
Avg.
1
2
3
4
5
Avg.
1
2
3
4
5

Avg.
June 16

1
2
3
4
5

Avg.

5.0
7.5
40.0
35.0
12.5
1.077

-

5.5
7.7
8.7
9.1
9.5
8.7

17.5
17.5
62.5
2.5
1.078

7.3
8.0
8.0
9.0
8.0

7.0
7.3
7.7
8.5
7.6

10.0
15.0
62.5
12.5
1.080

7.0
7.6
8.6
9.4
8.4

-

-

-

-

-

15.0
80.0
5.0
1.081

8.0
9.5
10.0
9.3

"

10.0
20.0
63.3
6.7
1.079

-

-

70.0
30.0
1.084

9.5
10.0
9.6

-

-

-

-

-

-

-

-

-

-

-

-

—

-

-

-

70.0
30.0
1.084

7.6
8.5
7.9
_

6.7
13.3
66.7
13.3
1.081

7.5
7.4
8.9
9.9

8.7

5.0
72.5
22.5
1.083

6.3
8.7
9-1

8.7

80.0
20.0
1.084

9.3
9.7
9.4

-

-

-

-

-

-

-

-

3.3

9.0
8.1

83.3
13.3
1.081

9.3

15.0
80.0

9.2

8.8

5.0

10.0

8.2

1.081

9.3

133

A p p e n d ix T a b le IV (Continued)
Irrig a tio n Levels
D a t e s of
Planting

Sp.Gr.
C lass

H e a vy
% of
T u­
bers

No r m a l

Chip
Color

% of
Tu­
bers

Chip
Color

None
% of
Tu­
bers

Chip
C o lo r

Ke nnebec
M ay

May

June

16

2

16

1
2
3
4
5
Avg.

7.5
12.5
10.0
60.0
10.0

1
2
3
4
5
Avg.

3.3
3.3
16.7
60.0
16.7
1.081

1.079

-

1
2
3
4
5
Avg.

7.5
77.5
15.0
1.083

1
2
3
4
5
Avg.

5.0
2.5
5.0
55.0
32.5
1.083

9.0
8,8
10.0
9.5
9.5
9.4
8.0
9.0
vQ
00

June

1

9.5
10.0
9-4
8.0
9.2
9.8
9.2
8.0
8.0
8.5
9.3
9.9
9.3

5.0
22.5
62.5
10.0
1.0 80

8.6
9.5
9.5
10.0
9.6

20.0
30.0
50.0
1.077

9.5
9-2
10.0
9.7

2.5
20.0
65.0
12.5
1.081

r
8.6
9.3

15.0
50.0
35.0
1.083

9.5
10.0
10.0
9.9

10.0
65.0
25.0
1.083

7.6
8.6
9.9
8.9

10.0
40.0
50.0
1.085

8.0
9.6
10.0
9.6

r
r
9.4
10.0
9.3

5.0
60.0
35.0
1.084

9.0
9.8
10.0
9.8

2.5
2.5
57.5
37.5
1.084

9.9
9.1

134
A p p e n d ix T ab le IV (C ontinued)
Irrig a tio n L e v e ls
Date s of
Planting

Sp.Gr.
C lass

Heavy
% of
Tu­
bers

Normal
% of
Tu­
bers

Chip
Color

Chip
Color

None
% of
Tu­
bers

Chip
Color

Pontiac
May 1

May 16

June 2

June 16

1
2
3
4
5
Avg.

32.5
25.0
17.5
22.5
2.5
1.070

5.9
6.0
6.7
7.0
7.0
6.3

17.5
25.0
20.0
37.5
1.073

-

-

5.5
6.2
7.6
7.6
-

6.4

1.073

6.9

1
2
3
4
f**
5
Avg.

20.0
40.0
32.5
7.5

6.5
6.4
7.2
7.3

32.5
35.0
20.0
12.5

5.5
6.0
6.3
7.0

1
2
3
4
5
Avg.
1
2
3
4
5
Avg.

1.069

6.7

5.0
42.5
50.0
2.5
1.078

5.0
5.5
6.2
7.3

5.0
10.0
32.5
52.5

6.0
7.3
6.6
6.8

5.9

-

-

1.076

6.7

1.068

5.0
10.0
85.0
-

1.0 80
6.6
10.0
36.7
46.7

5.3
6.0
6. 3
7.4

6.1

20.0
10.0
35.0
35.0
1.073

7.0
6.1
7.0
6.9

10.0
10.0
80.0

5.5
7.5
7.3
8.3

10.0

-

1.076

15.0
30.0
15.0
40.0

7.6

6.0
6.5
7.4
8.4
7.4

-

7.5
7.5
7.9
-

1.080

7.9

-

30.0
60.0
. 1.077

8.0
-

8.0
8.0
8.0

135
A p p e n d ix T able IV (Continued)
Irrig a tio n Levels
D a t e s of
Planting

Sp.Gr.
C lass

Heavy
% of
Tu­
bers

No r m a l

Chip
Colo r

% of
Tu­
bers

Chip
Colo r

None
% of
T u­
be r s

Chip
Color

R usset Rural
May 1

May 16

June

2

June 16

1
2
3
4
5
Avg.
1
2
3
4
5
Avg.
1
2
3
4
5
Avg.
1
2
3
4
5
Avg.

10.0
20.0
60.0
10.0
1.0 80

-

r
9.0
9.9
9.9
9.6

-

-

17.5
42.5
40.0
1.084

9.3
9.2
9.6
9.5

7.0
-

9.5
9.8
9.6

2.5
42.5
55.0
1.086

-

2.5
30.0
67.5
1.087

8.0
8.4
9.6
9.1

16.7
83.3
1.089

10.0
5.0
45.0
40.0
1.083

:

—
2.5
32.5
65.0
1.087

-

7.5
9.2
9.9
9.6

-

8.0
9.3
9.0

-

60.0
40.0
1.085

-

7.0
8.6
8.9
10.0
9.2
—
9.6
10.0
9.8

-

-

-

-

100.0
1.090

9.9
9.9

•
—

-

26.7
73.3
1.088

-

8.8
9.3
9.2

2.5
17.5
80.0
1.088

r
9.0
9.5
9.2

_

-

-

-

5.0
95.0
1.089

8.5
9.9
9.8

136
A p p en d ix T able IV (Continued)
I r r ig a t io n L e v e l s
D a t e s of
Planting

S p.Gr.
C la s s

% of
Tu­
bers

None

No r m a l

H eavy

Chip
C olo r

% of
T u­
bers

Chip
Colo r

% of
Tu­
bers

Chip
Color

Sebago
M ay 1

1
2

-

-

4
5
Avg.

5.0
22.5
67.5
5.0
1.0 80

7.0
7.6
8.3
8.0
8.1

1

3.3

7.0

3.3
70.0
23. 3
1.082

7.0

o

3

May 16

-

10.0
30.0
50.0
10.0

-

15.0
20.0
20.0
35.0
10.0
1.075

1.079

6. 6
8.1
8.8
7.0
8.2

-

-

-

7.3
8.3
8.5
8.2

-

8.0
7.8
10.0
9.3
10.0
9.0
-

'y
£

3
4
5
Avg.
June

2

1
2
3
4
5
Avg.

13.3
66,7
20.0
1.082

7.9
9-3
8.1

90.0
10.0
1.083

-

8.6
8.5
8.6
-

—

-

-

-

-

-

-

-

-

-

-

-

-

-

50.0
50.0
1.086

2.5
35.0
62.5
1.087

-

7.3
8.4
7.8

r
7.9
9.0
8.4

35.0
65.0
1.087

8.1
9.1
8.7

\

June 16

1
2
3
4
5
Avg.

-

-

5.0
52.5
42.5
1.085

-

7.0
7.9
8.7
8.1

-

7.5
45.0
47.5
1.085

-

-

-

-

-

-

-

-

8.0
8.1
8.6
8.3

55.0
45.0
1.086

8 . 8

9.3
9.0

137
Appendix Table

IV (Continued)

Irrig atio n Levels
D a t e s of
Planting

S p .Gr.
Class

Heavy
% of
Tu­
bers

N o r m al

Chip
Color

% of
Tu­
bers

Chip
Color

None
% of
Tu­
be r s

Chip
Colo r

505-3
May 1

May 16

J un e

June

2

16

1
2
3
4
r
D
Avg.

20.0
26.7
40.0
13.3
1.070

6.6

1
2
3
4
5
Avg.

-

-

1
2
3
4
5
Avg.
1
2
3
4
5
Avg.

47.5
50.0
2.5
1.078

5.9
6.4
6.9
7.5

7.7
8.0
8.0
7.8
*

5.0
52.5
42.5
1.077
2.5
30.0
42.5
25.0
1.073

6.0
6.6
7.1

30.0
15.0
37.5
17.5

5.8
7.1
7.3
7.8

60.0
35.0
5.0

6.8
8.3
r

1.070

6.9

1.068

7.0

22.5
62.5
15.0
1.073

6.6
7.4
8.8
7.4

25.0
55.0
20.0
1.073

7.0
7.5
6.3
7.1

5.0
5.0
45.0
45.0

4.5
5.5
6.4
6.6

1
30.0
70.0

1
8.1
8.4

6.8

1.076

6.4

1.079

8.3

7.0
7.2
7.4
7.5
-

7.5
22.5
40.0
30.0
1.074

6. 3
7.1
7.6
8.0
7.5

-

-

7.3

35.0
10.0
45.0
10.0
1.077

7.5
8.5
8.3
9.0
8.1

138
Appendix Table IV (Continued)

Irrigation Levels

Date s of
Planting

Sp.Gr.
Class

Heavy
% of
Tu­
bers

Normal

Chip
Color

% of
Tu­
bers

None

Chip
Color

% of
Tu­
bers

Chip
Color

Average
May 1

1
2
3
4
5
Avg.

11.3
15.8
27.5
39.7
5. 6
1.0 74

6.6
7.4
8.0
8.7
8.8
8.1

8.1
15.6
25.9
42.5
7.8
1.075

5.9
6.9
8.0
8.6
8.9
8.0

7.5
20.0
2 3.1
41.2
8.1
1.075

6.9
8.6
8.7
9.1
10.0
8.8

May 16

1
2
3
4
5
Avg.

4.6
11.3
24.7
43.8
15.5
1.077

6.7
7.2
7.5
8.4
9-1
8.1

5.9
11.5
25.1
44.3
13.1
1.077

5.8
7.0
7.6
8.5
9.5
8.1

11.2
9.4
15.6
46.3
17.5
1.078

6.1
7.3
8.4
8.8
9.7
8.5

June 2

1
2
3
4
5
Avg.

1.9
21.3
55.3
21.6
1.0 82

6.1
7.3
7.8
8.8
7.8

0.6
1.5
14.7
54.3
28.8
1.082

4.5
6.7
7.1
7.9
9.1
8.1

3.2
11.8
54.3
30.6
1.082

7.5
7.8
8.7
9.5
8.8

1
2
3
4
5
Avg.

1.6
8.3
19.6
47.7
22.7
1.079

7.0
7.4
7.4
8.2
9.5
8.2

2.4 .
7.8
16.9
48.5
24.2
1.079

6.2
7.0
8.0
8.6
9.3
8.5

1.8
6.2
16.2
50.6
25.0
1.079

8.0
7.9
8.8
9.0
9.6
9.0

June

16

*

—

-

139
Footnotes

to Appendix Table IV

1 = e x t r e m e l y d a r k; 10 = l i g h t yellow; 8.5 to 9
y el l ow ( m o s t d e s i r a b l e ) ; 7.5 to 10 = a c c e p t a b l e .

= golden

Z

Specific-gravity classes:
1 = b e lo w 1.064; Z = 1.064 to
1.070; 3 = 1.070 to 1.076; 4 = 1.076
to 1.088; 5 = 1.088 and o v e r .
Class
values
f o r w e i g h t e d a v e r a g e s : 1 = 1.0 6Z; Z = 1.067;
3 =
1.073; 4 = 1.08Z; 5 = 1.090.
3

A v e r a g e s of the chip c o l o r
specific-gravity class.

r a ti n g f o r the t u b e r s in t h a t

4

T h e s e a v e r a g e v a l u e s a r e w e i g h te d a c c o r d i n g to the p e r ­
c e n t a g e of t u b e r s in the s e v e r a l s p e c i f i c - g r a v i t y c l a s s e s .
The f i r s t
va lue of e a c h p a i r i s the w e i gh te d a v e r a g e spe cific g ra v i t y ; the s e c ­
ond i s the w e i g h t e d a v e r a g e of chip c o l o r r a t i n g s .
I n d i c a t e s p o t a t o e s h ad b e c o m e

rotten m storage.

140
Appendix Table V.
The percentage of tubers in each specificgravity class and the averages of chip color ratings^ of the
tubers of two varieties, three dates of planting, three levels
of irrigation, and four fertilizer analyses, Experiment B,
Lake City, 1952.
Irrigation Levels
Date s of
Planting

Sp.Gr‘ 2
Class

Normal

Heavy
% of
Tubers

Chlp 3
Color

% of
Tu­
bers

Chip
Color

None
% of
Tu­
bers

Chip
Color

Irish Cobbler-- No Fertilizer
May 1

May 16

June 16

1
2
3
4
5 „
A
4
Avg.
1
2
3
4
5
Avg.
1
2
3
4
5
Avg.

2.5
12.5
42.5
42.5
1.084
-

3.3
3.3
50.0
43.3
1.084
_

2.5
2.5
65.0
30.0
1.0 84

7.0
8.3
8.5
9-2
8.7

17.5
62.5
20.0
1.082

7.6
8.3
9.4
8.4

5.0
30.0
65.0
1.087

9.0
9.6
10.0
9.8

6.5
8.0
7.8
8.9
8.0

5.0
60.0
35.0
1.084

6.0
7.5
8.4
7.7

25.0
55.0
20.0
1.081

6.3
8.8
9.2
8.3

—

2.5
7.5
62.5
27.5
1.083

7.5
7.6
7.8
8.4
7.9

- .
70.0
30.0
1.0 84

9.2
9.4
9.3

8.0
8.0
7.7
8.7
8.0

141
Appendix Table V (Continued)

Irrigation Levels
Date s of
Planting

Sp.Gr.
Class

Heavy
% of
Tu­
bers

Chip
Color

Normal
% of
Tu­
bers

Chip
Color

None
% of
Tu­
bers

Chip
Color

5.0
15.0
10.0
60.0
10.0
1.079

7.0
9.0
9.0
9.3
10.0
9.2

Irish Cobbler--3-12-12 Fertilizer
May 1

May 16

June 16

1
2
3
4
5
Avg.

17.5
25.0
52.5
5.0
1.078

8.0
7.5
8.8
9.0
8.3

5.0
37.5
57.5
1.078

5.0
7.5
8.6
8.0

1
2
3
4
5
Avg.

2.5
2.5
35.0
50.0
10.0
1.079

7.0
7.0
7.4
8.2
9.0
7.9

2.5
5.0
17.5
70.0
5.0
1.079

r
8.0
8.2
8.7
10.0
8.4

1
2
3
4
5
Avg.

..

-

-

-

6.7
73.3
20.0
1.083

7.0
8.3
10.0
8.6

-

2.5
-

82.5
15.0
1.083

6.0
9.1
9.4
9.0

-

15.0
15.0
45.0
25.0
1.080
-

5.0
85.0
10.0
1.082

6.0
8.0
9.7
10.0
9.0
9.0
9.4
10.0
9-4

Irish Cobbler-- 3-0-0 Fertilizer
May 1

1
2
3
4
5
Avg.

—

10.0
22.5
57.5
10.0
1.079

7.0
. 7.5
8.2
9.3
8.0

5.0
25.0
62.5
7.5
1.080

6.5
7.4
7.9
9.2
7.8

—

5.0
45.0
50.0
1.086

-

—
r
9.4
10.0
9.4

142
Appendix Table V (Continued)

Irrigation Levels

Date s of
Planting

Sp
Gr.
Class

Heavy
% of
Tu­
bers

Normal

Chip
Color

% of
Tu­
bers

Chip
Color

None
% of
Tu­
bers

Chip
Color

Irish Cobble r- - 3-0 -0 F ertilizer (Continued)
May 16

June 16

1
2
3
4
5
Avg.
X
2
3
4
5
Avg.

2.5
20.0
42.5
35.0
1.083

8.0
7.0
8.0
8.5
8.0

5.0
25.0
57.5
12.5
1.080

2.5
35.0
62.5
1.086

6.0
7.6
9.0
8.4

40.0
60.0
1.087

7.0
7.1
7.8
8.6
7.7

8.0
9.0
8.6

10.0
20.0
50.0
20.0
1.0 80

45.0
55.0
1.086

7.5
8.0
9-0
9-8
8.8

8.8
9-8
9-4

Irish Cobbler-- 0-0-12 Fertilizer
May 1

May 16

1
2
3
4
5
Avg.
1
2
3
4
5
Avg.

2.5
15.0
67.5
15.0
1.081

8.0
9.0
8.0
9.1
8.3

6.7
26.7

r
7.8
_

46.6
20.0
1.078

8.7
9.3
8.5

__

5.0
25.0
65.0
5.0
1.079

6.0
6.8
8.4
10.0
8.0

5.0
15.0
75.0
5.0
1.0 80

8.0
8.0
9.7
r
8.9

20.0
62.5
17.5
1.082

8.0
8.6
9.2
8.6

5.0
5.0
20.0
45.0
25.0
1.080

7.0
7.0
8.3
9.3
10.0
9.0

143
Appendix Table V (Continued)

Irrigation Levels

Date s of
Planting

Sp.Gr.
Class

Heavy
------------------------% of
Tu° * ip
.
Color
bers

Normal
------------------------% of
TurC*iP
,
Color
bers

None
---------------% of
XupC1;1P
,
Color
bers

Irish Cobbler-- 0-0-12 Fertilizer (Continued)
June 16

1
2
3
4
5
Avg.

7.5
27.5
57.5
7.5
1.079

7.0
8.1
8.4
8.5
8.2

20.0
65.0
15.0
1.081

8.0
7.8
8.1
7.9

5.0
5.0
70.0
20.0
1.082

6.0
9.0
9.0
'9.6
8.9

Russet Rural - -No Fertilizer
-

1
2
3
4
5
Avg.

32.5
67.5
1.087

M ay 16

1
2
3
4
5
Avg.

—
15.0
85.0
1.089

June

1
2
3
4
5
Avg.

May 1

16

_

—

40.0
60.0
1.087

-

-

-

9.3
9.6
9.5

2.5
12.5
37.5
47.5
1.0 84

7.5
7.8
8.7
9.2
8.8

40.0
60.0
1.087

9.1
10.0
9.6

8.7
9-7
9.5

12.5
87.5
1.089

9.4
9-7
9.7

100.0
1.090

9.9
9.9

8.1
9.0
8.6

5.0
95.0
1.090

9.0
9.8
9.8

30.0
70.0
1.088

—
8.6
9.7
9.4

-

144
Appendix Table V (Continued)

Irrigation Levels

Date s of
Planting

Sp.Gr.
Class

Normal

Heavy
% of
Tu­
bers

Chip
Color

% of
Tu­
bers

Chip
Color

None
% of
Tu­
bers

Chip
Color

Russet R u r a l- - 3-12-12 Fertilizer
May 1

1
2
3
4
5

Avg.
May 16

-

10.0
20.0
60.0
10.0

r

1 .080

9 .2

4 5.0

8.9

9.9
9 .6

9.6

4 0.0

10.0

3 2.5

5

65.0

Avg.

8.6

40.0

4

1 .0 8 4

9 .5

—

:

1.083

9.2

_a

2.5

7 .5

-

9.5

4 2.5

9 .2

60.0

9.6

9.8

5 5.0

9.9
9 .6

4 0.0

10.0
9.8

-

-

9.0

5 .0

8.5

9.5

95.0

9.9
9 .8

1 .087

9.6

—
—

-

-

-

2.5

r

8.8
9 .3
9.2

1 7.5
80.0
1 .088

-

1.0 8 5

1 .086

1 .0 88

7.0

4 2 .5

-

7 3 .3

10.0

9.9

-

2 6 .7

-

5 .0

3

5

-

-

9 .3

7.0

4

-

1 7 .5

2.5

1
2
3

-

9 .0

1
2

Avg.
June 16

-

9.2

1.089

R u sse t R ural- - 3-0-0 F e r t i l i z e r
May 1

_

1
2
3

-

4

2 7 .5

5

Avg.

_

7 2 .5
1 .0 8 8

8.7
9 .1
8.9

-

-

2.5

8.0
8.8

20.0

9 .5

8 0.0

2 7 .5
7 0.0
1.0 8 7

9 .3

-

1.088

9.7

10.0
9.9

145
Appendix Table V (Continued)

I r r i g a t i o n Level;
D a te s of
Planting

Sp.Gr.
Class

He av y
% of
Tu­
be r s

No r m a l

Chip
Color

R usset Rural- -3-0-0
M ay 16

J une

16

1
Z
c?
4
5
Avg.
1
2
3
4
5
Avg.

—

10.0
40.0
50.0
1.085
-

5.0
95.0
1.090

_

8.0
8.5
9.4
8.9
8.0
8.9
8.8

% of
Tu­
be r s

F e rtilizer
_

13.3
86.7
1.089
100.0
1.090

Chip
C o lo r

None
% of
Tu­
bers

Chip
Colo r

(Continued)
_

-

_

—

9.1
9.2
9.2

25.0
20.0
55.0
1.084

8.0
9.7
9.8
9.3

8.8
8.8

100.0
1.090

8.8
8.8

R u sse t R u ra l--0 -0-12 F e r t i l i z e r
M ay 1

May 16

1
2
3
4
5
Avg.

7.5
55.0
37.5
1.084

1
2
3
4
5
Avg.

5.0
70.0
25.0
1.084

9.2
9.8
9.3

5.0
50.0
45.0
1.085

9.0
9.5
10.0
9.7

25.0
75.0
1.088

9.6
10.0

8.0
9.2
10.0
9.3

2.5
30.0
67.5
1.087

r
8.7
10.0
9.4

10.0
90.0
1.089

10.0
10.0
10.0

8.0

9.9

146
Appendix Table V (Continued)

Irrig a tio n Levels
Date s of
Planting

Sp.Gr.
Class

Normal

H ea vy

\

of

bers

Chip
Color

% of
Tu­
bers

Rus s e t R u r a l - - 0 - 0 - 12 F e r t i l i z e r
June

1
2
3o
4
5
Avg.

16

1

-

-

20.0
80.0
1.088

8.5
9.9
9.6

32.5
67.5
1.087

None

Chip
C o lo r

% of
m
Tubers

Chip
Color

(Continued)
-

-

9.3
9.6
9-5

1 = e x t r e m e l y d a r k ; 10 = l i g h t yellow;
y e l l ow ( m o s t d e s i r a b l e ) ; 7.5 to 10 = a c c e p t a b l e .

20.0
80.0
1.088

8.6
9.6
9.4

8.5 to 9 = golden

2

1 - below 1.064; 2 = 1.064 to
Specific-gravity classes:
1.070; 3 = 1.070 to 1.076; 4 = 1.076 to 1.088:1 5 = 1. 0 88 and o v e r .
1 = 1.062; 2 = 1.067; 3 =
C l a s s v a l u e s f o r w e i g h t e d a v e r a g e :s:
1.073; 4 = 1.082; 5 = 1.090.
3

A v e r a g e s of the chip c o l o r r a t i n g s f o r the t u b e r s in t h a t
specific- gravity c la s s .
^ T h e s e a v e r a g e v a l u e s a r e w e i gh te d a c c o r d i n g to the p e r ­
c e n t a g e of t u b e r s in the s e v e r a l s p e c i f i c - g r a v i t y c l a s s e s .
The f i r s t
v a lu e of e a c h p a i r i s the w e i g h t e d a v e r a g e s p ec if ic g ra vity ; the s e c ­
ond i s the w e i g h t e d a v e r a g e of chip c o l o r r a t i n g s .
r I n d i c a t e s p o t a t o e s h ad b e c o m e r o t t e n in s t o r a g e .

THE I N F L U E N C E OF

CERTAIN ENVIRONMENTAL FACTORS ON

THE P R O D UC TI O N AND QUALITY O F P O T A T O E S FOR
THE P O T A T O CHIP INDUSTRY

By
D a t t a j e e r a o K o n d j e e r a o Salunkhe

AN ABSTRACT
S u b m i t t e d to the School of G r a d u a t e Studies of Michigan
State C o lle ge of A g r i c u l t u r e and Applied Science
in p a r t i a l f u l f i l l m e n t of the r e q u i r e m e n t s
f o r the d e g r e e of

DOCTOR OF PHILOSOPHY

D e p a r t m e n t of F a r m

Year

1953

Crops

1
D A T T A J E E R A O K O N D JE E R A O SA L U N K H E

ABSTRACT

The i n v e s t i g a t i o n s p r e s e n t e d in th is p a p e r w e r e u n d e r t a k e n
to s tu d y the e f f e c t s of s o m e e n v i r o n m e n t a l f a c t o r s on t h e
g r a v i t y of p o t a t o e s

1.

Sjde c i f i c

specific

and the c o l o r of potato c h i p s .

g r a v i t y in r e l a t i o n to v a r i e t y .

R u s s e t R u r a l a nd

K e n n e b e c w e r e high; I r i s h C o b b l e r a nd Sebago w e r e m e d i u m ;
p e w a, P o n t i a c ,

a n d S eedling 5 0 5- 3 w e r e lo w in a v e r a g e

specific g r a v ­

ity; a n d K a t a h d i n w a s low in s p e c i f i c g r a v i t y a t E a s t L a n s i n g
but m e d iu m at Lake

2.

Chip­

(1951)

C ity (1951 and 1952).

S pe cif ic g r a v i t y in r e l a t i o n to d ate of p la ntin g.

the p o t a t o e s f r o m e a r l y p l a n t i n g h a d a h i g h e r a v e r a g e

In 1951,

specific g r a v ­

i t y t h a n t h o s e f r o m l a t e - p l a n t e d , b u t in 1952 t h e s e f in din gs w e r e

re­

versed.

3.
levels

S pec ific

The

different

of i r r i g a t i o n h a d no n o t i c e a b l e in flu en ce on the a v e r a g e

g r a v i t y of p o t a t o e s

4.
from

g r a v i t y in r e l a t i o n to i r r i g a t i o n .

s p e c if ic

in 1951 and 1952.

Spe cific g r a v i t y in r e l a t i o n

the u n f e r t i l i z e d p l o t s

g r a v i t y , f o l l o w e d by 3 - 0 - 0 ,

(0- 0-0)

to f e r t i l i z e r .

The p o t a t o e s

had the h i g h e s t a v e r a g e

s pe cif ic

3 - 1 2 - 1 2 , and 0 - 0 - 1 8 or 0 - 0 - 1 2 , in the

D A T T A J E E R A O K O N D JE E R A O S A L U N K H E

o r d e r of d e c r e a s i n g

average

( P l o t s w e r e f e r t i l i z e d a t the

5.

ABSTRACT

s p e c i f i c g r a v i t y in b o t h 1951 a n d 1952.
rate

of 1,000 p ou nd s p e r a c r e . )

Spe c ific g r a v i t y in r e l a t i o n to l o c a t i o n .

tatoes f r o m

In 1951, the p o ­

the L a k e City p l a n t i n g gav e ' h i g h e r s p e c i f ic g r a v i t y in

a ll v a r i e t i e s t h a n the p o t a t o e s f r o m the E a s t L a n s i n g p l a n ti n g .

6.

S pe cif ic g r a v i t y in r e l a t i o n to s e a s o n .

The a v e r a g e

g r a v i t y of p o t a t o e s of a g i v e n v a r i e t y w a s h i g h e r in the y e a r
t han in e i t h e r

7.
approved,

1950 o r

specific

1952

1951.

C o l o r of p ota to chip in r e l a t i o n to v a r i e t y .

Consum er-

d e s i r a b l e g old en y ellow chips w e r e o b ta i n a bl e f r o m R u s s e t

R ural, Kennebec,

and I r i s h C obble r v a r i e t i e s .

Com m ercially-acceptable

b r o w n i s h - y e l l o w c h i p s w e r e p r o c e s s e d f r o m K ata hd in v a r i e t y , and
dark,

u n s a l a b l e only c o u ld b e m a d e f r o m Chippewa, P o n t i a c , Sebago,

a nd S e e dlin g 50 5- 3.

8.

C o l o r of p ot a to chip in r e l a t i o n to date of p la nt i n g .

In 1950

a nd 1951 the e a r l y - p l a n t e d p o t a t o e s m a d e l i g h t e r - c o l o r e d c h i p s , b u t in
1952 the l a t e - p l a n t e d p o t a t o e s m a d e l i g h t e r - c o l o r e d chips.

3
D A T T A JE E R A O KO NDJEERAO SALUNKHE

9-

ABSTRACT

C o l o r of p o t a t o chip in r e l a t i o n to i r r i g a t i o n .

N onirrigated

p l o t s y i e l d e d p o t a t o e s , p r o d u c i n g l i g h t e r - c o l o r e d c hip s t h a n t h o s e
fro m ir r i g a t e d plots.

10.

C o l o r of p o t a t o c h ip s in r e l a t i o n to f e r t i l i z e r .

Plots f e r ­

t i l i z e d w i th 3 - 1 2 - 1 2 y i e l d e d p o t a t o e s p r o d u c i n g a c c e p t a b l y c o l o r e d
c h i p s, in th is

respect

potash fe r tiliz e r

s u p e r i o r to any o t h e r f e r t i l i z e r a n a l y s i s .

(0-0 —18 o r 0 - 0 - 1 2 )

l o w e r e d the a v e r a g e

The

s p e c i f ic

g r a v i t y of p o t a t o e s , b u t s u r p r i s i n g l y l i g h t e n e d the c o l o r of c h ip s in
1951 a nd 1952.

11.

C o l o r of p o ta to c hip s in r e l a t i o n to l o c a t i o n .

Potatoes

f r o m the p l a n t i n g s of L a k e C i t y gave l i g h t e r - c o l o r e d c h ip s t ha n t h o s e
f r o m E a s t Lansing.

12.

C o l o r of p o t a t o

c hips in r e l a t i o n to s e a s o n .

Within a

g iv e n v a r i e t y , p o t a t o c h i p s w e r e l i g h t e r in c o l o r in 1952 tha n e i t h e r
in 1950 o r

13.

1951.

C o l o r of p o t a t o c hips in r e l a t i o n to r e d u c i n g

sugars.

T h e r e w a s a d i r e c t r e l a t i o n b e t w e e n the a m o u n t of r e d u c i n g
in the p o t a t o a nd the c o l o r of p o ta t o c h i p s .

sugars

In 1950, the h i g h e r the

4
D A T T A J E E R A O K O N D JE E R A O SA L U N K H E

a m o u n t of r e d u c i n g
t e n t of r e d u c i n g

sugars,

ABSTRACT

the d a r k e r the c o l o r of c h i p s .

The c o n ­

s u g a r s a n d the c o l o r of p o t a to c hips v a r i e d n o t only

f r o m v a r i e t y to v a r i e t y ,

but a l s o within a v a r i e t y a nd w it h in the

same

s p e c i f i c - g r a v i t y c l a s s f r o m one date of p l a n t i n g to a n o t h e r .

14.

C o l o r of p o ta to c h ip s in r e l a t i o n to s t o r a g e t e m p e r a t u r e

a nd d u r a t i o n .
(41°

F.)

Chip c o l o r i m m e d i a t e l y a f t e r five m o n t h s c o ld s t o r a g e

of p o t a t o e s w a s

d a r k e r t ha n a f t e r two m o n t h s .

At the en d

of five m o n t h s c o ld s t o r a g e , f o ll o w e d by a cond itioning p e r i o d a t
78° E . ,

R u s s e t R u r a l m a d e l i g h t e r - c o l o r e d c h ip s t h a n a f t e r two

m o n t h s c o ld s t o r a g e , f ollo w e d b y a s i m i l a r conditioning p e r i o d , b u t
in K a t a h d i n p o t a t o e s t h e s e fin din gs w e r e
toes w e re

reversed.

K en n e b e c p o t a ­

c o n d i ti o n e d f a s t e r tha n I r i s h C o b b l e r , and K a t a h d i n p o t a t o e s

c o n d i t i o n e d f a s t e r t h a n Sebago.

With the t u b e r s

s t o r e d f o r five

m o n t h s a n d t h en c o n d i t i o n e d a t 78° F . , the c o l o r d i s t i n c t i o n b et w e en
l a t e a n d e a r l y p l a n t i n g w a s n ot n o t i c e a b l e , b u t w ith p o t a t o e s

stored

f o r two m o n t h s a n d c o n d it i o n e d l i k e w i s e , the f i r s t date of p l a n ti n g
gave l i g h t e r - c o l o r e d c h ip s t h a n th os e of l a t e p l a n t i n g s .
The o r d e r of r a n k i n g a s to c o l o r w as i d e n t i c a l f o r c h i p s p r o c ­
e s s e d d i r e c t l y out of c old s t o r a g e a s f o r chips f r o m the s a m e t u b e r s
a f t e r con ditio n in g .