IN T E R A C T IO N O F SOME E N V IR O N M E N T A L FA C T O R S AND
G R O W TH O F SA LV IA S P L E N D E N S K E R -G A W L

By

CALVIN C. C O O P E R

A

THESIS

S u b m i t t e d to the School of G r a d u a t e S t u d i e s of M i c h i g a n
State C o l l e g e of A g r i c u l t u r e and A p pl i e d S c i e n c 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 OF PH ILO SO PH Y

D e p a r t m e n t of H o r t i c u l t u r e

1954

ProQuest Number: 10008284

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ACKNOWLEGEMENT

The a u t h o r w i s h e s to e x p r e s s h i s g r a t i t u d e to
his m a jo r p r o f e s s o r ,

Dr,

Donald P .

W atson,

f or s u g g e s ­

t i o n s a nd d i r e c t i o n of the r e s e a r c h r e p o r t e d in t h i s t h e s i s .
S i n c e r e t h a n k s a r e a l s o e x p r e s s e d f or the
c o n s t r u c t i v e s u g g e s t i o n s of D o c t o r s L eo W. M e r i c l e ,

H arold

B. T u k ey , and A lvin L. K e n w o r t h y .
The a s s i s t a n c e of D r . E r w i n J .

B enne in the

d e t e r m i n a t i o n of the n u t r i e n t a n a l y s e s i s g r a t e f u l l y a c k ­
no wle d g e d .

IN T E R A C T IO N O F SOME EN V IR O N M EN TA L FA C T O R S AND
G R O W T H O F SA LV IA S P L E N D E N S K E R -G A W L

By

C a l v i n C. C o o p e r

AN A B S T R A C T

S u b m i t t e d to the School of G r a d u a t e S tu die s of M i c h i g a n
State C o l l e g e of A g r i c u l t u r e a n d A p p li e d S ci e nc 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 th e d e g r e e of

DOCTOR O F PHI LOSOPHY

D e p a r t m e n t of H o r t i c u l t u r e
Y e a r 1954

Approved

CA LV IN C. C O O P E R

ABSTRACT

T he i n t e r a c t i o n of e n v i r o n m e n t a l f a c t o r s upo n the g r o w t h
of S a l v i a s p l e n d e n s w a s s t u d i e d to o b t a i n i n f o r m a t i o n c o n c e r n i n g the
g r o w t h of S a l v i a a nd the p o s s i b i l i t i e s of i ts i n t r o d u c t i o n to th e
f l o r i s t pot plant in d u str y .
t iv a r s was c o m p a re d .
perature,

F o r t h i s p u r p o s e t he g r o w t h of t e n c u l -

T h e i n f lu e n c e of c o ld t r e a t m e n t , n ig ht t e m ­

"'pinching", p h o t o p e r i o d , r o o t t e m p e r a t u r e a n d l i g h t i n ­

tensity was studied.

Inform atio n was g ath ered concern in g the t i m ­

ing of a c r o p of S a lv ia f o r t h e C h r i s t m a s m a r k e t , a nd the k e e p i n g
q u a l i t y of t he plants a t r o o m t e m p e r a t u r e .
F o r the p r o d u c t i o n of s h o r t , d e n s e p l a n t s the c u l t i v a r s
of the d w a r f t yp e p r o v e d m o s t s u i t a b l e , a n d f o r t h e p r o d u c t i o n

of a

s l i g h t l y m o r e v i g o r o u s p l a n t t he c u l t i v a r s of t h e s e m i - d w a r f type
were recom m ended.

The cu ltiv ar, A m e r ic a ,

was selected for use

in a l l o h t e r e x p e r i m e n t s .
o
T h e 40 F c o n s t a n t t e m p e r a t u r e c o ld t r e a t m e n t f o r 1 w e e k
a p p e a r e d to r e t a r d g r o w t h m o r e when it w as s u p p l i e d a t t h e t w o t h a n a t the f o u r - n o d e s t a g e of g ro w t h .

At e i t h e r s t a g e , t h e i n f l u ­

e n c e of th e r e l a t i v e l y s h o r t p e r i o d of c o ld t r e a t m e n t w as not e x t r e m e ­
ly l a r g e .
T h e s tudy of n ig h t t e m p e r a t u r e i n f l u e n c e s i n d i c a t e d t h a t
o
S a l v i a g r e w m o r e v i g o r o u s l y a n d f l o w e r e d s o o n e r with 60 F t h a n

w i th 5 0 ° F n i g h t t e m p e r a t u r e .
t he p l a n t s w e r e young.

T h i s w as p a r t i c u l a r l y t r u e while

Some a d d i t i o n a l s t e m e l o n g a t i o n w a s o b -

t a i n e d by m o v i n g t h e p l a n t s f r o m 60 F to 50 IT n ig h t t e m p e r a t u r e
90 d a ys a f t e r s e e d i n g .

S t e m w e i g h t w as no t g r e a t l y i n f l u e n c e d by

n ig h t t e m p e r a t u r e a nd f l o w e r c o l o r w as n ot a f f e c t e d .
The r e m o v a l of the t e r m i n a l m e r i s t e m (a " p i n c h " ) r e ­
s u l t e d in p l a n t s w ith s h o r t ,

d e n s e g ro w t h .

P l a n t s " p i n c h e d " t wic e

w e r e l a r g e r a nd t oo k 10 d a y s l o n g e r to f l o w e r t h a n t h o s e " p i n c h e d "
once.

When p l a n t s w e r e " p i n c h e d " t h r e e t i m e s the f l o w e r s w h i c h

w e r e p r o d u c e d w e r e a p p r o x i m a t e l y 50 p e r c e n t s m a l l e r in s i z e .
It w a s r e c o m m e n d e d t h a t p l a n t s be g r o w n w ith one " p i n c h " e x c e p t
f o r s p e c i a l p u r p o s e s w h e r e a l a r g e r p l a n t would b e p r o f i t a b l e a nd
t h e n two " p i n c h e s " c ould be s u p p l i e d .
When s e e d w as p l a n t e d S e p t e m b e r 1st, 98 d a ys w e r e r e ­
q u i r e d f o r p r o d u c t i o n of f l o w e r i n g po t p l a n t s w i t h one " p i n c h " .

A

s c h e d u l e f o r the p r o d u c t i o n of a C h r i s t m a s c r o p w a s s u g g e s t e d .
S ome f l o r e t s w e r e o b s e r v e d to a b s c i s s a f t e r th e p l a n t s ha d
b e e n in t h e h o m e s 1 to 3 d a ys with m a n y f a l l i n g a f t e r a n a v e r a g e of
4 d a y s in the h o m e .

S e v e r a l m e t h o d s of p r e v e n t i n g the f l o r e t a b s c i s ­

s i o n w e r e a t t e m p t e d , but no e f f e c t i v e m e t h o d w a s found.

It w as

s u g g e s t e d t h a t f u r t h e r w o r k with g r o w t h r e g u l a t i n g s u b s t a n c e s m i g h t
prove successful.

Flow ers
periods.

w e r e p r o d u c e d u n d e r b o t h 8- a nd 16- h o u r photo -

A p h o t o p e r i o d i c i n h i b i t i o n of v e g e t a t i v e g r o w t h w a s o b s e r v e d

w h en t h e p l a n t s w e r e g r o w n w ith 8 - h o u r p h o t o p e r i o d s a n d the a m o u n t
of i nh i b i t i o n i n c r e a s e d w ith g r o u p s of p l a n t s t h a t w e r e s u p p l i e d with
a g r e a t e r n u m b e r of s h o r t d a y s .

A l o s s of a p i c a l d o m i n a n c e w a s

a l s o n o t e d in t h o s e p l a n t s s u p p l i e d w ith 60 o r m o r e 8 - h o u r p h o t o p e r i o d s .
In o r d e r to p r o d u c e a f l o w e r i n g S a lv ia p l a n t with r e l a t i v e l y s h o r t
l a t e r a l s of a p p r o x i m a t e l y the s a m e le n g t h , in the s h o r t e s t p e r i o d of
t i m e it w as r e c o m m e n d e d t h a t the p l a n t s be s u p p l i e d with 20 long
d a y s of 16- h o u r p h o t o p e r i o d s fo llo w ed by s h o r t d a y s c o n s i s t i n g of 8 h o u r p h o t o p e r i o d s u n t i l th e p l a n t s w e r e in f l o w e r .

In t h i s e x p e r i m e n t

the r e q u i r e d t i m e w as 98 d ay s f r o m t he d a te of s e e d i n g .

It w as

m e n t i o n e d t h a t t h e s e c o n d i t io n s c o u l d be a p p r o x i m a t e d f o r th e p r o ­
d u c t i o n of a C h r i s t m a s c r o p in M i c h i g a n by su p p ly in g the p l a n t s with
th e n a t u r a l p h o t o p e r i o d .

P h o t o p e r i o d h ad no o b s e r v e d i n f l u e n c e on

th e p l a n t s a f t e r t h e y w e r e in f l o w e r .
P l a n t s c o n s is te n tly p ro d u c e d g r e a t e r height in all t r e a t ­
m e n t s w hen t h e y w e r e g r o w n i n t h e f a ll with 7 0 ° F a n d 5 0 ° F r o o t t e m ­
p e r a t u r e with 100 p e r c e n t a n d 63 p e r c e n t lig ht i n t e n s i t y , t h a n w he n
t h e y w e r e g r o w n u n d e r t h e s a m e c o n d it i o n s d u r i n g t h e w i n t e r m o n t h s .
T h i s w a s t h o u g h t to be c a u s e d by a s h o r t e r p h o t o p e r i o d d u r i n g t h e
g r o w t h of the w i n t e r c r o p .

S t e m e l o n g a t i o n w as s l ig h t l y g r e a t e r when t h e p l a n t s
w e r e g r o w n with r e d u c e d , t h a n when t h e y w e r e g r o w n with f u ll l i g h t
intensity.
A m o r p h o l o g i c a l study of th e f l o w e r bud w a s m a d e , in
which five s t a g e s in f l o w e r bud d e v e l o p m e n t w e r e a r b i t r a r i l y d i s ­
tinguished.
The p l a n t s g r o w n with the 7 0 ° F r o o t t e m p e r a t u r e p r o ­
duc ed a p p r o x i m a t e l y t w i c e a s m u c h s t e m e l o n g a t i o n a s the p l a n t s
g r o w n with the 5 0 ° F r o o t t e m p e r a t u r e , but th e p l a n t s in a l l of th e
t r e a t m e n t s f l o w e r e d o v e r a p e r i o d of only 7 d a y s .
The l a r g e s t t o p - r o o t r a t i o w as o b t a i n e d f r o m p l a n t s g r o w n
w ith r e d u c e d l i g h t i n t e n s i t y a n d 7 0 ° F r o o t t e m p e r a t u r e .
A c c o r d i n g to e a c h of the m e t h o d s of d e t e r m i n i n g p l a n t
g ro w t h , th e 7 0 ° F r o o t t e m p e r a t u r e w as found to f a v o r the g r o w t h
of S a l v i a m o r e t h a n the 5 0 ° F r o o t t e m p e r a t u r e .
intensity fa v o red flowering,

The r e d u c e d li g h t

s t e m e lo n g at i o n , and n u t r i e n t a c c u m u l a t i o n

m o r e t h a n full lig h t i n t e n s i t y .

F u l l light i n t e n s i t y , h o w e v e r ,

in g r e a t e r a c c u m u l a t i o n of f r e s h and d r y w e ig h t.
F i f t e e n f i g u r e s and n i n e t e e n t a b l e s w e r e i n c l u d e d .

resulted

TABLE

OF CONTENTS
Page

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

1

R E V I E W O F L I T E R A T U R E ................................

2

Taxonomy

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

2

P h o t o p e r i o d .................... ......................................................................

2

L i g h t I n t e n s i t y .........................................................................................

4

In f l u en c e on P l a n t G r o w t h ....................................................

5

In f l u en c e on A b s c i s s i o n L a y e r ..........................................

11

T e m p e r a t u r e ..........................................................................................

12

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

14

P R O C E D U R E ...................................................................................................

18

T e s t s of C u l t i v a r s .................................................................................

18

I n t e r a c t i o n of Cold T r e a t m e n t a n d G ro w t h

19

N utrient A bsorption

. . . .

I n t e r a c t i o n of Night T e m p e r a t u r e and G ro wth

. . .

20

F o r m of P l a n t ...........................................................................................

20

T i m i n g of C o m m e r c i a l C r o p .....................................

21

K e e p in g Q u a l i t y .....................................................................................

22

I n t e r a c t i o n of P h o t o p e r i o d and G r o w t h . . . . . . .

25

I n t e r a c t i o n of Root T e m p e r a t u r e and L ight I n t e n ­
sity with G r o w t h ............................

26

R E S U L T S ..............................................................................................................

29

T e s t s of C u l t i v a r s ..............................................................................

29

I n t e r a c t i o n of Cold T r e a t m e n t and G r o w t h

. .

36

.

37

.

I n t e r a c t i o n of Nigh t T e m p e r a t u r e and G ro wth
F o r m of P l a n t ............................

40

T i m i n g of a C o m m e r c i a l C r o p ..........................................

41

K e e p i n g Q u a l i t y .....................................................................................

43

I n t e r a c t i o n of P h o t o p e r i o d and

G r o w t h .........................

45

I n t e r a c t i o n of Root T e m p e r a t u r e and L ig ht I n t e n ­
s ity with G r o w t h . . ..........................................................................

49

G e n e r a l ....................................................................................

. . .

49

F l o w e r Bud D e v e l o p m e n t ...............................................

52

P l a n t H e i g h t ..........................................................................................

56

F r e s h W e i g h t .....................................................................................

57

D r y W e i g h t .............................................................................

58

T o p - R o o t R a t i o .......................................................................

60

N u t r i e n t A c c u m u l a t i o n .........................................................

64

SYNOPSIS O F R E S U L T S .

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

66

D I S C U S S I O N .........................................................................................................

71

T e s t s of C u l t i v a r s .................................

71

I n t e r a c t i o n of Cold T r e a t m e n t and G r o w t h ...................

71

I n t e r a c t i o n of Night T e m p e r a t u r e and G r o w t h

72

. . .

F o r m of P l a n t .........................................................................................

74

T i m i n g of a C o m m e r c i a l C r o p ...............................................

74

K e e p i n g Q u a l i t y .....................................................................................

76

I n t e r a c t i o n of P h o t o p e r i o d and G r o w t h

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

78

I n t e r a c t i o n of Ro ot T e m p e r a t u r e and L ig h t I n t e n ­
s it y with G r o w t h ....................................................................................

81

SUMMARY
BI BLI OGRAPHY .

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

89
93

LIST O F T A B L E S

TABLE

Page

1.

Q u e s t i o n n a i r e f o r P u b l i c O pin io n of S a lv ia P l a n t s . .

23

2.

E f f e c t of P i n c h i n g C u l t i v a r s on G r o w t h of S a l v ia

34

3.

I n t e r a c t i o n of Cold T r e a t m e n t and G r o w t h ...............

4.

E f f e c t of Night T e m p e r a t u r e on H eigh t of P l a n t s . .. ' 35

.
35

5. E f f e c t of Nigh t T e m p e r a t u r e on R a t e a nd A m o u nt
of G r o w t h ...........................................................................

38

6. A v e r a g e N u m b e r of D a ys R e q u i r e d f o r F l o w e r i n g
With R e s p e c t i v e N u m b e r of P i n c h e s ...............................

38

7. A v e r a g e N u m b e r of D a y s f r o m Se eding R e q u i r e d
f or F l o w e r Bud D e v e l o p m e n t .................................................

42

8. R a t e of F l o w e r and L e a f A b s c i s s i o n f r o m P l a n t s
E x p o s e d to R o o m T e m p e r a t u r e in P r i v a t e H o m e s . .

42

9. I n t e r a c t i o n of P h o t o p e r i o d a nd T i m e on T o t a l S te m
E l o n g a t i o n p e r P l a n t .................................................................. .

46

.

10. I n t e r a c t i o n of P h o t o p e r i o d and T i m e on P l a n t
H e i g h t ..........................................................................................................

46

11. I n t e r a c t i o n of P h o t o p e r i o d a nd T i m e on N u m b e r of
Da ys R e q u i r e d f o r F l o w e r i n g .............................................

49

12. I n t e r a c t i o n of Root T e m p e r a t u r e and L i g h t I n t e n s i t y
on N u m b e r of Days R e q u i r e d f o r F l o w e r i n g in the
F a l l C r o p ..........................................
13. A p p r o x i m a t e L e n g t h of P h o t o p e r i o d O c c u r i n g D u r ­
ing G r o w t h of F a l l and W i n t e r C r o p s ............................

53

53

TABLE

Page

14. I n t e r a c t i o n of Root T e m p e r a t u r e and L i g h t I n ­
t e n s i t y on P l a n t H eight in C e n t i m e t e r s ........................

54

15. I n t e r a c t i o n of Root T e m p e r a t u r e and L ig h t I n ­
t e n s i t y on P r e s h Weight of S t e m s and R o o t s in
............................
G ram s . . . .

59

16. I n t e r a c t i o n of Root T e m p e r a t u r e and L ig h t I n ­
t e n s i t y on D r y Weight of S t e m s a nd R o o t s in
G r a m s .............................................................................................................

59

17. I n t e r a c t i o n of Ro o t T e m p e r a t u r e and L i g h t I n ­
t e n s i t y on T o p - R o o t R a ti o . . .
...........................................

60

18. I n t e r a c t i o n of Root T e m p e r a t u r e and L i g h t I n ­
t e n s i t y on N u t r i e n t E l e m e n t C o m p o s i t i o n of R o o t s
and T o p s ( P e r C e n t D r y W e i g h t ) ...............................................

61

19. T o t a l Weekly and A v e r a g e D aily R a d i a t i o n s of L ig h t
D u r i n g G r o w t h of W i nt e r C r o p .
..........................................

82

LIST O F F IG U R E S
FIG U R E

Page

1.

Sa lvia

P l a n t of the D w a r f Type . . .

31

2.

Sa lv ia

P l a n t of the S e m i - d w a r f Type .

32

3.

Sa lvia

P l a n t of the T a l l Type

33

4.

Salvia

P l a n t G r o w n Without P i n c h i n g . .

39

5.

S al vi a

P l a n t G r o w n With Two P i n c h e s

39

6.

G r e e n h o u s e E q u i p m e n t ..........................................................

47

7.

S al vi a P l a n t s 95 Days A f t e r Seeding D e m o n s t r a t i n g
the Influe nc e of P h o t o p e r i o d on V e g e ta t i v e G ro w th .

47

8.

C a m e r a l u c i d a D r a w i n g of a Salvia F l o w e r Bud . .

50

9.

Influ en c e of E i g h t and Root T e m p e r a t u r e on Bud
Developm ent . . .
. ..........................................

51

I n t e r a c t i o n of Root T e m p e r a t u r e and E ig h t I n t e n s it y
on G r o w th of Sa lvia 58 Da ys A f t e r S e e d i n g ...................

55

I n t e r a c t i o n of Root T e m p e r a t u r e and Light I n t e n s it y
on G ro w th of Sa lvia 105 D a ys A f t e r S e e d i n g ...................

55

12.

A c c u m u l a t i o n of N u t r i e n t s in F a l l and W i n te r C r o p s

62

13.

Inf lu e nc e of Root T e m p e r a t u r e and L ig ht I n t e n s it y
on A c c u m u l a t i o n of N u t r i e n t s .

62

Inf lu enc e of L i g h t I n t e n s i t y on A c c u m u l a t i o n of
N u t r i e n t s in F a l l and W i n te r C r o p s .................................

63

I nflue nce of Root T e m p e r a t u r e on A c c u m u l a t i o n of
N u t r i e n t s in F a l l a nd Winter, C r o p s „ . .
...................

63

10.

11.

14.

15.

.

1

INTRODUCTION

T h e r e is a l i m i t e d s e l e c t i o n of f l o w e r i n g p l a n t s a v a i l a b l e at
C hristm as.

S a lv ia s p l e n d e n s K e r - G a w l (Salvia) h a s o u t s t a n d i n g and

a p p ro p ria te color,

grows rapidly,

and a p p e a r s to h ave p o s s i b i l i t i e s

a s a p o p u l a r a nd p r o f i t a b l e pot p l a n t f o r the C h r i s t m a s m a r k e t .
In o r d e r to p r o d u c e f l o w e r s f or h o li d a y m a r k e t s ,

accurate

t i m i n g of the c r o p is e s s e n t i a l , and d e p e n d s upon the r e a c t i o n of the
s p e c i e s to light, t e m p e r a t u r e ,
greenhouse.

and' th e a r t i f i c i a l c o n d i t io n s of the

D i f f e r e n c e s a m o n g c u l t i v a r s in r e s p e c t to e n v i r o n m e n t a l

re sp o n se a r e also im portant.
T h i s i n v e s t i g a t i o n was d e s i g n e d to study the v a r i e t i e s and c o n ­
d it i o n s m o s t f a v o r a b l e f or the

c o m m e r c i a l g r e e n h o u s e p r o d u c t i o n of

Salvia , i ts s u i t a b i l i t y a s a pot p l a n t in the h o m e , and to o b t a i n i n f o r ­
m a t i o n c o n c e r n i n g the in f l u e n c e 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 i ts
grow th.

R EV IEW OF L IT E R A T U R E

T ax on om y

In H o r t u s Second,

B a i l e y h a s d e s c r i b e d the g en us S a lv ia as

b e l o ng in g to the f a m i l y L a b i a t a e , which in g e n e r a l h a s f o u r angle
stem s,

opposite or w horled le a v e s,

f l o w e r s , two o r f o u r s t a m e n s ,

i r r e g u l a r two-lipped gamopetalous

s u p e rio r four-lo bed ovary,

and f r u i t of four o n e - s e e d e d n u t l e t s .

two s t i g m a s ,

S a u n d e r s (1934) s t a t e d t h a t while

two p a i r s of the s t a m e n s d ev elo p , the p o s t e r i o r p a i r is r e p r e s e n t e d
by v e r y s m a l l l o b e - l i k e e n l a r g e m e n t s .

A l th o u g h only one p a i r of f u n c ­

ti o n a l s t a m e n s d e ve lo p in Sa lv ia (Salvia s p l e n d e n s ) and s o m e o t h e r
species,

S a u n d e r s (1934, 1940) o b s e r v e d t h a t n o r m a l l y f o u r a n d r o e c i u m

b u n d l e s a r i s e f r o m the c e n t r a l c y l i n d e r in e x a c t l y the s a m e way a s in
t h o s e s p e c i e s which p r o d u c e two p a i r s of f un c t i o n a l s t a m e n s .

P h o t o p e r iod

In 1891, B a i l e y r e p o r t e d b e i n g a ble to in d u c e f l o w e r i n g and
s e e d f o r m a t i o n in s p i n a c h ( Sp in ac ia o l e r a c e a ) and l e t t u c e ( L a c t u c a
s a ti v a ) with the u s e of e l e c t r i c l i g h t s to l e n g t h e n the p e r i o d , of i l l u m ­
i n a ti o n .

G a r n e r and A l l a r d (1920) e x t e n s i v e l y i n v e s t i g a t e d the e f f e c t

of the r e l a t i v e l e n g t h of day on f l o w e r i n g .

T h e y t e r m e d the r e s p o n s e

of o r g a n i s m s to the r e l a t i v e l e n g t h of day a s p h o t o p e r i o d i s m ,

and

3.

c l a s s i f i e d p l a n t s into t h r e e g e n e r a l g r o u p s in r e g a r d to t h e i r r e ­
s p o n s e to p h o t o p e r i o d : (1) s p e c i e s w h o s e f l o w e r i n g is not a f f e c t e d
by the d u r a t i o n of the e x p o s u r e to light,

(2) s p e c i e s which f l o w e r only

whe n the d u r a t i o n of the e x p o s u r e to l i g h t is s h o r t e r t h a n the c r i t i c a l
period for flowering,

and (3) s p e c i e s w hich f lo w e r only when the

d u r a t i o n of the r e s p o n s e to lig ht is l o n g e r t ha n the c r i t i c a l .

In a d d i ­

t i o n to f l o w e r i n g r e s p o n s e , M u r n e e k (1948) o b s e r v e d a p h o t o p e r i o d i c
i n h i b i t i o n of v e g e t a t i v e g r o w t h with a s h o r t p h o t o p e r i o d in
n o r m a l l y f l o w e r e d when s u p p li e d with a s h o r t p h o t o p e r i o d .

plants that
G arner

an d A l l a r d s u c c e e d e d in in du cin g f l o w e r i n g and s e e d i n g in M a r y l a n d
M a m m o t h t o b a c c o ( N ic o ti a n a t o b a c u m ) by e x p os in g the p l a n t s to a
" s h o r t " light p erio d .

C o s m o s ( C o s m o s b i p i n n a t u s ) and p o i n s e t t i a

( E u p h o r b i a p u l c h e r r i m a ) w e r e p r e v e n t e d f r o m f l o w e r i n g d u r i n g the
s h o r t d ays of the w i n t e r m o n t h s by i l l u m i n a t i n g the p l a n t s f r o m s u n ­
s e t to m i d n i g h t .

The f l o w e r i n g of p l a n t s in r e s p o n s e to a s h o r t p h o t o ­

p e r i o d w a s b e l i e v e d by H a m n e r (1938) to be due to a s t i m u l u s which
was p r o d u c e d by the l e a v e s of the p l a n t d u r i n g the d a r k p e r i o d .

D ur­

ing the s u c c e e d i n g light p e r i o d t h i s s u b s t a n c e was b e l i e v e d to be
b r o k e n down.

H a m n e r u s e d t h i s to e x p la i n why s h o r t p h o t o p e r i o d

p l a n t s f l o w e r e d m u c h m o r e q uickly when s u p p li e d with a p h o t o p e r i o d
d e c i d e d l y l e s s t h a n the c r i t i c a l t h a n when s u p p l i e d with one s l i g h t l y
l e s s t h a n the c r i t i c a l .

4.

The w o r k of G i l b e r t (1926) i n d i c a t e d t h a t r e s p o n s e to photo p e r i o d m i g h t be i n f l u e n c e d by t e m p e r a t u r e a n d h u m i d i t y .

G ilb ert

(1926) o b s e r v e d in s o y b e a n s (Soya Max) and c otto n ( G o s s y p i u m sp. )
t h a t t h e r e was a d e fi ni te r e t a r d a t i o n of f l o w e r i n g with l o w e r t e m p e r ­
a t u r e a nd h i g h e r h u m i d i t y .

C o s m o s f l o w e r e d e a r l i e r with l o w e r

t e m p e r a t u r e and h i g h e r h u m i d i t y .

S a lv ia and b u c k w h e a t ( F a g o p y r u m

e s c u l e n t u m ) p r o d u c e d no c ha ng e in p h o t o p e r i o d r e s p o n s e a s a r e s u l t
of v a r i a t i o n s in t e m p e r a t u r e and h u m i d i t y .
R o b e r t s and S t r u c k m e y e r (1938) found t h a t S a lv ia f l o w e r e d
u n d e r a s h o r t p h o t o p e r i o d of 9 h o u r s and g r e w v e g e t a t i v e l y u n d e r a
long p h o t o p e r i o d of 16 h o u r s .

A rthur,

G u t h r i e a nd N e w e ll (1930) o b ­

t a i n e d a n a b u n d a n c e of f l o w e r s when S a lv ia p l a n t s w e r e e x p o s e d to a
p h o t o p e r i o d of 15 h o u r s o r l e s s .

H a m n e r (1938) o b t a in e d f l o w e r s

f r o m p l a n t s of S a lv ia u n d e r a p h o t o p e r i o d of 14 h o u r s , but c o n c l u d e d
t h a t the " n u m b e r of f l o w e r s p r o d u c e d a t t h i s p h o t o p e r i o d w as g r e a t l y
i n f l u e n c e d by the s upply of n i t r o g e n " .

L ig h t I n t e n s i t y
A s m a l l e r r e d u c t i o n in l i g h t i n t e n s i t y was o b t a i n e d u n d e r a
c l o th n e t t i n g by G r a y (1934) on cloudy t h a n on c l e a r d a y s .

A ngstrom

(1919) d i s t i n g u i s h e d b e t w e e n r a d i a t i o n f r o m the sky and r a d i a t i o n f r o m
the sun and c o n c l u d e d t h a t the c l o t h n e t s h a d in g m a t e r i a l cut out v e r y
l i t t l e of the r a d i a t i o n f r o m the sky.

T h i s r a d i a t i o n f r o m th e sky w as

5.

relatively great.

With a high sun and a c l e a r sky it was a b o u t 20

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

and its p e r c e n t a g e i n c r e a s e d r a p i d l y

with i n c r e a s e in c l o u d i n e s s .
In fluen ce on P l a n t Growth:

As e a r l y as 1836 D a u b e r r y c o n ­

c l u de d t h a t light i n t e n s i t y h ad a g r e a t e r in fl u e nc e on p l a n t p r o c e s s e s
t h a n did the h e a t e m i t t e d by the light r a y s .
He s t a t e d ,
by p l a n t s ,

" B o t h the e x h a l a t i o n and the a b s o r p t i o n of m o i s t u r e

so f a r a s t h e y depe nd upon the i nf lu en c e of light, a r e

a f f e c t e d in the g r e a t e s t d e g r e e by the m o s t l u m i n o u s r a y s " .
L o o m i s (1933) p o i n t e d out t h a t s i n c e the lig h t r a y s a r e known
to h a v e a l a r g e in f l u e n ce upon p h o t o s y n t h e s i s ,

growth substance f o r ­

m a t i o n and a c t i v i t y , and p i g m e n t a t i o n in g r o w in g p l a n t s , the lig h t
r a y s c a n a l s o be e x p e c t e d to in f l u en c e m o r p h o g e n e s i s a nd h i s t o g e n s i s .
Furtherm ore,

Huxley (1932) s t a t e d t h a t it a p p e a r e d h ig h l y p r o b a b l e

t h a t light e x e r t s i t s i nf lu en ce in the d e v e l o p m e n t of p l a n t s in m a n y
wa ys which a r e not c l e a r l y u n d e r s t o o d .
B u r k h o l d e r (1936) p r o d u c e d a r a t h e r t h o r o u g h r e v i e w of " T h e
r o l e of li gh t in the life of p l a n t s " .

In t h i s r e v i e w it was qu ite g e n e r ­

a lly a g r e e d t h a t t h e r e i s a n o p t i m u m light i n t e n s i t y f o r the g r o w t h
of e a c h s p e c i e s .

In the c a s e of m a n y p l a n t s t h i s o p t i m u m wa s found

to be c o n s i d e r a b l y l e s s t h a n fu ll s u n lig ht on a c l e a r day.

D a v i s and

H o a gl a nd (1928) found t i s s u e f o r m a t i o n to be m o r e " e f f i c i e n t " when

6

the i l l u m i n a t i o n was d i s t r i b u t e d at a m o d e r a t e i n t e n s i t y o v e r a
l o n g e r p e r i o d of t i m e t h a n u n d e r the o p p o s i t e c o n d i t io n s of high
lig h t i n t e n s i t y and s h o r t d u r a t i o n .

The o p t i m u m l i g h t i n t e n s i t y f o r

a g i v e n s p e c i e s w as o b s e r v e d by C o m b s (1910) and H e a r n (1922) to
c h a n g e with the age of the p l a n t .

A s the p l a n t s g r e w o l d e r ,

they b e ­

c a m e l e s s s e n s i t i v e to li g h t and the light i n t e n s i t y w hic h w as o p t i ­
m u m f o r the p r o d u c t i o n of d r y m a t t e r i n c r e a s e d with the i n c r e a s i n g
age of the p l a n t s .
P o s t (1931) and L a u r i e (1932) s u g g e s t e d t h a t v a r i a t i o n s in
p l a n t g r o w t h u n d e r r e d u c e d lig h t i n t e n s i t y m i g h t be p a r t i a l l y due to
s l o w e r t r a n s p i r a t i o n , h i g h e r h u m i d it y , h i g h e r soil m o i s t u r e ,

and

h i g h e r t e m p e r a t u r e u n d e r the s ha d e s t r u c t u r e .
In " T h e r o l e of l i g h t in the life of p l a n t s " by B u r k h o l d e r (1936)
it was p o in t e d out t h a t the e ff e ct of lig ht i n t e n s i t y upon g r o w t h could
be o b s e r v e d in c h a r a c t e r i s t i c r e s p o n s e s of the p l a n t.

Stem e longa­

tion, f r e s h and d r y weight of s t e m s and r o o t s , f l o w e r i n g an d f r u i t i n g ,
m o i s t u r e and n u t r i e n t a c c u m u l a t i o n ,

and fo lia ge s t r u c t u r e w e r e all

a f f e c t e d by the i n t e n s i t y of the l i g h t u n d e r which t h e p l a n t s w e r e
gr ow n.
The p r e s e n c e of d a ylig ht t e n d e d to inh ibit s t e m e l o n g a t i o n of
p l a n t s (Went, 1941).

Went found t h a t the i n t e n s i t y of the su n li g h t was

of g r e a t e r i m p o r t a n c e in i n h i b itin g s t e m e lo n g a t i o n in p e a ( P i s u m

s a t i v u m v a r . L i t t l e M a r v e l ) t h an was the d u r a t i o n of the i l l u m i n ­
a ti on .

The i n t e n s i t y of the s u n li g h t w as found by P o r t e r (1936) to

be i n v e r s e l y r e l a t e d to the e lo n g a t i o n of the s t e m s of t o m a t o ( L y c o p e r s i c u m e s c u l e n t u m ) p l a n t s g ro w n u n d e r full i n t e n s i t y ,
a nd q u a r t e r i n t e n s i t y of s un lig h t in the g r e e n h o u s e .

ha lf i n t e n s i t y

P o p p (1926) o b ­

s e r v e d t h a t the g r e a t e s t s t e m e lo n g a t i o n of s o y b e a n s g r o w n u n d e r
l i g h t i n t e n s i t i e s r a n g i n g f r o m 26 to 4, 285 foot c a n d l e s o c c u r r e d u n d e r
an i l l u m i n a t i o n of 560 foot c a n d l e s and the l e a s t a m o u n t of e lo n g a t i o n
took p l a c e u n d e r an i l l u m i n a t i o n of 26 foot c a n d l e s .

In g e n e r a l ,

it

a p p e a r e d t h a t b e l o w a c e r t a i n m i n i m u m i n t e n s i t y of l i g h t the i n v e r s e
r e l a t i o n b e t w e e n li g h t i n t e n s i t y and s t e m e l o n g a t i o n d i s a p p e a r e d and
s t e m e l o n g a t i o n was i n h ib i t e d by a s e v e r e l y low li g h t i n t e n s i t y .
A r t h u r and S t e w a r t (1931) found t h a t the f r e s h and d r y w e ig h ts
of s t e m s and r o o t s of p l a n t s g r o w n u n d e r r e d u c e d r a d i a t i o n d e p e n d e d
l a r g e l y on the m a g n i t u d e of th e t o t a l radiation,,
(Hel i a n t h u s s p . ) ,

salvia, buckwheat,

When s u n f l o w e r

d a h l ia (Da hlia s p . ) ,

and t o b a c c o

p l a n t s w e r e g r o w n u n d e r 100, 78, 58 and 35 p e r c e n t t o t a l r a d i a t i o n
d u r i n g J u n e and J u l y ,

a ll of t h e s e p l a n t s e x c e p t S al v ia p r o d u c e d

g r e a t e r f r e s h and d r y w eight of t i s s u e when the p l a n t s w e r e s h a d e d
w ith c h e e s e c l o t h t h a n when the p l a n t s w e r e g r o w n in the op e n sunlight,
When t h e s e s a m e s p e c i e s w e r e g r o w n u n d e r the s a m e c o n d i t i o n s d u r ­
ing A u g u s t and S e p t e m b e r , the p l a n t s g r o w n in the op en s u n l i g h t p r o -

d u c e d the m a x i m u m a m o u n t of d r y weight.
T e m p e r a t u r e h a s b e e n shown to be v e r y i m p o r t a n t in d e t e r ­
m i n i n g the o p t i m u m l i g h t i n t e n s i t y f or d r y w eight a c c u m u l a t i o n .
B o l a s (1934) found t h a t at a h i g h e r t e m p e r a t u r e a h i g h e r li g h t i n t e n s i t y
p ro v e d o p tim u m fo r d ry weight a c c u m u latio n .

He p l o t t e d the r a t e of

d r y w eight a c c u m u l a t i o n f o r t o m a t o e s d u r i n g a 7 - h o u r p e r i o d a t 60,
and 8 5 ° F o v e r a r a n g e of i n t e n s i t y f r o m 100 to 1, 000 foot c a n d l e s .

75
At

6 0 ° F m a x i m u m d r y we ight a c c u m u l a t i o n o c c u r r e d a t a p p r o x i m a t e l y
200 foot c a n d l e s ,

while a t 7 5 ° F it o c c u r r e d at a p p r o x i m a t e l y 750 foot

c a n d l e s and at 8 5 ° F ,

1,000 foot c a n d l e s .

M u c h v a r i a b i l i t y in g r o w t h r e s p o n s e to li gh t i n t e n s i t y h a s b e e n
reported.

The f r e s h w ei g h t of p ota to (Sola num t u b e r o s u m ) , r a d i s h

(R a p h a n us s a t i v u s ) , s o m e p a r t s of w h ic h w e r e u n d e r g r o u n d p a r t s ,
c o tto n and l e t t u c e , h a s b e e n found by Shantz (1913) to i n c r e a s e with
d e c r e a s i n g l i g h t i n t e n s i t y f r o m 50 to 15 p e r c e n t of full s u n l i g h t in
Louisiana.

None of t h e s e p l a n t s w a s a b le to g r o w be yond the s e e d l i n g

sta ge when the su n li g h t wa s r e d u c e d to 6 p e r c e n t of full s u n i i g h t 0 No
d r y w e i g h t d e t e r m i n a t i o n s w e r e m a d e by S hantz.
S h i r l e y (1929) found t h a t the a m o u n t of d r y m a t t e r p r o d u c e d
by p l a n t s of s u n f l o w e r ( H e l i a n th u s a n n u u s ) ,

g e u m (G e u m s p . ) and

b u c k w h e a t was a l m o s t d i r e c t l y p r o p o r t i o n a l to the lig h t i n t e n s i t y up
to the h i g h e s t i n t e n s i t i e s a v a i l a b l e u n d e r two 150 0-watt i n c a n d e s c e n t

l a m p s with 12 h o u r s i l l u m i n a t i o n daily.

D u r i n g the w i n t e r m o n t h s

the d r y weight p r o d u c t i o n was a l m o s t d i r e c t l y p r o p o r t i o n a l to lig h t
i n t e n s i t y up to the h i g h e s t i n t e n s i t i e s a v a i l a b l e in the g r e e n h o u s e .
D u r i n g the s u m m e r ,

these plants exhibited a tendency tow ard a slower

r a t e of d r y w e i g h t p r o d u c t i o n a t the h i g h e r i n t e n s i t i e s of i l l u m i n a t i o n .
S h i r l e y f u r t h e r o b s e r v e d t h a t the i n t e n s i t y of the s u n lig h t of m i d ­
s u m m e r could be r e d u c e d 50 p e r ce nt without g r e a t l y a f f e c t i n g the
g r o w t h of th e p l a n t s .

A f u r t h e r r e d u c t i o n to 20 p e r c en t of full lig h t

i n t e n s i t y c a u s e d a d e c r e a s e in d r y w e ig h t a c c u m u l a t i o n .
be c o r r e l a t e d with the d e c r e a s e in lig h t i n t e n s i t y .
vations w e re ,

in g e n e r a l ,

T h i s could

T h e s e two o b s e r ­

c o n f i r m e d by C l e m e n t s and Long (1934)

u s i n g s u n f l o w e r a nd c l a r k i a ( C l a r k i a e l e g a n s ) with t r e a t m e n t of " f u l l " ,
32, 16, and 8 p e r c e n t s u n l i g h t a s f u r n i s h e d by l a t h h o u s e s .
t a n t r e c o r d i n g s w e r e m a d e of the i n t e n s i t y .

No c o n s ­

L u b i m e n k o (1908), w o r k ­

ing with p l a n t s of pine ( P i n u s sp. ), a s h ( F r a x i n u s sp. ), and l i n d e n
( F i l i a sp. ) o b t a i n e d r e s u l t s whic h s e e m to be s i m i l a r to t h o s e of
S h i r l e y (1929).

L u b i m e n k o m a d e no m e a s u r e m e n t s of lig h t i n t e n s i t y

and it is t h e r e f o r e d if fic ult to m a k e a c o m p a r i s o n of d a t a .

Chandler

(1953) o b t a i n e d i n c r e a s e s in f r e s h weight p r o d u c t i o n by r o s e ( R o sa
h y b r i d a ) p l a n t s u n d e r full s u n li g h t a s c o m p a r e d to p l a n t s g r o w n
u n d e r r a d i a t i o n r e d u c e d by the u s e of l a y e r s of c h e e s e c l o t h .

Records

of the lig h t i n t e n s i t y u n d e r e a c h t r e a t m e n t w e r e m a d e with a L e e d s and

10

N o r t h r u p S p e e d o m a x Type G r e c o r d e r .
G a r n e r and A l l a r d (1920) o b t a i n e d a d ef inite d e c r e a s e in the
n u m b e r of f l o w e r s a nd f r u i t s p r o d u c e d on s o y b e a n p l a n t s u n d e r r e ­
duc ed li gh t i n t e n s i t y .

S i m i l a r r e d u c t i o n s in f lo w e r bud and f r u i t f o r ­

m a t i o n w e r e o b s e r v e d by K r a y b i l l (1923) when p e a c h ( P r u n u s p e r s i c a )
and a p p le ( M alu s p u m i l a ) t r e e s w e r e g r o w n u n d e r r e d u c e d p r e v a i l i n g
d a y l ig h t f or a p e r i o d of t h r e e y e a r s .

P o r t e r (1936) o b t a i n e d t w o -

t h i r d s p r o d u c t i o n of t o m a t o f r u i t when the l i g h t i n t e n s i t y w as r e d u c e d
50 p e r c e n t b el o w n o r m a l ,
t e n s i t y was c u t 7 5 p e r c e n t .

a nd o n e - h a l f p r o d u c t i o n when the l i g h t i n ­
T i m e of f l o w e r i n g and f r u i t i n g of t o m a t o

a nd a l a r g e n u m b e r of o t h e r p l a n t s w e r e found to be d e l a y e d c o n s i d e r ­
a b l y u n d e r low lig h t i n t e n s i t y ( Z i ll ic h , 1926; S h i r l e y ,

1929).

M o d e r a t e v a r i a t i o n s in s o il m o i s t u r e w e r e found by S h i r l e y
(1929) to c a u s e i n s i g n i f i c a n t c h a n g e s in the d r y we ight p r o d u c e d by
p l a n t s of t o m a t o , t o b a c c o ,

geum,

s u n f lo w e r a nd o t h e r p l a n t s , p r o v i d ­

ing the m o i s t u r e c o n t e n t w a s not low enough to a p p r o a c h the wilting
coefficient,

o r high enough to a p p r o a c h s a t u r a t i o n .

V a r i a t i o n s in lig ht

i n t e n s i t y c a u s e d s i g n i f i c a n t d i f f e r e n c e s in the m o i s t u r e c o n t e n t of p l a n t
tissue.

A c c o r d i n g to w o r k of C l e m e n t s and M a r t i n (1934) and K r a m e r

(1940) with sunflower, and B a i l e y and J o n e s (1941) with b l u e b e r r y
b u s h e s ( V a c c i n i u m sp, ), w a t e r a b s o r p t i o n by r o o t s sh ow ed a c l o s e
r e l a t i o n s h i p to s o i l t e m p e r a t u r e .

W a t e r a b s o r p t i o n i n c r e a s e d with a

11.

r i s e in t e m p e r a t u r e to a m a x i m u m above which f u r t h e r i n c r e a s e
in t e m p e r a t u r e r e s u l t e d in w a t e r a b s o r p t i o n at a s l o w e r r a t e and
in a s m a l l e r q u a n t it y .

E i t h e r e x t r e m e l y low o r high soil t e m p e r a ­

t u r e s c a u s e d wilting w hen t r a n s p i r a t i o n wa s s u f f ic ie n t l y high.
P o r t e r (1936) w o r k i n g w ith t o m a t o e s ,
w o r k i n g with r o s e s ,

and C h a n d l e r (1953)

found t h a t p l a n t s p r o d u c e d a g r e a t e r e x p a n s e

of l e a f s u r f a c e a t l o w e r lig ht i n t e n s i t i e s , but the l e a v e s w e r e
t h i n n e r and m a y h a ve ha d l e s s t o t a l m a s s .
were la rg e r,

The e p i d e r m a l c e l l s

s t o m a t e s m o r e n u m e r o u s , and the m e s o p h y l l and m i d ­

v e in w e r e l a r g e r .

The g r e a t e r e x p a n s e of l e a f s u r f a c e u n d e r r e ­

d uc ed li gh t i n t e n s i t y w a s found by P e n f o u n d (1931) to a l l o w g r e a t e r
e x p o s u r e and t e n d e d in s o m e d e g r e e to c o m p e n s a t e f o r the s m a l l e r
q ua n t i ty of t o t a l li g h t r e c e i v e d p e r u nit of l e a f s u r f a c e e x p o s e d .
P o r t e r (1936) b e l i e v e d t h a t the p a r t i a l l y s h a d e d l e a v e s of
t o m a t o u s e d t h e i r l i m i t e d supply of l i g h t m o r e e f f i c i e n t l y t h a n the
u n s h a d e d l e a v e s u s e d t h e i r n o r m a l supply of l ig h t.

He e v e n r e p o r t e d

a l a r g e v a r i a t i o n in the a b i l i t y of d i f f e r e n t p l a n t s of the s a m e s p e c i e s
to u t i l i z e the a v a i l a b l e light.
I nf lu e nc e on A b s c i s s i o n L a y e r :

M y e r s (1940) o b s e r v e d t h a t

the p e t i o l e s of C o l e u s ( C ole us b l u m e i ) te nd e d to a b s c i s s m o r e r a p i d l y
when the p l a n t s w e r e p l a c e d in the d a r k t h a n when the p l a n t s w e r e
p l a c e d in the l ig h t .

T h i s a b s c i s s i o n w a s found to be d e l a y e d if the

p l a n t s w e r e t r e a t e d with 0. 5 to 1. 0 p e r c e n t of h e t e r o a u x i n in
lanolin.

L a R u e (1936) was a b le to d e la y the a b s c i s s i o n of p e t i o l e s

f r o m whic h the l e a f b l a d e s had b e e n r e m o v e d by t r e a t i n g the t i p s
of the p e t i o l e s with 0. 5 p e r c e n t h e t e r o a u x i n in l a n o li n .

T em peratur e
It i s t ho u gh t t h a t e a c h p l a n t s p e c i e s h a s an o p t i m u m a i r
t e m p e r a t u r e f o r g r o w t h ( B u r k h o l d e r , 1936).

F or practical purposes

P o s t (1949) h a s l i s t e d o p t i m u m night a i r t e m p e r a t u r e f o r the g r o w t h
of c o m m o n g r e e n h o u s e c r o p s .

F o r salvia,

P o s t a g r e e d with R o b e r t s

a n d S t r u c k m e y e r (1938) t h a t the o p t i m u m n ig h t t e m p e r a t u r e f o r g r o w ­
ing S a lv ia was b e t w e e n 55 and 6 0 ° F .
H o ll e y (1942) s t a t e d t h a t the i m p o r t a n c e of a i r t e m p e r a t u r e
b e c a m e i n c r e a s i n g l y s i g n i f i c a n t a s the light i n t e n s i t y d e c r e a s e d .

He

found t h a t with c a r n a t i o n s (Dianthus c a r y o p h y l l u s ) g r o w in g u n d e r a
light i n t e n s i t y of 100 to 200 foot c a n d l e s , the p r o d u c t i o n of c a r b o h y ­
d r a t e s w as so low t h a t the a m o u n t of m a t e r i a l r e s p i r e d e a s i l y e x ­
ceeded that m anufactured.
T e m p e r a t u r e in the s u r f a c e l a y e r of soil w as e f f e c t i v e l y
r e d u c e d by a s m u c h a s 14°F by Dravid(1940) with the u s e of m u l c h e s
of f r e n c h c h a l k , with h e a v y w a t e r i n g s e qua l to o n e - q u a r t e r i nch of
rain,

and with c o v e r i n g s of v e g e t a t i o n .

A com prehensive review

of t h e i m p o r t a n c e of s o il t e m p e r a t u r e to p l a n t g r o w t h was p u b ­
l i s h e d by R i c h a r d s ,

H ag en , and M c C a l l a (1952).

D o r i n g (1935),

R o u s c h a l (1935) and K r a m e r (1942) c o n c l u d e d t h a t the i m p o r t a n c e
of s o il t e m p e r a t u r e to g r o w t h v a r i e d w ith the p l a n t s p e c i e s .

In

g e n e r a l , t he y found t h a t g r o w t h of t r o p i c a l p l a n t s could be m o r e
c l o s e l y r e l a t e d to so il t e m p e r a t u r e s t h a n could the g r o w t h of p l a n t s
n a t i v e to t e m p e r a t e c l i m a t e s .
The o p t i m u m soil t e m p e r a t u r e f or f o r a g e c r o p s ,
by d r y w e ig ht p r o d u c t i o n ,

as m e a s u r e d

was found by J o n e s and T i s d a l e (1921),

D a r r o w (1939), Stuckey (1942), B r o w n (1943), and E a r l e y a nd C a r t t e r
(1945) to v a r y with v a r i e t y , but t h e r e was a t e n d e n c y f o r top g r o w t h
of e a c h c r o p to be r e d u c e d by b oth e x c e s s i v e l y h ig h an d e x c e s s i v e l y
low t e m p e r a t u r e s .
C a m p (1927).

S i m i l a r r e s u l t s w e r e o b ta in e d with c o tt on by

Yield of f l o w e r s was o b s e r v e d to be r e d u c e d by e i t h e r

e x c e s s i v e l y h igh o r low t e m p e r a t u r e s s u pp li e d to b e a n s ( P h a s e o l u s
vulgaris)

by B u r k h o l d e r (1920), and to r o s e s by P f a h l e t. a l.

and Kohl et. a l . (1949).

(1949),

T he w o r k of J o n e s and T i s d a l e (1921) h as

b e e n i n t e r p r e t e d by E a r l e y and C a r t t e r (1945) a s showing a r e l a t i o n
b etw een light intensity,
s o y b e a n s (Glycine Max).

r o o t t e m p e r a t u r e , and r o o t d e v e l o p m e n t in
It w as o b s e r v e d t h a t r o o t g r o w t h i n c r e a s e d

with i n c r e a s e in t e m p e r a t u r e f r o m 35 to 7 5 ° F , but only to an e x t e n t
l i m i t e d by the lig h t i n t e n s i t y .

• R o b e r t s (1953) o b s e r v e d 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 g r o w t h
of a e r i a l p a r t s of the s t r a w b e r r y ( F r a g a r i a sp. ) and i n c r e a s e in r o o t
tem perature,

but t h i s p o s i t i v e c o r r e l a t i o n did not e x i s t b e t w e e n r o o t

g r o w t h and r o o t t e m p e r a t u r e .

C o n s e q u e n t l y , he c o n c l u d e d t o p - r o o t

ratio in c r e a s e d as root te m p e r a t u re in c re a s e d .

A progressive

de­

c r e a s e in the a m o u n t of r o s e r o o t s w as r e p o r t e d by Shanks and L a u r i e
(1949) when the r o o t t e m p e r a t u r e w as i n c r e a s e d f r o m 5 6 ° F to 7 2 ° F
and the a i r t e m p e r a t u r e w as m a i n t a i n e d a t 6 0 ° F d u r i n g the night.
C a nn o n (1917) was a b l e to i n c r e a s e s hoot g r o w t h u n d e r u n f a v o r a b l y
low a t m o s p h e r i c t e m p e r a t u r e by m a i n t a i n i n g r o o t t e m p e r a t u r e s f a v o r ­
able f o r good g r o w t h .

The m a t u r i t y date of s t o c k ( M a th io la i nc an a),

c a l e n d u l a ( C a l e n d u l a s p . ) , and s n a p d r a g o n ( A n t i r r h i n u m m a j u s ) was
o b s e r v e d by A l l e n (1934) to be a f f e c t e d v e r y l i t t l e by v a r i a t i o n s in
s o il t e m p e r a t u r e .

N utrient Absorption

F r o m w o r k c o m p l e t e d in 1933, N i gh tin g ale c o n c l u d e d t h a t
S alv ia w as v e r y s e n s i t i v e to the l e v e l of n i t r a t e s in the n u t r i e n t s o l u ­
t ion.

G r o u p s of Sa lv ia p l a n t s w e r e g r o w n f o r 8 w e e k s u n d e r a 7 - h o u r

a nd a 17- h o u r p h o t o p e r i o d .

At the end of t hi s p e r i o d th e p l a n t s w e r e

t r a n s f e r r e d to a 1 4 - h o u r p h o t o p e r i o d .

Half of e a c h g ro u p w as s u p p li e d

with a n u t r i e n t s o l u t i o n l a c k i n g n i t r o g e n in c o n t r a s t to t h e o t h e r h a l f

with a n i t r a t e n u t r i e n t s o l u ti on .

When the s h o r t p h o t o p e r i o d p l a n t s

w e r e g ive n the n u t r i e n t s o lu ti o n m i n u s n i t r a t e ,

" th ey s hed t h e i r

b l o s s o m s p r o f u s e l y and c o n t i n u e d to g r o w for t h r e e and a h a lf w ee ks
when the e x p e r i m e n t w as d i s c o n t i n u e d " .
H a ge n (1952) h a s r e p o r t e d t h a t he found it d if fic ult to s e p a r a t e
the e f f e c t s of low t e m p e r a t u r e on the a b s o r p t i o n p r o c e s s f r o m t h o s e
on t r a n s l o c a t i o n and a s s i m i l a t i o n .
nutrient absorption,

A f t e r r e v i e w i n g the s u b j e c t of

he c o n c l u d e d t h a t t h e r e w as not s uf f i c i e n t e v i d e n c e

a v a i l a b l e to p r o v e t h a t a r e d u c e d r a t e of n u t r i e n t a b s o r p t i o n w as r e ­
s p o n s i b l e f o r the slo w g r o w t h of p l a n t s a t low r o o t t e m p e r a t u r e .
N evertheless,

H oa gla nd (1923) and A sh b y and Oxley (1935) had p r e ­

v i o u s l y c o n c l u d e d t h a t n u t r i e n t a b s o r p t i o n by r o o t s w as i n f l u e n c e d by
lig h t i n t e n s i t y ,

c o n c e n t r a t i o n of the n u t r i e n t s olu tio n ,

aid t e m p e r a t u r e .

H o a g l a nd and D a v is (1923) o b s e r v e d the r a t e of u pt a k e of b r o m i n e
and c h l o r i n e by N i t e l l a c e l l s to be m o r e r a p i d by i l l u m i n a t e d c e l l s t h a n
by c e l l s which w e r e k e p t in the d a r k .

The q ua li t y and q u a n t i t y of lig ht

w a s not d e s i g n a t e d , but the c o n c e n t r a t i o n of b r o m i n e and c h l o r i n e in
the c e l l s w as p r o p o r t i o n a l to the n u m b e r of h o u r s of d a il y i l l u m i n a t i o n .
T he y e x p l a i n e d t h a t " T h e a b s o r p t i o n of ions by p l a n t s f r o m dilute s o l u ­
t i o n s i n v o l v e s e n e r g y e x c h a n g e s with lig ht a s the u l t i m a t e s o u r c e of
the e n e r g y " .
G r a c a n i n (1932) r e p o r t e d no d i f f e r e n c e in the a b s o r p t i o n of

p h o s p h o r u s by p l a n t s of b a r l e y ( H o r d e u m v u l g a r e ) when s h o o t s w e r e
i l l u m i n a t e d o r k ep t in the d a r k .

K r a y b i l l (1923) o b s e r v e d the l e a f

t i s s u e of a pp le a nd p e a c h t r e e s g ro w n in the " s h a d e " to be c o n s i d e r ­
a bly h i g h e r in m o i s t u r e and t o t a l n i t r o g e n t h a n the l e a f t i s s u e of
t r e e s g r o w n in t he sun.

S i m i l a r r e s u l t s w e r e o b t a i n e d by B l a c k m a n

and T e m p l e m a n (1940) with g r a s s e s and c l o v e r ( T r i f o l i u m r e p e n s )
c o m p a r i n g r a d i a t i o n of 37 to 44 p e r c e n t with full s un lig ht.
The m a n g a n e s e c o n t e n t of l e a v e s of s o y b e a n (Glycine m a x ) ,
snapbean (P haseolus vulg aris),

and t o b a c c o w as o b s e r v e d by McCool

(1935) to d e c r e a s e with d e c r e a s e in lig h t i n t e n s i t y .
g r o w n in s o i l u n d e r full,

P la n ts were

58 an d 35 p e r c e n t s o l a r r a d i a t i o n , the r e ­

d uc ed r a d i a t i o n b e i n g p r o v i d e d by c h e e s e c l o t h and u n b l e a c h e d m u s l i n .
A l a r g e r a m o u n t of t o t a l n i t r o g e n , p o t a s h ,

and p h o s p h o r u s

w a s a c c u m u l a t e d in coffee (Coffea a r a b i c a ) p l a n t s g ro w n u n d e r full
s un lig h t t h a n w as a c c u m u l a t e d i n p l a n t s g r o w n u n d e r d ef in it e r e d u c ­
t i o n s of full s o l a r r a d i a t i o n ( A r r i l l a g a and G o m e z , 1942; T a n a d a ,
1946).

In th e w o r k of A r r i l l a g a and G o m e z (1942), the r e d u c e d r a d i a ­

t io n of t w o - t h i r d s ,

one-half,

o n e - t h i r d full su nl ig h t was f u r n i s h e d

by l a t h h o u s e s with the l a t h s s p a c e d to give the d e s i r e d r a d i a t i o n .
S o l a r r a d i a t i o n r e c o r d s w e r e s u p p li e d by M i c r o m a x r e c o r d e r s and
P yrheliom eter s .
S e e d l in g s of a s h w e r e g r ow n by S t e i n b a u e r (1932) u n d e r low

17.

l i g h t i n t e n s i t i e s of 31, 48,

70, and 130 foot c a n d l e s of i n c a n d e s ­

c e n t l i g h t with c o n t r o l l e d t e m p e r a t u r e and h u m i d i t y ,

The c o n c e n ­

t r a t i o n of th e n u t r i e n t s was v a r i e d f r o m 0.1 to 1.0 a t m o s p h e r e to
t e s t the e ff ect of n u t r i e n t supply upon the l e n g th of the p e r i o d of
s u r v i v a l a t s u b n o r m a l light i n t e n s i t i e s .

Steinbauer o bserved that

a g r e a t e r r e s p o n s e to an i n c r e a s e in n u t r i e n t s was found a t the
h i g h e r l i g h t i n t e n s i t i e s but the m i n i m u m lig h t r e q u i r e m e n t could
not be l o w e r e d by i n c r e a s i n g the a m o u n t of a v a i l a b l e n u t r i e n t s .
W a n n e r (1948a, b) s u g g e s t e d t h a t s a l t a b s o r p t i o n f r o m h i g h e r
c o n c e n t r a t i o n s was l e s s d e p e n d e n t upon t e m p e r a t u r e t h a n s a l t
a b s o r p t i o n f r o m l o w e r c o n c e n t r a t i o n s b e c a u s e l e s s e n e r g y was
r e q u i r e d to c o m p l e t e the a b s o r p t i o n of the s a l t .

This th eory was

s u p p o r t e d by r e s u l t s o b t a i n e d by R o b e r t s (1953) with s t r a w b e r r y .
He found t h a t the c o n c e n t r a t i o n of p o t a s s i u m ,
in both l e a v e s and r o o t s of

phosphorus,

p l a n t s g r o w n a t 45,

55,

a nd b o r o n

65, and 7 5 ° F

r o o t t e m p e r a t u r e c ould be c l o s e l y c o r r e l a t e d with the c o n c e n t r a t i o n
of s a l t s in the n u t r i e n t s o lu ti o n .

It was found f u r t h e r t h a t r o o t t e m ­

p e r a t u r e w as an i n s i g n i f i c a n t f a c t o r in the c o n c e n t r a t i o n of a s h in
the a e r i a l p o r t i o n s of the p l a n t s .

T he c o n c e n t r a t i o n of a s h in the

r o o t s i n c r e a s e d with t e m p e r a t u r e above 5 5 ° F .

At 45 and 7 5 ° F r o o t

t e m p e r a t u r e t h e a s h c o n t e n t of the r o o t s was i n s i g n i f i c a n t l y d i f f e r ­
ent.

R oberts,

a l s o , t h e o r i z e d t h a t t h i s cou ld have b e e n due to the

o
r e d u c t i o n in g r o w t h a t the 45 F r o o t t e m p e r a t u r e .

18

PROCEDURE

T e s t s of C u l t i v a r s

In o r d e r to c o m p a r e the h ab it of g r o w t h of d i f f e r e n t c u l t i ­
vars,

s i x p l a n t s of e a c h of t e n c u l t i v a r s of Sa lv ia s p l e n d e n s w e r e

g r o w n in 6 - i n c h p o t s in the g r e e n h o u s e with a 60° F a h r e n h e i t night
t e m p e r a t u r e (F N T) d u r i n g the m o n t h s of M a r c h ,
1953 .

T he c u l t i v a r s u s e d w e r e :

piece,

S p l e n d e n s A m e r i c a , A m e r i c a f or Z u r u c h ,

S ple n de ns S c a r l e t Sage,

St, J o h n s F i r e ,

S p le nd e n s B r i g h t n e s s ,

by V a u g h n ' s Seed C o m p a n y , C h i c a g o ,
of F i r e (Ba ll Seed C o m p a n y ,

I l l i n o i s) ,

A p r i l and May,
Vaughn's M a s t e r ­
C la ra Bedman,

Rose F la m e (furnished
Bonfire,

W e st C h i c a g o , I ll i n o i s ) .

and B l a z e

An 8 - h o u r

p h o t o p e r i o d w a s p r o v i d e d by c o v e r i n g t he p l a n t s with a b l a c k s a t e e n
clo th f r o m 16:30 to 08:30 h o u r s E a s t e r n S t a n d a r d T i m e .

T hree plants

of e a c h c u l t i v a r w e r e p i n c h e d ( c u l t u r a l t e r m u s e d to d e s c r i b e the r e ­
m o v a l of t e r m i n a l g rowth) d i s t a l to the t h i r d node and t h r e e p l a n t s
w e r e a l l o w e d to g r o w without pinc hing.
E a c h c u l t i v a r was c o m p a r e d on the b a s i s of f l o w e r c o l o r ,
p l a n t h e ig h t, p l a n t s h a p e with and without pin ch in g ,
(four w h o r l s of e x p a n d e d s e p a l s ) ,
plant.

date of f l o w e r i n g

and n u m b e r of f l o w e r s h o ot s p e r

i V .

I n t e r a c t i o n of Cold T r e a t m e n t and G ro wth

To d e t e r m i n e the e ff e ct of a cold t r e a t m e n t on young p l a n t s ,
p l a n t s of the c u l t i v a r ,

A m e r i c a w e r e p l a n t e d in 4 - i n c h p o t s ,

grown

in t h e g r e e n h o u s e a t 50 and 60° F N T w ithout pinc hing, and s u p p lie d
with the fo llo win g s i x t r e a t m e n t s ,

u s i n g five p l a n t s p e r t r e a t m e n t :

(a) P l a n t s g r o w n a t 50° F N T in the g r e e n h o u s e
1. C o n t i n u a l 50° F N T
2. C o n s t a n t 40° F

T (F ahrenheit te m p e ra tu re ) for

7 d a ys a s so on as p l a n t s h ad r e a c h e d a t w o - n o d e
s e e d l i n g sta ge
3. C o n s t a n t 40

o

F

T f o r 7 d a ys a s soon a s p l a n t s had

r e a c h e d a f o u r - n o d e s e e d l in g sta ge
(b) P l a n t s g r o w n at 6 0 ° F N T in t h e g r e e n h o u s e
1. C o n t in u a l 60° F N T
2. C o n s t a n t 40° F T f o r 7 d a y s a s soon a s p l a n t s had
r e a c h e d a t w o - n o d e s e e d l i n g sta ge
3. C o n s t a n t 4 0 ° F T f o r 7 d ays a s soon a s p l a n t s had
r e a c h e d a f o u r - n o d e s e e d l in g s ta ge
The 7 - d a y c old t e m p e r a t u r e t r e a t m e n t s c o n s i s t e d of p l a c i n g
the p l a n t s in a 4 0 ° F c o n s t a n t t e m p e r a t u r e c h a m b e r w h e r e t h e y w e r e
i l l u m i n a t e d with 200 foot c a n d l e s of f l o r e s c e n t lig h t f o r 12 h o u r s a
day.

A f t e r t h e c old t e m p e r a t u r e t r e a t m e n t , the p l a n t s w e r e r e t u r n e d

to the g r e e n h o u s e to 50 and 60° F N T r e s p e c t i v e l y ,
to g r o w to m a t u r i t y .

R a t e of shoot elo n ga ti o n ,

and a ll ow e d

date of f l o w e r i n g

and f r e s h w ei gh t of the a e r i a l p o r t i o n of the p l a n t s w e r e r e c o r d e d .

I n t e r a c t i o n of Night T e m p e r a t u r e and G r o wth

It was d e s i r e d to study the g r o w t h r e s p o n s e of Sa lv ia g ro w n
a t 50 and 60

o

F N T w ithout p i n c h i n g .

w e r e sown F e b r u a r y 1, 1952.

S e ed s of c u l t i v a r A m e r i c a

One h u n d r e d and sixty p l a n t s w e r e

g r o w n in 4 - i n c h p o t s a t 50 and 60

o

F N T,

The s e e d l i n g s w e r e

p l a n t e d in 4 - i n c h p ots 37 d a y s a f t e r s e e d i n g .

N in e ty d a y s a f t e r s e e d

ing 40 p l a n t s f r o m e a c h t r e a t m e n t w e r e m o v e d to the o p p o s it e t e m ­
p e r a t u r e to c o m p l e t e t h e i r g r ow th .
The r a t e of shoot e lo n g a t i o n and date of f l o w e r i n g at the
different te m p e r a t u r e s was rec o rd e d .

O bservations were made

on f o li a g e and f l o w e r bud a p p e a r a n c e .

F o r m of P l a n t

In g r o w i n g a g r e e n h o u s e c r o p it i s helpf ul to know how
m a n y t i m e s the s h o o ts of a p l a n t sh ould be " p i n c h e d 11 to p r o d u c e
d e s ira b le plants m o st rapidly.

S e e d s of c u l t i v a r A m e r i c a w e r e

sown on O c t o b e r 14, 1952, and a l l o w e d to g e r m i n a t e a t 60° F N T.
T w e n t y ^ o n e d ay s a f t e r s e e d i n g the s e e d l i n g s w e r e t r a n s p l a n t e d .

21.

T h i r t y - f i v e d ay s a f t e r s e e d i n g the p l a n t s w e r e p l a c e d in 6 - i n c h
pots,

a nd s u p p l i e d with the following f o u r t r e a t m e n t s ,

u s i n g 15

plants p e r tre a tm e n t;
1. P l a n t s not " p i n c h e d 1'
2. P l a n t s " p i n c h e d " o nc e d i s t a l to the t h i r d node,

49 days

after seeding
3. P l a n t s " p i n c h e d " t w i c e ,

once d i s t a l to the t h i r d node of

t e r m i n a l shoot, a n d o nc e d i s t a l to the t h i r d node of p r i ­
m a ry la t e r a l shoots,

83 d a y s a f t e r s e e d i n g

4. P l a n t s " p i n c h e d " t h r e e t i m e s ,
of t e r m i n a l s h o o t s ,

once d i s t a l to the t h i r d node

once d i s t a l to the t h i r d node of p r i ­

m a r y l a t e r a l s h o o t s , and once d i s t a l to th e t h i r d node of
s e c o n d a r y l a t e r a l sh o o ts 106 d a ys a f t e r s e e d i n g .
The d a te of f l o w e r i n g a s well a s the f o r m of th e p l a n t p r o d u c e d
u n d e r e a c h t r e a t m e n t w as r e c o r d e d .

T i m i n g of a C o m m e r c i a l C r o p

S ee ds of c u l t i v a r A m e r i c a w e r e p l a n t e d on A u g u st 15, S e p t e m ­
b e r 1, a nd S e p t e m b e r 15, 1953,
f l a t s 20 d a y s a f t e r s e e d i n g .

The s e e d l i n g s w e r e t r a n s p l a n t e d in

F o r t y d ay s a f t e r s e e d i n g , t h e p l a n t s w e r e

p o t t e d in 6 - i n c h p o t s , a nd the t e r m i n a l g r o w t h d i s t a l to the t h i r d node
was r e m o v e d .

E a c h g r o u p w as g ro w n in the g r e e n h o u s e a t 60° F N T

with 15 p l a n t s in the A u g u st 15, and S e p t e m b e r 15 p l a n t i n g s ,
p l a n t s in the S e p t e m b e r 1 p l a n t i n g .

F i f t y p l a n t s f r o m the g r o u p sown

on S e p t e m b e r 1 w e r e g r o w n by the M o l e s t a F l o r a l C o m p an y ,
Rapids, Michigan,
houses,
pots,

Ithaca,

and 50

Grand

a nd 50 p l a n t s w e r e g r o w n by the W ay sid e G r e e n ­

Michigan,

All of the p l a n t s w e r e p o t t e d in 6 - i n c h

and p i n c h e d once a t the t h i r d node of the t e r m i n a l shoot.

D ata

w e r e c o l l e c t e d on the r a t e of bud d e v e l o p m e n t and date of f l o w e r i n g .

K e e p i n g Q ua lity

To c o l l e c t i n f o r m a t i o n on c o n s u m e r opinion of k e e p i n g q u a l ­
ity, t h i r t y p l a n t s of the c u l t i v a r A m e r i c a w e r e p l a c e d in h o m e s in
the a r e a of E a s t L a n s i n g ,
15 d a y s .

Michigan,

in t h e c u s t o d y of r e s i d e n t s for

Q u e s t i o n n a i r e s ( T a b l e 1) w e r e su p pl ie d to o b t a i n o pi ni on s

of the c o n s u m e r .

It w as e x p l a i n e d to the r e s i d e n t s t h a t f l o r e t d r o p

r e f e r r e d to the a b s c i s s i o n of the in d iv id u a l l a t e r a l f l o r e t s .
P re lim in a ry tests,

using four plants p e r t r e a t m e n t ,

were

m a d e to s tu d y the e f f ect of t h r e e t r e a t m e n t s on k e ep i n g q u a li ty .
1. 60° F N T s u p p li e d 21 days b e f o r e f l o w e r i n g with
c h e m i c a l t r e a t m e n t of 12. 5 p p m of p a r a - c h l o r o p h e n o x y
a c e t i c a c i d a p p l i e d by the dip m e t h o d
2. 50° F N T s u p p l i e d 21 d ays b e f o r e f l o w e r i n g , no c h e m i
cal tre a tm e n t
3. 60° F N T s u p p l i e d 21 d a y s b e f o r e f l o w e r i n g , no c h e m i
cal tre a tm e n t

23

TABLE

1

QU ES T ION NAI RE FOR OBTAINING P U B L IC OPINION O F SALVIA P L A N T S

It would be a p p r e c i a t e d if you will a c c e p t t h i s s a l v i a p l a n t and
c a r e f o r it a s i s y ou r u s u a l p r a c t i c e .
P l e a s e r e c o r d the following i n f o r m a t i o n and r e t u r n f o r m to
C a l v i n C. C o o p e r , D e p a r t m e n t of H o r t i c u l t u r e .
PLEASE CHECK;
1. How o f te n a r e you w a t e r i n g the p l a n t ?
E v e r y day

3 t i m e s a week

once a week

What s o u r c e of h e a t do you have in y ou r h o m e ?
F orced air

Steam

Hot W a t e r

What t y p e of fue l do you u s e ?
C oal

Oil

Gas

What w as the a p p r o x i m a t e r o o m t e m p e r a t u r e ?
75 °

85°

65°

55°

Was the p l a n t
In e a s t window

In south window

In w e s t window

In n o r t h window

N e a r a window

F a r f r o m window

6. D ate t h r e e l e a v e s ha d f a l l e n _________________________________
D ate s ix l e a v e s h a d f a l l e n ____________________________________
D a t e m a n y l e a v e s had f a l l e n _________________________________
7. D ate t h r e e f l o r e t s h a d f a l l e n
fallen

; Date s i x f l o r e t s had

;D ate m a n y f l o r e t s h ad f a l l e n

Z4

T A B L E 1 (Continued)

8.

D ate of d i s c a r d of p la nt

9.

Would you be i n c l i n e d to buy one of t h e s e p l a n t s f r o m a f l o r i s t at
2 / 3 the p r i c e of a p o i n s e t t i a ?
ye s
perhaps
no

10. G e n e r a l op in io n of p l a n t a s pot p l a nt f o r the h om e:
Good

Fair

Any c o m m e n t s on r e v e r s e of page

Poor

.

25

At the date of f l o w e r i n g two p l a n t s f r o m e a c h of the t h r e e
t r e a t m e n t s r e m a i n e d in t h e g r e e n h o u s e with 60° F N T and two p l a n t s
w e r e m o v e d to a r o o m t e m p e r a t u r e of 70° F f o r o b s e r v a t i o n .

I n t e r a c t i o n of P h o t o p e r i o d and G ro w th

S a lv ia h a s b e e n r e p o r t e d to p r o d u c e f l o w e r s only when it
w a s g r o w n u n d e r ITs h o r t d a y s " .

To f u r t h e r study t h i s r e s p o n s e ,

20

p l a n t s of t h e c u l t i v a r A m e r i c a , f r o m .seed p l a n t e d S e p t e m b e r 15, 1953
w e r e g r o w n in 6 - i n c h p o t s .
L i g h t p e r i o d s of 16 and 8 h o u r s w e r e a p p l i e d in 2 4 - h o u r c y c l e s ,
the r e m a i n i n g h o u r s of e a c h 24 c o n s i s t i n g of d a r k n e s s .

The following

c o m b i n a t i o n s of p h o t o p e r i o d w e r e u s e d with f o u r p l a n t s in e a c h t r e a t ­
m e n t:
1. 1 6 -h o u r l i g h t p e r i o d f o r 110 d ays followed by 8 - h o u r
l i g h t p e r i o d f o r 0 d ay s
2. 16- h o u r l i g h t p e r i o d f o r 65 d a y s f ollow ed by 8 - h o u r
l i g h t p e r i o d f or 45 d a y s
3. 1 6 -h o u r l i g h t p e r i o d f o r 50 d a y s, followed by 8 - h o u r
lig h t p e r i o d f o r 60 d a y s
4. 1 6 -h o ur l i g h t p e r i o d f o r 35 d a y s , followe d by 8 - h o u r
li g h t p e r i o d f o r 75 d a y s
5.

8 - h o u r l i g h t p e r i o d f o r 110 d a y s fo llo we d by 8 - h o u r
l ig h t p e r i o d f o r 0 days

26.

All of the p l a n t s w e r e p i n c h e d 35 d a y s a f t e r s e e d in g ,

and only f o u r

l a t e r a l s w e r e a l l o w e d to d e v el o p p e r p l a n t .
At the end of 110 d a y s two p l a n t s f r o m e a c h t r e a t m e n t w e r e
p l a c e d in a 16- h o u r p h o t o p e r i o d and two in an 8 - h o u r p h o t o p e r i o d f o r
10 d a y s .

The 16- h o u r p h o t o p e r i o d w as s u p p li e d by exte nd in g the n o r ­

m a l d ai l y p e r i o d of l i g h t with 100 foot c a n d l e s of i n c a n d e s c e n t light
f r o m 04:00 to 2 0 : 0 0 h o u r s .

The 8 - h o u r p h o t o p e r i o d w as s u p p li e d by

r e d u c i n g the n o r m a l daily p e r i o d of lig h t by m o v i n g the p l a n t s into a
d a r k c h a m b e r b e t w e e n 16:30 and 08;30 h o u r s .
w as r e c o r d e d .

The d ate of f l o w e r i n g

O b s e r v a t i o n s w e r e m a d e on the a p p e a r a n c e of the

p l a n t s and f l o w e r s g r o w n u n d e r e a c h p h o t o p e r i o d i c t r e a t m e n t .

I n t e r a c t i o n of R o o t T e m p e r a t u r e a n d L ig ht I n t e n s i t y
With G r o w t h
F o u r c o n t r o l l e d t e m p e r a t u r e t a n k s c o n s i s t i n g of l a r g e i n s u l a t e d
v a t s of w a t e r w e r e c o n s t r u c t e d with h e a t i n g a n d r e f r i g e r a t i o n c o i l s .
T h e r m o s t a t s c o n t r o l l e d the t e m p e r a t u r e of the r o o t m e d i u m w ithin a
t h r e e - d e g r e e r a n g e ( F i g u r e 6).
in the w a t e r .

E a rth e n w are crocks were suspended

T h e s e c r o c k s c o n t a i n e d q u a r t z s a n d and 0 . 5 H o a g l a n d ' s

c o m p l e t e n u t r i e n t s o l u t i o n (Hoagland and A r n o n , 1950) in which the
plants w ere placed.

E a c h w e e k the s a n d in which the p l a n t s w e r e g r o w ­

ing w as d r a i n e d , l e a c h e d with one l i t e r of d i s t i l l e d w a t e r ,

and d r a i n e d

27.

again.

T h e d r a i n s w e r e t h e n c l o s e d and one l i t e r of n u t r i e n t s o l u ­

tio n was a d d e d a nd a l l o w e d to r e m a i n in the c r o c k s .

If n e c e s s a r y ,

an a d d i t i o n a l o n e - h a l f l i t e r of n u t r i e n t s o l u ti on was a dd ed d u r i n g the
period betw een teachings.

T h is was m o r e o fte n n e c e s s a r y at the 7 0 ° F r o o t

t e m p e r a t u r e t h a n at the 5 0 ° F r o o t t e m p e r a t u r e .
Se ed s of c u l t i v a r A m e r i c a w e r e sown in soil on S e p t e m b e r 23
and a l l o w e d to g e r m i n a t e a t 60° F N T.

T h e s e e d l i n g s w e r e a llo w e d

to g r o w in s o i l f o r a p e r i o d of 35 d ays when t h e y had p r o d u c e d a p p r o x ­
i m a t e l y t h r e e to f o ur n o d e s of v e g e t a t i v e g r o w t h .
w e r e r e m o v e d f r o m the soil,

At t h a t t i m e they

and a f t e r the r o o t s w e r e t h o r o u g h l y and

c a r e f u l l y w a s h e d , the p l a n t s w e r e p l a c e d in the s a n d in the c o n s t a n t
t e m p e r a t u r e t a n k s to g r o w to m a t u r i t y .

The following t r e a t m e n t s w e r e

a r r a n g e d with 24 p l a n t s p e r t r e a t m e n t :
o
1. 50 F r o o t t e m p e r a t u r e ,

63 p e r c e n t su n li g h t

o
2. 50 F r o o t t e m p e r a t u r e ,

100 p e r c e n t sun lig h t

o
3. 70 F r o o t t e m p e r a t u r e ,

63 p e r c e n t s u n lig ht

4.

o
70 F r o o t t e m p e r a t u r e , 100 p e r c e n t sunlight

The a i r w a s 60

o

F N T in e a c h t r e a t m e n t . ■The lig h t i n t e n s i t y

w as r e d u c e d on the two t r e a t m e n t s with the u s e of c h e e s e c l o t h c o v e r ­
ing { F i g u r e 6).

The p l a n t s w e r e grow n a t the n o r m a l p h o t o p e r i o d

( a p p r o x i m a t e l y 10. 5 to 12. 5 h o u r s of daylight) o c c u r r i n g a t E a s t L a n s i n g ,
Michigan,

d u r i n g O c t o b e r , N o v e m b e r , a nd D e c e m b e r .

Date of f l o w e r i n g ,

28

h e i g h t of p l a n t s ,

f r e s h and d r y w e ig h t of s t e m s ,

w ei g h t of r o o t s w e r e r e c o r d e d .

f r e s h and d r y

O b s e r v a t i o n s w e r e m a d e on f olia ge

and f l o w e r s i z e and c o l o r .
The n u t r i e n t c o n t e n t of s t e m a nd r o o t t i s s u e was d e t e r m i n e d
a s a p e r c e n t a g e on ov en d r y w eigh t b a s i s .
by the m o d i f i e d K j e l d a h l m e t h o d , ^ 2 ^ 5

T o t a l NO^ w as d e t e r m i n e d
precip itation as am m onium

p h os ph o m o l y b d a t e a nd v o l u m e t r i c e v a l u a t i o n , and

by the f l a m e

photom eter .
T he p r e v i o u s r o o t t e m p e r a t u r e e x p e r i m e n t wa s r e p e a t e d by
s owing s e e d s on D e c e m b e r 1, 1952, and m o v i n g the p l a n t s to the s a m e
t a n k s 40 d a y s a f t e r s e e d i n g .

The p l a n t s w e r e g ro wn a s b e f o r e , and

a t the n o r m a l p h o t o p e r i o d ( a p p r o x i m a t e l y 10 to 12 h o u r s of light)
■occurring in E a s t L a n s i n g , M i c h ig a n ,
and M a r c h .

during Jan u ary ,

February,

At 7 2 - h o u r ( 3 -day) i n t e r v a l s the t e r m i n a l bud was r e ­

m o v e d f r o m one p l a n t in e a c h t r e a t m e n t and k i ll e d and fix ed in FAA.
The b ud s w e r e d e h y d r a t e d and c l e a r e d with the ethyl a lc o h o l,
f o r m s e r i e s and e m b e d d e d in p a r a f f i n .
cut 10 m i c r o n s in t h i c k n e s s ,

L o n g i t u d i n al s e c t i o n s w e r e

s t a i n e d with C o n a n t ' s q u a d r u p l e s t a i n

and m o u n t e d p e r m a n e n t l y in C a n a d a b a l s a m .
d a te of f l o w e r i n g ,

chloro­

R a t e of bud d e v e l o p m e n t ,

h e i g h t of p l a n t s , f r e s h and d r y w eight of s t e m s ,

f r e s h and d r y w ei g h t of r o o t s w e r e r e c o r d e d .
m a d e on f o l i a g e a nd f l o w e r s i z e a nd c o l o r .

O bservations w ere

and

A c o n t in u o u s r e c o r d i n g of the li g h t i n t e n s i t y in the d i f f e r e n t
t r e a t m e n t s w a s m a d e w ith a L e e d s and N o r t h r u p S p e e d o m a x type G
recorder.

T he n u t r i e n t c o n t e n t of s t e m and of r o o t t i s s u e (NO^,

and K 2 O) w e r e d e t e r m i n e d a s b e f o r e .

RESULTS

T e s t s of C u l t i v a r s

The p l a n t s of a l l of the c u l t i v a r s u s e d in t h i s c o m p a r i s o n
w e r e p l a n t e d in s e e d f l a t s 19 d a y s a f t e r s e e d i n g .

The t e r m i n a l g ro w th

w as r e m o v e d d i s t a l to t h e t h i r d nod e 36 d ays a f t e r s e e d i n g when the
p l a n t s w e r e p l a c e d in 6 - i n c h p o t s .
At the t i m e of f l o w e r i n g the ' ' p in c he d " p l a n t s w e r e s h o r t e r
and m o r e d e n s e in t h e i r g r o w t h h a b i t t h a n the " n o n - p i n c h e d " p l a n t s
of the s a m e c u l t i v a r .

An a v e r a g e of 2, 3 m o r e f l o w e r s and 4. 6 f e w e r

l a t e r a l f l o w e r b u d s w e r e p r o d u c e d on " p i n c h e d " p l a n t s t h a n on p l a n t s
t h a t w e r e not " p i n c h e d " .

In g e n e r a l ,

a t the 5 p e r c e n t l e v e l t h e r e

w e r e no s i g n i f i c a n t d i f f e r e n c e s in the n u m b e r of l a t e r a l f l o w e r buds
and f l o w e r s p r o d u c e d a m o n g the c u l t i v a r s .

T he only c a s e of s i g n i f i ­

c a n c e w a s w h e r e p l a n t s of c u l t i v a r R o s e F l a m e p r o d u c e d no l a t e r a l
f l o w e r b u d s on the n o n - p i n c h e d p l a n t s .
the 1 p e r c e n t l e v e l .

T his wa s s i g n i f i c a n t l y l e s s at

-> u .

B a s e d on p l a n t s t h a t w e r e p i n c h e d o nc e, the c u l t i v a r s of
S a l v ia g r o w n a p p e a r e d to be of t h r e e g e n e r a l t y p e s of growth;
1. Dwarf;

C u l t i v a r s St, J o h n ' s F i r e and V a u g h n ' s

M a s t e r p i e c e w e r e i n c l u d e d in t h i s ty p e.
to 17,5 c e n t i m e t e r s in h e ig h t ,

The p l a n t s a v e r a g e d 17. 0

w hic h w as s i g n i f i c a n t l y s h o r t e r at

the 1 p e r c e n t l e v e l t h a n p l a n t s of t h e s e m i - d w a r f and t a l l t y p e s .
Th ey d e v e l o p e d a s h o r t ,

d e n s e type of g r o w t h ( F i g u r e 1) and p r o ­

d u c ed f l o w e r s of b r i l l i a n t r e d c o l o r .
2. S e m i - d w a r f ;
i c a f or Z u r u c k ,
this type.

Bonfire,

C u l t i v a r s S p le nd en s A m e r i c a , A m e r ­

B l a z e of F i r e ,

and R o s e F l a m e w e r e of

T he p l a n t s a v e r a g e d 21.2 to 2 7 . 0 c e n t i m e t e r s in he igh t

w hich w as s i g n i f i c a n t l y t a l l e r t h a n the d w a r f and s i g n i f i c a n t l y
s h o r t e r t h a n the t a l l g r o u p at the 1 p e r c e n t l e v e l .
produced a m o d e ra te ly short,

T he c u l t i v a r s

d e n s e type of g r o w t h ( F i g u r e 2), and

b r i l l i a n t r e d f l o w e r s w ith the e x c e p t i o n of c u l t i v a r R o s e F l a m e .
T hi s c u l t i v a r p r o d u c e d lig h t pink f l o w e r s .
3. T a l l :

C u ltiv a rs C la r a Bedman,

S ple nd en s S c a r l e t

Sage, and S p l e n d e n s B r i g h t n e s s w e r e of t h i s ty p e .

The p l a n t s a v e r ­

a g e d 35. 0 to 47. 0 c e n t i m e t e r s in h ei gh t which was s i g n i f i c a n t l y
t a l l e r t h a n the o t h e r two t y p e s a t the 1 p e r c e n t l e v e l .
tall,

They developed a

open, type of g r o w t h ( F i g u r e 3), but did p r o d u c e f l o w e r s of

brilliant red color.

F i g u r e 1.

Salvia p l a n t of the d w a r f type e x h i b i ti n g the s h o r t ,
d e n s e g r o w t h t y p i c a l of t h i s g ro up.

F igure 1

F i g u r e 2.

S a lv ia p l a n t of the s e m i - d w a r f type e x h ib i t i n g the
m o d e ra te ly short,

d e n s e g r o w t h t y p i c a l of t h i s group.

F ig u re Z

F i g u r e 3,

S a l v i a p l a n t of the t a l l type e x h ib i t i n g the t a l l ,

o p e n g r o w t h t y p i c a l of t h i s g r o up .

33

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35

TABLE

3

I n t e r a c t i o n of Cold T r e a t m e n t and G row th
50°F N T
C o n t i n u a l 4 0 ° F T e m p , at
5 0 ° F N T 2 Node 4 Node

60°F N T
C ontinual 4 0 ° F T e m p , at
6 0 ° F N T ~2 Node 4 Node

T i m e f o r F l o w e r i n g (Days)
124.4

126.4

123.8

103.4

107.4

105.4

L . S. D. 5% 3. 9
L. S. D. 1% 5 . 3
S te m E l o n g a t i o n ( C e n t i m e t e r s )
26.30

26.70

25.60

35.90

35.10

35.30

39.36

52„ 30

L . S, D. 5% 10. 34
L . S. D. 1% 13, 99
T o t a l S tem Weight ( G r a m s )
44.60

55.20

41.80

44.72

L. S. D, 5% 11. 46
L. S, D . 1% 15. 51
S t e m Weight p e r Unit Stem L e ng th ( G m / C m )
1.746

2.134

1.638

1.254

1.122

1.430

L . S. D. 5% 0. 328
L . S. D. 1% 0. 443

TABLE

4

E f f e c t of Night T e m p e r a t u r e on Height of P l a n t s
T r eatm ents
Days

50°F N T

50° to 60° F N T

60° to 5 0 ° F N T

60°F N T

A v e r a g e Height in C e n t i m e t e r s
30
60
90
115*

1. 41
4. 65
20. 53
26. 28

1. 43
4. 28
21. 33
29. 72

2. 70
18 . 28
- - 38. 38

2. 69
17. 85
- - 35. 94

L . S. D. ** 5% 1. 20
L .S .D .
1% 1.59
'■'Average n u m b e r d a y s .
’^■'Between t r e a t m e n t s .

M e a s u r e m e n t s m a d e a t d ate of f l o w e r i n g

.

The n u m b e r of d a y s r e q u i r e d f or f l o w e r p r o d u c t i o n v a r i e d
with the c u l t i v a r .

A p p r o x i m a t e l y 7 d ays l e s s was r e q u i r e d f o r f l o w e r ­

ing of th e d w a r f c u l t i v a r s t h a n wa s r e q u i r e d for m o s t of the s e m i ­
d w a r f and t a l l c u l t i v a r s .

I n t e r a c t i o n of Cold T r e a t m e n t and G rowth

T o t a l s t e m w e ig h t an d s t e m e l o n g a t i o n w e r e not s i g n i f i c a n t l y
i n f l u e n c e d by c old t r e a t m e n t ( 4 0 ° F c o n s t a n t t e m p e r a t u r e f o r 7 days)
r e g a r d l e s s of w h e t h e r th e p l a n t s w e r e p r o v i d e d with a 50° o r 60° F N T.
The n u m b e r of d ay s r e q u i r e d f o r f l o w e r i n g when p l a n t s w e r e
s u p p l i e d w ith a 5 0 ° F N T w as not s i g n i f i c a n t l y i n f l u e n c e d by cold t r e a t ­
m ents.

The plants,

a t the 2 - node s t a g e ,

when s u p p l i e d with a 60° F N T and a c old t r e a t m e n t
r e q u i r e d a s i g n i f i c a n t l y g r e a t e r n u m b e r (four) of

days f o r f l o w e r i n g to o c c u r , t h a n w as r e q u i r e d f o r t h o s e s up p lie d with
6 0 ° F N T a nd no cold t r e a t m e n t .

When t r e a t e d a t th e f o u r - n o d e sta ge

the i n c r e a s e (two d a ys ) o v e r the p l a n t s given no cold t r e a t m e n t was
not s i g n i f i c a n t .
S t e m w e i g h t p e r unit of s t e m e lo n g a ti on in p l a n t s g r ow ing at
5 0 ° F N T w as i n c r e a s e d (0. 388 g r a m s ) s i g n i f i c a n t l y by the c old t r e a t ­
m e n t s u p p l i e d a t t h e t w o - n o d e s t a g e , but not when the cold t r e a t m e n t
w as s u p p l i e d a t the f o u r - n o d e s t a g e .

With p l a n t s g ro w n at th e 60 F N T

the s t e m w e i g h t p e r unit of s t e m e l o n g a t i o n w as not s i g n i f i c a n t l y in-

f l u e n c e d by the c old t r e a t m e n t s u p p l i e d at the tw o- o r the f o u r - n o d e
st a g e ( T a b l e 3).

I n t e r a c t i o n of Night T e m p e r a t u r e and G ro w th

S a lv ia p l a n t s g r o w n at the 50° F N T b e c a m e c h l o r o t i c and
g r e w slo w ly f o r 60 d a y s .

N e c r o s i s did not de ve lo p and the p l a n t s

g r a d u a l l y r e g a i n e d t h e i r g r e e n c o l o r within 30 m o r e d a y s , and
g r e w to m a t u r i t y .

The g r o w t h i n c r e m e n t a s i n f lu e n c e d by night t e m ­

p e r a t u r e ( T a b l e 4) sh o ws quite c l e a r l y the r e t a r d a t i o n of g r o w t h at
50 F N T d u r i n g the f i r s t 60 d a y s , a nd the i n c r e a s e in g ro w th r a t e
after this perio d .

M oving p l a n t s to the o p p o s i t e t e m p e r a t u r e 90 days

a f t e r s e e d i n g gave i n c r e a s e s in f i n a l s t e m e l o n g a t i o n which in both
g r o u p s w e r e s i g n i f i c a n t l y g r e a t e r when c o m p a r e d to the e l on g a t i o n
of the p l a n t s t h a t c o n t i n u e d to g r o w a t the o r i g i n a l t e m p e r a t u r e .

Both

g r o u p s of p l a n t s w hic h w e r e g r o w n a t 6 0 ° F N T d u r i n g the f i r s t 90
days of t h e e x p e r i m e n t p r o d u c e d a p p r o x i m a t e l y 9 c e n t i m e t e r s m o r e
e lo n g a t i o n t h a n the g r o u p s g r o w n . a t 5 0 ° F N T.

These differences

w ere highly significant.
The f l o w e r s p r o d u c e d in a ll t r e a t m e n t s w e r e e s s e n t i a l l y
e qu a l in c o l o r a n d q u a l i ty .

F l o w e r i n g at 50° F N T r e q u i r e d 17,3

m o r e d ay s on the a v e r a g e t h a n did f l o w e r i n g a t 6 0 ° F N T.

Plants

o
°
g r o w n a t 50 F N T d u r i n g t h e f i r s t 90 d ay s and at 60 F N T d u r in g

38

TABLE

5

E f f e c t of Night T e m p e r a t u r e on R a te and A m o u nt of Gr owth
T reatm ent s
Li* S„ D.

50°F N T

50° to 6 0 ° F N T

60° to 5 0 ° F N T

60°F N T

T i m e f r o m Seed to F l o w e r (Days)
124.3

122.0

107.0

107.0

5% 2. 03
1% 2. 69
T o t a l A v e r a g e S t e m Weight at F l o w e r i n g ( G r a m s )
46.20

44.45

48.18

44.00

5% 4. 06
1% 5 . 3 7
A v e r a g e S t e m Weight p e r C e n t i m e t e r of S t e m L e n g th ( G r a m s )
1.76

1.50

1.26

1.22

5% 0. 20
1% 0. 26

TABLE

6

A v e r a g e N u m b e r of Days R e q u i r e d for F l o w e r i n g with R e s p e c t i v e
N u m b e r of " P i n c h e s "
T r eatm ent
No " P i n c h "
Da ys

102

One " P i n c h "
126

Two " P i n c h e s "
136

Three "P in ch es1
146

F i g u r e 4.

Sa lvia p l a n t g ro w n without " p i n c h i n g " .

F i g u r e 5.

S a l v i a p l a n t g ro wh with two " p i n c h e s " ; one a p p l i e d
d i s t a l to the t h i r d node of the t e r m i n a l shoot,

a nd

one d i s t a l to the t h i r d node of the p r i m a r y l a t e r a l s h o o t s .

the r e m a i n d e r of the e x p e r i m e n t f l o w e r e d on an a v e r a g e of 2. 3 days
e a r l i e r t h a n p l a n t s g r o w n the e n t i r e t i m e at 5 0 ° F N T.

Moving p l a n t s

f r o m a 6 0 ° F N T to a 50 F N T 90 d ays a f t e r s e e d i n g did not s i g n i ­
f i c a n t l y a f f e c t t h e n u m b e r of days r e q u i r e d f o r f l o w e r i n g (Table 5).
T h e r e w e r e no 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 the t r e a t ­
m e n t s in t o t a l s t e m w e i g h t p e r p l a n t.

T h e r e s e e m e d to be a t r e n d

t o w a r d g r e a t e r s t e m weight p e r c e n t i m e t e r of s t e m le ngth in p l a n t s
g r ow n a t the 5 0 ° F N T ( T a b l e 5).

The d i f f e r e n c e s , howe v e r ,

were

not s i g n i f i c a n t .

F o r m of P l a n t

The " n o n - p i n c h e d " t r e a t m e n t p r o d u c e d no l a t e r a l b r a n c h i n g
of th e p l a n t a t th e t i m e of f l o w e r i n g ,

and c o n s e q u e n t l y p r o d u c e d

p l a n t s w ith u n d e s i r a b l e f o r m s i m i l a r to t h a t in F i g u r e 4.

If the

p l a n t s w e r e a l lo w e d to c ontinue to g r o w in the g r e e n h o u s e for a p p r o x ­
i m a t e l y 30 d a y s l a t e r a l b r a n c h e s with l a r g e f l o w e r s d e velope d,
F i g u r e 4.

P i n c h i n g th e p l a n t s once, t w ic e, o r t h r e e t i m e s p r o d u c e d

p l a n t s with f o r m s i m i l a r to t h a t shown in F i g u r e 2.

One " p i n c h "

p r o d u c e d p l a n t s with s u f f i c i e n t b r a n c h i n g to give d e s i r a b l e f o r m and
r e q u i r e d the l e a s t t i m e f o r f l o w e r i n g of any t r e a t m e n t ,

si n c e 10 d a y s

was a d d e d to the t i m e r e q u i r e d f o r f l o w e r i n g with e a c h a d d it i o n a l
" p i n c h " ( T a b l e 6).

P l a n t s w hic h w e r e " p in c h e d " tw ic e p r o d u c e d

41

l a r g e r p l a n t s with l a r g e f l o w e r s ( F i g u r e 5).

T hree "pinches"

p r o d u c e d p l a n t s of a bout the s a m e o v e r a l l s i z e a s did two " p i n c h e s " .
The f l o w e r s ,

a l th o u g h m o r e n u m e r o u s w e r e only h alf a s l a r g e a s

t h o s e p r o d u c e d by p l a n t s with one o r two p i n c h e s .

T i m i n g of a C o m m e r c i a l C r o p

C r o p one, f o r w hich the s e e d was sown A u gu st 15, 1953,
r e a c h e d t h e f l o w e r i n g st a g e o v e r a r a n g e of 4 days with the a v e r a g e
date of f l o w e r i n g b e i n g N o v e m b e r 13, 1953 (90 da ys).

Although the

s e e d f o r t h e s e c o n d c r o p was sown only 16 d a ys l a t e r , the p l a n t s in
t h i s g r o u p f l o w e r e d a p p r o x i m a t e l y 21 d ay s a f t e r the f i r s t c r o p .

The

d a t e s a t w h ic h t h e s e p l a n t s r e a c h e d the f l o w e r i n g st a g e r a n g e d o v e r
12 d a y s ,

with the a v e r a g e da te of f l o w e r i n g b e in g D e c e m b e r 7, 1953

(98 d a y s ) .

T he f l o w e r i n g d a t e s f o r c r o p t h r e e , f o r which the s e e d

was sown S e p t e m b e r 15, 1953, r a n g e d o v e r a p e r i o d of 4 d ay s with
the a v e r a g e d a t e of f l o w e r i n g b e in g D e c e m b e r 23, 1953 (99 days).
The n u m b e r of d a y s r e q u i r e d f o r c r o p one to f lo w e r was si gn if ic a n t ly
l e s s at the 1 p e r c e n t l e v e l t h a n th e n u m b e r of d ays r e q u i r e d f o r c r o p
two and t h r e e to f l o w e r .

T h e n u m b e r of days r e q u i r e d f o r c r o p s two

and t h r e e to f l o w e r w e r e not s i g n i f i c a n t l y d i f f e r e n t ( Ta b le 7).
F r o m T a b l e 7 it c a n be o b s e r v e d t h a t at 6 0 ° F N T a p e r i o d
of f r o m 16 to 19 d a y s w a s r e q u i r e d for f l o w e r d e v e l o p m e n t to p r o c e e d

TABLE

7

A v e r a g e N u m b e r of D a y s f r o m Se eding R e q u i r e d f o r F l o w e r Bud
Developm ent

Stage F i v e '
C r o p one
C r o p two
C rop th re e

Flowering

74
79
80

90
98
99

L . S. D. 5% 4 . 4
L . S . D . 1% 5 . 9
* Stage five is t h a t s t a g e in f lo w e r bud d e v e l o p m e n t when the
o v e r a l l l e n g t h of th e bud is 1. 5 c m a nd the f lo w e r p a r t s a r e all
differentiated.

TABLE 8
R a t e of F l o w e r and L e a f A b s c i s s i o n f r o m P l a n t s E x p o s e d to R oo m
T e m p e r a t u r e in P r i v a t e H o m e s
T i m e in N u m b e r of Days

A bscission
Of P a r t s
P e r Plant

1-3

4-6

7 -9

3 florets
6 florets
M any f l o r e t s
3 leaves
6 leaves
Many l e a v e s

26
17
4
5
1
0

3
10
6
5
4
0

1
2
9
11
4
3

10-12
0
1
5
5
8
2

13-15
0
0
3
0
4
9

lS-^
0
0
3
4
9
16

Average
2. 5
3.7
8. 5
8. 1
11. 4
14. 3

f r o m s t a g e five to f l o w e r i n g .
T he fifty p l a n t s g r o w n by the M o l e s t a F l o r a l C o m p a n y
r e a c h e d the f l o w e r i n g s t a g e o v e r a n e x t e n d e d p e r i o d of 3 we eks
and w e r e m u c h s m a l l e r a t the t i m e of f l o w e r i n g t h a n t h o s e gro wn
by the i n v e s t i g a t o r at t h e c o l l e g e .

Somewhat la r g e r plants were

o b t a in e d by the W a y s i d e F l o r a l C o m p a n y and the f l o w e r i n g sta ge
was r e a c h e d at d a t e s which m o r e n e a r l y c o r r e s p o n d e d with r e ­
s u l t s of t h e i n v e s t i g a t o r .

K e e p i n g Q ua lity

E i g h t e e n of the t h i r t y p l a n t s in the c u st od y of r e s i d e n t s
e x h ib it e d e v i d e n c e of f l o r e t a b s c i s s i o n d u r i n g the f i r s t day (T able
8).

Two and o n e - h a l f d a y s e l a p s e d on the a v e r a g e , h o w e v e r , b e ­

f o r e t h r e e f l o r e t s had a b s c i s s e d f r o m t he p l a n t s .

Six f l o r e t s a b -

s c i s s e d 3, 7 d a y s a n d m a n y a b s c i s s e d 8. 5 d a ys a f t e r the p l a n t s w e r e
m o v e d to r o o m t e m p e r a t u r e in the h o m e s .

This indicated that

p l a n t s r e m a i n e d in o p t i m u m c o n d i t i o n in a h o m e f o r an a v e r a g e
p e r i o d of 4 to 8 d a y s .
T he f o lia ge a p p e a r e d to be m u c h m o r e d u r a b l e u n d e r h o m e
c o n d i ti o n s ( T a b l e 8).

An a v e r a g e of 8.1 days p a s s e d b e f o r e t h r e e

l e a v e s a b s c i s s e d , 11.4 d a y s b e f o r e six,
leaves ab scissed .

and 14.3 days b e f o r e m a n y

At the end of the 15-day p e r i o d , the f o l i a g e of

16 p l a n t s r e m a i n e d in good c o n d it i o n .

The o t h e r 14 p l a n t s had b e e n

n e g l e c t e d , b e c a u s e t h e r e s i d e n t s w e r e not i n t e r e s t e d in the p l a n t s a f ­
t e r the f l o w e r s c e a s e d to be a t t r a c t i v e .
The v a r i a b i l i t y in f r e q u e n c y of w a t e r i n g ,
tem perature,

and l o c a t i o n of the p l a n t in the h o m e ,

h e a ti n g m e th o d ,
a p p e a r e d to have

no c o n s i s t e n t e f f e c t on the l e n g t h of p l a n t life in the h o m e .
In t h e p r e l i m i n a r y t e s t s no f l o r e t a b s c i s s i o n o c c u r r e d on
any p l a n t s t h a t w e r e a l l o w e d to r e m a i n in the g r e e n h o u s e with 6 0 ° F N T
r e g a r d l e s s of w h e t h e r t h e y w e r e p r e v i o u s l y t r e a t e d with a dip of 12. 5
p pm p a r a - c h l o r o p h e n o x y a c e t i c a c i d with 6 0 ° F N T, no c h e m i c a l t r e a t o
o
m e n t with 50 F N T, o r no c h e m i c a l t r e a t m e n t with 60 F N T.

Flo w er

a b s c i s s i o n o c c u r r e d f r o m the p l a n t s in all t h r e e t r e a t m e n t s 2 d ays a f t e r
they w e r e m o v e d to a r o o m t e m p e r a t u r e of 7 0 ° F f o r o b s e r v a t i o n .
o
r a t e of a b s c i s s i o n w as s l ig h t l y r e d u c e d by the 50 F N T.

The

At the end

of 5 d a y s a n a v e r a g e of 33. 5 f l o r e t s had a b s c i s s e d f r o m p l a n t s t r e a t e d
o
with 12. 5 p p m of p a r a - c h l o r o p h e n o x y a c e t i c a c id with 60 F N T, and
p l a n t s e x p o s e d to no c h e m i c a l t r e a t m e n t with 60 F N T, while only an
a v e r a g e of 12 f l o r e t s had a b s c i s s e d f r o m p l a n t s s u p p li e d with no c h e m ­
i c a l t r e a t m e n t a nd 5 0 ° F N T f o r 21 d a y s b e f o r e m o vin g to the r o o m
tem perature.
F o l i a g e e x p a n s i o n was r e t a r d e d and f l o w e r i n g d e l a y e d 7 days
on p l a n t s t r e a t e d w ith p a r a - c h l o r o p h e n o x y a c e t i c a c i d and 60 F N T in

45.

the g r e e n h o u s e .

Slight c h l o r o s i s d e v e lo p e d in the f olia ge within a

we ek a f t e r m o v i n g the p l a n t s to the 5 0 ° F N T.
a p p e a r e d b e f o r e the p l a n t s w e r e in f l o w e r ,

T hi s c h l o r o s i s d i s ­

and t i m e of f l o w e r i n g

was not a l t e r e d by the l o w e r t e m p e r a t u r e a t this sta ge in d e v e l o p m e n t

I n t e r a c t i o n of P h o t o p e r i o d a nd Grow th

T o t a l s t e m e l o n g a t i o n w as r e d u c e d on p l a n t s p r o v i d e d with
a n 8 - h o u r p h o t o p e r i o d c o m p a r e d to p l a n t s r e c e i v i n g a 16- h o u r p h o t o period.

T h i s d i f f e r e n c e w as p r e s e n t a f t e r the p l a n t s had b e e n gro wing

f o r 50 d a y s , a nd w as

in g e n e r a l m a i n t a i n e d a s g r o w t h p r o g r e s s e d .

The r e d u c t i o n in t o t a l s t e m e lo n g a t i o n a t the end of 110 d a y s of g ro w th
w as s i g n i f i c a n t a t a t l e a s t t h e 5 p e r c e n t l e v e l when the p l a n t s w e r e
e x p o s e d to 60 o r m o r e s h o r t d a y s , T a b l e 9.

M o r e t h a n 60 s h o r t days

t e nd e d to c a u s e l e s s t o t a l s t e m e l o n g a ti o n ( F i g u r e 7), h o w e v e r , t h e s e
d i f f e r e n c e s w e r e not s i g n i f i c a n t a m o n g the p l a n t s s up plie d with 60,
and 110 s h o r t d a y s ,

75

T a b l e 9.

The a v e r a g e a m o u n t of l i n e a r g r o w t h w as l i k e w i s e l e s s when
the p l a n t s w e r e s u p p l i e d with an 8 - h o u r p h o t o p e r io d , F i g u r e 7.
A f t e r 110 d a y s of g r o w th , the p l a n t s su p p li e d with 60, 7 5 and 110 s h o r t
days w e r e s i g n i f i c a n t l y and c o n s e c u t i v e l y s h o r t e r a t the 1 p e r c e n t
l e v e l t h a n t h o s e s u p p l i e d with 110 long d ays c o n s i s t i n g of a 16- h o u r
p h o t o p e r i o d ( T a b le 10).

T h e s e d i f f e r e n c e s w e r e e v i d e n t a f t e r 50 d ay s

TABLE

9

I n t e r a c t i o n of P h o t o p e r i o d and T i m e on T o t a l S t e m E l o n g a t i o n
P e r Plant

Days F r o m
See ding

L. S. D.

Cm .
6. 60

Cm ,
2. 95

Cm .
2. 30

5% 14, 68
1 % 20. 33

38. 87 34. 00 21. 50

19. 50

16. 75

5% 31.12
1% 43.10

90. 00

6 2 . 6 3 55. 63 50. 25

116. 50

72. 88

83.13

5% 2. 00
1% 2 . 7 7

70
90

5% 33. 02 134.38
1% 4 5 . 7 3

Cm .
4. 85

110

Cm .
3. 55

50

110

0

Sho r t Day s
45
60
75

91. 38 90. 75

TABLE

10

I n t e r a c t i o n of P h o t o p e r i o d and T i m e on P l a n t Height
Days F r o m
Seeding

50

L. S. D.
0

5%
1%

. 70

S h o r t Days
45
60

110

Cm .

Cm .

Cm.

Cm .

2. 03

1 . 48

1. 04

0. 85

0. 70

5. 94

5. 25

4. 38

13.13

12. 25

20. 88

22.13

■97

70

5% 4. 09
1% 5 . 66

12. 50 10. 94

90

5%
1%

7 . 07
9 . 79

28. 50 21 . 13

110

Cm .

75

5% 9 . 10
1% 12 . 60

15.19

41. 00 31 . 31 26. 00

F i g u r e 6.

G r e e n h o u s e e q u i p m e n t showing the e a r t h e n w a r e c r o c k s
s u s p e n d e d in f o u r c o n s t a n t t e m p e r a t u r e t a n k s ,

and the r e ­

d u c e d l i g h t i n t e n s i t y p r o v i d e d to two g r o u p s with the u s e of
c he e s e c l o t h .

F i g u r e 7.

S a l v i a p l a n t s 95 d a y s a f t e r s e e d i n g d e m o n s t r a t i n g the i n ­
f l u e n c e of p h o t o p e r i o d on v e g e t a t i v e g r o w t h .

T he n u m b e r s

b e lo w the p l a n t s i n d i c a t e the n u m b e r of s h o r t d a y s the p l a n t s
had r e c e i v e d a t the t i m e the p h o t o g r a p h w a s t a k e n .
to r i g h t ,

F r o m left

the p l a n t s a r e t y p i c a l of g r o u p s w h ic h r e c e i v e d 95 long

d a y s (LD) follow ed by 0 s h o r t d ay s (SD), 65 LD f o ll o w e d by 30
SD,

50 LD follow ed by 45 SD,

0 LD f ollow ed by 95 SD.

35 LD f o llo w e d by 60 SD, a nd

F igure 7

and t h r o u g h o u t the r e m a i n d e r of the e x p e r i m e n t .

T h o s e p l a n ts s u p ­

p li e d with 45 s h o r t d a y s e x h i b i t e d r e d u c t i o n in h e ig h t, but t h i s r e d u c ­
tion w as not s i g n i f i c a n t u n ti l 90 d ay s a f t e r se e d in g .
In a d d i t i o n to h a v i n g a d e fi ni te a f f e c t on s t e m elonga tion,
p h o t o p e r i o d a p p e a r e d to a f fe c t a p i c a l d o m i n a n c e .

When the p l a n ts

w e r e s u p p l i e d with 60, 75, and 110 s h o r t d a y s , the f ou r l a t e r a l s all
p r o d u c e d a p p r o x i m a t e l y e qual e l o n g a ti o n .

When no s h o r t d a ys , or

only 45 s h o r t d a ys w e r e s u p p l i e d , the two l a t e r a l s e m e r g i n g f r o m
the m o r e d i s t a l node of the m a i n s t e m a t t a i n e d m u c h g r e a t e r e l o n g a ­
tion t h a n the two l a t e r a l s e m e r g i n g f r o m the m o r e p r o x i m a l node
( F i g u r e 7).
All t r e a t m e n t s p r o d u c e d f l o w e r i n g p l a n t s , a lth ou gh the t i m e
r e q u i r e d f o r f l o w e r i n g in the d i f f e r e n t t r e a t m e n t s r a n g e d o v e r a p e r ­
iod of 10 d a y s .

T h o s e s u p p li e d with no s h o r t d ays r e q u i r e d the l o n g e s t

p e r i o d of t i m e to f l o w e r (108 d a y s ) .

T h o s e s u p p li e d with 45 and 110

s h o r t d a y s w e r e i n t e r m e d i a t e in n u m b e r of days r e q u i r e d for f l o w e r i n g
(105 d a y s ) .

P l a n t s s u p p li e d with 60 s h o r t days r e q u i r e d s lig h tly l e s s

t i m e (102 d a y s ),

a nd a s i g n i f i c a n t l y s h o r t e r t i m e (5 p e r c e n t le ve l) f o r

f l o w e r p r o d u c t i o n t h a n t h o s e p l a n t s s u p p li e d with no long d a y s .

Those

r e c e i v i n g 75 s h o r t d a y s p r o d u c e d f l o w e r s in the s h o r t e s t p e r i o d of
t i m e and in a p e r i o d s i g n i f i c a n t l y s h o r t e r at the 5 p e r c e n t l e v e l t h a n 0,
45, and 110 s h o r t day t r e a t m e n t s ,

T a b l e 11.

40

TABLE

11

I n t e r a c t i o n of P h o t o p e r i o d a nd T i m e on N u m b e r of Days R e q u i r e d
for Flow ering

L. S. D.

0

45

S ho r t Day s
75
60

110

Bud Stage V

5% 5. 51
1% 7. 60

93

88

84

81

91

Flow ering

5% 5.10
1% 7 . 0 2

108

105

102

98

105

P h o t o p e r i o d a p p e a r e d to h ave no a f f e c t on the p l a n t s o r
t h e i r f l o w e r s 110 d ays a f t e r s e e d i n g when two p l a n t s f r o m e a c h t r e a t ­
m e n t w e r e s u p p l i e d with t e n s h o r t d ay s c o n s i s t i n g of 8 - ho u r p h o t o ­
periods,

and two p l a n t s w e r e s u p pl ie d with ten long d ays c o n s i s t i n g

of 16- h o u r p h o t o p e r i o d s .

I n t e r a c t i o n of Ro ot T e m p e r a t u r e and
L ig h t I n t e n s i t y with G ro w th

General:

o
A f t e r 14 day s of e x p o s u r e to 50 F r o o t t e m p e r a t u r e ,

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

s tu n t e d gro w th,

dark

g r e e n f o l i a g e a n d a n t h o c y a n i n d e v e l o p m e n t in the p e t i o l e s and s t e m s .
In c o n t r a s t ,

the p l a n t s p r o v i d e d w ith 7 0 ° F r o o t t e m p e r a t u r e w e r e

growing vigorously,

show ing b r i g h t g r e e n fo li a g e a n d no a n t h o c y a n i n

d e v e l o p m e n t in the p e t i o l e s a n d s t e m s .
Tw enty-one days la t e r ,

and t h r o u g h o u t the r e m a i n d e r of t h e i r

F i g u r e 8.

C a m e r a l u c i d a d r a w i n g of a S a l v i a f l o w e r bud d e m o n ­
s t r a t i n g the five a r b i t r a r y s t a g e s in d e v e l o p m e n t .

e P 'acT
s t ? n

M.

of

LIGHT a ROOT TEM P,

on BUD

DEVELOPM ENT

TREA TMENT

T ■' V F

,V

/

/:

<r

50° F
REDUCED
LIGHT

77

86

92

95

98

50° F
FULL
LIGHT

77

86

92

95

98

70° F
REDUCED
LIGHT

77

80

83

8 6

92

70° F
FULL
LIGHT

80

83

86

92

95

Figure 9

g r o w t h the p l a n t s a t t he 5 0 ° F r o o t t e m p e r a t u r e e x h i b i t e d l e s s e v i d e n c e
of c h l o r o s i s ,

and g r e w m o r e r a p i d l y t h a n b e f o r e .

The p l a n t s e x p o s e d

to 7 0 ° F r o o t t e m p e r a t u r e g r e w the m o s t r a p i d l y , p r o d u c e d t h i c k e r
stem s,

la rg e r leaves,

a n d g r e a t e r s t e m e l o n g a t i o n ( F i g u r e s 10 and 11).

F l o w e r Bud D e v e l o p m e n t : F i v e a r b i t r a r y s t a g e s in the d e v e l ­
o p m e n t of the f l o r e t s w e r e d i s t i n g u i s h e d : 1. Sepal p r i m o r d i a p r e s e n t ;
2, p e t a l p r i m o r d i a p r e s e n t ; 3. f i r s t i n d i c a t i o n of r e p r o d u c t i v e p r i m o r ­
dia; 4. d e v e l o p i n g a n d r o e c i u m ; 5. g y n o e c i u m p r e s e n t and a n d r o e c i u m
in a d v a n c e d s t a g e s of d e v e l o p m e n t ( F i g u r e 8).

The n u m b e r of d ays r e ­

q u i r e d f o r t he d e v e l o p m e n t of t h e r e s p e c t i v e s t a g e s in e a c h of the f ou r
t r e a t m e n t s i s r e c o r d e d in F i g u r e 9.
R o o t t e m p e r a t u r e and lig ht i n t e n s i t y had l i t t l e in fl u e nc e on the
t i m e of f l o r e t i n i t i a t i o n .

o
F l o r e t s d e v e l o p e d m o r e slowly a t the 50 F

o
t h a n a t the 70 F r o o t t e m p e r a t u r e .

However,

while t h e i r d e v e l o p m e n t

o
w as l e s s r a p i d d u r i n g the e a r l i e r s t a g e s when e x p o s e d to a 50 F r o o t
tem perature,

it was l e s s r a p i d d u r i n g the l a t e r s t a g e s when the p l a n t s

o
w e r e p r o v i d e d with a 70 F r o o t t e m p e r a t u r e ( F i g u r e 9).
The p e r i o d of t i m e r e q u i r e d f o r f l o w e r i n g at 5 0 ° F r o o t t e m ­
p e r a t u r e w a s not c o n s i s t e n t l y l o n g e r t h a n the p e r i o d of t i m e r e q u i r e d
o
a t 70 F„

P l a n t s f l o w e r e d in the s h o r t e s t p e r i o d of t i m e when p r o v i d e d

with 7 0 ° F r o o t t e m p e r a t u r e a n$ the r e d u c e d (63 p e r cent) light i n t e n o
s it y , and r e q u i r e d t h e l o n g e s t p e r i o d of t i m e when s u p p l i e d with 70 F

53 .

TABLE

12

I n t e r a c t i o n of Ro ot T e m p e r a t u r e and L i g h t I n t e n s i t y on N u m b e r of
D a y s R e q u i r e d f o r F l o w e r i n g in the F a l l C r o p

L .S .D .

50°F
~
Reduced Full
Light
L ig ht
Intensity Intensity

Days r e q u ire d
fo r flow ering

85.57

81.36

TABLE

13

7 0°F
Reduced
L ig h t
Intensity

77.29

Full
L ig h t
Inten­
sity

86.79

5% 29. 09
1% 3 8 . 8 2

A p p r o x i m a t e L e n g t h of P h o t o p e r i o d O c c u r r i n g D u r i n g G r o w t h of
F a l l and W i n t e r C r o p s '
Da ys of C r o p G r o w t h
1 to 35 Days

35 to 70 Day s

70 to 105 Days

Fall crop

13 h r s 3 0 m i n
to
11 h r s 30 m i n

11 h r s 30 m i n
to
10 h r s 20 m i n

10 h r s 20 m i n
to
10 h r s 10 m i n

Winter crop

10 h r s 20 m i n
to
10 h r s 10 m i n

10 h r s 10 m i n
to
11 h r s 0 m i n

11 h r s 0 m i n
to
12 h r s 10 m i n

'"From P o s t,

1949, p. 71.

54.

TABLE

14

L. S. D.

83 d a y s

105 d ay s

5% 10. 16
13. 56
**1%

50°F
Reduced
Light
Intensity

-0
o
0

I n t e r a c t i o n of Root T e m p e r a t u r e and L i g h t I n t e n s i t y on P l a n t He ight
in C e n t i m e t e r s

Full
L ig h t
Inten­
sity

Reduced
Light
Intensity

Full
L ight
Inten­
sity

F a ll Crop
13,39
12,61

28. 69

38. 11

29.23

50. 46

58. 64

29.11

27. 54

29.20

5% 11. 04
1% 14. 76
W i nt er C r o p
9.38
9.15

105 d a y s * *
5%
1%

6. 85
9 .14

'’' A v e r a g e day of f l o w e r i n g
* 5‘cDay of h a r v e s t

55

INTERACTION
AND

LIGHT

58

REDUCED
50°

OF

INTENSITY
DAYS

LIGHT

FU LL

RO O T

TEMPERATURE

ROOT
ON

TEMPERATURE
GROWTH

AFTER

SALVIA

SEEDING

RE DU CED

LIGHT

OF

70°

LIGHT

FULL

LIGHT

ROOT

TEMPERATURE

Figure 10

INTERACTION
AND

LIGHT

OF

INTENSITY

105

DAYS

ROOT
ON

TEMPERATURE
GROWTH

AFTER

OF

SALVIA

SEEDING

REDUCED

FULL

RE DU CED

FU LL

LIGHT

LIGHT

LIGHT

LIGHT

F i g u r e 11

r o o t t e m p e r a t u r e and full {100 p e r cent) light i n t e n s i t y .

None of

t h e s e d i f f e r e n c e s w e r e s i g n i f i c a n t (T ab le 12).
P lant H eight:

P l a n t s g r o w n with 5 0 ° F r o o t t e m p e r a t u r e

p r o d u c e d m o r e l i n e a r g r o w t h with r e d u c e d lig ht i n t e n s i t y .
o
p l a n t s w e r e s u p p l i e d w ith 7 0 F r o o t t e m p e r a t u r e ,

When

t h e i r he ig ht was

l e s s with r e d u c e d l i g h t i n t e n s i t y in t he f a l l c r o p , a nd g r e a t e r with
r e d u c e d l i g h t i n t e n s i t y in the w i n t e r c r o p .

None of t h e s e d i f f e r e n c e s

w e r e l a r g e eno ug h to be s i g n i f i c a n t .
In c o n t r a s t to the e f f e c t of lig h t i n t e n s i t y ,

root te m p e ra tu re

i n f l u e n c e d p l a n t h e i g h t s i g n i f i c a n t l y a t the 1 p e r c e n t l e v e l .

Plant

o
.
o
h e i g h t w a s a l w a y s g r e a t e r with 70 F t ha n with 50 F r o o t t e m p e r a ­
t u r e ( T a b l e 14, F i g u r e s 10 and 11).
P l a n t h e i g h t 105 d ay s a f t e r s e e d i n g w as c o n s i s t e n t l y g r e a t e r
in the f a l l c r o p t h a n in the w i n t e r c r o p u n d e r a ll c o n di ti o n s of r o o t
t e m p e r a t u r e and l i g h t i n t e n s i t y .
f l u e n c e of p h o t o p e r i o d on g ro w th ,

In the s e c t i o n c o n c e r n i n g the i n ­
it w a s found t h a t d u r a t i o n of s p e c i ­

f ie d l e n g t h s of p h o t o p e r i o d did a f f e c t v e g e t a t i v e g ro w th .

Thus,

it

was s e e n t h a t t h i s w as a n a f f e c t of the n a t u r a l p h o t o p e r i o d o c c u r i n g
d u r i n g the g r o w t h of the c r o p s .

A p p r o x i m a t e v a l u e s f o r th e n a t u r ­

a l l y o c c u r i n g p h o t o p e r i o d d u r i n g the g r o w t h of the two c r o p s a r e
g i v e n in T a b l e 13.

57

F r e s h Weight:

F r e s h w eight of both s t e m s and r o o t s was

g r e a t e r with full l i g h t t h a n with r e d u c e d light i n t e n s i t y r e g a r d l e s s of
the r o o t t e m p e r a t u r e .
however,

T h e a m o u n t of i n c r e a s e in the f r e s h weigh t w a s,

g r e a t e r whe n t h e p l a n t s w e r e g r o w n with 7 0 ° F t ha n with 5 0 ° F

root te m p e r a tu re .

In the f a l l c r o p , p l a n t s which w e r e s u p p li e d with

the 5 0 ° F r o o t t e m p e r a t u r e e x h i b i t e d i n s i g n i f i c a n t d i f f e r e n c e s in f r e s h
w eig h t a s a r e s u l t of d i f f e r e n t lig h t i n t e n s i t i e s .

Plants

g r o w n with 7 0 ° F

r o o t t e m p e r a t u r e a l s o e x h i b i t e d i n s i g n i f i c a n t d i f f e r e n c e s in s t e m weight
due to l i g h t i n t e n s i t y , h o w e v e r the r o o t s of t h e s e p l a n t s had a f r e s h
w eig h t w hic h w a s 21.4 g r a m s m o r e t h a n the f r e s h w eight of r o o t s of
p l a n t s s u p p l i e d with a r e d u c e d l i g h t i n t e n s i t y .

T h i s d i f f e r e n c e w as s i g ­

n i f i c a n t a t the 1 p e r c e n t l e v e l .
T he s a m e g e n e r a l t r e n d s a p p e a r e d in the w i n t e r c r o p .
t e s t s of s i g n i f i c a n c e w e r e m a d e on w e i g ht s of the w i n t e r c r o p ,
p l a n t s f r o m the i n d iv i d u a l t r e a t m e n t s w e r e w eig he d as a g ro u p .

No
s i n c e the
The d i f ­

f e r e n c e s in f r e s h w e ig h t p r o d u c t i o n due to lig ht i n t e n s i t y w e r e g r e a t e r
t h a n in t h e f a l l c r o p with the e x c e p t i o n of r o o t w e ig ht of p l a n t s g r o w n
o
with 70 F r o o t t e m p e r a t u r e .

H e r e the i n c r e a s e with full lig h t i n t e n s i t y

was n o t a s g r e a t a s in the f a l l c r o p .
The d i f f e r e n c e s in f r e s h w eight of s t e m s a nd r o o t s of p l a n t s
g r o w n w ith 7 0 ° F r o o t t e m p e r a t u r e an d 5 0 ° F r o o t t e m p e r a t u r e w e r e s i g ­
n i f i c a n t a t the 1 p e r c e n t l e v e l in the f a l l c r o p .

The f r e s h w ei gh t of s t e m s

a v e r a g e d 7. 2 t i m e s h e a v i e r and f r e s h w eig ht of r o o t s a v e r a g e d 4. 8 t i m e s
o
o
h e a v i e r with 70 F t h a n with 50 F r o o t t e m p e r a t u r e .

T h e s e d i f f e r e n c e s in

f r e s h w e ig ht p r o d u c t i o n a s a r e s u l t of t e m p e r a t u r e d i f f e r e n c e s w e r e g r e a t ­
e r in t h e w i n t e r c r o p w h e r e f r e s h w e ig ht of s t e m s a v e r a g e d 11. 4 t i m e s
h e a v i e r and f r e s h w ei gh t of r o o t s a v e r a g e d 8 . 6 t i m e s h e a v i e r with the
7 0 ° F r o o t t e m p e r a t u r e ( T a b l e 15).
D r y W e i g h t : I r r e s p e c t i v e of r o o t t e m p e r a t u r e ,

d r y weight of

s t e m s a n d r o o t s in the f a l l c r o p w a s a l s o g r e a t e r with full t h a n with r e ­
d uc ed l ig h t i n t e n s i t y .

T h e d i f f e r e n c e s in d r y w e ig ht b e c a u s e of light

i n t e n s i t y w e r e no t s i g n i f i c a n t a t t h e 5 p e r c e n t l e v e l with the p l a n t s gro wn
o
a t a 50 F r o o t t e m p e r a t u r e .
root t e m p e r a t u r e ,

o
When the p l a n t s w e r e g ro w n with a 70 F

an a v e r a g e of 2 . 7 g r a m s m o r e d r y we ight of s t e m s ,

and 2 . 6 g r a m s m o r e d r y w eig ht of r o o t s was p r o d u c e d with the full light
intensity.

T h e s e d i f f e r e n c e s w e r e s i g n i f i c a n t ( T a ble 16).
Th e s a m e g e n e r a l t r e n d s e x i s t e d in the w i n t e r c r o p .

The

i n c r e a s e s in d r y w e i g h t with full l i g h t i n t e n s i t y in the w i n t e r c r o p
were la rg e r,

e x c e p t f o r the d r y w e ig h t of r o o t s p r o d u c e d by p l a n t s

s u p p l i e d w ith a 7 0 ° F r o o t t e m p e r a t u r e .

H e r e the i n c r e a s e with

full l i g h t i n t e n s i t y w as not a s g r e a t a s in the fall c r o p .
R o o t t e m p e r a t u r e did n ot in f l u e nc e t h e d r y weight of s t e m s
an d r o o t s a s m u c h a s f r e s h w e i g h t.

D r y w eight p r o d u c t i o n of p l a n t s

g r o w n w i t h a 7 0 ^ F r o o t t e m p e r a t u r e w as c o n s i s t e n t l y g r e a t e r t h a n

59,

TABLE

15

Reduced
L ig h t
Intensity

h
o
o
r-

in
o
0

I n t e r a c t i o n of Ro ot T e m p e r a t u r e a nd L i g h t I n t e n s i t y on F r e s h
Weight of S t e m s a n d R o o t s in G r a m s

Full
Light
Inten­
sity

R educ ed
L ig ht
Intensity

Full
L ig h t
Inten­
sity

F a ll Crop
S t e m w e ig h t
7. 58
L . S. D a 5% 17. 20
1% 2 2 . 9 9

9. 08

53. 29

68. 02

R o o t w ei g h t
4. 33
L . S . D . 5% 8 . 6 9
1% 11.62

6. 49

16. 63

37, 99

W inter C rop
Stem weight

2.00

3. 57

25. 30

36. 44

Root weight

1.03

3.15

11 . 70

18 . 66

TABLE

16

I n t e r a c t i o n of Root T e m p e r a t u r e and L ig ht I n t e n s i t y on D ry
Weight of S t e m s and R o o t s in G r a m s
70°F

50°F
Reduced
Light
Intensity

Full
L ig h t
Inten­
sity

R e du ce d
Light
Intensity

Full
L ig ht
Inten­
sity

F a ll Crop
S t e m w e ig h t
L . S . D . 5%
1%
R oo t weight
L . S a D. 5%
1%

1. 02

1. 36

6. 09

8. 83

0. 30

0. 34

1. 08

3. 68

2.3 0
3. 08
1. 63
2.18
Winter Crop

S t e m weigh t

0.29

0. 83

3.10

5. 50

R o o t w e ig h t

0. 04

0.19

0. 90

2. 45

60.

t h a t of p l a n t s g r o w n with a 5 0 ° F r o o t t e m p e r a t u r e .

The i n c r e a s e s in

d r y w eig ht of s t e m s a nd r o o t s of p l a n t s g r o w n with a 7 0 ° F r o o t t e m ­
p e r a t u r e w e r e s i g n i f i c a n t a t the 1 p e r c e n t l e v e l with the e x c e p t i o n of
the d r y w e ig h t of r o o t s p r o d u c e d by p l a n t s su p p li e d with a r e d u c e d
light in te n sity .

H e r e t h e r e was no s i g n i f i c a n c e .

T he d r y weight of

the s t e m s a v e r a g e d 6 „ 2 t i m e s h e a v i e r and the d r y we ight of the r o o t s
a v e r a g e d 2. 3 t i m e s h e a v i e r with the 7 0 ° F t h a n with the 5 0 ° F r o o t
tem perature.

The i n c r e a s e s in d r y weight a s a r e s u l t of d i f f e r e n c e s

in t e m p e r a t u r e w e r e g r e a t e r in the w i n t e r c r o p with an a v e r a g e of
8„7 t i m e s a s m u c h s t e m weight,

and an a v e r a g e of 17.7 t i m e s a s m u c h

r o o t w e i g ht p r o d u c e d with the 7 0 ° F r o o t t e m p e r a t u r e {Table 16).
T op-root Ratio:

Both t e m p e r a t u r e a n d l i g h t i n t e n s i t y a p p e a r e d

to a f f e c t the t o p - r o o t r a t i o c o n s i d e r a b l y .
on a f r e s h w e i g h t b a s i s ,

With the c a l c u l a t i o n s m a d e

a l a r g e r r a t i o was c o n s i s t e n t l y o b ta in e d at

the r e d u c e d l i g h t i n t e n s i t y and the 7 0 ° F r o o t t e m p e r a t u r e ( T able 17).
TABLE

17

50 F
Reduced Light F ull Light
Intensity
Intensity

o
0

I n t e r a c t i o n of R o o t T e m p e r a t u r e and L ig ht I n t e n s i t y on T o p - R o o t R a t io

R e d u c e d L ig ht
Intensity

F u l l L ig h t
Intensity

F r e s h Weight B a s i s
Fall crop
W inter crop

1. 75

1.40

3. 20

1. 79

1 . 94

1.13

2 . 16

1. 95

61

TABLE

18

I n t e r a c t i o n of R o ot T e m p e r a t u r e a nd E i g h t I n t e n s i t y on N u t r i e n t
E l e m e n t C o m p o s i t i o n of R o o t s and T o p s ( P e r C e n t D r y Weight)
50°F
Reduced
Light
Intensity

Full
Light
Intensity

70°F
Reduced
Light
Intensity

Full
Light
Intensity

F a ll Crop
R oots
%N
%P
%K

1.63
0.1 75 "
1 . 91

1.66 v
0. 180**
1 . 09

1. 01
0. 146
0. 911

1. 43
0. 172
1. 45

T ops
%N
% P
%K

3. 18
0. 370
3. 26

3. 19
0. 338
2. 73

3. 90
0. 496
3. 36

4. 02
0. 454
3. 95

1. 61
0, 210
2. 59

Winter Crop
R oots
%N
%P
%K
T ops
% N
%P
%K

2. 96
'r *

3. 39

3. 33

1. 40
0.184
1. 88

2. 56
0. 268
3. 17

2. 79
0. 256
4. 13

3. 26
0. 456
2. 90

2. 47

>\<

3. 98
0. 478
4. 51

‘R e s u l t s f r o m s in gle d e t e r m i n a t i o n s b e c a u s e of i n s u f f i c ie n t
s a m p l e . All o t h e r v a l u e s a r e a v e r a g e s of d u p l i c a t e d e t e r m i n a t i o n s .
^ ‘' i n s u f f i c i e n t s a m p l e to m a k e d e t e r m i n a t i o n s .

62

ACCUM
ULATION

OF

NUTRIENTS

IN FALL

AND W
INTER

CROPS

PERCENT
N IT R O G E N

P H O S P H O R U S

4 .0 0 -

P O T A S S IU M

3.00-

R O O TS

T O P S

R O O T S

136409FALL

T O P S

CROP

R O O T S

WINTER

T O P S

CROP

Figure 12
INFLUENCE OF ROOT TEM
PERATURE AND LIGHT INTENSITY
ON ACCUMULATION OF NUTRIENTS
PE RC EN T
5 0 0 -

N IT R O G E N

P O T A S S IU M

P H O S P H O R U S

400

3.00

2.00

69

il IM

0.00
R O O TS

T O P S

^

R O O T S

50*

T O P S

1111

50*

H

70*

6 3 % LIGHT
70*

R O O TS

1 0 0 % LIGHT

F i g u r e 13

T O P S

63 „

INFLUENCE OF LIGHT INTENSITY ON ACCUM
ULATION
NUTRIENTS IN FALL AND W
INTER CROPS
N IT R O G E N

P H O S P H O R U S

OF

P O T A S S IU M

3.00

57

I*:-:-:-

Ik.
R O O T S

T O P S

R O O T S

T O P S

FALL

111

63%

R O O TS

100%
WINTER

LIGHT

WINTER

TO PS

FALL

LIGHT

Figure 14

INFLUENCE
OF

OF

ROOT

NUTRIENTS

TEMPERATURE

IN

FALL

AND

ON

ACCUM
ULATION

W
INTER

CROPS

PERCENT
N IT R O G E N

P O T A S S IU M

P H O S P H O R U S

4.00 —

3.00

W :s :

I

in .
R O O T S

R O O T S

T O P S

SSft:

FA LL

50'

WINTER

F i g u r e 15

T O P S

R O O T S

T O P S

6 4.

N u t r i e n t A c c u m u l a t i o n , F a l l and Winter C r o p s ;

The d a ta f o r

the a v e r a g e a c c u m u l a t i o n of n i t r o g e n , p h o s p h o r u s , and p o t a s s i u m with
an a t m o s p h e r e a t 6 0 ° F N T, a r o o t t e m p e r a t u r e of 5 0 ° F o r 7 0 ° F and
a r e d u c e d (63 p e r cent) o r full (100 p e r cent) a v a i l a b l e lig h t i n t e n s i t y
a r e g i v e n in T a b l e 18.
The a c c u m u l a t i o n of n i t r o g e n , p h o s p h o r u s , a nd p o t a s s i u m in
the r o o t s

wa s h i g h e r in the w i n t e r c r o p t h a n in the f all c r o p .

a c c u m u l a t i o n in the t o p s , h o w e v e r , was not a s c o n s i s t e n t .

Their

More p o t­

a s s i u m a c c u m u l a t e d in t h e t o p s , while n i t r o g e n and p h o s p h o r u s did not
r e a c h a s h igh a l e v e l of c o n c e n t r a t i o n in the to p s in the w i n t e r c r o p
( F i g u r e 12).
R e d u c e d l ig h t i n t e n s i t y f a v o r e d a h i g h e r a c c u m u l a t i o n of all
t h r e e n u t r i e n t s in b oth to p s and r o o t s ,
two e x c e p t i o n s to t h i s g e n e r a l t r e n d ,
the fa ll c r o p .

F i g u r e 14„

Analyses produced

both of w hic h a p p e a r e d only in

A s m a l l e r c o n c e n t r a t i o n of p h o s p h o r u s wa s found in the

t ops a nd of p o t a s s i u m in the r o o t s of p l a n t s s u p pl ie d with r e d u c e d lig h t
intensity.
o
It w as e v i d e n t t h a t a t the 70 F r o o t t e m p e r a t u r e n i t r o g e n ,
p h o s p h o r u s a nd p o t a s s i u m t e n d e d to a c c u m u l a t e m o r e in the t o p s and
l e s s in the r o o t s t h a n at the 5 0 ° F r o o t t e m p e r a t u r e .

These trends are

r e p r e s e n t e d in F i g u r e 15.
T he i n f l u e n c e of lig ht i n t e n s i t y upon n u t r i e n t a c c u m u l a t i o n

65

f o l l o w e d the s a m e t r e n d s when the d a t a f o r the two c r o p s w e r e
c o m b i n e d to show the a v e r a g e a c c u m u l a t i o n of n u t r i e n t s with
e a c h c o m b i n a t i o n of t e m p e r a t u r e and lig h t i n t e n s i t y ,
One e x c e p t i o n ,
roots

F i g u r e 13.

w as a h i g h e r c o n c e n t r a t i o n of p o t a s s i u m in the

o
of p l a n t s g r o w n w it h full light i n t e n s i t y and with a 50 F

root t e m p e r a t u r e .

When th e r o o t t e m p e r a t u r e wa s 7 0 ° F , t h e r e

was a h i g h e r c o n c e n t r a t i o n of p o t a s s i u m in the r o o t s of p l a n t s
g r o w n with r e d u c e d l i g h t i n t e n s i t y .
The p l a n t s g r o w i n g with a r e d u c e d lig h t i n t e n s i t y a c c u m ­
u l a t e d a n a v e r a g e of 0„ 05 p e r c e n t m o r e n i t r o g e n ,
m o re phosphorus,

0. 021 p e r c en t

and 0 . 4 5 p e r c e n t m o r e p o t a s s i u m in the r o o t s ;

and a c c u m u l a t e d a n a v e r a g e of 0. 21 p e r c e n t m o r e n i t r o g e n ,
per cent le ss phosphorus,

0, 012

and 0 . 4 8 p e r c e n t m o r e p o t a s s i u m in

o
o
the t o p s when g r o w n with 70 F t h a n when g r ow n with 50 F r o o t
tem p eratu re.

6b ,

SYNOPSIS OF R E S U L T S

The t e n c u l t i v a r s t h a t w e r e t e s t e d f or g e n e r a l g r o w t h c h a r ­
a c t e r s w e r e a b l e to be c l a s s i f i e d into t h r e e g e n e r a l g ro u ps :
1. D w a r f ,

2. S e m i - d w a r f ,

and 3. T a l l ,

dwarf types pro d u ced a ttra c tiv e ,
b ein g " p i n c h e d " o n c e .
v a r i e d with c u l t i v a r ,

Only the d w a r f and the s e m i ­

s h o r t p l a n t s with d e n s e g r ow t h a f t e r

T h e n u m b e r of d a y s r e q u i r e d f o r f l o w e r i n g
but wa s not c o n s i s t e n t l y l o n g e r o r s h o r t e r in

any one of the g r o u p s ,
A c old t r e a t m e n t of 4 0 ° F c o n s t a n t t e m p e r a t u r e did not
s i g n i f i c a n t l y i n f l u e n c e t o t a l s t e m w eight and s t e m l e n g t h of p l a n t s
g ro w i n g a t 50° o r 6 0 ° F N T.

S t e m w eight p e r unit of s t e m le n g th

was s i g n i f i c a n t l y i n f l u e n c e d by the c old t r e a t m e n t only when the p l a n t s
w e r e g r o w i n g with a 5 0 ° F N T and when the cold t r e a t m e n t was s u p ­
p l i e d a t the t w o - n o d e s t a g e of g r o w t h .

The n u m b e r of d ays r e q u i r e d

f o r f l o w e r i n g w as s i g n i f i c a n t l y i n c r e a s e d by a cold t r e a t m e n t only
when t h e p l a n t s w e r e g r o w i n g with a 6 0 ° F N T and when t r e a t e d a t
the t w o - n o d e s t a g e of g r o w t h .

T h e s e p l a n t s r e q u i r e d f o u r m o r e days

f o r f l o w e r i n g t h a n did t h o s e p l a n t s g ro win g with 6 0 ° F N T and not
s u p p l i e d with a c old t r e a t m e n t .
o
V e g e t a t iv e g r o w t h w a s d e f i n i t e l y r e t a r d e d with a 50 F N T.
T h i s w a s p a r t i c u l a r l y a p p a r e n t d u r i n g the f i r s t 60 days of p l a n t g r ow t h
whe n c h l o r o s i s w as e v i d e n t .

As the p l a n t s b e c a m e o l d e r t h e i r r a t e

of g r o w t h i n c r e a s e d and at the d a te of f l o w e r i n g the p l a n t s g ro w i n g
with the 5 0 ° F N T p r o d u c e d an a v e r a g e of nine c e n t i m e t e r s l e s s s t e m
e l o n g a t i o n t h a n p l a n t s g r o w i n g with 6 0 ° F N T.
T h o s e p l a n t s t h a t w e r e m o v e d to the o p p o s i t e night t e m p e r ­
a t u r e 90 d a y s a f t e r s e e d i n g a t t a i n e d an a v e r a g e of 2. 5 to 3. 4 c e n t i ­
m e t e r s g r e a t e r s t e m e lo n g a t i o n t h a n t h o s e r e m a i n i n g a t the o r i g i n a l
tem perature s .
Night t e m p e r a t u r e did not g r e a t l y i n flu e nc e t o t a l s t e m
w e ig h t o r s t e m w ei gh t p e r u n it l e n g t h .

The f l o w e r s w e r e of e q ua lly

good c o l o r and q u a l i t y in a l l t r e a t m e n t s , b ut the n u m b e r of days
r e q u i r e d f o r t h e i r p r o d u c t i o n was s i g n i f i c a n t l y i n c r e a s e d with the
5 0 ° F N T.
P l a n t s g r o w n w ith one " p i n c h " p r o d u c e d m o r e d e s i r a b l e f o r m
s i m i l a r to t h a t shown in F i g u r e 2.

M o r e t h a n one " p i n c h " s e r v e d to

i n c r e a s e the s i z e of the p l a n t and the t i m e r e q u i r e d f o r p r o d u c t i o n ,
but did not g r e a t l y i m p r o v e the f o r m .

F l o w e r s i z e w as c o n s i d e r a b l y

s m a l l e r on p l a n t s r e c e i v i n g t h r e e " p i n c h e s " .
N i n e t y d a y s w e r e r e q u i r e d to p r o d u c e f l o w e r i n g p l a n t s f r o m
s e e d sown A u g u s t 15th.

When s e e d was sown S e p t e m b e r 1st and 15th,

98 and 99 d a y s w e r e r e q u i r e d r e s p e c t i v e l y .

F l o w e r i n g p l a n t s f o r the

C h r i s t m a s m a r k e t w e r e p r o d u c e d f r o m s e e d sown S e p t e m b e r 1st.
O n e - h a l f of th e p l a n t s m o v e d to h o m e s e x h i b it e d e v i d e n c e of

68

f l o r e t a b s c i s s i o n d u r i n g the f i r s t day,

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

a n a v e r a g e of 8. 5 d a y s a f t e r the p l a n t s w e r e m o v e d to the h o m e s .
The f o l i a g e w as m o r e d u r a b l e u n d e r h o m e c o n d i t i o n s .
of 8 d a ys p a s s e d b e f o r e t h r e e l e a v e s a b s c i s s e d ,

An a v e r a g e

and the foliage of

o v e r h a l f of the p l a n t s w a s in good c o n d it i o n at the end of the 15- day
period.

T he f r e q u e n c y of w a t e r i n g , h e a t i n g m e t h o d , t e m p e r a t u r e ,

a nd l o c a t i o n of the p l a n t in the h o m e had no c o n s i s t e n t e f fe c t on the
life of the p l a n t in the h o m e .

No f l o r e t a b s c i s s i o n o c c u r r e d in the

g r e e n h o u s e f r o m p l a n t s t r e a t e d with p a r a - c h l o r o p h e n o x y a c e t i c a c i d
and g r o w n a t e i t h e r 5 0 ° F N T o r 6 0 ° F N T.

The r a t e of f l o r e t a b ­

s c i s s i o n a f t e r t h e p l a n t s w e r e m o v e d to r o o m t e m p e r a t u r e was not
g r e a t l y i n f l u e n c e d by the c h e m i c a l t r e a t m e n t , but w as r e d u c e d by
the 5 0 ° F N T.
T o t a l s t e m e l o n g a t i o n and p l a n t h e i g h t was l e s s on p l a n ts
p r o v i d e d with a n 8 - h o u r p h o t o p e r i o d , t h a n on p l a n t s p r o v i d e d with
a 16- h o u r p h o t o p e r i o d .

The r e d u c t i o n in s t e m e lo n g a ti o n and plan t

h e i g h t i n c r e a s e d d i r e c t l y with an i n c r e a s e in the n u m b e r of d ays
with 8 - h o u r p h o t o p e r i o d s ,

F i g u r e 7.

A pi c a l d o m i n a n c e was a f f e c t e d

w he n t h e p l a n t s w e r e s u p p l i e d with 45 o r l e s s s h o r t p h o t o p e r i o d s .
F l o w e r i n g p l a n t s w e r e p r o d u c e d in a l l t r e a t m e n t s with the l a r g e s t
n u m b e r of d a y s b e i n g r e q u i r e d f o r f l o w e r p r o d u c t i o n by p l a n t s p r o ­
v i d e d w ith no s h o r t p h o t o p e r i o d s ,

and t h e s m a l l e s t n u m b e r be ing

69.

r e q u i r e d by p l a n t s p r o v i d e d with 75 s h o r t p h o t o p e r i o d s .

Photo­

p e r i o d ha d no a p p a r e n t i n f l u e n c e on the p l a n t s a f t e r they w e r e in f l o w e r ,
o
The p l a n t s w ith the 50 F r o o t t e m p e r a t u r e g r e w m u c h m o r e
slowly, p r o d u c e d m o r e d ee p g r e e n f o l i a g e , a nd d e v e lo p e d m o r e a n t h o c y a n i n in t h e i r p e t i o l e s a nd s t e m s t h a n did the p l a n t s g ro w n at the
70°F root te m p e ra tu re .

In s p i t e of the l a r g e d i f f e r e n c e in the v e g e ­

t a t i v e g r o w t h , f l o w e r s w e r e i n i t i a t e d in a ll t r e a t m e n t s a t a p p r o x i m a t e l y
the s a m e t i m e .

T he d e v e l o p m e n t of f l o r e t s was o b s e r v e d and five

s t a g e s in d e v e l o p m e n t w e r e a r b i t r a r l y d i s t i n g u i s h e d .

F l o r e t s on

o
p l a n t s g r o w i n g with a 50 F r o o t t e m p e r a t u r e w e r e o b s e r v e d to de ve lo p
o
m o r e s lo wly t h a n t h o s e on p l a n t s growitig with a 70 F r o o t t e m p e r ­
a t u r e , but n e i t h e r r o o t t e m p e r a t u r e n o r light i n t e n s i t y had any s i g n i ­
f i c a n t i n f l u e n c e on r a t e of f l o r e t d e v e l o p m e n t ,
r e q u ir e d for flowering.

o r n u m b e r of days

Although the d i f f e r e n c e w as not s i g n i f i c a n t ,

the l o n g e s t p e r i o d of t i m e f o r f l o w e r i n g w as r e q u i r e d f o r p l a n t s g r o w ­
ing with full li gh t i n t e n s i t y ,

and t h e s h o r t e s t p e r i o d of t i m e was r e -

o
q u i r e d with r e d u c e d l i g h t i n t e n s i t y with 70 F r o o t t e m p e r a t u r e .
o
o
P l a n t s g r o w i n g with e i t h e r 50 F or 70 F r o o t t e m p e r a t u r e
a t t a i n e d in g e n e r a l g r e a t e r s t e m e l on g a t i o n u n d e r r e d u c e d light in tensity.

o
T h o s e p l a n t s g r o w i n g w ith 70 F r o o t t e m p e r a t u r e p r o d u c e d

a t l e a s t t w i c e a s m u c h s t e m e l o n g a t i o n a s p l a n t s g r o w i n g with the
50°F root te m p e ra tu re ,

with t h e i n c r e a s e s b e i n g g r e a t e r with full

70

light intensity,

F i g u r e s 10 a n d 11.

F r e s h and d r y w ei gh t of b oth s t e m s and r o o t s was g r e a t e r
with full l i g h t i n t e n s i t y t h a n with r e d u c e d light i n t e n s i t y r e g a r d ­
l e s s of r o o t t e m p e r a t u r e .

The l a r g e s t v a l u e f o r t o p - r o o t r a t i o s

was o b t a i n e d f r o m p l a n t s g r o w n with r e d u c e d lig h t i n t e n s i t y and
o
70 F r o o t t e m p e r a t u r e ,
In g e n e r a l ,

T a b l e 16.

a h i g h e r a c c u m u l a t i o n of n i t r o g e n , p h o s p h o r u s

and p o t a s s i u m w as found in the w i n t e r t h a n in the fall c r o p ( F i g u r e 12).
N u t r i e n t s t e n d e d to a c c u m u l a t e m o r e in the t o p s and l e s s
o
o
in t h e r o o t s with a 70 F t h a n with a 50 F r o o t t e m p e r a t u r e
u r e 15).

(Fig­

A r e d u c e d light in tensity favored a hig her a ccum ula tio n

of a l l t h r e e n u t r i e n t s in b o t h t o p s an d r o o t s .

Two e x c e p t i o n s to

this g e n e ral rule w ere a s m a lle r concentration

of p h o s p h o r u s in

t o p s a n d of p o t a s s i u m in r o o t s when g r o w n with r e d u c e d light i n t e n ­
s i t y ( F i g u r e 14).

71

DISCUSSION

T e s t s of C u l t i v a r s

C o m p a r i s o n of the c u l t i v a r s g r o w n i n d i c a t e d that,

if a

d w a r f p l a n t (17. 0 c m high) was d e s i r e d , St. J o h n ' s F i r e o r V a u g hn 's
M a s t e r p i e c e would be s u i t a b l e .
desired,

If a l a r g e r p l a n t (24. 0 c m high) was

S p le n d e n s A m e r i c a , A m e r i c a f o r Z u r u c k ,

Bonfire, or

B l a z e of F i r e would p r o d u c e a s u i t a b l e p l a n t with b r i l l i a n t r e d f l o w ­
e r s and den se grow th.

R o s e F l a m e p r o d u c e d a d e n s e g ro wth , but

was c o n s i d e r e d to be u n d e s i r a b l e b e c a u s e of the lig h t p ink f lo w e r
color.

C u l t i v a r s of t he t a l l typ e, C l a r a B e d m a n ,

Sple nde ns S c a r l e t

Sage, and S p l e n d e n s B r i g h t n e s s did not a p p e a r to be s u i t a b l e f o r
pot p l a n t c u l t u r e b e c a u s e of t h e i r e x t r e m e h ei g h t ( 35 .0 to 4 7 . 0 cm)
and s p r e a d i n g g r o w t h .
The n u m b e r of d ay s r e q u i r e d f or f l o w e r i n g v a r i e d s lightly
( T a b le 2) with t h e d w a r f c u l t i v a r s f l o w e r i n g a p p r o x i m a t e l y 7 days
e a r l i e r t h a n the s e m i - d w a r f c u l t i v a r s .

I n t e r a c t i o n of Cold T r e a t m e n t a n d G r o w t h
o
The c o ld t r e a t m e n t of 40 F c o n s t a n t t e m p e r a t u r e , when it
wa s s u p p l i e d a t th e f o u r - n o d e s t a g e , f o r 7 d ay s h a d no s i g n i f i c a n t

influence upon t h e g r o w t h m e a s u r e m e n t s .

When t he cold t r e a t m e n t

72.

w a s s u p p l i e d a t t he t w o - n o d e s t a g e ,

it had no highly s i g n i f i c a n t i n ­

f l u e n c e s , but the p l a n t s g r o w n a t 6 0 ° F n ig h t t e m p e r a t u r e {F N T)
o
r e q u i r e d m o r e d a y s f o r f l o w e r i n g , a nd the p l a n t s g r o w n a t 50 F N T
p r o d u c e d m o r e s t e m w e i gh t p e r u n it of s t e m l e n g t h when the cold
t r e a t m e n t w a s s u p p l i e d a t t h e t w o - n o d e s t a g e ( T a bl e 3).
It a p p e a r e d f r o m t h e s e d a t a t h a t g ro w th of S a lv ia was m o r e
g r e a t l y r e t a r d e d when the p l a n t s w e r e s u p pl i e d with a cool t e m p e r a ­
t u r e a t t h e t w o - n o d e s t a g e t h a n when the cool t e m p e r a t u r e was su p pl i e d
a t the f o u r - n o d e s t a g e of g ro w t h .

At e i t h e r s t a g e , h o w e v e r , the i n ­

f lu e n c e of a r e l a t i v e l y s h o r t p e r i o d of c ool t e m p e r a t u r e was not l a r g e .

I n t e r a c t i o n of Night T e m p e r a t u r e and G ro w t h

The o p in io n t h a t S a lv ia g r o w t h w as m o r e g r e a t l y r e t a r d e d
by cool t e m p e r a t u r e a t the e a r l i e r s t a g e s of g r o w t h was s u p p o r t e d
by the r e s u l t s o b t a i n e d f r o m stu dy in g the in fl ue n c e of 50
on g r o w t h .

o

, °
and 6 0 F N T

o
D u r i n g the f i r s t 60 d a y s , t h o s e p l a n t s g ro w in g a t 60 F N T

p r o d u c e d a p p r o x i m a t e l y f o u r t i m e s a s m u c h s t e m e lo n g a t i o n as p l a n ts
o
g r o w i n g a t 50 F N T.

o
A f t e r 115 d a y s of g ro w t h t h o s e p l a n t s a t 60 F N T

p o s s e s s e d only 1.3 t i m e s a s m u c h s t e m e l o n g a ti o n a s p l a n t s gro wn a t
o
50 F N T ( T a b l e 4).

The n u m b e r of days r e q u i r e d f o r f l o w e r i n g wa s

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

if it w as s u pp lie d d u r i n g

e a r l i e r s t a g e s of g r o w t h , but t h i s was n ot t r u e if it was s u p pl i e d a f t e r

73 .

90 d a y s f r o m the d a te of s e e d i n g ( T ab le 5).
H o lle y (1942) s t a t e d t h a t the i m p o r t a n c e of a i r t e m p e r a ­
t u r e b e c a m e i n c r e a s i n g l y s i g n i f i c a n t as the lig ht i n t e n s i t y d e c r e a s e d .
Since t h e p l a n t s w e r e s u p p l i e d with a g r a d u a l l y i n c r e a s i n g i n t e n s i t y
of l i g h t s u c h a s o c c u r s in M i c h i g a n f r o m F e b r u a r y to May, the r e ­
t a r d e d g r o w t h w h ile the p l a n t s w e r e young m a y not h av e b e e n c a u s e d
e n t i r e l y by t h e 5 0 ° F N T„
R e v e r s i n g t he t e m p e r a t u r e 90 d ay s a f t e r s e e d i n g gave
s t a t i s t i c a l l y s i g n i f i c a n t i n c r e a s e s in fi na l s t e m e l o n g a ti o n when
c o m p a r e d to p l a n t s w h ich c o n ti n u e d to g r o w a t the o r i g i n a l t e m p e r ­
atures.

It is b e l i e v e d t h a t the i n c r e a s e in s t e m e lo n g a ti o n of

o
o
p l a n t s g r o w i n g a t the 50 F N T and m o v e d to 60 F N T 90 days
a f t e r s e e d i n g w a s the r e s u l t of a m o r e o p t i m u m n ig ht t e m p e r a t u r e
for lin e a r growth.

S i m i l a r l y , t he p l a n t s f o r m e r l y g r o w n a t the

o
60 F N T w e r e p r o b a b l y h ig h in n i t r o g e n and when m o v e d to a
o
50 F N T an i n c r e a s e in s t e m e l o n g a t i o n r e s u l t e d .

F i f t y and

6 0 ° F n i g h t t e m p e r a t u r e did not in f lu e n c e s t e m weight, f lo w e r
color or quality.
In g e n e r a l ,

the r e s u l t s of t h i s e x p e r i m e n t i n d i c a t e d t ha t

t h e 6 0 ° F N T f a v o r e d the g r o w t h of S alvia, and t h a t s o m e a d d i t io n a l
s t e m e l o n g a t i o n c ould be o b t a i n e d by m o vi n g the p l a n t s to a 50
F N T 90 d a y s a f t e r s e e d i n g .

T h i s is in a g r e e m e n t with i n f o r m a t i o n

74

f u r n i s h e d by R o b e r t s and S t r u c k m e y e r (1938) and P o s t (1949)
w h e r e the o p t i m u m n i g h t t e m p e r a t u r e f o r g ro w th of d a lv ia was
give n a s 55

°

°
to 60 F N T.

F o r m of P l a n t

The r e m o v a l of the a p i c a l g r o w t h d i s t a l to the t h i r d node
(a np i n c h n ) r e s u l t e d in the f o r m a t i o n of b r a n c h e s and s u b s e q u e n t
i m p r o v e m e n t in the a p p e a r a n c e of p l a n t s when c o m p a r e d to t h o s e
whic h w e r e not " p i n c h e d " .

When m o r e t h a n one " p i n c h " was a pp li e d

an a d d i t i o n a l 10 d a y s of g r o w i n g t i m e p e r "‘p i n c h ” was n e c e s s a r y to
produce flowering plants.

U n l e s s the l a r g e r p l a n t s t h a t would be

obtained fro m additional "pinches" w ere especially desired ,

it was

not f e l t t h a t m o r e t h a n one " p in c h " r e s u l t e d in p l a n t s t h a t w e r e
s u f f i c i e n t l y m o r e a t t r a c t i v e to w a r r a n t the a d d i t io n a l t i m e r e q u i r e d
fo r t h e i r p r o d u c t i o n .

A r e d u c t i o n in f l o w e r s i z e was p a r t i c u l a r l y

a p p a r e n t on p l a n t s t h a t w e r e p i n c h e d t h r e e t i m e s .

Thus,

in o r d e r

to o b t a in a c o m b i n a t i o n of t h e l a r g e s t p l a n t with l a r g e f l o w e r s , the
p l a n t s s hould not be p i n c h e d m o r e t h a n t w i c e .

T i m i n g of a C o m m e r c i a l C r o p

The p r o p e r t i m e f o r sowing s e e d in a g r e e n h o u s e to o bta in
f l o w e r i n g p l a n t s f o r C h r i s t m a s 1953 p r o v e d to be the f i r s t wee k in

75.

Septem ber.
ing p l a n t s .

T h i s a l l o w e d a p p r o x i m a t e l y 98 d a ys to p r o d u c e f l o w e r ­
On th e b a s i s of i n f o r m a t i o n o b t a in e d in t h i s a n d p r e l i m ­

inary experim ents,

the f ollo w ing s c h e d u l e w as d e v i s e d f o r the p r o ­

d u c t i o n of a C h r i s t m a s c r o p of S alv ia in M i c h i g a n with n a t u r a l p h o t o ­
period .
1. Sow s e e d S e p t e m b e r 1 to 7 a nd g e r m i n a t e a t 60 to 7 0 ° F N T.
2. S pa ce s e e d l i n g s 1 1/2 x 1 1/2 i n c h e s in f l a t s S e p t e m b e r 20
to 27.

G r o w at 6 0 ° F N T.

3. P o t the p l a n t s in 5 to 6 i n c h p o ts O c t o b e r 10 to 17, and r e ­
m o v e the t e r m i n a l g r o w t h d i s t a l to the t h i r d n ode.

Grow

t he p l a n t s a t 6 0 ° F N T.
4. F l o w e r i n g p l a n t s m a y be e x p e c t e d by D e c e m b e r 7 to 14.
5. The p l a n t s s hould b e w a t e r e d f r e e l y .

F e r t i l i z e w eekly at

a r a t e e q u i v a l e n t to 1 to 1 1/2 o u n c e s of 12-31-14 f e r t i l i z e r
p e r 50 p l a n t s .
The p e r i o d d u r i n g which the p l a n t s in e a c h c r o p r e a c h e d the
st a g e of f l o w e r i n g r a n g e d f r o m 4 to 12 d a y s .

P r e l i m i n a r y work has

i n d i c a t e d t h a t g r e a t e r u n i f o r m i t y in s t a g e of g r o w t h of the p l a n t s could
be o b t a i n e d by t h e u s e of a d e s i r a b l e c u l t i v a r w hich w as v e g e t a t i v e l y
propagated.

76.

K e e p i n g Q ua li t y

A b s c i s s i o n of f l o r e t s b e g a n f r o m 1 to 3 days a f t e r the p l a n t s
w e r e m o v e d to the h o m e s .

The l e a v e s r e m a i n e d on the p l a n ts u n d e r

the c o n d i t i o n s of th e h o m e .
plants,

On the b a s i s of d ata o b ta in ed f r o m t h e s e

it w a s c o n c l u d e d t h a t t i m e a nd r a t e of f l o r e t a b s c i s s i o n w e r e

not i n f l u e n c e d by t h e f r e q u e n c y of w a t e r i n g , the h e a t i n g m e t h o d , or
the t e m p e r a t u r e of the r o o m .

In s p it e of the d u r a b i l i t y of the l e a v e s ,

the a v e r a g e a t t r a c t i v e p e r i o d of the p l a n t s was only 4 to 8 days a s a
r e s u l t of f l o r e t a b s c i s s i o n .
Th e p a r a - c h l o r o p h e n o x y a c e t i c a c i d w as not e ff ectiv e in r e ­
duc ing f l o r e t a b s c i s s i o n at the c o n c e n t r a t i o n u s e d when it was a pp li ed
21 d ay s b e f o r e f l o w e r i n g .

A 50 F N T f o r 21 d ays b e f o r e f lo w e r i n g

did a p p e a r to h av e s o m e r e l a t i o n to a r e d u c t i o n in f l o r e t a b s c i s s i o n
a f t e r t h e p l a n t s w e r e m o v e d to r o o m t e m p e r a t u r e .

The i n flu en c e of

the 5 0 ° F N T in r e t a r d i n g f l o r e t a b s c i s s i o n w a s not s u ff ic ie nt to m a k e
Salvia an e x t r e m e l y d e s i r a b l e p l a n t to be u s e d a s a pot p l a n t in the
home.
T h e o r i e s a r e s u g g e s t e d c o n c e r n i n g f l o r e t a b s c i s s i o n of
Sa lv ia .

The w o r k of L a R u e (1936) in s u c c e s s f u l l y d el a y in g th e a b s c i s ­

s io n of C o l e u s p e t i o l e s with g r o w t h h o r m o n e s a f t e r the l e a f b l a d e s
ha d b e e n r e m o v e d s e r v e d to i n d i c a t e t h a t the u s e of g r o w t h r e g u l a t o r s

77.

in d e l a y i n g t h e a b s c i s s i o n of l e a v e s w a s p o s s i b l e .

The r e s u l t s o b ­

t a i n e d f o r S a l v ia by no m e a n s e l i m i n a t e d the p o s s i b i l i t y t ha t f l o r e t
a b s c i s s i o n m i g h t be r e t a r d e d by the t i m e l y a p p l i c a t i o n of a n o p t i m u m
q u a n ti ty of s o m e g r o w t h s u b s t a n c e .

It was c o n c l u d e d t ha t f l o r e t

a b s c i s s i o n w a s not i n f l u e n c e d by the r o o m t e m p e r a t u r e s which w e r e
supplied.
No f l o r e t a b s c i s s i o n o c c u r r e d f r o m p l a n t s t h a t r e m a i n e d in
the g r e e n h o u s e .

M y e r s (1940) o b s e r v e d t h a t the a b s c i s s i o n of p e t i o l e s

of C o l e u s p l a n t s p l a c e d in t h e d a r k w as m o r e r a p i d t h a n the a b s c i s s i o n
f r o m t he p l a n t s p l a c e d in the li g h t .

It was p o s s i b l e t h a t r e l a t i v e h u m i ­

dity a n d / o r l i g h t i n t e n s i t i e s m i g h t h av e b e e n a f a c t o r in the r a p i d
r a t e of a b s c i s s i o n a t r o o m t e m p e r a t u r e .

The e f f e c t i v e n e s s of the

5 0 ° F N T in r e d u c i n g the r a t e of f l o r e t a b s c i s s i o n a f t e r the p l a n t s w e r e
m o v e d to r o o m t e m p e r a t u r e could h av e b e e n due to a n i n c r e a s e in the
p e r c e n t a g e of c a r b o h y d r a t e s in the p l a n t .

T h i s c ou ld have r e s u l t e d in

g r e a t e r r e s i s t a n c e to l o w e r r e l a t i v e ' h u m i d i t y .
The a v a i l a b i l i t y of n u t r i e n t s m a y have b e e n involved in the
r a t e of f l o r e t a b s c i s s i o n a s w a s found by N i g h ti n g a l e (1933).

He c o n ­

c lu d e d t h a t S a l v i a w a s v e r y s e n s i t i v e to the l e v e l of n i t r a t e s in the
n u t r i e n t s o l u t io n ,

and when the p l a n t s w e r e s u p p li e d with a s h o r t

p h o t o p e r i o d a nd a n u t r i e n t s o l u t i o n m i n u s n i t r a t e he s t a t e d that:
nthey s h e d t h e i r b l o s s o m s p r o f u s e l y ” .

I n t e r a c t i o n of P h o t o p e r i o d and G r o w th

Sa lv ia p l a n t s a t t a i n e d p r o g r e s s i v e l y l e s s h e ig h t and l e s s
t o t a l s t e m e l o n g a t i o n a s t he y w e r e s u p p li e d with an i n c r e a s i n g n u m ­
b e r of s h o r t d ay s d u r i n g the 110 d ays of g r ow t h ( F i g u r e 7, T a b l e s 9
and 10).

T h i s w a s in a g r e e m e n t w ith r e s u l t s of M u r n e e k (1948) who

o b s e r v e d a " p h o t o p e r i o d i c i n h i b i t io n " of v e g e t a t i v e g row th of p l a n t s
t h a t f l o w e r e d when s u p p l i e d with a s h o r t p h o t o p e r i o d .

Since s h o r t

d e n s e g r o w t h w a s d e s i r a b l e in the p r o d u c t i o n of a t t r a c t i v e pot p l a n ts
t h i s r e s p o n s e of S a l v i a to s h o r t p h o t o p e r i o d s w as v e r y i m p o r t a n t .
The a p p e a r a n c e of a p i c a l d o m i n a n c e in p l a n t s su pp lie d with
65 o r m o r e l on g d ay s m a y h ave b e e n r e l a t e d to the m o r e r a p i d s t e m
e l o n g a t i o n t h a t o c c u r r e d when the p l a n t s w e r e s u p p l i e d with long day
c o n s i s t i n g of 16- h o u r p h o t o p e r i o d s .

The p l a n t s s u p p li e d with 65 o r

m o r e l on g d a y s w e r e g r o w n u n d e r 16- h o u r p h o t o p e r i o d s f o r 30 or
m o r e d a ys a f t e r the t e r m i n a l p o r t i o n of the m a i n s t e m wa s r e m o v e d .
T h is c o u ld h a v e i n f l u e n c e d t h e l a t e r a l s on t h e s e p l a n t s to d e velop
m o r e r a p i d l y t h a n the l a t e r a l s on th e p la n ts t h a t w e r e su p p li e d with
s h o r t d a y s of 8 - h o u r p h o t o p e r i o d s a f t e r the t e r m i n a l p o r t i o n of the
m a i n s t e m w as r e m o v e d .

C o n s e q u e n t l y , t h e r e cou ld have b e e n a

m o r e r a p i d r a t e of a c c u m u l a t i o n of g r ow t h r e g u l a t i n g s u b s t a n c e in
t h e s t e m s of the p l a n t s g r o w n w ith a 16- h o u r p h o t o p e r i o d .

T his

c o u ld h a v e t e n d e d to in h ib it the e l o n g a t i o n o f the l a t e r a l s e m e r g i n g
f r o m t he l o w e r p o r t i o n s of the m a i n s t e m ; a t h e o r y t h a t is a t l e a s t
p a r t i a l l y s u p p o r t e d by M u r n e e k (1948) who s t a t e d t h a t g r ow t h in he ight
c ould be p h o t o p e r i o d i c a l l y i n h i b i t e d d u r i n g the i n i t i a t i o n of f l o r a l p r i m ordia,

the p e r i o d of full b l o o m ,

and th e p e r i o d of f r u i t and s e e d f o r ­

m ation.

The r e s u l t s of t h i s e x p e r i m e n t s e e m e d to i n d i c a t e t h a t u n d e r

c e r t a i n p h o t o p e r i o d s a g r o w t h in h i b it in g s u b s t a n c e was p r o d u c e d by
the p l a n t and t r a n s l o c a t e d to t h e l o w e r p o r t i o n s of the s t e m s even
b e f o r e f l o r a l i n i t i a t i o n took p l a c e .
F l o w e r s w e r e p r o d u c e d in a ll t r e a t m e n t s i n d e p e n d e n t of the
photoperiods supplied.

T h i s did not a g r e e with the r e s u l t s o b ta in ed

by R o b e r t s and S t r u c k m e y e r (1938) w h e r e S a lv ia p l a n t s w e r e r e p o r t e d
to h av e g r o w n v e g e t a t i v e l y w ith p h o t o p e r i o d s of 16 h o u r s o r l o n g e r .
A s h o r t e r p e r i o d of t i m e (98 days) was d e f i n i t e l y r e q u i r e d fo r f lo w e r
p r o d u c t i o n when the p l a n t s w e r e s u p p li e d with 20 long d ay s followed
by s h o r t d a y s f o r the r e m a i n d e r of t h e i r g ro w th .
s u p p li e d w ith a l l s h o r t d a y s ,
in th e o t h e r t r e a t m e n t s ,
f l o w e r i n g ( T a b le 11).

If the p l a n t s w e r e

o r the n u m b e r of long d ays d e s i g n a t e d

a l o n g e r p e r i o d of t i m e was r e q u i r e d f or

The p l a n t s s up p lie d with 20 long d a y s fo llowed

by s h o r t d ay s p r o d u c e d m o r e r a p i d g ro w th i n i t i a l ly t h a n t h o s e p l a n t s
s u p p l i e d w ith a ll s h o r t d a y s .

Thus,

when the p l a n t s w e r e m o v e d to

the e n v i r o n m e n t of the s h o r t day, the l e a v e s b e c a m e s u f f ic i e n t ly

80.

m a t u r e to s y n t h e s i z e the f l o w e r i n i t i a t i n g s u b s t a n c e a t a n e a r l i e r
date.

T h o s e s u p p l i e d w ith a g r e a t e r n u m b e r of long d ays m a y not

have b e e n a b l e to a c c u m u l a t e s u f f i c i e n t m a t e r i a l to c a u s e i n i t i a t i o n
of f l o w e r s u nt il a g r e a t e r n u m b e r of d a y s had e l a p s e d .

This r e a s o n ­

ing is s u p p o r t e d by H a m n e r (1938) when he c o n c lu d ed th a t p l a n ts
w hic h gave a s h o r t p h o t o p e r i o d i c type of r e s p o n s e a c c u m u l a t e d the
f lo w e r i n i t i a t i n g s u b s t a n c e d u r i n g the d a r k p e r i o d .

D u r in g the lig ht

p e r i o d t h i s a c c u m u l a t e d m a t e r i a l was b e l i e v e d to be b r o k e n down.
T h us , o nc e the l e a v e s w e r e m a t u r e enough to be s e n s i t i v e to the
p h o t o p e r i o d , the f l o w e r i n i t i a t i n g s u b s t a n c e c ould be a c c u m u l a t e d
m o r e r a p i d l y w ith a l i g h t p e r i o d d e c i d e d l y l e s s t h a n the c r i t i c a l .
In o r d e r to p r o d u c e f l o w e r s on a p l a n t with r e l a t i v e l y s h o r t
but u n i f o r m l a t e r a l s in the s h o r t e s t p e r i o d of t i m e ,

one should supply

the p l a n t with 20 days of a 16- h o u r p h o t o p e r i o d followed by s h o r t days
of 8 - h o u r p h o t o p e r i o d s u n t i l the p l a n t is in f l o w e r .

Fortu nately these

c o n d i t io n s c a n b e c l o s e l y a p p r o x i m a t e d in M i c h ig a n f or the p r o d u c t i o n of
a C h r i s t m a s c r o p of S a lv ia by u s i n g the p h o t o p e r i o d s t h a t e x i s t n a t u r ­
a lly in the F a l l of t h e y e a r .

81.

I n t e r a c t i o n of Root T e m p e r a t u r e a nd L ight I n t e n s i t y with
Growth

A c o n s t a n t r e d u c t i o n of lig ht i n t e n s i t y w as not o bt a in e d by
the u s e of c h e e s e c l o t h in t h i s e x p e r i m e n t ( Ta ble 19).

A c c o r d i n g to

A n g s t r o m (1919) th e r e a s o n a c o n s t a n t r e d u c t i o n w as not obta in ed
wa s t h a t the c h e e s e c l o t h cut out only a p o r t i o n of the r a d i a t i o n which
c a m e f r o m the sky, and w as m o s t e f f e c t i v e in r e d u c i n g the r a d i a t i o n
w h ic h c a m e f r o m the sun.

T he p e r c e n t a g e of the t o ta l r a d i a t i o n

w h ic h w a s f r o m the sky i n c r e a s e d with i n c r e a s e d c l o u d i n e s s and thus
the p e r c e n t a g e of r e d u c t i o n of r a d i a t i o n t h a t could be o bt a i n e d with
the u s e of the c h e e s e c l o t h w a s d e c r e a s e d with i n c r e a s e d c l o u d i n e s s .
D e t e r m i n a t i o n of d ate of f l o w e r i n g , of p l a n t he ig h t, of f r e s h
.weight, of d r y w eig h t, a n d of n u t r i e n t a c c u m u l a t i o n m i g h t be u s e d a s
a n in d e x of q u a n t i t y of g r o w th .

The c o n c l u s i o n s which w e r e a r r i v e d

a t in r e g a r d to the i n f l u e n c e of r o o t t e m p e r a t u r e and light i n t e n s i t y
upon the g r o w t h of S a l v i a d e p e n d e d upon which of t h e s e c r i t e r i a w e r e
selected.
U sing th e d a te of f l o w e r i n g a s an index, it was found t ha t
n e i t h e r r o o t t e m p e r a t u r e n o r lig h t i n t e n s i t y had a ny s i g n i f i c a n t i n f l u ­
e n c e a t the 5 p e r c e n t l e v e l ( T a b le 12).
by A l l e n (1934) w ith M a t h i o l a ,

S i m i l a r r e s u l t s w e r e o b ta in e d

C a l e n d u l a , and A n t i r r h i n u m .

In both

the F a l l a n d W i n t e r c r o p s h o w e v e r , the p l a n t s g ro w n with the 7 0 ° F

TABLE

19

T o t a l W ee k ly and A v e r a g e D aily R a d i a t i o n s of L ight D u r i n g Grow th
of W i n t e r C r o p
______ F u l l L i g h t
_________ R e d u c e d L ig h t
P e r Wk. in
Ave/D ay
P e r Wk. in A v e / D a y
F t . Cd. H r s
F t . Cd.
F t.C d.H rs
Ft.C d.
Hr s .
Hr s .

P e r Cent
of F u ll
L ight
Inte nsity

J a n . 11 -17

51, 700

7, 386

43,900

6, 271

84. 9

J a n . 18-24

52,800

7, 543

38,500

5, 500

72. 9

J a n . 25-31

74, 200

10,600

5 3, 3 0 0

7, 614

71. 8

Feb.

1-7

75,200

10, 743

3 9 ,9 0 0

5, 700

53. 1

Feb.

8-14

95,600

13,657

54, 000

7, 714

56. 5

F e b . 15-21

153,700

21, 957

99,100

14,157

64. 5

F e b . 22-28

178,600

25,514

127, 600

18,229

71. 4

M ar.

1-7

159,800

22,829

71, 600

10,229

44. 8

M ar.

8-14

140,900

20, 129

66,300

9, 471

47. 1

A v e r a g e p e r c e n t of full li g h t i n t e n s i t y

63.0

83

r o o t t e m p e r a t u r e a n d 63 p e r c e n t lig ht i n t e n s i t y p r o d u c e d f l o w e r s
a b o u t 4 d a y s b e f o r e t h e p l a n t s in any of the o t h e r t r e a t m e n t s .

Ac­

c o r d i n g to H a m n e r (1938) p l a n t s w h ic h f l o w e r e d when s u p p lie d with
a p h o t o p e r i o d s h o r t e r t h a n th e c r i t i c a l , p r o d u c e d the f lo w e r i n it i a t i n g
s u b s t a n c e d u r i n g the d a r k p e r i o d .

D u r i n g the light p e r i o d a p o r t i o n

of t h i s s u b s t a n c e w a s b e l i e v e d to be d e s t r o y e d o r b r o k e n down, with
the a m o u n t d e s t r o y e d o r b r o k e n down depe nding upon the l e ng th of the
li g h t p e r i o d .

In t h i s e x p e r i m e n t it s e e m e d v e r y p r o b a b l e t ha t the

f l o w e r i n i t i a t i n g s u b s t a n c e w a s not b r o k e n down a s r a p i d l y by p l a n t s
s u p p l i e d w ith a r e d u c e d l ig h t i n t e n s i t y , and t h e r e f o r e a q u an tity of
m a t e r i a l s u f f i c i e n t to s t i m u l a t e f l o w e r i n i t i a t i o n was able to be a c ­
c u m u l a t e d s o o n e r with r e d u c e d l i g h t i n t e n s i t y .

It-was a l s o p o s s i b l e

t h a t the l e a v e s of the p l a n t s g r o w n in r e d u c e d lig h t i n t e n s i t y w e r e able
to f u n c t io n m o r e e f f i c i e n t l y in the p r o d u c t i o n of the f lo w e r i n it i a ti n g
substance.

P o r t e r (1936) w as of the opinion th a t the l e a v e s of t o m a t o

p l a n t s g r o w n in p a r t i a l s h a d e w e r e a b l e to u s e t h e i r l i m i t e d supply of
lig h t m o r e e f f i c i e n t l y .

He e v e n o b s e r v e d a l a r g e v a r i a t i o n in the

a b i l i t y of d i f f e r e n t p l a n t s of the s a m e s p e c i e s to u t i l i z e the a v a i l a b l e
light.
T h i s d i f f e r e n c e in f l o w e r i n g date a s in fl ue n c e d by lig h t i n t e n o
s i t y , did not a p p e a r w hen the p l a n t s w e r e g r o w n with 50 F r o o t t e m p e r -

84.

atur e .

P o s s i b l y t h i s w as b e c a u s e the low r o o t t e m p e r a t u r e was the

lim iting fa c to r.
U sing th e h e i g h t of the p l a n t s a s an index of g ro w th , light
i n t e n s i t y did not h a v e s i g n i f i c a n t in f lu e n c e on g r o w t h ( T able 13).

There

a p p e a r e d to b e a s l i g h t t r e n d t o w a r d a g r e a t e r s t e m e lo n g a ti o n with
red u ced light intensity.

L i g h t i n t e n s i t y did not a p p e a r to h ave a s g r e a t

an i n f l u e n c e on s t e m e l o n g a t i o n a s s e e m e d to be i n d i c a t e d by o b s e r ­
v a t i o n s of Went (1941) and P o r t e r (1936).

Went (1941) c o n c lu d e d th a t i n ­

t e n s i t y of t h e s u n l i g h t w as a n i m p o r t a n t f a c t o r in inhibiting s t e m e l o n ­
g a tio n.

P o r t e r (1936) o b s e r v e d t h a t lig h t i n t e n s i t y was i n v e r s e l y r e l a ­

ted to s t e m e l o n g a t i o n .
S t e m e l o n g a t i o n w ith 7 0 ° F r o o t t e m p e r a t u r e w as r o u g h l y two
to t h r e e t i m e s g r e a t e r t ha n w ith 5 0 ° F r o o t t e m p e r a t u r e ( T a ble 13).
This w as in g e n e r a l a g r e e m e n t with r e s u l t s o b t a i n e d by R o b e r t s (1953)
who u s e d the s a m e e q u i p m e n t to s tu dy the inf lu e nc e of f o u r r o o t t e r n p e r a t u r e s f r o m 56

o

o

to 72 F on the g r ow t h of s t r a w b e r r y .

Roberts ob­

s e r v e d 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 g r ow t h of a e r i a l p a r t s of the
s t r a w b e r r y and an i n c r e a s e in r o o t t e m p e r a t u r e .
The p l a n t h e i g h t p r o d u c e d in the F a l l c r o p was c o n s i s t e n t l y
g r e a t e r t h a n the p l a n t h e i g h t p r o d u c e d in c o r r e s p o n d i n g t r e a t m e n t s of
the W i n t e r c r o p ,

A p h o t o p e r i o d i c in h i b it i on of v e g e t a t i v e g ro w th was

o b s e r v e d a n d s i n c e the n a t u r a l l y o c c u r i n g p h o t o p e r i o d was not m o d i ­
f ie d, it i s m o s t p r o b a b l e t h a t the v a r i a t i o n in the p h o t o p e r i o d b et w e en
t he F a l l a nd the W i n t e r c r o p s w a s the f a c t o r involved in the c o n s i s t e n t
d i f f e r e n c e s in s t e m e l o n g a t i o n .

By r e f e r e n c e to T ab le 14, it m a y be

o b s e r v e d t h a t d u r i n g the g r o w t h of the F a l l c r o p the le ng th of the
p h o t o p e r i o d w as d e c r e a s i n g f r o m 13 h o u r s and 30 m i n u t e s to 10 h o u r s
a n d 10 m i n u t e s ; and d u r i n g the g r o w t h of the w i n t e r c r o p the len g th of
the p h o t o p e r i o d was i n c r e a s i n g f r o m 10 h o u r s and 20 m i n u t e s to 12 h o u r s
and 10 m i n u t e s .
C o n s i d e r i n g f r e s h w e ig ht a s an i ndex of gro w th, t h e r e was a
d ef i n it e a nd c o n s i s t e n t t r e n d in b oth c r o p s t o w a r d an i n c r e a s e in
g r o w t h of b o t h r o o t s an d s t e m s with the h i g h e r r o o t t e m p e r a t u r e and
l ight i n t e n s i t y .

The d i f f e r e n c e s in f r e s h we ight of r o o t s and s t e m s a s

a r e s u l t of d i f f e r e n t l i g h t i n t e n s i t i e s ,

w e r e in m o s t i n s t a n c e s not s t a t i s ­

t i c a l l y s i g n i f i c a n t a t the 5 p e r c e n t l e v e l .

T h e r e w a s, h o w e v e r , a c o n ­

s i s t e n t t r e n d t o w a r d a n i n c r e a s e in we ight with full li gh t i n t e n s i t y
(T able 15).

T h i s p r o d u c t i o n of g r e a t e r f r e s h weight with full light i n ­

t e n s i t y w as in a g r e e m e n t with r e s u l t s o b t a i n e d by A r t h u r and S t e w a r t
(1931).

T h e y found t h a t the f r e s h a nd d r y weight of s t e m s and r o o t s of

S a lv ia i n c r e a s e d a s s u n li g h t w a s i n c r e a s e d f r o m 35 to 58 to 78 to 100
p e r c e n t r a d i a t i o n in J u n e and J u l y .

T h e i r r e s u l t s i n d i c a t e d t h a t Salvia

wa s a b le to u t i l i z e f ull r a d i a t i o n in J u n e and J u l y m o r e e ff ic i e nt ly t h a n

o t h e r p l a n t s u s e d in the t e s t s .
The i n c r e a s e s in f r e s h w eig ht of s t e m s and r o o t s a s a r e s u l t
of a n i n c r e a s e in r o o t t e m p e r a t u r e in the p r e s e n t i n v e s t i g a t i o n w e r e
c o n s i s t e n t and h i g h l y s i g n i f i c a n t ( T a ble 15).

T h is i n d i c a t e d t h a t the

g r o w t h of S a l v i a a s m e a s u r e d by a c c u m u l a t i o n of f r e s h weight was
g r e a t l y i n h i b i t e d by a lo w r o o t t e m p e r a t u r e of 5 0 ° F .
As w ith f r e s h weight, t h e r e was a d efin ite and c o n s i s t e n t
t r e n d t o w a r d a g r e a t e r d r y w eight a c c u m u l a t i o n in b oth s t e m s and
r o o t s w ith the h i g h e r r o o t t e m p e r a t u r e and li gh t i n t e n s i t y (T able 16).
T h i s w as in a g r e e m e n t w ith the r e s u l t s o b ta in e d by A r t h u r and S t e w a r t
(1931).

T h e t r e n d t o w a r d an i n c r e a s e in d r y weight of s t e m s and r o o t s

with full l i g h t i n t e n s i t y e x i s t e d i n d e p e n d e n t of r o o t t e m p e r a t u r e .

The

o
a m o u n t of i n c r e a s e w a s s i g n i f i c a n t with 70 F r o o t t e m p e r a t u r e , but
o
not with 50 F r o o t t e m p e r a t u r e .
Root t e m p e r a t u r e did not i n flu en c e the d r y weight of s t e m s
and r o o t s a s m u c h a s f r e s h w eight, h o w e v e r the i n c r e a s e s in d r y
o
,
weight p r o d u c t i o n with 70 F r o o t t e m p e r a t u r e w e r e s i g n if ic a n t e xc ep t
fo r r o o t s p r o d u c e d w i th r e d u c e d l i g h t i n t e n s i t y .

T his was r e a s o n a b l e

s i n c e B o l a s (1934) found t h a t with a h i g h e r t e m p e r a t u r e a h i g h e r light
i n t e n s i t y w as o p t i m u m f o r d r y we ight a c c u m u l a t i o n .
The t o p - r o o t r a t i o c a l c u l a t e d on a f r e s h w e ig h t b a s i s was
l a r g e r in a l l i n s t a n c e s with 70° t h a n with 50 F r o o t t e m p e r a t u r e ,

87.

a n d w as l a r g e r with r e d u c e d t h a n with full lig ht i n t e n s i t y .

Seventy

d e g r e e s r o o t t e m p e r a t u r e with r e d u c e d lig h t i n t e n s i t y p r o d u c e d the
l a r g e s t t o p - r o o t r a t i o , th u s it c ould be c o n c lu d e d th a t 7 0 ° F r o o t
t e m p e r a t u r e and 63 p e r c e n t t o t a l light i n t e n s i t y w e r e m o r e f a v o r ­
able to top t h a n to r o o t g r o w t h (T able 17).

R o b e r t s (1953) o bta ined

s i m i l a r r e s u l t s w ith the s t r a w b e r r y .
Reduced light intensity favored a general higher a c c u m u ­
l a t i o n of n u t r i e n t s in s t e m s and r o o t s .

T h i s e x p la in e d the g e n e r a l

h i g h e r a c c u m u l a t i o n of n u t r i e n t s in the W i n t e r t ha n in the F a l l c r o p
( F i g u r e 12),

s i n c e s o m e w h a t h i g h e r ligh t i n t e n s i t i e s w e r e r e c e i v e d

d u r i n g the F a l l t h a n d u r i n g the W inte r m o n t h s .
With the e x c e p t i o n of the a c c u m u l a t i o n of p h o s p h o r u s in the
t o p s and of p o t a s s i u m in t h e r o o t s ,
higher accum ulation

of n i t r o g e n ,

it was found t h a t t h e r e wa s a
phosphorus,

and p o t a s s i u m in

p l a n t s s u p p l i e d with r e d u c e d li g h t i n t e n s i t y ( F i g u r e 14).

T h e r e is

m u c h d i s a g r e e m e n t in the l i t e r a t u r e in r e l a t i o n to the influe nce of
light i n t e n s i t y upon the a c c u m u l a t i o n of n u t r i e n t s in p l a n t s .

One

f a c t o r whic h w a s in v o l v e d in t h i s co nf u s i o n was the a b s e n c e of a c c u r ­
a te r e c o r d s of l i g h t i n t e n s i t i e s in m o s t d a t a .
r e c o r d s w ere offered,
r e s u l t s obtained.

In m a n y r e p o r t s no

and it w as e v e n m o r e diff icult to c o m p a r e the

In sp it e of t h i s ,

it a p p e a r e d t h a t the in flu e nc e of

l i g h t i n t e n s i t y upon n u t r i e n t a c c u m u l a t i o n v a r i e d with s p e c i e s ,

as

88 .

h a s b e e n d i s c u s s e d p r e v i o u s l y ( pa g e s 14 to 17).
At t h e 7 0 ° F r o o t t e m p e r a t u r e ,

n i t r o g e n , p h o s p h o r u s and

p o t a s s i u m t e n d e d to a c c u m u l a t e m o r e in the tops and l e s s in the r o o t s
o
t h a n a t the 50 F r o o t t e m p e r a t u r e ( F i g u r e 15).

H a ge n (1952) c o n ­

t r a r y to p r e v i o u s t h e o r i e s of H o a g la n d (1923), and A s hb y and Oxley
(1935) f e l t t h a t t h e r e w as not s u f f i c i e n t e v i d e n c e a v a i l a b l e to p r o v e
t h a t a r e d u c e d r a t e of n u t r i e n t a b s o r p t i o n was r e s p o n s i b l e f o r slow
g r o w t h of p l a n t s a t lo w r o o t t e m p e r a t u r e .

He f e l t t h a t e i t h e r or

b o t h a r e d u c e d r a t e of t r a n s l o c a t i o n o r a s s i m u l a t i o n could a l s o e a s i l y
be in v o lv e d .

The r e s u l t s of t h i s e x p e r i m e n t s e e m e d to s u p p o r t

H agen's ideas.

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

n u t r i e n t s in the t o p s and l o w e r a c c u m u l a t i o n in the r o o t s with a
o
70 F r o o t t e m p e r a t u r e c o u ld e a s i l y h av e b e e n a s s o c i a t e d with a m o r e
r a p i d r a t e of t r a n s l o c a t i o n a t the h i g h e r r o o t t e m p e r a t u r e .
A c c o r d i n g to e a c h of the m e t h o d s of d e t e r m i n i n g p l a n t g r o w t h
t h a t h av e b e e n d i s c u s s e d , t h e 7 0 ° F
f a v o r the g r o w t h of S a l v i a .
a b u n d a n t top g r o w t h ,

r o o t t e m p e r a t u r e w as found to

F o r the p r o d u c t i o n

of e a r l i e r f l o w e r i n g ,

and h i g h e r n u t r i e n t a c c u m u l a t i o n ,

l i g h t i n t e n s i t y w as found to,

in g e n e r a l ,

give b e t t e r r e s u l t s ; while

f o r g r e a t e r f r e s h and d r y w e i g h t a c c u m u l a t i o n ,
sity p ro d u c e d b e t t e r r e s u l t s .

a reduced

the full lig h t i n t e n ­

89

SUMMARY

T he i n t e r a c t i o n of e n v i r o n m e n t a l f a c t o r s up on the g r o w t h
of S a l v i a s p l e n d e n s

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

g r o w t h of S a l v i a a nd the p o s s i b i l i t i e s of it s i n t r o d u c t i o n to the f l o r i s t
pot p l a n t i n d u s t r y .
com pared.

F o r t h i s p u r p o s e the g r o w t h of 10 c u l t i v a r s was

T he i n f l u e n c e of c old t r e a t m e n t ,

’' p i n c h i n g " , p h o t o p e r i ’od, r o o t t e m p e r a t u r e ,
studied.

night t e m p e r a t u r e ,
and l i g h t i n t e n s i t y was

I n f o r m a t i o n was g a t h e r e d c o n c e r n i n g the t i m i n g of a c r o p

of S a l v i a f o r the C h r i s t m a s m a r k e t ,

and the k e e p i n g q u a lity of the

p l a n t s at r o o m t e m p e r a t u r e .
F o r t he p r o d u c t i o n of s h o r t ,

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

t he d w a r f t y p e p r o v e d m o s t s u i t a b l e , a nd f o r the p r o d u c t i o n of a
s l i g h t l y m o r e v i g o r o u s p l a n t , the c u l t i v a r s of the s e m i - d w a r f type
w ere recom m ended.

T he c u l t i v a r , A m e r i c a ,

w as s e l e c t e d f o r

u s e in a l l o t h e r e x p e r i m e n t s .
The 4 0 ° F c o n s t a n t t e m p e r a t u r e cold t r e a t m e n t f or one week
a p p e a r e d to r e t a r d g r o w t h m o r e when it was s u p p l i e d a t t h e t w o t h a n a t th e f o u r - n o d e s t a g e of g r o w t h ,

At e i t h e r s t a g e , the in f lu e n c e

of t h e r e l a t i v e l y s h o r t p e r i o d of c old t r e a t m e n t was not e x t r e m e l y
large.
The study of n i g h t t e m p e r a t u r e i n f l u e n c e s i n d i c a t e d t h a t

•

S a l v i a g r e w m o r e v i g o r o u s l y a nd f l o w e r e d s o o n e r with 6 0 ° F tha n
with 5 0 ° F n ig h t t e m p e r a t u r e .
p l a n t s w e r e young.

T h i s was p a r t i c u l a r l y t r u e while the

Some a d d i t i o n a l s t e m e lo n g a ti o n was o b ta in e d

by m o v i n g the p l a n t s f r o m 60° to 5 0 ° F n i g h t t e m p e r a t u r e 90 days
a fte r seeding.

S t e m w eight was not g r e a t l y i n f l u e n c e d by night

t e m p e r a t u r e a nd f l o w e r c o l o r w as not a f f e c t e d .
The

r e m o v a l of the t e r m i n a l m e r i s t e m (a " p in c h " ) r e s u l t e d

in p l a n t s w ith s h o r t ,
larger,

dense growth.

P l a n t s ’’pinched'* t w i c e w e r e

a n d t oo k 10 d a y s l o n g e r to f l o w e r t h a n t h o s e ’’p i n c h e d " o nc e.

When p l a n t s w e r e "pinched** t h r e e t i m e s the f l o w e r s which w e r e
p r o d u c e d w e r e a p p r o x i m a t e l y 50 p e r c e n t s m a l l e r in s i z e .

It wa s

r e c o m m e n d e d t h a t p l a n t s be g r o w n with one " p i n c h " e x c e p t f or s p e c i a l
p u r p o s e s w h e r e a l a r g e r p l a n t would be p r o f i t a b l e and t h e n two
" p i n c h e s " c ould be supplied*
When s e e d w a s p l a n t e d S e p t e m b e r 1st, 98 d a y s w e r e r e ­
q u i r e d f o r p r o d u c t i o n of f l o w e r i n g pot p l a n t s with one " p i n c h " .

A

s c h e d u l e f o r the p r o d u c t i o n of a C h r i s t m a s c r o p w a s s u g g e s t e d .
Some f l o r e t s w e r e

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

b e e n in the h o m e s f r o m 1 to 3 d a y s with m a n y f a l l i n g a f t e r a n a v e r ­
age of 4 d a y s in t h e h o m e .

S e v e r a l m e t h o d s of p r e v e n t i n g the f l o r e t

a b s c i s s i o n w e r e a t t e m p t e d , but no e f f e c t i v e m e t h o d w as found.

It

91.

w a s s u g g e s t e d t h a t f u r t h e r w o r k with g r o w t h r e g u l a t i n g s u b s t a n c e s
might prove su c c e ssfu l.
F l o w e r s w e r e p r o d u c e d u n d e r b o t h 8- and 1 6 -hour photo periods.

A p h o t o p e r i o d i c i n h i b i t i o n of v e g e t a t i v e g r ow t h w as o b s e r ­

ved whe n the p l a n t s w e r e g r o w n with 8 - h o u r p h o t o p e r i o d s , a nd the
a m o u n t of i n h i b i t i o n i n c r e a s e d with g r o u p s of p l a n t s t h a t w e r e s u p ­
p l i e d w i th a g r e a t e r n u m b e r of s h o r t d a y s .

A l o s s of a p i c a l d o m i n ­

a n c e w a s a l s o n o t e d in t h o s e p l a n t s s u p p l i e d with 60 o r m o r e 8 - h o u r
photoperiods.

In o r d e r to p r o d u c e a f l o w e r i n g S al v ia p l a n t with r e l a ­

t i v e l y s h o r t l a t e r a l s of a p p r o x i m a t e l y the s a m e le n g t h ,

in the s h o r t e s t

p e r i o d of t i m e it w a s r e c o m m e n d e d t h a t the p l a n t s be s u p p li e d with
20 l ong d a y s of 1 6 - h o u r p h o t o p e r i o d s f ollow ed by s h o r t d ays c o n s i s t ­
ing of 8 - h o u r p h o t o p e r i o d s u ntil t h e p l a n t s w e r e in f l o w e r .

In t h is

e x p e r i m e n t th e r e q u i r e d t i m e w a s 98 d a y s f r o m the date of s e e d i n g .
It w as m e n t i o n e d t h a t t h e s e c o n d i t i o n s c ou ld be a p p r o x i m a t e d for the
p r o d u c t i o n of a C h r i s t m a s c r o p in M i c h i g a n by s up ply in g the p l a n t s
w ith t h e n a t u r a l p h o t o p e r i o d .

P h o t o p e r i o d had no o b s e r v e d in f lu e n c e

on the p l a n t s a f t e r t h e y w e r e in f l o w e r .
P l a n t s c o n s i s t e n t l y p r o d u c e d g r e a t e r h e i g h t in a l l t r e a t ­
m e n t s w he n t he y w e r e g r o w n in the F a l l with 7 0 ° F and 5 0 ° F r o o t
t e m p e r a t u r e with 100 p e r c e n t a nd 63 p e r c e n t l ig h t i n t e n s i t y , t h a n

92.

w h e n t h e y w e r e g r o w n u n d e r t h e s a m e c o n d i t i o n s d u r i n g the W in te r
m onth s.

T h i s w a s t h o u g h t to be c a u s e d by a s h o r t e r p h o t o p e r i o d

d u r i n g the g r o w t h of t h e W i n t e r c r o p .
S t e m e l o n g a t i o n was s l i g h t l y g r e a t e r when the p l a n t s w e r e
g r o w n with r e d u c e d ,

t h a n when t h e y w e r e g ro w n with full l i g h t i n ­

tensity .
A m o r p h o l o g i c a l study of t h e f l o w e r bud w as m a d e ,

in

whic h f iv e s t a g e s in f l o w e r bud d e v e l o p m e n t w e r e a r b i t r a r i l y d i s t i n ­
guished .
T he p l a n t s g r o w n with the 7 0 ° F r o o t t e m p e r a t u r e p r o d u c e d
a p p r o x i m a t e l y t w i c e a s m u c h s t e m e lo n g a t i o n as the p l a n t s g r o w n
w ith t h e 5 0 ° F r o o t t e m p e r a t u r e , but the plants- in all of the t r e a t m e n t s
f l o w e r e d o v e r a p e r i o d of only 7 d a y s .
T he l a r g e s t t o p - r o o t r a t i o w a s o b t a i n e d f r o m p l a n t s g r o w n
with r e d u c e d l i g h t i n t e n s i t y a nd 7 0 ° F r o o t t e m p e r a t u r e .
A c c o r d i n g to e a c h of t he m e t h o d s of d e t e r m i n i n g p l a n t g ro wth ,
the 7 0 ° F r o o t t e m p e r a t u r e w a s found to f a v o r the g r o w t h of S a lv ia
m o r e t h a n the 5 0 ° F r o o t t e m p e r a t u r e .
favored flowering,

s t e m elongation,

than full light in te n sity .

The r e d u c e d li g h t i n t e n s i t y

and n u t r i e n t a c c u m u l a t i o n m o r e

F u ll light in tensity , ho w ev er,

r e s u l t e d in

g r e a t e r a c c u m u l a t i o n of f r e s h a nd d r y weight.
F i f t e e n f i g u r e s and n i n e t e e n t a b l e s w e r e included,,

93

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