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MECHANICAL INJURY TO PEA BEAN SEED
TREATED AT THREE MOISTURE LEVELS

By

Celio Barriga Solorio

A THESIS

Submitted to the College of Agriculture of Michigan
State University of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of

MASTER QF SCIENCE

Department of Farm Crops

1959

ACKNOWLEDGMENT

The author wishes to express his sincere
appreciation to Dr. A. L. Andersen for suggesting the
problem, and to Dr. S. T. Dexter and Dr. M. W. Adams
for their guidance in the course of this investigation
and preparation of the manuscript.

The author is grateful for the financial

assistance of the Rockefeller Foundation.

ii

MECHANICAL INJURY TO PEA BEAN SEED
TREATED AT THREE MOISTURE LEVELS

By

Celio Barriga Solorio

AN ABSTRACT

Submitted to the College of Agriculture of Michigan
State University of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Farm Crops

1959

APProved \EZZZZTO I:Z;Z/ Ii;é;Z;;?fi§QZLI

 

ABSTRACT

Seeds of 41 strains of white pea beans at 3
moisture contents were mechanically beaten in a motor-
driven rotor. Simple examination determined visible
injury, whereas invisible or internal injury was deter-
mined by germination in sand.

The analysis of the data relating to normal
and abnormal seedlings (invisible injury) indicated
highly significant differences between strains and be-
tween moisture levels. Both visible and internal damage
were greater in beans at low than at higher moisture
contents. The number and the vigor of normal seedlings
decreased as the moisture content of the seed decreased.

When seed that was not beaten was planted,
initial moisture contents (from 9 to 15.7%) made no dif-
ference in vigor or extent of germination.

Loss of one cotyledon and loss of the plumule
("baldheads") were the two commonest abnormalities in

the injured seedlings, but many other types were observed.

iv

TABLE OF

INTRODUCTION. . . . . . . .
REVIEW OF LITERATURE. . . .
MATERIALS AND METHODS . . .
RESULTS . . . . . . . . . .
DISCUSSION. . . . . . . . .
SUMMARY . . . . . . . . . .
LITERATURE CITED. . . . . .

CONTENTS

Page

0 O O O O O O O O O O O 18

LIST OF TABLES

Table Page

1 Visible injury in 41 strains of bean seed, per
cent of germination and the average weight per
seedling. 0 O O O O O I O O O O O O O O O O O O 18

1A Average per cent of seed with visible injury. . 27

2 Analysis of variance of the number of normal
seedlings in pea beans. . . . . . . . . . . . . 36
3 Average number of normal seedlings. . . . . . . 37
4 Analysis of variance of the number of seedlings
that had lost one cotyledon . . . . . . . . . . 39
5 Average number of seedlings that had lost one
cotyledon O O O O O O O O O O O O O O O O O O 0 4O
6 Analysis of variance of the number of "bald-
head" Seedlings O O O O O O O 0 O O O O O O O O 42
7 Average number of "baldhead" seedlings. . . . . 43
8 Analysis of variance of the number of normal

seedlings in the second experiment. . . . . . . 48

9 Average number of normal seedlings in the second
experiment. . . . . . . . . . . . . . . . . . . 49

vi

Figure

10
ll
12
13

14

15

16

LIST OF FIGURES

Container showing the way in which different

relative humidities were obtained. . .

Showing the way in which the seed was arranged

in the containers. . . . . . . . . . .

Showing a small machine used for beating the

seed 0 O O O O O O O O O O O O O O O 0
Showing abnormal seedlings . . . . . .

Showing abnormal seedlings . . . . . .

Seedlings that had lost the hypocotyl and the

primary roots. . . . . . . . . . . . .

Showing the effect of the loss of one cotyledon

Vigor of normal seedlings. . . . . . .
Vigor of normal seedlings. . . . . . .
Vigor of normal seedlings. . . . . . .
Vigor of normal seedlings. . . . . . .
Vigor of normal seedlings. . . . . . .

Showing the effect on the seedlings of
mechanical injury to the seed. . . . .

Showing the effect on the seedlings of
mechanical injury to the seed. . . . .

Showing the effect on the seedlings of
mechanical injury to the seed. . . . .

Showing the effect on the seedlings of
mechanical injury to the seed. . . . .

vii

Page

12

14

15
29
29

31
32
33
33

34
34

46

46

47

47

INTRODUCTION

Pea beans are a particularly important agricul-
tural crop in the central and east central portions of the
lower Peninsula of Michigan. According to Agricultural
Statistics Michigan produced in 1955 and 1956, respect-
ively, 4.5 and 5.3 million 100 pound bags of pea beans.

The value of the 1956 crop amounted to ,33.4 million dol-
lars. Michigan is the leading producer of white pea beans
for commercial canning.

Mechanical damage during harvest or subsequent
handling is an important problem with this crop. Split
seeds or seeds with broken or loosened seed coats are un-
acceptable to the canners. Roughly treated seed beans
often produce "baldhead" or other abnormal seedlings in
which loss of cotyledons, terminal bud or primary leaves
leads to unsatisfactory growth. These are general problems
in the pea bean industry, whether in California, Colorado,
Idaho, Michigan or New York. In Michigan, some years have
been marked by extended periods of relatively low humidity
during harvest which often leads to a considerable percent-
age of seed injured by mechanical harvesting.

The main object of this experiment was to find

out whether any differences exist among strains of pea
beans in susceptibility to damage when the seeds were
subjected to mechanical beating at various levels of
seed moisture.

In addition, the experiment was designed to
provide some information about the level of moisture
at which the seeds being beaten suffer considerable
damage, and the relationship between visible and in—
ternal damage and reduction in germination or seedling

vigor.

REVIEW OF LITERATURE

/ Damage incurred by bean seed either in thresh—
ing or during the cleaning processes or by both operations,
are classified in the literature as visible or as internal
injury, the latter not being detectable until germination.

At the turn of the century, practically all the
bean seed was grown in the eastern states, but seedborne
blights and anthracnose, which are easily spread under
humid conditions, forced the seed industry to move to the
semi-arid regions of the west. After the move west, seed
germination problems became more serious. This was prob-
ably due to effects related to lower humidity at harvest
time, new varieties, and increased mechanization.

The percentage of visible and internal injury
of seed is a function of the variety used, the level of
maturity or moisture of the seed at harvest time and the
violence of the mechanical handling.

Mechanical harvesting operations. Harter (7)
reported "baldhead" in 0-30 per cent of dry beans seedlings
and in 10-20 per cent of snap bean seedlings. Whitney (16)

reported in the summer of 1929 that an alarming deficiency

in stand of certain lots of California-grown lima beans

was experienced by certain growers in the East. (Borth-
wick (4) studied various types of mechanical injuries in
baby lima beans in California and found that "baldhead"
occurain.a range of 2 to 10 per cent. On the basis of
examination of 105 samples of bean seed offered for sale
in Maine seed stores, Steinbauer (14) concluded that the
frequency of ”baldhead" varied from 1 to 25 per cent. In-
galls (8) survey of commercial bean samples showed "bald-
heads” varying in a range of 0-17 per cent. Associated
Seed Growers, Inc., (1) found that the percentage of seed
broken by mechanical means varied from 1 to 30 per cent
for the variety Tendergreen.

Harter (7) was the first to study the cause of
”baldhead" or "snakehead" in common field beans Engsgglgg
Vglgaris.UJ-In the."baldhead" seedlings the plumule may be
entirely absent or only vestiges of it might remain. The
plumule may at times appear to remain attached to the
epicotyl although it is fractured just beneath the primary
leaves, thus rendering normal development impossible. He
reported that the per cent of loss from ”baldhead" plants
varies according to the variety, the method of handling
the crop, and the season. He concluded that "baldhead"
results from three distinct causes: one cause, which is

by far the most common, is mechanical injury, the second

is bacteria and the third insects.

Zaumeyer and Thomas (17) defined "snakehead"
as an injury of germinating bean seed,which is caused
by the seed corn maggot Hylemya cillicrura (Bond). This
insect causes serious damagex to beans throughout the
United States; it is a pest of beans particularly in the
East, from Virginia northward and in Michigan. The symp-
toms of "snakehead" differ from those of "baldhead" in
that the plumule and other affected parts are made ragged
by the chewing insects, whereas with "baldhead" the frac-
ture or injury is clean out. In the case of "baldhead"
caused by bacteria Harter (7) pointed out that the entire
plumule might be more or less completely lost or that the
primary leaves might be badly mutilated, the terminal bud
often being destroyed by the organism. ”Baldhead” plants
yield less than normal plants (5, 11, 14, 15). They ma-
ture later (5, 6, 8, 12, 15) and they are smaller than
normal plants (8, 12).

According to Associated Seed Growers, Inc., (1)
and Harter (7) "baldhead" plants usually develop axillary
shoots between the joints of the cotyledons and hypocotyl.

Barter (7) found that the epicotyl is fractured
just below the plumule by the threshing machine and that
the average diameter of the epicotyl in the embryonic

stage is less in snap beans susceptible to "baldhead"
than in more resistant field beans. .

Atkin (2) found that seed coats of resistant
varieties generally adhere much more tightly to the coty-
ledons than do those of susceptible varieties and that
the cotyledons of some varieties fit much more closely
together than do those of others. Tight seed coats and
close fitting cotyledons could prevent or reduce movement
of the cotyledons and thus protect the embryo from damage.

Borthwick (4) reported that the damage found
in baby lima bean seedlings from machine threshed seed
indicates that practically every part of the embryo is
susceptible to some kind of threshing injuryf’ Types of
injury in seedlings of the lima beans are described (3, 4)
in the following way:

Injuries toghypocotyl and radicle. Complete
loss of the radicle is of comparatively frequent occur-
rence. In these cases the lower end of the hypocotyl
calluses over and gives rise to adventitious roots. As
a result, insuffiCient hypocotyl remains to raise the
cotyledons above ground in the manner characteristic of
these beans. The cotyledons themselves remain below ground,
and the epicotyl only elongates. More commonly fracture

of the hypocotyl or root does not extend completely across

it.

Injury to the cotyledons. One cotyledon may
be broken at its point of attachment to the stem, the
other functioning normally; or both cotyledons may be
absent although the plumule is uninjured. In many cases
the cotyledon is not broken completely from the plant,
but remains attached by small strands of tissue. Callus
tissue develops at the broken surfaces, and not infre- I
quently adventitious roots arise from this callused area
of the cotyledon. When on a seedling a cotyledon is found‘
with a crack crossing it transversely, although the outer
end is still attached, the food reserve in the loosely
attached part has not been used as has that of the lower
part of the cotyledon.

McCollum (10) reported that hand picked and
hand shelled snap beans showed marked varietal differen-
ces in susceptibility to cotyledonal cracking during ger-
mination. A high incidence of cracking was found in strains
B 1762, B 1229-1-2-6, Rival and Top-crop. No cracking
was observed in the variety Cherokee except where the
testae were broken. In the most susceptible strain tested,
B 1762, the maximum cotyledonal breakage occurred after
storage at a relative humidity of 15 per cent, and a mini-
mum breakage at 56 per cent. The injury to the hypocotyl,
the radicle and the cotyledons often retarded the growth

of the seedlings (l, 3, 4).

McAlister and Orland (9) reported that during
germination and early development of Earlyana and Lincoln
soybeans 1/3 of the phosphorus, 2/3 of the potassium,

l/2 of the ether extractable substances, 1/3 of the pro—
tein and nearly all of the sugars had been transferred

to the seedling. Very little of the magnesium and none
of the calcium left the cotyledons. Removal of the coty-
ledons from the seedlings of either of the varieties at
emergence or 2 dayslater resulted in a decreased plant
size throughout the growing season.

Handenburg and Etc (6) artificially produced
"baldhead" bean plants under controlled conditions both
in the greenhouse and in the field, using California-grown
red kidney seed. The amputation treatment took place
6 days and 11 days respectively after planting in the
greenhouse and in the field. They found that of the various
types of abnormalities only that one which involved the
loss of both primary leaves was sufficient to cause a sig-
nificant reduction in yield. Loss of the terminal bud
did not affect yield. The primary leaves were specially
important in the early growth of the plant as they enhanced
development of the root system, drew nutrients from the

cotyledons and stimulated growth of the terminal bud.

Loss of one primary leaf was unimportant because appar-
ently the loss had a compensating action tending to ac-
celerate the growth of the remaining vegetative tissue.

Atkin (2) found that varieties differ signifi-
cantly in their susceptibility to injury. The resistance
to injury of the white seeded variety Streamliner in comp
parison with white seeded Tendergreen that is susceptible
indicates that desirable white seeded varieties resistant
to seed injury can probably be developed by plant breed-
ing.

Bainer and Borthwick (3) worked with bean seed
at 5.8, 9.6, 14.1 and 15.9 per cent of moisture and they
found that beans of low moisture were damaged to a greater
extent by a threshing machine. The cylinder speeds re-
quired to produce 15 per cent of total damage in Fordhook
beans containing 15.9, 17.3 and 18.8 per cent of moisture
were 1,150, 1,330 and 1,600 feet per minute respectively.
Beans of 10.6 per cent moisture content, rolled down a
45° slide, showed a total damage of approximately 4.5,
8.6 and 15.3 per cent respectively for slide distances
of 6.4, 10.5 and 15 feet.

. Associated Seed Growers, Inc., (1) reported
that seed of 8, 10 and 12 per cent moisture were dropped

several times from different heights. The results showed

10

that mechanical damage to bean seed is cumulative; many
low drops may cause as much loss in germination as one
or two high drops. They found also that moisture content
of the seed is related to susceptibility to injury; the
lower the seed moisture content, the greater the damage.
#flPerry (13) reported in the variety Michelite

that the damage, splits and checked seed coats, was about
proportional to height of the drop up to 45 feet and the
damage was reduced considerably at higher temperatures
and higher moisture contents.

According to the data cited above moisture con-
tent and perhaps temperature are of fundamental importance

in the threshing of seed beans.

MATERIALS AND METHODS

Forty one strains of white pea beans were used'
in this study. They were grown at Saginaw, Michigan,
and were harvested in September, 1958. See Table No. 1 .
The plants were hand threshed. The seed was passed over
a round hole 16/64 screen on the top and 12 3/4/64 screen
on the bottom to obtain seed of uniform size. 'From each
one of the strains 450 grams (2100-1100 seeds), of seed
lwere selected. In order to obtain three levels of moisture
in the seed samples, subsamples were stored in three 20-
gallon-capacity sheet iron cans containing saturated solu-
tions of sodium chloride, sodium bromide and calcium chloride,
to give relative humidities, at equilibrium, of approxi-
mately 75%, 58% and 32% respectively at room temperatures.
These solutions were placed in the bottoms of the containers.
A small motor was attached to the outside of the cover of
each can, with a small connected fan inside to stir the
air. A rod, vertically placed in each container, was used
to agitate the saturated solutions from time to time. See
Figure l.

The seed samples were placed in perforated plas-

tic cups. The cups were arranged at five different levels

11

12

 

 

Figure 1. Container showing the way in which different
relative humidities were obtained.

13

as shown in Figure 2. In this way the seed was kept in
the cans for 36 days.

Immediately after removing the cups from the
cans, five samples from every level of the seed were drawn
in order to determine the moisture content.

Seed samples were dried in an electric oven
at 100° C. for 60 hours. After this period they had reached
approximately constant weight. Water content was calcu—
lated from loss of weight in the oven. Another portion
of each seed sample was mechanically beaten with a small
machine in which the beans dropped into a motor-driven
plastic paddle-wheel, rotating at 977 r.p.m. See Figure 3.
Visible injury was detected in the following way: (a)
Counting the number of seeds with no visible injury; (b)
counting the number of seeds with visible injury; and (c)
counting the number of seeds split or broken.

Internal injury was detected by a germination
test as follows: The seed, after having been mechanically
beaten, was kept in open bags for 40 days at room tempera—
ture. This allowed all samples, including the check lots
(not beaten) to reach essentially the same moisture con-
tent before planting. From every strain, at each succes-
sive level of moisture, 150 seeds with no visible injury

were selected.

14

 

 

 

Figure 2. Showing the way in which the seed was arranged
in the containers.

l5

 

Figure 3. Showing a small machine used for beating the
seed.

16

These seeds were then planted in flats filled
with steamed sand. There were four treatments, the check
(unbeaten), the high, the medium and the low moisture
beans without visible injury. Two rows of each, with
25 seeds per row, were planted in each flat. Fifty seeds
were considered a replicate. Three replications in a
split plot design were used.

Twelve days after planting, the numbenaof the
following types of abnormal bean seedlings were recorded.
(a) Normal seedlings with two cotyledons, two primary
leaves, terminal bud present and no deformation of the
hypocotyl; (b) seedlings that had lost one cotyledon;

(c) "baldhead" seedlings which had lost both the terminal
bud and the primary leaves; (d) seedlings that had lost
both cotyledons; (e) seedlings that had lost one primary
leaf; (f) seedlings that had lost both primary leaves,
but not the terminal bud.

In March, 1959, after examining the results
of the first experiment, ten strains were selected and
a second test performed.

Levels and determination of moisture were ob-
tained in the same way as in the first study.

From each strain 100 grams of the sample were

mechanically beaten and the rest of the sample was not.

17

From every level of moisture, both the seed mechanically
beaten and the unbeaten check lots were planted at once,
at the moisture contents that the seed had reached in
each conditioning can. A check, at equilibrium with room
moisture conditions, was used in addition.

The seed was planted as in the first experiment,
using the same design. However, the number of seeds (with-
out visible injury), used per strain was 75, so 25 seeds
were planted in each of three replications. In this ex-

periment only the internal injury was tested.

RESULTS

In the first experiment, bean seed at about

15.5, 12.3 and 9.7 per cent of moisture was mechanically

beaten.

Tables 1 and 1A give the percentages of visibly

injured seed, germination and the weight per seedling.

Table l

Visible injury in 41 strains of bean seed, per cent of
germination and the average weight per seedling.

Entry Varie- Per

Number ties

1 Mich-
elite

injured

Per
cent cent
of of
Moist- visibly
ure

seed
check
15.5 2.9
12.3 41.6

9.7 54.1

Per
cent
with

cracked

seed
coat

2.2
18.3
18.9

18

Per Per
cent cent
of of
broken ger-
or mina—
split tion
seed
100.0
0.7 98.0
23.3 77.3
35.2 67.3

Weight,
grams,
aerial
part
per
seed-
ling

1.00

1.00
0.83
0076

check
Sani-
1ac 15.5 3.3
12.3 30.6
9.7 59.9
Row
Number
1958
Saginaw
Planting
check

860 15.5 4.4

12.3 44.2
9.7 60.8
check

863 15.5 4.6

12.3 48.5
9.7 64.4
check
864 15.5 5.8
12.3 47.2

9.7 63.2

19

2.7
15.2
27.8

3.8
25.3
33.6

3.7
27.7
27.7

4.4
23.6
27.2

0.6
15.4
32.1

0.6
18.9
27.2

0.9
20.8

3607

1.4
23.6
36.0

100.0

94.0
62.0

34.7

99.3
92.0
52.0
34.7

100.0

98.0
66.0

45.3

99.3
98.7
63.3
34.0

0.88

0.81
0.63
0.54

1.05
1.02
0.70
0.60

0.93
0.88
0.64
0.63

0.91
0.90
0.67
0.56

—— u—IJII

 

if; =

10

840

841

842

845

847

check

15.5

12.3
9.7'

check

15.5

12.3
9.?

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

13.4
63.7
81.0

8.5
47.7
66.7

5.5
51.6
66.6

5.5
50.2
68.0

5.3
48.1
65.9

20

9.3
31.1

33.8

6.7
27.4
29.0

3.4
24.4
19.3

3.8
22.5
26.7

5.3
23.2
27.5

4.1
32.6
47.2

1.8
20.3
37.7

2.1
27.2
47.3

1.7
27.7
4103

0.0
24.9
3804

99.3
90.7
61.3
43.3

99.3
92.0
64.7
46.7

100.0
88.7
54.7
38.7

100.0
94.7
64.0
56.7

99.3
92.0
54.0
40.7

1.00
0.97
0.67
0.66

0.93
0.87
0.69
0.64

0.91
0.86
0.63
0.57

1.00
0.99
0.74
0.71

0-93
0.90
0.63
0.64

 

 

11

12

13

14

15

848

850

851

852

854

check

15.5

12.3
9.7

check

15.5

12.3
9.?

check

15.5

12.3
9.7

check

1505 '

12.3
9.7

check

15.5

12.3
9.7

10.2
55.4
72.5

14.3
66.4
83.8

7.2
60.3

79.0

8.0
57.9
72.3

4.0
56.9
70.4

21

8.7
31.9
34.3

12.3
41.1
30.8

5.0
27.8
27.5

6.3
25.0
23.8

3.5
25.2
21.6

1.5
23.5
38.2

2.0
25.3
53.0

2.2
32.5
51.5

1.7
32-9
4805

0.5
31.7
4808

100.0
92.0
64.7
43.3

100.0
92.7
54.0
40.0

100.0
94.7
52.0
40.0

100.0

95.3
58.0

55.3

99.3
94.7
58.0
40.7

0.90
0.85
0.60
0.56

0.88
0.85
0.63
0.53

0.98
0.90
0.63
0.60

1.08
0.98
0.67
0.67

0.98
0.94
0.69
0.64

-—-—-LL--—-— _

 

3?

C ’
32m

.u 1,15. I

.........£ 3533.4.
L . .. . N. fl... 2‘" .

1...... a. w.

.x, I

16

17

19

20

21

855

856

866

867

868

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

5.5
50.8
72.3

4.3
63.0
75.7

4.5
55.9
76.0

1804
60.8
78.4

7.7
59.5
75.9

22

4.5
24.3
25.0

3.1
27.7
21.6

3.7
31.9
32.2

16.8
32.5
31.0

5.8
28.5
23.4

1.0
26.5
47.3

1.2
35.3
54.1

0.8
24.0
43.8

1.6
28.3
47.4

1.9
31.0
52.5

100.0

94.0
50.7
47.3

100.0
100.0

61.3
51.3

94.7
99.3
46.0
35.3

100.0

93.3
35.3
34.7

98.7
94.7
54.7
34.0

1.04
0.99
0.74
0.64

0.99
0.98
0.74
0.72

0.99
0.93
0.64
0.65

1.03
0.87

0.59
0.66

0.97
0.90
0.69
0.63

22

23

24

25

26

870

871

872

873

874

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

7.6
53.9
72.8

8.2
58.5
72.8

4.2
53.7
70.3

1.6
4206
63.3

2.3
34.7
56.4

23

6.0
23.7
23.3

7.2
30.5
21.4

3.4
25.0
2009

1.3
14.9
17.7

1.6
16.8
15.2

1.6
30.2
49.5

1.0
28.0
51.4

0.8
28.7
49.4

0.3
27.7
45.6

0.7
17.9
41.2

100.0
97.3
64.7
43.3

100.0
100.0
71.3
60.0

100.0
96.0
58.0
49.3

100.0
99.3
79.3
66.7

98.0
98.0
77.3
52.0

0.98
0-93
0.68
0.67

0.94
0.89
0.71
0.64

0.99
0.95
0.80
0.69

0-99
0.95
0.85

0075

1.04
0.96
0.80
0.74

 

 

 

’.rl.ll‘

J 333m. 14......

. .. J_

I...“..
‘

53439.3 .
. flab, .

J.

w .

27

28

29

30

31

876

877

878

879

880

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

2.5
51.7
69.5

1.9
41.6
63.5

2.0
50.4
68.0

2.0
44.0
64.4

4.6
46.4
69.8

24

2.1
28.9
24.1

1.6
19.5
28.2

2.0
32.8
29.7

1.6
27.2
26.5

4.0
23.6
28.6

0.4
22.8
45.4

0.3
22.1
35.3

0.0
17.6
38.3

0.4
16.8
37.9

0.6
22.8
41.2

100.0
96.7
59.3
40.0

99.3
94.7
42.7
28.0

99.3
86.0
40.7
37.3

100.0
96.7
45.3
25.3

99.3
98.7
58.7
45.3

0.95
0.90
0.67
0.63

0.93
0.83
0.55
0.57

0.97
0.92
0.59
0.58

0.93
0.87
0.53
0.56

0.94
0.85
0.60
0.57

”tr—.1!

 

 

32

33

34

35

36

882

883

884

885

886

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3-
9.7

6.4
54.3
72.7

10.5

59.9
69.8

10.0
60.6
77.8

21.3
61.5
81.8

19.8
65.4
77.0

25

5.5
32.7
30.1

8.6
29.6
27.1

8.6
30.7
31.2

18.9
33.3
33.9

17.6

33.1
29.0

0.9
21.6
42.6

1.9
30.3
42.7

1.4
29.9
46.6

2.4
28.2

47.9

2.2
32.3
4800

100.0
88.7
32.7
28.0

99.3
92.7
50.0
28.7

99.3
93.3
50.0
32.7

100.0
93.3
57.3
35.3

100.0
98.7
67.3
49.3

0.93
0.81

0.52
0.60

1.10
1.08
0.78
0.79

0.88
0.80
0.49
0.50

0.90
0.81
0.58
0.60

0.92
0.88
0.64
0.60

 

37

38

39

40

41

887

889

890

891

892

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

check

15.5

12.3
9.7

6.3
51.2
6708

12.7
55.6
70.5

8.7
52.9
72.8

7.0
53.0
70.0

3.3
49.6
72.1

26

5.5
29.0
28.4

11.0
33.6
32.9

7.9
28.9
33.8

5.5
27.7
27.5

3.0
26.3
30.4

0.8
22.2
39.4

1.7
22.0

37.6

0.8
34.7
39.0

1.5
25.3
42.5

0.3
23.3
41.7

99.3
95.3
48.0
37.3

98.7
86.7
39.3
28.0

100.0
88.0
30.0
23.3

100.0
98.0
61.3
42.0

98.7
97.3
59.3
42.0

0.96
0.83
0.67
0.67

0.92
0.77
0.48
0.56

0.96
0.80
0.55
0.59

0.91
0.93
0.60
0.51

0-95
0.92
0.70
0.55

 

check
42 893 15.5 10.7
12.3 50.5
9.7 70.8

96.0 0.93

9.2 1.5 96.7 0.89
27.0 23.5 54.0 0.58
35.5 35.3 39.3 0.67

Table 1A

Average per cent of seed with visible injury. 41 strains
were mechanically beaten at three moisture levels.

Per cent Per cent
of of visibly
moisture injured
seed
1505 7.2
12.3 52.2
9.7 70.3

In all the forty one strains of beans, the per-

centage of damage varied inversely with the level of seed

Per cent Per cent
of cracked of broken
seed cost or split
seed
6.0 1.2
27.0 25.5
27.3 43.0

moisture. In general, the strains that showed slight

visible injury at a high level of moisture, also showed

a relatively low percentage of visible injury at medium

and low percentages of moisture. See Table 1. According

to Table 1A the seed suffered considerable visible damage

at 12.3 per cent of moisture or less.

“ .31431"; 5'" C I.’

 

‘A-‘H

Jul-nu

28

Seed with no visible injury was planted in moist
sand. 19,703 seedlings had come up 12 days after plant-
ing, and were classified as follows:

(a) "Normal" seedlings 15,523; (b) seedlings
that had lost one cotyledon 2384; (c) "baldhead" seedlings
1727; (d) seedlings that had lost both cotyledons 5; (e)
seedlings that had lost one primary leaf 27; (f) seedlings
that had lost both primary leaves 37.

Baldhead seedlings in general emerged later
than did normal seedlings and their cotyledons remained
green longer than did those of the other seedlings as
shown in Figure 4.

A few seedlings showed combinations of the above
abnormalities but were included as shown below. Seedlings
that had lost one cotyledon and one primary leaf were
included in category (b); seedlings that had lost both
one leaf and two cotyledons were included in category (d);
seedlings that had lost both one cotyledon and two primary
leaves were included in category (f). A few exceptional
-seedlings occurred in which their cotyledons were attached
to the hypocotyl by callus tissue. In this case the coty-
1edons remained green. Some of the abnormalities are
illustrated in Figures 4 and 5. In seedlings that came

up 15 days after planting abnormalities of a different

 

      

Figure 4. Showing, from left to right, a normal seedling,
a seedling that had lost one cotyledon and one
primary leaf, a seedling that had lost both
primary leaves and one cotyledon, and a "bald-
head" seedling.

 

 

Figure 5. Showing, from left to right, a normal seedling,
a seedling that had lost one cotyledon, a
"baldhead" seedling, and a seedling that had
lost one primary leaf.

30

kind were observed: the cotyledons remained below the
sand level (hypogeous); in this case only the epicotyl
(plumule or first leaves and terminal bud) elongated;
these seedlings had no primary roots but a set of adventi-
tious or secondary roots developed between the hypocotyl
and the epicotyl where the cotyledons are attached as ii
shown in Figure 6. In this study, however, these seed- :
lings were considered as non-germinated seed. '

In the "per cent of germination" were included 4

 

only seedlings of the categories (a), (b), and (e), and
in the determination of the weight per seedling were in-
cluded all the seedlings that had come up (for every level
of moisture plus the check) 12 days after planting. The
per cent of germination and the weight per seedling for
every level of seed moisture plus the check are shown in
Table 1. In all three levels of moisture, seedlings that
had lost one cotyledon were smaller than those with both
cotyledons. See Figure 7.

The vigor of the normal seedlings of the check
(T) was equal to that of the normal seedlings obtained
from seed high in per cent of moisture, but was superior
to that of the normal seedlings obtained from seed of
medium and low per cent of moisture. See Figures 8, 9,

10, 11 and 12.

 

31

 

 

 

 

I
f
z‘
i
4'
Seedlings that had lost the hypocotyl and the

Figure 6.
primary root.

   

Figure 7. Showing the effect of the loss of one cotyledon:
from left to right, the check (T) and the three
moisture levels.

    

V
,
‘ O
r.‘
~.-.-..... on .- -4.ng .

 

A

Figure 8. Vigor of normal seedlings (12 days after plant-
i ), at three moisture levels plus the check
(33 in the strain No. 25.

 

I

Figure 9. Vigor of normal seedlings (12 days after plant-
ing), at three moisture levels plus the check
T

  

in the strain No. 1.

 

C ..fl.-.-.-.~ :- u - .. .. .. .. --

 

 

Figure 10. Vigor of normal seedlings (12 days after plant-
ing), at three moisture levels plus the check
T

in the strain No. 2.

 

 

   

 

Figure 11. Vigor of normal seedlings (12 days after plant-
1 at three moisture levels plus the check
(ng) in the strain No. 28.

 

 

37

Figure 12. Vigor of normal seedlings (12 days after plant-
), at three moisture levels plus the check
(ng in the strain No. 38.

 

 

 

35

The abnormalities in the seedlings as well as
the differences in germination, vigor and average weight
per plant in the three levels of moisture and those of
the check (T) are to be attributed to the mechanical beat-
ing of the seed. See Figures 13, 14, 15 and 16.

Analysis of variance of the data relating to
the number of normal seedlings, and the seedlings with
various injuries are shown in Tables 2 to 9, and in gen-
eral are self-explanatory. There were highly significant
differences between strains, between moisture levels, and
isometimes between replications for the number of normal
and injured seedlings. A highly significant interaction
was found between strains times moisture levels for seed-

ling injury.

 

~' '
l
, ..
Vagin‘ . .g

36

Table 2

Analysis of variance of the number of normal seedlings
in pea beans.

Source DF
Total 491
R 2
S 40
Error (a). 80
T 3
S X T 120
Error (b) 246

SS

139561.73
186.51
5206.31
512.16
127997.29
3919.46
1740.00

**Significant at the 1% level

r—IICDW

Replications
Strains (of beans)

MS

93.25
130.16
6.40
42665.76
32.66
7.07

l4-57**
20.34**

6034.76**
4.62**

Treatments (levels of moisture plus the check)

11“ m H

(nah—w
- . I

 

37

Table 3

Average number of normal seedlings.

Entry
number

\DQOU'I-FWNH

F’ +4 be F’ F4 +4 :4 F’ +4
\O -< ox \n .p O: n) +4 <3

Check

50.0
50.0
49.7
50.0
49.7
49.7
49.7
50.0
50.0
49.7
49.7
50.0
50.0
50.0
49.7
50.0
49.7
47.3

Treatments
15.5 12.3
48.7 31.3
45.0 21.0
44.0 17.3
47.3 18.7
49.0 19.7
45.0 23.3
45.3 27.0
43.3 18.3
46.3 23.0
45.7 20.0
44.3 22.0
41.7 16.0
45.7 16.3
47.7 16.7
46.3 20.7
46.7 19.7
50.0 25.0
47.0 10.0

9.7

26.3
10.3

8.0
12.3
11.0
13.3
18.0
12.3
20.3
18.7
10.3
10.7
11.7
17.0
13.7
15.3
17.0

8.7

CM

39.0
31.6
29.8
32.1
32.4
32.8
35.0
30.1
34.9
33.5
31.6
29.6
30.9
32.8
32.6
32.9
35.4
28.3

20
21
22
23
24
25
26
27
28
29
3o
31
32
33
34
35
36
37
38
39
4o
41
42

Treatment
average

50.0
49-3
50.0
50.0
50.0
50.0
49.0
50.0
49.7
49.7
50.0
49.7
50.0
49.3
49.7
50.0
50.0
49.7
49.3
50.0
50.0
49.3
48.0

49.7

42.0
45.0
47.7
49.0
47.3
48.3
49.0
46.0
46.0
39.3
44.7
44.3
40.0
45.0
44.3
45.3
45.7
42.0
36.3
39.3
46.7
47.3
47.0

45.3

38

9.3
17.3
21.3
27.3
23.7
36.7
31.0
16.3
12.0

9.7

9.3
17.0

7.0
17.7
11.3
19.0
19.0
15.3

6.3

8.0
18.0
18.7
15.0

18.4

10.7
11.0
15.3
18.7
14.3
27.0
18.3
10.0
8.7
10.0
8.3
11.3
8.3
10.0
9.0
10.7
13.3
14.0
7.0
7.3
8.0
11.3
10.3

12.9

28.0
30.7
33.6
36.3
33.8
40.5
36.8
30.6
29.1
27.2
28.1
30.6
26.3
30.5
28.6
31.3
32.0
30.3
24.7
26.2
30.7
31.7
30.1

39

Differences:

Between strains means

Between treatments means

Between treatments within
a strain

Between strains within a
treatment or within dif—
ferent treatments

Table

2.05
0.67
4.27

4.26

4

L.S.D.
5%

1%

2.72
0.88

5.64

5.65

R.E.
5% 1%

2.56 5.59
0.72 0.94
4.65 6.00
5.32 7.01

Analysis of variance of the number of seedlings that had

lost one cotyledon.

Source DF SS

Total 491 11652.26
R 2 80.27
S 40 781.09
Error (a) 80 417.90
T 3 7652.50
S X T 120 1274.00
Error (b) 246 1446.50

** Significant at the 1% level
R

Replications
S Strains (of beans)

T

MS

40.14
19.53
5.22
2550.83
10.62
5.88

Treatments (levels of moisture plus the check)

7.69**
3-74**

433.81**
l.81**

Table 5

Average number of seedlings that had lost one cotyledon.

Entry
number

\OGDKImUl-P-WNF‘

+4 +4 +4 +4 +4 +4 +4 F’ +4
\D -4 ox \n -> u: n: +4 <3

Check

OOOOOOOOOOOOOOOOOO

I
\N

o
\N

Treatments
15.5 12.3
0.3 7.0
2.0 10.0
2.0 8.7
1.7 14.3
0.3 12.0
0.3 7.3
0.3 5.3
1.0 9.0
0.7 9.0
0.3 6.7
1.7 10.3
4.7 11.0
1.7 9.7
0.0 12.0
1.0 8.3
0.3 5.7
0.0 5.3
2.7 13.0

9.7

7.0
7.0
9.0
10.0
6.0
8.3
5.3
7.0
8.0
1.7
11.3
9.0
8.3
10.3
5.7
8.3
8.7
9.0

ON

3.6
4.8
4.9
6.5
4.6
4.0
2.8
4.3
4.4
2.2
5.9
6.2
4.9
5.6
3.8
3.6
3.6
6.2

20
21
22
25
24
25
26
27
28
29
50
51
32
55
54
55
56
57
58
59
40
41
42

O O O O O O O O O O O O O O O O O O O O O O O
O
\N

Treatment
average

0
O
O

4.7
2.5
1.0
1.0
0.7
1.5
0.0
2.5
1.5
5.7
5.7
5.0
4.5
1.0
2.5
1.5
5.7
5.7
7.0
4.7
2.3
1.5
1.0

2.0

41

4.7
10.0
11.0

8.3

5.3

3.0

7.7
13.3

9.0
10.3
13.3
12.3

9.3

5.3
13.7

9.7
14.7

8.7
13.3

7.0
12.0
11.0
12.0

9.6

6.7
6.0
6.3
11.3
10.3
6.3
7.7
10.0
5.3
8.7
4.3
11.3
5.7
4.0
7.3
7.0
11.3
4.7
7.0
4.3
13.0
9.7
9.3

7.8

4.9
4.6
4.6
5.2
4.1
2.7
3.8
6.4
3.9
5.7
5.3
7.2
4.8
2.7
5.8
4.5
7.4
4.8
6.8
4.0
6.8
5.5
5.6

42

Differences: L.S.D. R.E.
5% 1% 5% 1%
Between strains means 1.85 2.46 2.31 3.01
Between treatments means 0.61 0.80 0.66 0.86
Between treatments within ‘
a strain 3.90 5.14 4.22 5.46

Between strains within a
treatment or within dif-
ferent treatments 3.88 5.14 4.83 6.42

Table 6

Analysis of variance of the number of "baldhead" seedlings.

Source DF SS MS F
Total 491 6418.95

R 2 18.12 9.06 N.S.

S 40 701.70 17.54 4.56**
Error (a) 80 308.38 3.85

T 3 3594.33 1198.11 312.64**
S X T 120 856.25 7.13 1.87**
Error (b) ' 246 940.17 5.82

** Significant at the 1% level

N.S. = Not significant

R Replications

Strains (of beans)

Treatments (levels of moisture plus the check)

S
T

43

Table 7

Average number of "baldhead" seedlings

Treatments
Entry _
number Check 15.5 12.3 9.7 S
l 0 0.3 6.7 9.0 4.0
2 0 1.3 4.3 5.3 2.8
3 0 1.0 8.3 6.0 3.8
4 0 0.7 2.7 2.7 1.5
5 0 0.7 7.0 6.7 3.6
6 0.3 3.7 7.3 9.7 5.3
7 0 3.7 10.0 7.0 5.2
8 0 3.3 9.0 10.3 5.7
9 0 2.0 10.7 8.7 5.3
10 0 3.0 14.3 10.7 7.0
11 0 1.3 5.0 3.3 2.4
12 0 3.3 1.7 3.7 2.2
13 0 2.3 7.7 8.3 4.6
14 0 2.0 8.0 7.3 4.3
15 0 2.0 8.7 7.0 4.4
16 0 1.7 8.7 5.7 4.0
17 0 0.0 8.3 5.7 3.5
19 0 0.0 2.7 3.3 1.5

20
21
22
25
24
25
26
27
28
29
50
51
32
55
54
55
56
57
58
59
40
41
42

Treatment
average

OOOOOOOOOOOOOOOOOOOOOOO

O
O
O

44

3.3
2.0
1.0
0.0
1.0
0.0
0.3
1.0
2.3
5.0
2.3
0.7
3.3
3.0
2.7
2.7
0.0
2.0
3.7
4.0
0.7
0.7
1.0

1.8

8.7
8.7
5.7
4.7
6.0
3.7
5.0
4.3
7.7
7.3
5.7
8.0
5.3
9.7
7.3
6.3
1.0
5.0
4.0
8.7
7.0
3.7
6.7

6.6

5.3
7.7
5.7
4.3
3.3
4.3
6.0
7.0
5.0
3.3
4.0
3.3
4.7
4.7
5.7
6.0
5.3
4.7
2.0
4.7
4.7
4.3
4.0

5.6

4.3
4.6
3.1
2.3
2.6
2.0
2.8
3.1
3.8
3.9
2.8
3.0
3.3
4.3
3.9
3.8
124
2.9
2.4
4.3
3.1
2.2
2.9

45

Differences: L.S.D. R.E.
5% 1% 5% 1%

Between strains means 1.59 2.11 1.96 2.60
Between treatments means 0.49 0.65 0.54 0.70
Between treatments within

a strain 3.13 4.13 3.38 4.37
Between strains within a

treatment or within dif-

ferent treatments 3.18 4.22 3.96

5.25

In the second experiment seed from 10 strains
was mechanically beaten by a small machine (as in the first
experiment), at about 15.7, 12.0, 9.0 and 9.7 (room moisture
not beaten seed), per cent of moisture.

The 4,556 seedlings that had come up 12 days
after planting were classified as shown below.

(a) Normal seedlings 4136; (b) seedlings that
had lost one cotyledon 224; (c) "baldhead" seedlings 196.

The per cent of germination and the weight of
the aerial part of the normal seedlings were taken for
each treatment and the check.

There was no difference in per cent of germina-
tion and vigor of the normal seedlings, 12 days after plant-
inglfrom the seed not mechanically beaten and planted
with initial moisture of about 15.7, 12.0, 9.0 and 9.7

per cent.

46

 

Figure 13.

 

Showing the effect on the seedlings (10 days
after planting), of the mechanical injury to
seed at three moisture levels plus the check
(T) in the strain No. 25.

 

 

Figure 14.

Showing the effect on the seedlings (10 days
after planting). of the mechanical injury to
seed at three moisture levels plus the check
(T) in the strain No. 1.

 

 

Figure 15.

Figure 16.

 

47

 

Showing the effect on the seedlings (10 days
after planting). of the mechanical injury to
seed at three moisture levels plus the check
(T) in the strain No. 2.

 

 

Showing the effect on the seedlings (10 days
after planting), of the mechanical injury to
seed at three moisture levels plus the check
(T) in the strain No. 3.

48

Table 8

Analysis of variance of the number of normal seedlings
in the second experiment.

Source of DF SS MS F
variation

Total 119 9455.5

R 2 12.0 6.00 4.55*
S 9 206.7 22.97 17.40**
Error (a) 18 23.8 1.32

T 3 8968.2 2989.40 1916.28**
S X T 27 151.3 5.60 3.59**
Error (b) 60 93.5 1.56

**Significant at the 1% level
*Significant at the 5% level

R = Replications
S = Strains (of beans)
T = Treatments (levels of moisture plus the check)

49

Table 9

Average number of normal seedlings in the second experiment.

Entry Treatment
number Check 15.7 12.0 9.0 ’5

1 25.0 24.7 11.3 8.3 17.3

2 25.0 24.0 7.7 4.7 15.3

3 25.0 23.3 8.7 4.7 15.4

4 25.0 25.0 7.7 6.3 16.0
25 25.0 25.0 14.0 9.3 18.3
26 25.0 24.3 11.3 6.7 16.8
28 25.0 24.7 6.0 3.3 14.8
35 25.0 22.7 6.7 5.0 14.8
36 25.0 22.3 8.3 5.0 15.2
38 25.0 20.7 5.3 3.7 13.7
Treatment
average 25.0 23.7 8.7 5.7
Differences: L.S.D. R.E.

5% 1% 5% 1%

Between strains means 0.99 1.35 1.13 1.55
Between treatments means 0.64 0.85 0.77 1.00
Between treatments within

a strain 2.00 2.66 2.40 3.12
Between strains within a

treatment or within dif-

ferent treatments 2.10 2.88 2.42 3.34

9

50

There was a small number of seedlings of the
category (b) and (c); for this reason these were not ana—
lyzed.

The results from the analysis of the number of
normal seedlings in both the first and the second experi-
ment and the determination of visibly injured seed in the
first experiment showed that there was a highly signifi—
cant difference in susceptibility to internal injury by
seed and that there was a slight relationship between the

visible and the internal injury of these strains.

DISCUSSION

The study of mechanical damage in beans is com-
plicated not only by the number of factors that are in-
volved in it, but also by the deficiency of information
concerning the parts of the seed that are responsible
for the resistance possessed by some varieties. This
resistance can be established by a visible examination
and by germination of mechanically beaten seed. Examina—
tion of the data on visible injury, in Table 1, shows
no consistent differences between strains. This may well
be due to the lack of replications, the small size of
the samples, variability in the operation of the mechani-
cal beater, and the difficulty in observing injury.

Examination of the data on germination and ab-
normal seedlings, however, shows highly significant dif-
ferences between varieties. Perry (13) had a similar
experience in determining injury to beans from dropping.
In general, however, the strains with the least visible
injury showed the least abnormalities in germination.

In all the strains the per cent of germination in the
beaten seed was less when the moisture in the seed was

low.

51

52

The specific pattern of injury varied consider-
ably in the 41 strains. For example, strain 36 was the
most susceptible to injury involving loss of one cotyledon;
strain 10 was the most resistant. (See Table 5.) Strain
10, however, was the most susceptible to injury in the
plumule ("baldhead") and strain 36 the most resistant.
(See Table 7.) These findings indicate that the injury
in these two strains varies according to the part of the
seed that is more susceptible to injury in each variety.
An anatomical study of these strains might establish some
of the reasons for greater resistance of various types
of injury in some strains than in others. Harter (7)
attributed the resistance of varieties to mechanical in-
jury to the larger diameter of the hypocotyl in the em-
bryonic stage. Atkin (2) attributed this resistance to
the closer adherence of the seedcoats and cotyledons in
resistant than in susceptible varieties.

Food used during germination and in the early
stages of seedling growth is largely derived from the
accumulations in the thick cotyledons. More seedlings
were found with one lost cotyledon than with all other
abnormalities combined. McAlister (9) found that the
removal of the cotyledons from soy beans in the early

stages of seedlings development decreased plant size.

53

Leaves are the food-making organs of the plant.
In this study, in seedlings that had lost both primary
leaves, the terminal buds often turned chlorotic and died.
In ”baldhead" seedlings the cotyledons remained green
for some time. In seedlings that had lost one primary
leaf chlorosis was not found but the vigor of these seed-
lings was less than that of normal plants. Figure 5.
Handenburg and Etc (6) who artificially pro-
duced "baldhead" bean plants, from 6 to 11 days after
emergence, reported that loss of the terminal bud did
not affect yield and that the loss of one primary leaf
was unimportant in plant development. The differences
in vigor between normal seedlings from seed of the same
strain but with three levels of moisture is shown in Fig-
ures 8, 9, 10, 11 and 12. These differences are believed /d
to be due to invisible injury in mechanically beaten seed. 5
In this case the seed suffered injury that may have had fix
some effect in the physiological processes of the seed; 3
there may have been some chemical reactions in the seed,
or obstructions in the movement of the food reserves in
the cotyledons. In this study the cotyledons of these
41 strains showed cross cracks but only in the seed that
was beaten at 12.3 and 9.7 per cent of moisture. I

McCollum (10) reported that hand picked and

54

hand shelled snap beans of the varieties and strains,
Cherokee wax, 49-3, Commodore, Top Crop, Rival,
B122941-2-6 and B1762 all showed cotyledonal cracking
during germination when germinated under an excess of
water, except the variety Cherokee.

In the second experiment seed planted with
initial moisture of about 15.7, 12.0, 9.7 and 9.0 per
cent in these strains (not beaten seed), did not have
any effect on the germination or vigor of the seedlings
12 days after planting.

Ingalls (10) found that when beans at 20 per
cent of moisture were germinated in sand the seedlings
were more uniform than were seedlings from seed of 10

and 15 per cent of initial moisture.

SUMMARY

Forty one strains of pea beans were brought
to three moisture levels, and were mechanically beaten
to find out if there are differences among strains in

susceptibility to mechanical damage.

A. Visible injury

1. Strains differed considerably in degree
of visible injury due to mechanical beating.

2. There was an obvious relationship between
the per cent of visible injury and the moisture content
in each strain, the lower the moisture content of the
seed, the greater the visible damage. At about 12.5 per
cent of moisture in the seed, a considerable visible and
internal damage was observed, when the seed was beaten

at 997 r.p.m.

B. Invisible injury, as determined in germination tests.

1. There were highly significant differences
between strains and between moisture levels in the number
of (a) normal seedlings, (b) various types of abnormal

seedlings.

55

56

2. The number of ”normal" seedlings and the
per cent of germination in beaten seed decreased as the
content of seed moisture decreased.

3. The per cent of initial moisture (15.7,
12.0, 9.7 and 9.0), in these strains (not beaten seed),
did not have any effect on the germination or vigor of

the seedlings 12 days after planting.

0. Study of germination abnormalities is a far more sen-
sitive measure of mechanical damage than is simple exam-

ination for visible injury.

LITERATURE CITED

J/,
1. Associated Seed Growers, Inc. A study of mechanical

10.

injury to seed beans. Asgrow Monograph. 1:1-45.

1949.
Atkin, John D. Relative susceptibility of snap beans

varieties to mechanical injury of seed. Amer. Soc.

Hort. Sci. Proc. 72:370-373. 1958.

Bainer, Roy, and Borthwick, H. A. Thresher and other
mechanical injury to seed beans of the lima type.
Calif. Agric. Exp. Sta. Bull. 580. 1934.

Borthwick, H. A. Thresher injury in baby lima beans.
Jour. Agr. Res. 44:503-510. 1932.

Crosier, Willard. Baldheads in beans, occurrence
and influence on yields. Proceedings of the Asso-
ciation of Official Seed Analysts. 118-123. 1942.

Handenburg, E. V., and Eto, W. H. The role of snake—
head plants in beans. Amer . Soc. Hort. Sci. Proc.
51:486-492. 1948.

Harter, L. L. Thresher injury a cause of baldhead
in beans. Jour. Agr. Res. 40:371-384. 1930.

Ingalls, R. A. A study of the occurrence of bald-
heads in beans and a comparison of their field per-
formance with that of normal plants. Proceedings
of the Association of Official Seed Analysts. 177-
183. 1945-1946.

McAlister, Dean F., and Orland A. Krober. Translo-
cation of food reserves from soybean cotyledons and
their influences on the development of the plant.
Plant Physiology 26 (3):525-538. 1951.

McCollum, J. P. Factors affecting cotyledonal crack-

ing during the germination of beans (Phaseolus vul-
garis). Plant Physiology 28: (2):267-274. 1953.

57

11.

12.

13.

14.

15.

16.

17.

58

Murphy, Donald M. Bean improvement and bean diseases
in Idaho. Idaho Agr. Exp. Sta. Bull. 238. 1940.

Nutile, G. E. Growth and yield of baldhead bean
plants in the field. Proceedings of the Association
of Official Seed Analysts 184-188. 1946.

Perry, J. S. Mechanical damage to pea beans as af-
fected by moisture, temperature, and impact loading.
Thesis for the degree of Ph.D., Mich. State Univ.

1959.

Steinbauer, G. P. Effect of baldhead injury in bean
seedlings on yield of dry beans. Me. Agr. Exp. Sta.
Bull. 438, p. 657. 1945.

Wester, R. E. Comparison of yield between normal
and baldhead snap beans plants. Seed World 61 (2):
8-100 1947.

Whitney, W. A. Mutilated seed a contributing factor
in defective stands of Lima beans (abstract). Phy-
topath. 20:134-135. 1930.

Zaumeyer, W. J., and Thomas, H. Rex. A monographic
study of bean diseases and methods for their control.
U.S.D.A. Tech. Bull. 868. 1957.

 

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