Some Physico-Chemical Factors of the
Fruit Influencing Speed of Germination
of Sugar Beet Seed'
F. W.
SNYDER 2 Received fo,- /mblication Ap,-iI 9, I962 Speed of germination of the sugar beet seed is controlled
largely by the physico-chemical characteristics of fruit tissue which
surrounds the true seed (2) 3. In the commercial varieties ex­
amined, chemical composition of the fruit seemed to play the
major role in regulating the rate of germination (2). Sedlmayr
(1) has demonstrated that seeds harvested from different plants
of a sugar beet variety may not germinate at the same rate and
that this germination characteristic is heritable.
Tests have been conducted to determine some factors which
control speed of germination of open-pollinated seed from in­
dividual plants. This paper describes techniques which indicate
the potential rate of germination of seed samples as ,,,,ell as the
correlations between the techniques and actual germination.
Methods and Materials
Ripe seeds were harvested from 65 plants of five progeny
groups of US 401. Samples were harvested as they matured over
54 days, but the majority were collected between August 9 and
September 6, 1957. The seed balls on a given plant were harvested
when at least 80 percent were dry and straw-colored. Normally
three weeks were required for maturing, and since only traces of
precipitation were recorded between July 23 and August 2Q,
seedballs from some plants were not exposed to rain before har­
vest. Although the seedballs on plants within a progeny group
tended to mature about the same time, some were . exposed to
more rain than others.
The speed of germination for each seed sample was determined
by two methods: I-The liquid-contact method (2) involved
germinating the seeds while the seed balls were in contact with a
mineral nutrient solution of 10.1 atmospheres osmotic pressure.
Eighty seedballs (each considered as a single unit and appearance
of first seedling root indicating germination) were used for each
sample. Percentage of germination were recorded for 2, 3, and
1 Cooperative
investigations of the Crops Research Division, Agricultural Research
Service, U. S. Departm ent of Agriculture , and th e MiChigan Agricultural Expe riment Station.
Approved for publication as Journal Articl e #2620 , MiChiga n Agricultural Experiment
Station.
2 Plant
Physiologist. Crops Research Division. Agricultural Research Service, U. s.
Department of Agriculture. East Lansing, Michigan.
:3 Numbers in parentheses refer to literature cited.
372
JOURNAL OF THE
A. S. S. B. T.
5 days; 2- In the blotter method) 40 seedballs were placed on a
blotter (4Y2 X 4% inch es) moistened with tap water.
Speed oE germination data (Table 1) are cod ed for simplicity of
comparison and designated as a speed-of-germination ind ex; the
first digit representing the 2-day ger mination, the second the 3­
day, and the third the 5-day germination. The cod ing is as fol­
lows: 1 represents 0 to ] 9 percent germination ; 2, 20 to 29; 3,
30 to 39; 4,40 to 49; 5, 50 to 59; 6, 60 to 69; 7, 70 to 79; 8, 80 to
89; and 9, 90 to 100. For example, for clone 3 18 the speed-of­
germination index for the liquid-contact method is 136. This
means that the 2-day germination is between 0 and 19 percent,
since the first digit is 1. The second digit, "3", represents a per­
centage between 30 and 39 for the 3-day germination and the
digit "6" a germination between 60 and 70 percent for the 5-day
value. Thus, a speed-oE-germination ind ex of 999 represents a
very rapid and compl ete germinat io n and an ind ex of III a very
slow and incomple te germination as of the fifth day.
In both the liquid-contact and the blotter methods of germ­
ination, the speed of germination represents the integrated phys­
ical and che mical effect of tb e fruit on the germinating seed, as
well as the physical and che mica l attributes of tbe seed itself. An
additional test was used to separate the effect of the chemi ca l
factors Erom that of tbe physical factors in ·the fruit. The germina­
tion and growth of wbeat on water extracts of seed balls were
selected to indi ca te differe nces in their che mical compos ition . Th e
procedure for the wheat test was as follows: Air-dried seed balls
(1 gram for 10 milliliters of distilled water) were soaked for 18
hours in the refrigerator. The ex tra ct was decanted. FOllr milli­
liters of extrac t were added to 25 kernels of ·w heat (Genesee
variety, certified) placed on a filter paper in a Petri dish. After
96 hours the fresh weight of the wheat grow n on th e extrac t was
compared with that grown on distill ed water. The aver"age of
four replications was then expressed as a percentage of the fresh
weight on distilled water. The average weight of the 25 dry wheat
kern els was subtracted from the total fresh weight of v"heat seed­
lings to obtain a more precise valu e for water absorption during
the growi n g period.
The specific conductance of th e seedball extrac t, which is a
measure of the quantity of electrolytes in solution, was determined
for each sample by diluting 10 milliliters of the extract to 90.
The pH also was recorded. Since speed of germination is known
to be affected by osmotic stress, the relations between specific
conductance of the seed ball extrac t and the other tests were
established.
­
VOL. ) 2,
No. 5,
APRIL
1963
373
Table I.-Comparison of germination and certa in seedball characteristics of 65 seed samples of sugar
beet variety US 401.
P roge ny
and
plant
ulunbcrs
.:,
086:
318
236
266
243
288
305
256
257
295
312
311
Liquidcontact
Blotter
Specific
cond u ctance
(mhos x 10-' )
136
489
179
138
134
899
157
123
488
11 7
789
799
699
699
499
478
189
169
155
149
114
113
22
33
26
34
41
48
44
788
999
999
899
899
999
777
999
677
999
167
134
499
999
459
999
899
899
799
689
489
479
357
268
J59
146
J34
128
]]8
117
25
55 1
62 1
553
550
565
596
560
584
568
617
577
549
178
999
799
899
899
677
179
688
168
999
899
289
167
399
999
799
799
799
699
599
579
489
479
479
478
269
258
129
21
37
21
30
28
37
23
40
607:
226
204
144
188
999
999
599
189
579
358
199
159
098:
469
514
528
524
472
443
426
493
52~
477
433
45 1
519
517
457
~
Speed-of­germi na tion
ind cx 1
141:
58 1
547
1
51
14
52
52
~8
29
31i
:11
17
52
24
49
40
19
69
29
79
60
Wheat test
on secdba ll
extract ( %
of grow th
on water)
94
95
106
76
57
39
69
45
95
41
53
102
94
94
100
83
106
88
98
89
103
103
31
IO ~l
40
50
SeedbaUs
shedding
seedcaps
(percent)
0
3
2
2
I
0
54
23
25
27
27
II
28
29
22
28
29
22
29
29
29
54
29
13
13
0
74
8
39
22
27
27
22
27
27
29
27
27
22
29
29
22
13
55
23
42
40
61
92
89
43
38
23
50
0
0
62
32
7
2
I
Ind ex for 2-, 3-, and 5-d ay germ in a ti on va lues . See details for m Et hod s of COding in the text.
(Con tinued on next page)
II
42
20
30
8
9
4
44
0
2
21
7
4
42
48
16
0
22
25
38
22
29
22
21
28
21
27
8
13
32
27
0
8
2
36
96
95
100
92
92
89
97
67
62
92
99
95
97
36
44
Harvest da t.c
(days a ft er
A ug. 8, 1957)
28
27
J OURl' lAL
374
O F TH E
A. S. S. B. T.
"
Table 1. (continued) Table L-Cofllparison of germination and certa in seedball cbaracteristics oC 65 seed samples of sugar beet "ariel)' US 401.
Wheal test
Speed-oC-germination
Seed b ai ls
on seedbal1
Progeny
l
index
sbedding H ar"est da te
Specific
extract ( %
and
(days aCter
of growth
seedea ps
plant
Liquid ·
conductance
6
(Mhos x 10 - )
on water)
(percent) Aug. 8, 1957)
nunlbers
contact
Blotter
197
136
140
172
128
211
194
61 3:
368
401
34 2
372
358
379
403
361
360
353
362
383
01 5
393
1
188
156
179
244
114
134
135
159
139
139
137
11 4
114
112
65
43
51
46
51
23
61
41
50
36
63
35
99
30
134
899
899
899
689
378
357
159
148
138
128
127
116
115
113
14
14
22
29
40
26
48
55
37
59
50
52
11 3
55
106
103
104
103
98
103
75
62
51
80
37
58
60
46
577
999
255
999
157
146
III
157
358
134
138
389
')­
-~
Index for 2-. 3-, and 5 -d ay germinati on values.
c.....__
II
0
2
21
8
II
II
21
I
0
0
5
0
I
3
2
9
52
0
4
0
0
0
27
28
27
27
28
27
22
I
22
4
0
0
0
II
II
11
13
II
See d e tail s for mEth od s of coding in the text.
Table 2.--Con-elation coeffici ents b e tween speed of germination and certain other seedball attributes
of 65 selected samples of US 401.
;...
":::v
!:lv
::I
'0
:::
0
V
v
:.::
'i;j
"
'"""
-0 .85 "
-­ 0.71 ' ,
Blolle r - 2 day
- 0.60 "
Blotte r
3 da y
- 0,45 ' •
Bl o tter - 5 da y
Liq uid-co ntac t 2 d ay - 0.2 1
Liq uid -contact 3 da y - 0.28 '
Liquid -contac t - 5 d ay - 0. 18
- 0.21
% shed scedca ps
Da le h a rves l
- 0.3 7 "
\'Vheal test
e..
'v"
't)
"~
r
'"
'0
'0
e<)
e.
~
t;;
~
!S
;:'"
-0
.;
cr
t;;
:::
0
v
:::
v<0
'0
~
.;
"'"
~
~
;.:l
;.:l
0.28 '
0.27 '
0.27*
0,46 "
0.67 ' •
0. 88 ' •
0.4 2 ' ,
0.4 5 "
0.46 ' ,
0.57 -­ ·
0. 83 ' ,
0.40 ' ,
0. 39 ' •
0.29 '
0.27 '
0.66 ' •
0. 56 "
0.45 "
;...
'"
'"
't)
cr
6-
'"
v
<0
v
;.:l
0.11 ' ,
0,43 ' •
,
0. 38
0. 39 "
>-
>-
'"
'"
'"...
.::
'0
't)
'"
.::"
0
0
~
~
0.43 ' •
0.67 "
0. 85 t
0.59 "
0.90 "
,j,
• Indicates r -va lue g rca te r th an th a t required f Ol' sig nif ica n ce (0.25) a t the 5% le ve L
•• Indi ca tes r -va lue g rea te r th a n th a t required fo r sig ni f ica nce ( 0.32) a t the 1% le veL
>­
'"
'0
N
...
.::
0
~
0.7 3"
VOL. 12, No.5,
APRIL
1963
375
Some measure of the physical attributes of the seedball may
be derived from the tightness of the seedcaps or lids covering the
ovarian cavities. Thus, the percentage of seedballs having lost
or shed seedcaps was determined by examination of 200 seed balls
per sample.
The six values which characterized each of the 65 seed samples
(Table I) , were employed in calculating the coefficients of correl­
ation in Table 2. Actual percentages of germination were em­
ployed in the calculations.
Discussion of Results
All correlations were significant, except three involving
specific conductance. Specific conductance was correlated inverse­
ly with the other attributes.
A coefficient of determination., which indicates the per cent
of the variation in two variables that is concomitant or simul­
taneous, may be calculated by squaring the coefficient of correla­
tion and multiplying the result by 100. Expressed in this manner,
many of the relations appear less significant. Only seven of the
37 coefficients of determination equal or exceed 50 percent. As
might be expected for either the liquid-contact or the blotter
methods of germination, the coefficients of determination for the
2- versus 3-day and the 3- versus 5-day comparisons were between
69 and 80. However, coefficients for the 2- versus 5-day compar­
isons were less than 50. The coefficient of determination for 2-day
blotter germination versus specific conductance was 50 and versus
the wheat test 54, while the coefficient for specific conductance
versus the 'w heat test was 72. Thus, the blotter method of germ­
ination, the specific conductance, and the wheat test appeared
to measure the same variables in approximately the same way.
Since the three tests appear to give the same general informa­
tion, a choice of tests would be permitted. In contrast, the liquid­
contact method of germination apparently measured a different
set of factors which contributed to the speed of germination. Of
the attributes examined, speed of germination by the liquid­
contact method correlated best with the percentage of seed balls
shedding seedcaps. The relative tightness with which the seed­
caps are attached may affect speed of germination by physically
restricting the flow of water and oxygen to the seed.
The electrolytes in the seedball, as measured by specific con­
ductance, correlated significantly (-0.71 for 2-day) with speed
of germination by the blotter method. The differential response
• Koch , E. J. Presentation of Experimental Results. Symposium sponsored by Amer. '
Soc. Hort. Sci. anI Biometric Soc. at Pennsylvania State Univ. August, 1959.
376
]OVR:\AL OF THt
A. S. S. B. T .
may be the result of the osmotic stress imposed by the solution
employed in the liquid-contact method which may mask the
influence of electrolytes in the seeclball.
The pH values for the seed ball extracts ranged from 6.2 to
7.3. These deviations from neutrality appeared to have no sig­
nificant effect on the germination response.
Although no data are presently available to relate the quantity
of organic inhibitors to the specific conductance values, they may
be closely related, since the speed of germination does not appear
to be controlled solely by the quantity of electrolytes in the
seedbaJI. Exposing ripe or nearly ripe seedballs to rain leaches
soluble organic substances as well as inorganic electrolytes from
them. The significant correlation between date of harvest and
specific conductance probably reflects the leaching effect of rain
on the seedballs harvested later in the season (Table !1).
T~lb]e 3.-Relation of pl"ccipiLalion in 3-week period before harvesting of seed and the
specific conductance o( the seed ball extract.
Day of Harvest
period
Number of
samples
1st (Aug-ust 9)
8th to 13th
21st
22nd
27th to 32nd
54 th
4
Rainfall in 3-week
period before harvest
Inches
1. 35"
Trace
0.90
1.07
1.47
0.75
15
4
9
31
2
A vcrage sped Cie
conductance
Mhos x 10-"
54
55
33
27
31
61
.. Precipitation occurred on the 19(h da y before han"es t.
Summary
Seed harvested from 65 US 401 sugar beet plants, and which
had been selected for a range of germination characteristi.cs, was
germinated by the liquid·contact and blotter methods. The
specific conductance and pH of the seedball extract for each
sample were measured. vVheat was grown on a portion of the
extract for 96 hours and its fresh weight was expressed in terms
of growth or wheat on distilled water. The percentage of seed­
balls shedding seedcaps was determined for each sample. Co­
efficients of correlation between the various tests were calculated.
Most of the tests were significantly correlated. All tests, except
specific conductance, were positively correlated. Altbough the
liquid-contact and blotter methods of germination were signifi­
cantly correlated, the coefficient or determination indicated that
they do not measure precisely the same attributes. On the basis
of simplicity and amount of information derived from a test, the
377
VOL. 12, No. 5, APRI L 1963
blotter m eth od of germin a tio n a nd the specific conducta nce of
the seedball extract are sugges ted as th e most useful tests to
evaluate the speed of germina tio n.
Literature Cited
(1) SEDLMAYR, T. E. 1960. Ge ne ti c studi es on sp eed o f germination in suga r
beets (B eta. v lIig(lTi s L.). Doctoral Di sserta ti o n , D epa rtme nt o f Farm
Cro ps, M ichi ga n Sta te Un iversit y, Eas t La nsing, Mi chiga n .
(2) SN YDER, F. W. 1959. InHue nce o f the seed ball o n speed o f germina tio n
of suga r beet seeds. Amer. Soc. Suga r Beet Techn o!. J. 10 (6) : 513­
520.