140
L. W. WOODSTOCK
suggested that the seed coat might have restricted oxygen diffusion to the
embryo. The time of seed coat rupture was negatively correlated with
respiratory rates 27 to 29 hrs after planting, i. e., the sooner the seed coat
was ruptured by the elongating radicle, the higher the respiratory rates
(Fig. 2b). The following relationships are indicated: Initial respiratory
rates are related to seedling growth rates during the first 24 hours of
germination, which in turn, are related to the time of seed coat rupture
(between 22 and 32 hrs after the start of imbibition). In other experiments,
seedling growth during the first 24 hrs was highly correlated with seedling
growth during the subsequent 2-3 days.
The effect of gamma-irradiation on the respiration and growth of corn, wheat,
sorghum and radish seeds: In assessing the significance of changes in respiration
relative to changes in seedling growth, we wished to determine (a) whether
the above relationships occurred in species other than corn, and (b) whether
other types of injury would cause similar differences in respiration. We,
therefore, determined the effects of gamma-irradiation on the respiration
and seedling growth of corn, wheat, sorghum, and radish (Table 1).
Treatments of SO krads markedly inhibited seedling growth in all four
species, but reduced seed viability only slightly [17].
The growth-inhibiting SO-krad treatment always either inhibited
oxygen uptake, increased the RQ, or did both when respiration was
measured in 100 % oxygen [17]. This suggests either that the mechanism
Table 1. Effect of y-irradiation on respiration and growth of seeds.
Kind
Dose
Q0 2
Resp.
Stem
Time
of
Axis
Meas.
Seeds
(krad) Cui O 2 hr- l seed-l) Quot.
(mm)
(Days)
Corn
0
2.6
2.4
30 ± 4.6
4
Corn
5
3.9
1.6
37 ± 4.3
4
Corn
20
3.3
1.S
31 ± 5.3
4
Corn
SO
1.7
3.3
9 ± 1.7
4
Wheat
0
3.1
0.77
29 ± 2.5
6
Wheat
5
3.4
0.88
38 ± 4.5
6
Wheat
20
3.0
0.S7
27 ± 1.9
6
Wheat
80
2.8
0.96
13 ± 0.5
6
Sorghum
0
1.2
0.67
16 ± 2.1
4
Sorghum
5
1.0
0.80
22 ± 1.1
4
Sorghum
20
1.0
0.90
15 ± 0.8
4
Sorghum
80
0.7
1.43
7 ± 0.5
4
Radish
0
2.7
0.74
82 ± 4.0
4
Radish
5
2.6
0.77
90 ± 5.4
4
Radish
20
2.3
0.78
78 ± 6.5
4
Radish
80
2.0
0.85
52 ± 2.6
4
from: L. W. WOODSTOCK and O. L. JUSTICE, Radiation Botany 7, 129 (1967)
L. W. WOODSTOCK
suggested that the seed coat might have restricted oxygen diffusion to the
embryo. The time of seed coat rupture was negatively correlated with
respiratory rates 27 to 29 hrs after planting, i. e., the sooner the seed coat
was ruptured by the elongating radicle, the higher the respiratory rates
(Fig. 2b). The following relationships are indicated: Initial respiratory
rates are related to seedling growth rates during the first 24 hours of
germination, which in turn, are related to the time of seed coat rupture
(between 22 and 32 hrs after the start of imbibition). In other experiments,
seedling growth during the first 24 hrs was highly correlated with seedling
growth during the subsequent 2-3 days.
The effect of gamma-irradiation on the respiration and growth of corn, wheat,
sorghum and radish seeds: In assessing the significance of changes in respiration
relative to changes in seedling growth, we wished to determine (a) whether
the above relationships occurred in species other than corn, and (b) whether
other types of injury would cause similar differences in respiration. We,
therefore, determined the effects of gamma-irradiation on the respiration
and seedling growth of corn, wheat, sorghum, and radish (Table 1).
Treatments of SO krads markedly inhibited seedling growth in all four
species, but reduced seed viability only slightly [17].
The growth-inhibiting SO-krad treatment always either inhibited
oxygen uptake, increased the RQ, or did both when respiration was
measured in 100 % oxygen [17]. This suggests either that the mechanism
Table 1. Effect of y-irradiation on respiration and growth of seeds.
Kind
Dose
Q0 2
Resp.
Stem
Time
of
Axis
Meas.
Seeds
(krad) Cui O 2 hr- l seed-l) Quot.
(mm)
(Days)
Corn
0
2.6
2.4
30 ± 4.6
4
Corn
5
3.9
1.6
37 ± 4.3
4
Corn
20
3.3
1.S
31 ± 5.3
4
Corn
SO
1.7
3.3
9 ± 1.7
4
Wheat
0
3.1
0.77
29 ± 2.5
6
Wheat
5
3.4
0.88
38 ± 4.5
6
Wheat
20
3.0
0.S7
27 ± 1.9
6
Wheat
80
2.8
0.96
13 ± 0.5
6
Sorghum
0
1.2
0.67
16 ± 2.1
4
Sorghum
5
1.0
0.80
22 ± 1.1
4
Sorghum
20
1.0
0.90
15 ± 0.8
4
Sorghum
80
0.7
1.43
7 ± 0.5
4
Radish
0
2.7
0.74
82 ± 4.0
4
Radish
5
2.6
0.77
90 ± 5.4
4
Radish
20
2.3
0.78
78 ± 6.5
4
Radish
80
2.0
0.85
52 ± 2.6
4
from: L. W. WOODSTOCK and O. L. JUSTICE, Radiation Botany 7, 129 (1967)