Early Pod-filling Stage Research Articles

Corn Earworm Control, 1988

Abstract This test was designed to evaluate 4 insecticides against CEW in late planted, double-cropped soybean after wheat. Soybeans, planted 15 Jun, were treated with test insecticides 31 Aug when plants were in the early pod fill stage. Applications were made using a CO2-pressurized air sprayer, with 8002 EVS flat spray nozzles at 1.97 kg/cm2 that delivered a volume of 128.1 liters/ha. A randomized complete block design was used with 4 replications. Individual plots were 6 rows (50.8-cm spacing) by 7.6 m. Treatments were evaluated prior to appalication and at 1, 5, 7, and 14 DAT by comparing the number of CEW larvae/0.9 m row. Pod damage was compared by counting the pods and damaged pods on 5 plants/plot.

Corn Earworm Control, 1988

Abstract This test was designed to evaluate 4 insecticides against CEW in late planted, double-cropped soybean after wheat. Soybeans, planted 1 Jul, were treated with test insecticides on 31 Aug when plants were in the early pod fill stage. Applications were made using a CO2-pressurized sprayer, with 8002 EVS flat spray nozzles at 1,97 kg/cm2 delivering 128.1 liters/ha. A randomized complete block design was used with 4 replicates. Individual plots were 4 rows (48.3-cm row spacing) by 6.1 m. Treatments were evaluated prior to application and at 1, 5, 7, and 14 DAT by comparing the number of CEW larvae/25 sweeps taken with a 15-cm-diam sweep net. Pod damage was compared by counting the number of pods and damaged pods on 5 plants/plot. Yield was measured from 12.2 m row/plot.

Supplemental nitrogen fertilizer to soybeans. IV. Influences of soil conditions on the yield response to supplemental nitrogen.

土壌条件が大豆の窒素追肥による増収効果に及ぼす影響について検討した。とくに, 窒素追肥が作物体の窒素同化に及ぼす効果を解析するため, 根粒非着生大豆系統を対照に用い, 供試栽培品種の窒素同定量, 追肥窒素の吸収量や追肥窒素による窒素固定の減少量を推定した。堆肥投与によって土壌の肥沃度を高めた時, 窒素追肥による増収量や増収率は低下した。逆に, 土壌からの窒素供給量が減少するにしたがい, 窒素追肥による増収効果は逓増した。土壌の種類が異なる場合には, 無追肥条件下での作物体の土壌窒素吸収量, 窒素固定量や全窒素同化量の大小と, 追肥の増収効果には直接的な関係は認められなかった。しかし, 開花期から最大繁茂期までの同化窒素量を高める効果が大きい土壌条件の下では, 追肥による増収効果も大きかった。追肥効果が高かった原因は, 灰色低地土のシルト質埴壌土では, 無追肥時の窒素固定機能が低く, 追肥による窒素固定の低下が少なかったためであった。主た, 灰色低地土の壌土の中には, 追肥窒素が迅速に吸収され, 追肥窒素の利用率が極めて高かったものもあった。一方, 黒ボク土の壌土は, 窒素追肥による窒素固定の減少が著しく, 同等の土性の灰色低地土の壌土に比べでも追肥効果が上がらなかった。その著しい窒素固定阻害は, 黒ボク土の可給態燐酸の濃度が低いためであると推察された。

The Effect of a Growth Retardant Compound (B4) onPhaseolusBeans

SummaryWhen the growth retardant B4 was applied to Phaseolus beans at the primary leaf stage or at one week before flowering, a temporary dwarfing effect occurred and less total vegetative growth was produced. Although these pre-flowering treatments delayed the production of peak pod numbers, no effect on final seed yield occurred. In contrast, an application of B4 during the early pod-fill stage gave a less marked reduction in vegetative tissue, but increased seed yield by 16%. It is suggested that this extra yield may have resulted from a reduction in pod shading by leaves which enabled a greater direct contribution to seed yield from pod photosynthesis. Alternatively, a restriction in growth of new leaves may have given a greater transfer of assimilate to the pods from older leaves.

Symbiotic Nitrogen Fixation in Soybeans. I. Effect of Photosynthetic Source‐Sink Manipulations1

Symbiotic nitrogen fixation of two field grown soybean [Glycine max (L.) Merr.] varieties, ‘Chippewa 64’ and ‘Clay,’ was measured at 7 to 10 day intervals starting at flowering, using the acetylene reduction assay. At he end of flowering, treatments were applied which were designed to alter the relationship between the photosynthetic source and sink components in the plants. The treatments were supplemental light, 25% shade, 50% depodding, 60% defoliation, and control.Total acetylene reduction activity per plant increased in both varieties during the flowering period, reached a maximum near the end of flowering, and then declined markedly during the early podfilling stage. The activity decline was due to a decline in the specific activity of the nodules, and occurred immediately prior to the time when the growth rate of the pods (including seed) exceeded that of the total plant tops in the respective varieties. Treatments designed to enhance he photosynthetic source/sink ratio (supplemental light and depodding) maintained nodule activity well above the control in both varieties. Conversely, treatments designed to reduce the source/sink ratio (shading and defoliation) decreased nodule activity below the level of the control. Treatment effects on total plant protein recovered at maturity closely reflected the treatment effects on total nodule activity. The results of this study are interpreted as evidence that symbiotic nitrogen fixation in these varieties declined during podfilling as the result of inadequate assimilate supply to the nodules.