Effect of Sowing Time on Dry Matter Production and Seed Production of Soybean

[摘要] The effects of three sowing times, from May 30 to July 20, on growth, dry matter production and seed production, were investigated in 1982 and 1983 using two soybean ecotypic cultivars, autumn and medium. 1. With a delay in sowing time, the number of days from sowing to flowering and to maturation was reduced. The stem length, the number of nodes and branches, and LAI were also decreased. 2. The productive structure at the pod-setting stage showed more photosynthetic organs in the autumn type and in plants sown earlier than in the medium type or those sown later. The light transmission coefficient (K) showed a negative correlation with SLA. 3. Such growth parameters as RGR, NAR and CGR, progressed in similar patterns, regardless of the cultivar or sowing time, but the decreases during later growth stages were more rapid with a delay in sowing time. 4. Seed yield was reduced with a delay in sowing time, resulting from the reduction in the number of pods and seeds. There was also accompanying decrease in biomass. 5. Judging from the results, a medium type cultivar, Kan-nari No. 1, did not respond enough to differences in sowing time that we easily can select an optimum time for sowing. On the other hand, the autumn type cultivar, Akiyoshi, has an optimum sowing time in warmer districts in Japan of around late June.

[学科分类] 农业科学（综合）

[关键词] Dry matter production;乾物生産;Ecotype;子実生産;Growth analysis;生態型;Seed production;生長解析;Sowing time;ダイズ;Soybean;播種期