Abstract
To clarify the influence of sowing times on seed production, soybean cultivars 'Tamahomare' was sown at 1 week interval, from June 4 to July 23, in 1982 and 1986. The number of nodes in main stem decreased with delay of sowing time from June 4 to June 25, but there was little difference in sowing from June 25 to July 16. On the other hand, the number of branches and total nodes per plant decreased with delay of sowing time. Especially the decrease of branches in soybeans sown in July was remarkable. The seed yield per unit area was correlated with ripened pod number per unit area. As the number of nodes and branches were greater, the number of ripened pods increased. In sowing from early to middle June, grain/stem ratio was low, due to both of high death rate of branches and low podding rate on lower-nodal-position branches. On the other hand, in sowing from middle to late July 100 seed weight tended to be low, because of short ripening period. Therefore, it was suggested that an optimum sowing time of a medium type cultivar 'Tamahomare' is from late June to ealy July in Sanyo districts.
