Abstract
In order to make it clearer to understand the varietal difference of the relative flowering period and the relative growing period, and the interrelations to other characters, the effects of daylength on the flowering period and the seed forming period were studied in the experiments of 1953 to 1954. 1. The daylengths from 10 to 18 hours appeared to have greater effect on both of the said periods than on the period to flowering at hours of threshold shorter than the critical daylength. Such an effect differed between the varieties in parallel with the lengths of the periods under short daylength, that is, great on the flowering and the seed forming periods of indeterminate soybeans and the, seed forming periods of determinate large seeded soybeans, while less on both of thc periods of determinate and small seeded soybeans. 2. The difference in the effect of daylength mentioned above was clear between the soybeans of summer soybean type and intermediate type due to the sudden leap of the period at the threshold daylength. 3. Such results seem to make it easy to consider the varietal difference in the relative periods and the interrelations to determinate vs. indeterutinate growth habit and seed size under natural daylength in fields, as shown schematically in Fig. 3.
