Floral inhibition in relation to photoperiodism in Biloxi soybean

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Abstract
Various lengths of photoperiod were applied in diurnal cycles and as intervening treatments during the 2d 24 hours of 48 hours (bidiurnal) cycles to study the inhibitory processes which influence the flowering of Biloxi soybean (Glycine max). When plants were exposed to 7 consecutive 24-hour long cycles, flowering increased with increasing photoperiod from 2 to 5 hours; from 5 to 10 hours it was maximum, and it decreased from 10 to 14 hours. No flowering occurred with photoperiods longer than 14 hours. When plants were exposed to 7 short days (8 hour photoperiod 16 hour dark period[long dash]donor cycles) which were alternated with 7 intervening days during which the length of the photoperiod was varied, the flowering varied with length of the photoperiod during intervening cycles. Intervening cycles with high light intensity photoperiods were inhibitory from 12.75 to 14 1/2 hours and stimulatory from 3 to 12 hours, whereas photoperiods of 2 and 12 1/2 hours were innocuous. Low light intensity photoperiods shorter than 12 hours were generally innocuous, while those longer than 12 hours were progressively inhibitory. The experimental results obtained indicate that the flowering response of Biloxi soybean is controlled by an interaction between stimulatory and inhibitory processes.