Separation of the effects of photoperiod and hormones on sex expression in cucumber

The effects of photoperiod on the sex expression of cucumber flowers were examined in relation to the endogenous GA and ethylene production with short day (SD)- and long day (LD)-sensitive cultivars under controlled environmental conditions.Growth of plants was greatly reduced under LD in both types of cultivars. Reflecting this, GA activity was greater and ethylene evolution less in plants grown under SD than in those under LD. However, the number of pistillate flowers increased under SD and LD in SD- and LD-sensitive cultivar, respectively, indicating that a change in sex expression did not coincide with hormonal changes in the SD-sensitive cultivar. Thus, the effect of photoperiod on the sex expression was found to be separate, at least in part, from the effect of GA or ethylene in cucumber.