PHOTOPERiODIC RESPONSES IN LUFFA
Guan Peicong ( Department of Horticulture, South China Agricultural University, Guangzhou )
Development of both Luff a cylindrica ( cv.Shui-gua ) and L. acutan-gula(cvs. Wu-er, Deng-feng and Qing-pi ) was inhibited in longdays, but was promoted in shortdays. These results are similar to that reported by Bose et al. ( 1975 ) and Hideyuki Takahashi et al. ( 1986 ). The critical daylength for induction of pistillate flower in L. cylindrica was around 12-16h.in the report of Hideyuki Takahashi et al. ( 1986 ) , but our experiment show that L.acutangula can also produce female flower in 10-20h. of daylength or even less shortdays. Different cultivars of L.acutangula are not the same in shortday reactions. They fall into two groups: one group, with Wu-er, Deng-feng and Shuang-qing has strict demands to shortdays, the other group, with Qing-pi and Tang-dong has no strict demands comparatively. Shortday treatments can greatly stimulat femaleness development of plants,make them produce female and male flower earlier and increase the number of female flowers and the ratio of female to male flower, with more days of shortday increase those effects. Shortday response is slow before the cotyledon expanding, thereafter, response is sensitive,therefore,shortday treatments should begin after the cotyledon expanding.