Effect of GA3 and Ehtephon on sex expression and oil yield in medicinal pumpkin (Cucurbita peop var. styriaca)

Evidence had accumulated from a number of experiments indicating that plants growth regulators levels may modify the sex expression of flowering plants. The effect of foliar application of Ethephon (2-chloroethylphosphoric acid: 100, 200 and 300 mgl?1) and gibberellin (GA3: 25, 50 and 75 mgl?1) on growth and flowering of medicinal pumpkin (Cucurbita pepo var styriaca) were studied. The plant growth regulators were applied on 4 true leaf stages for tree time. The results of the study showed that, spraying of gibberellin at (25, 50 and 75 mgl?1) during 4 leaf stage hade more significantly effects of vegetative growth and increased the flowering, So that enhanced the seed yield and oil seed per hectare than control and Ethephon treatments. Spraying of Ethephon at (100, 200 and 300 mgl?1), significantly enhanced the yield by increasing the female flower and decreased the sex ratio.