Effect of GA₃ and Silver Compounds on Staminate Flower Induction in Gynoecious Parthenocarpic Cucumber under Naturally Ventilated Polyhouse Condition

Abstract

Cucumber (Cucumis sativus L.) is a predominantly cross-pollinated self-fertile species characterized by diverse floral morphologies, including staminate, pistillate, and hermaphroditic flowers, which generally develop singly at each node. The determination and differentiation of floral sex in cucumber are profoundly regulated by exogenous application of plant growth regulators, which can alter floral architecture and sex expression. Gynoecious parthenocarpic cucumber lines, which are highly advantageous for off-season production due to their exclusive female flowering habit and seedless fruit development, naturally lack staminate flowers. Therefore, the exogenous induction of male flowers through hormonal treatments becomes imperative for effective line maintenance and seed propagation in breeding programs. A study conducted under Naturally Ventilated Polyhouse Condition” during Kharif season of 2023 and Summer season of 2024 in the naturally ventilated polyhouse of Department of Horticulture, S.K.N. College of Agriculture, Jobner (Jaipur) with aimed to manipulate the sex expression in the gynoecious parthenocarpic cucumber variety ‘PPC-6’ using a Randomized Block Design (RBD) with three replications. Three different chemicals viz., Gibberellic acid (GA3) @ 500 and 1000 ppm, silver  nitrate (Ag NO3) and silver thiosulphate (Ag2S2O3) @ 300 and 500 ppm were sprayed at 2-4 leaf stage at 7 days interval till the 10-12 leaf stage whereas, control was sprayed with distilled water only. Among the three chemicals, silver thiosulphate @ 300 ppm exhibited superior results for days taken to first staminate flowering (28.45 days), lowest node on which first staminate flower initiated (4.52), highest node number up to which staminate flower appeared (23.61), induced maximum staminate flowering nodes (19.09) and maximum number of staminate flowers per plant (134.28) was recorded under treatment MG5 (Ag2S2O3 @ 300 ppm) while, MG4 (AgNO3) was superior over other treatments in terms of diameter of staminate flower (5.30 cm). All the seven treatments were found to produce staminate flower, except control.