Efeito do ácido 2-cloroetilfosfônico (Ethephon) no florescimento e na frutificação do pepino (Cucumis sativus L)

Resumo

Two experiments were performed under greenhouse conditions to study the effects of ethephon (2-chloroethylphosphonic acid), on sex expression, growth and production of the monoecious cucumber (Cucumis sativus L.) "Aoday" cultivar. The applications were made by spraying to runoff at the seedling stage or at various other stages of plant development. 

Increasing ethephon concentrations (100, 200 and 400 ppm) caused significant increases in the number of pistillate (female) flowers which were located primarily on the main stem. The same ethephon concentrations caused a significant decrease in the number of staminate (male) flowers, and in the formation of these flowers at higher nodes. The application of 500 ppm of ethephon at the seedling stage followed by two applications of 250 ppm was effective in transforming monoecious cucumber plants into completely gynoecious plants. The ethephon treatments of 200 and 400 ppm resulted in significant increases in the early yield of plants. However, at the end of the growth cycle, the marketable fruit production of treated plants was not statistically different from that of control plants. The application of several ethephon sprays did not affect the number of mature fruits produced per plant or seed germination percentage but reduced significantly plant height and internode length.