Control of sex expression in Cantaloupe (Cucumis melo L.) by ethephon application at different growth stages

Tests were done to investigate the effect of ethephone to control male flowers in melon. The tests were done as a split plot experiment in a randomized complete block design with three replications during two years at the Agriculture and natural resource Research Center of Tehran-Iran. The main factor was three growth stages (3 and 6-leaf stages and early reproductive growth) and four levels (0, 100, 200 and 300 mg l -1 of effective substance ethephon) selected for tests in subplots. Traits measured in the experiment were: the appearance time of female flowers per plant, numbers of male and female flowers recorded 7 and 14 days after being sprayed with ethephon, total yield, and ratio (female/male) of flowers. Results showed that plant response to increasing concentrations of ethephon differed according to a plant’s stage of development. With increasing ethephon concentration, times for flower emergence (male and female) were delayed. The highest yield (26430 kg ha -1) was obtained with consumption of 200 ppm ethephon in trifoliate plants. In this case, the ratio of male to female flowers was the highest (81.5%). A high dose of ethephon (over 200 ppm) at all stages of plant growth, especially at the reproductive growth stage was associated with reductions of yield and ratio of female to male flowers.