Use of ethephon on a summer squash line.

To determine the effects of ethephon application on a summer squash line (Cucurbita moschata), four concentrations (0, 200, 400 and 600 ppm) of the product were applied at the 1^st, 1^st and 3 ^rd and 1^st and 5^th true leaf stages. Three replications of ten plants for each treatment were set out in a complete randomized block design. Number of flowers and mature fruits per plant were evaluated. A second experiment was carried out to evaluate the number of true leaves and leaf area per plant 54 days after sowing. Ethephon was applied only at the 1^st true leaf stage using the same product concentrations as in the first experiment. It was concluded that this summer squash line was very sensitive to ethephon, showing a reduction of leaf area, number of flowers and mature fruits per plant. A large reduction in the male to female flower ratio was observed, mainly due to a reduction in the number of male flowers/plant. Reversion of male to female flowers however was not enough for a complete change in the sex expression of this line from monoecious to gynoecious.

Cucurbita moschata; sex expression; flowers.