Chemical Reversion of Sex Expression on Dioecious Cucumber with Ethephon and a Benzothiadiazole1

Abstract The effects of 5-methyl-7-chloro-4-ethoxycarbonylmethoxy-2, 1, 3-benzothiadiazole (MCEB), a proposed inhibitor of ethylene action, and (2-chloroethyl) phosphonic acid (ethephon) on sex expression were observed in androecious and gynoecious phenotypes of cucumber ( Cucumis sativus L.) under greenhouse conditions. MCEB had no effect on the androecious phenotype while ethephon (50 ppm) induced pistillate flowers. The effect of MCEB and ethephon treatment was a marked reduction in the number of ethylene-induced pistillate flowers except when there was a 48-hour period between applications of ethephon and MCEB. In the gynoecious phenotype, MCEB (75 ppm) induced staminate flowers, ethephon had no effect, and the effect of MCEB and ethephon treatment was to induce staminate flowers at relatively high concentrations of MCEB (150 ppm).