The effect of in vivo and in vitro applications of ethrel and GA3 on sex expression in bitter melon (Momordica charantia L.)

Bitter melon (Momordica Charantia L.) is an important vegetable crop with nutritional and medicinal qualities. As a member of cucurbitaceae it is monoecious with varying proportions of staminate and pistillate flowers. This study was undertaken to determine the effects of various applications of ethrel and gibberellic acid (GA(3)) on sex modification in M. charantia. In the first set of experiments, various concentrations of hormones were added to the seed germination medium, in the second, adult plants growing in the field were sprayed with aqueous solutions of ethrel or GA(3) three times at three-day intervals. The number and sex of open flowers was recorded daily for 60 days after the first flower opened and total number of staminate and pistillate flowers was calculated at the end of the experiment. The highest frequency (29.5%) of pistillate flowers was observed in plants treated with 500 ppm ethrel at germination. Similarly, spraying of adult plants with 100 ppm GA(3) increased the proportion of pistillate flowers to 26% relative to 15% in untreated controls. Both ethrel and GA(3) induced significantly higher number of pistillate flowers than control. In vitro hormone application during seed germination was much more successful than spraying of field grown plants.