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| Fig:- Female Flower |
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| Fig:- Male Flower |
plants that have an imbalance sex ratio of male-female flowers that causes lower fruit yield. Different
research works on cucurbits like bitter gourd and other related crops in respect of plant growth regulators, plant nutrients, and priming practices have been conducted in different parts of the world. Literature related to the present study has been reviewed and found that bitter gourd genotypes produced larger male-female ratio and the induction of male flower was earlier than that of female ones. Growth regulators have a significant positive effect on yield and yield components. Application of gibberellic acid (GA3) enhanced the length of the main vine but decreased the primary branches while ethylene producing chemicals Canadian Environmental Protection Act (CEPA) increased the number of primary branches per plant. Application of auxin like 1-naphthaleneacetic acid (NAA) at 50 and 100 ppm and CEPA at 150 ppm also proved to be effective in inducing earlier female flowers at lower node. Application of CEPA at 150 ppm and NAA at 50 ppm was found to be the best treatments for reducing sex ratio by increasing the female flowers by suppressing the male ones and consequently induce higher yield.
Table 1: Effect of different levels of plant growth regulators and NPK fertilizers on sex expression in bitter gourd.
Table 2. Interaction effect of different levels of NPK fertilizers and plant growth regulators on initiation of first flower (male and female) grown in summer
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| *No. of days after sowing of seeds. F: Effect of different levels of NPK fertilizers. PGR: Effect of different plant growth regulators. F × PGR = Interaction effect of different levels of NPK fertilizers and plant growth regulators. CV: Coefficient of variance. |
Conclusions
Among the many factors which determine the low yield, sex ratio and synchrony of male-female flowers and suitable genotype are more important. Days to first flower initiation, number of total female flower and sex ratio was significantly influenced by different genotypes. The days to first male and female flowers varied from 39.4 to 51.17. The results indicated that the days to flower initiation might be controlled by inherent characters of genotypes.
Application of different doses of plant growth regulators and NPK fertilizer significantly influenced the female flower induction and synchrony of male-female flowers. Application of CEPA at 150 ppm and NAA at 50 ppm produced a lower sex ratio by increasing the female flowers by 40 and 28% over control (no spray). Among the plant growth regulators, CEPA is the superior of all for producing the maximum number of female flowers plant-1. On the other hand, the combined effect of treatment