EFFECT OF VINE CLIPPING ON FLOWERING AND SEX EXPRESSION IN WATERMELON PLANT DURING WINTER SEASON WITH AMBIENT AND ELEVATED TEMPERATURE BY LOW-TECH GREENHOUSE

Although watermelon fruits have year-round demand to the all classes and ages people in Bangladesh but its cultivation is mostly concentrated to the summer season. Previously we failed to cultivate the watermelon in winter season by elevating temperature using low-tech greenhouse where fruit production was mostly limited due to the poor initiation of female flower. It is thought that apical dominance is responsible under warmer low-tech that’s why excessive vine growth was occurred along with poor initiation of pistillate flower. Therefore the present study was carried out in 2016/2017 autumn and winter season in the Department of Crop Botany, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh to investigate whether the vine clipping could facilitate the female flowering along with fruit setting through reducing the effect of apical dominance in growing watermelon plants. Four varieties of watermelon viz. Sonya, Black Dorin, Badsha and Dragon were grown both in low-tech and that at outside. Both low-tech plants and that grown at outside were treated with (i) no vine clipped (control), (ii) mother vine clipped following the emergence of fourth primary vine, and (iii) all primary vines regularly clipped allowing mother or cotyledonary vine only. Air and soil temperatures increased inside the low-tech than that at outside which significantly hastened all the phenophase events like days to appearance of first vine, first leaf, and first male and first female flowers, and first physiological maturity of fruit. Results showed that initiation of female flowering in low-tech watermelon plants slightly improved when primary vines were clipped allowing mother vine only, and there was no effect on female flowering when mother vine was clipped. Consequently, vine clipping treatments did not significantly improve fruit setting and yield in watermelon plants. Therefore, investigation using plant growth regulators is suggested for exploring watermelon cultivation using low-tech greenhouse during winter season in Bangladesh.