Induction of polyploidy in watermelon (Citrullus lanatus (Thunb.) Matsum and Nakai.)

摘要

Polyploidy was induced in three varieties of watermelons (Citrullus lanatus (Thunb.) Matsum and Nakai) by colchicine treatments. Colchicine treatments of 0.2 and 0.3 per cent treatments to shoot apices of six to seven day old seedlings of the three varieties viz., Arka. Manik, Sugar Baby and Triumph for four consecutive days were effective in inducing polyploidy. However colchicine treatment to seeds was ineffective. Polyploid plants have broader and thicker leaves of dark green colour, larger stomata and pollen grain and reduced pollen fertility, delayed flowering and fruit size than their respective diploids. Anther squashes of the five polyploid C-1 plants of the three varieties showed chromosome number of 2n=44 as against 2n=22 in their respective diploids.Watermelon (Citrullus lanatus (Thunb.) Matsum and Nakai.) having the chromosome number of 2n=22 is a vegetable fruit crop containing high amount of water alongwith sweet taste i.e. dessert fruit mainly grown in tropical and subtropical areas during summer season. Development of seedless watermelon fruit has been emphasized in watermelon. Polyploidy plays important role in the development of seedless triploid watermelon A triploid plant can be produced by crossing tetraploid (4n) female with diploid (2n) male.