Development of colchitetraploids with improved fertility in watermelon

Tetraploid plants were produced in the watermelon cultivar ‘Sugar Baby’ through seedling treatment with colchicine solution (0.5%). Path coefficient analysis was conducted to find out the relative contribution of selected characters towards number of seeds across C1, C2 and C3 generations of tetraploid population originated from 0.5% colchicine treatment. Direct effect of number of chloroplasts per guard cell was found highly significant for seed number (r = 0.269). Among other characters days to emergence of male (r =-0.307) and female flower (r =-0.259) and gourd cell width (r =-0.33) exhibited highly significant negative direct effect on seed number. Tetraploids could be improved for seed number by selecting the plants in each generation with high chloroplasts per guard cell (>22), earliness to form male flower (<48 days), female flower (<53) and low gourd cell width (<22 μm).