Studies to Improve Seed Germination in Tetraploids Watermelon (Citrullus lanatus Thunb.)

Genetic improvement to produce seedless watermelon offers high quality fruits. This paper describes about problems related with tetraploid seed germination, various seed treatment to improve tetraploid seed germination and the morphological variations observed between the tetraploid and diploid seeds. Diploid watermelon seeds of three genetic backgrounds were treated with colchicine (0.2, 0.3 and 0.4%) and PEG (0.5%) as an adjuvent. Polyploid watermelon seeds have poor germination and low seedling vigor mainly due to thick seed coat and seed coat adherence to emerged cotyledons. In order to enhance the germination, the tetraploid seeds were subjected to five different seed treatments i.e; acid scarification, GA3 treatment, humidification, mechanical scarification and water soaking for 48hrs. Among the various treatments tested, maximum germination was recorded in the seeds subjected to water soaking for 48 hrs in all the three varieties. Tetraploids produce less number of seeds per fruit than those of diploids. Diploid seeds had complete filled cavity with embryo whereas tetraploids developed weak embryo with some empty cavity hence lower seed germination.