[Enhancement of plantlet regenerative efficiency of watermelon in vitro]

The purpose of this study was to enhance shoot regenerative efficiency of watermelon by optimizing culture parameters. Cotyledons at 4-day seedlings were explanted and cultured on MS medium supplemented with different combinations of hormones. In "Yixuan" cultivar, the plantlet regenerative frequency and shoots produced by per explant was as low as 10% and 0.4 respectively at all combinations tested when distal parts of cotyledons were inoculated. Whereas, maximum regenerative frequency of 100 percentage and 10.3 shoots regenerated from per explant were observed on MS medium supplemented with 5 mg/L BA and 0.1 mg/L IAA using basal parts of cotyledons as explants. Likewise, in "Jingxinmuben" cultivar, the highest regenerative frequency of 100 percentage and 6.9 shoots regenerated from per explant were obtained when proximal parts of cotyledons were cultured on MS medium containing 2 mg/L BA and 0.5 mg/L IAA. In the present study, adventitious buds were initiated after only 4 d in culture and intact plantlets were obtained in 40 d culture. This will facilitate quicker gene transformation and polyploidy induction of watermelon in vitro.