Preliminary Study on the Induction in vitro of Tetraploid Mini-watermelon

[Objective] The study aimed to lay a foundation for breeding the triploid mini-watermelon.[Method] With the cotyledons of good inbred line MH-39-1 in diploid mini-watermelon as explants,the induction in vitro of tetraploid mini-watermelon was studied.[Result] The differentiation rate of adventitious buds from its cotyledons treated with 100 mg/L colchicine was up to 66.7% and the average number of adventitious buds differentiated from its cotyledons was 6.7.The induction rate of tetraploid in treatment with 400 mg/L colchicine was 20.0%.The differentiation rate of adventitious buds was 83.3% in treatment with colchicine for 12 h and 16.7% in treatment with colchicine for 48 h.The induction rate of tetraploid in treatment with colchicine for 24-36 h was 16.7%.The differentiation rate of adventitious buds was 83.3% in treatment with 4.0 mg/L BA and 58.3% in treatment with 1.0 mg/L BA.The rooting rates of regenerated buds on the 4 rooting media were higher than 90%,the average rooting number of regenerated seedlings on the media without plant growth regulator was only 6.5,that on the media with NAA was more than 10 and the roots were short and thick.[Conclusion] It was preliminarily determined that the suitable concn.and treatment time for inducing tetraploid mini-watermelon in vitro with colchicine were 400 mg/L and 24 h.