1 Institute of Vegetables and Flowers，Chinese Academy of Agricultural Sciences，Beijing 100081，China；2 College of Agronomy，Yanbian University，Yanji 133002，Jilin，China；3 Shouguang Vegetable Research and Development Center， Chinese Academy of Agricultural Sciences，Shouguang 262704，Shandong，China
Abstract：In order to establish a high efficient watermelon cotyledon regeneration culture system，this paper took watermelon variety ‘Xiangxiu’of small fruit type as test material；selected cotyledon cultured under aseptic conditions for 4-5 days as explant；and studied the effects of exogenous hormones（6-BA， NAA，IAA and IBA）on the regeneration of watermelon cotyledons in vitro．Results showed that the optimal medium for inducing adventitious buds was MS + 2.25 mg · L-1 6-BA + 0.1 mg · L-1 NAA．The induction rate was 90.56%．The optimal medium for adventitious bud elongation was MS + 1.0 mg · L-1 6-BA + 0.50 mg · L-1 IAA．The optimal medium for rooting was 1/2MS + 1.0 mg · L-1 IBA．The rooting rate could reach 93.33%． The survival rate of regeneration seedling after acclimitation and transplant could reach 98.33%．It took about 63 days from cotyledon inoculation to acquisitio of transplantable regenerated seedlings．
