（1State Key Laboratory of Vegetable Biobreeding，Institute of Vegetables and Flowers，Chinese Academy of Agricultural Sciences，Beijing 100081，China；2Harbin Academy of Agricultural Sciences，Harbin 150030，Heilongjiang，China）
Abstract：The cotyledon nodes of 10 cultivars with different genotypes were used as explants to study the effects of exogenous phytohormone concentration ratios，method of obtaining explants，types and concentrations of antibiotics on the regeneration efficiency in Cucurbita maxima Duch．The results showed that the regeneration efficiency was greatly affected by the genotype and exogenous phytohormones concentration ratio in the shoot induction medium．The optimal formula of the shoot induction medium is 1.0-2.0 mg·L-1 6-BA + 0.5 mg·L-1 ABA．The cutting time，cutting method，and inoculation method of explants are also important factors affecting the regeneration efficiency．After seeding for 24-48 h，cutting 1/2 or 1/4 cotyledon nodes for explants and inserting them at 45o angle on the shoot induction medium can improve the regeneration efficiency．Supplemented with 100 mg·L-1 Cefotaxime sodium（Cef）in shoot induction medium can effectively inhibit bacterial infection．
