Abstract: The cotyledons and hypocotyls of early-ripen nectarine varieties, ‘Huaguang’ and ‘Shuguang’, were cultured in order to study the factors affecting their regeneration, such as density and combination of plant growth moderators, culture medium and embryo developing phases. Cotyledons of different development stages, namely 30, 40, 50, 60 days after blossom and mature cotyledons respectively, was cultured with MS medium mixed with BA, TDZ, ZT, KT and NAA. The results showed that the best time to culture cotyledons of‘Huaguang’was 60 days after blossom and the regeneration rate of the cotyledons was 75% when they were cultured with MS + TDZ 2 mg/L +NAA 0.04 mg/L. Mature cotyledons, 68 days after blossom, were the best for‘Shuguang’and the regeneration rate was 6617% when the cotyledons were cultured with MS +BA 8 mg/L +NAA 0.04 mg/L. There was no remarkable difference between upper and lower hypocotyls in their culture. The Gmedium combined with TDZ 3.0 mg/L, KT 1.0 mg/L, and NAA 3.0 mg/L was the best for Huaguang's hypocotyls regeneration. The QL medium combined with TDZ 2.0 mg/L and NAA 0.5 mg/L was the best for Shuguang's hypocotyls regeneration. The hypocotyls could directly regenerate plants.

Key words: Nectarine, Hypocotyl, Cotyledon, Plant regeneration