Abstract: Hybrid plants were obtained from 5 crosses between Cymbidium sinense and Cymbidium hybridium. The genotype of germination by protocorm like-body (PLB) of C. hybridium is controlled by dominant gene (s) . Because all of these hybrid embryos , whatever C. sinense ×C. hybridium or C. hybridium ×
C. sinense , are germinated by PLB , which is the same as C. hybridium. Four factors of NH₄NO₃ 、KH₂ PO₄ 、6-BA and NAA with three different concentration (L₉) were designed to study the effects on induction and propagation of PLB of C. ‘Jin Zui ’×C. ‘Forgotten Fruits’. Analysis of variance shows : The different concentration among the factors which are NH₄NO₃ 、KH₂PO₄ and 6-BA influences the induction and propagation of PLB directly , There is no difference with different concentration of NAA. NH₄NO₃ 1650 mg·L ^-1 (MS normal levels) , higher concentration of KH₂PO₄ (170 - 850 mg·L ^-1) and BA densities (1 - 10 mg·L ^-1) was favorable to propagation of PLB. There are extremely remarkable differences among 9 media , the best is C5 medium with NH₄NO₃ 1650 mg·L ^-1,KH₂PO₄ 340 mg·L^-1and 6-BA 10 mg·L ^-1 .

Key words: Cymbidium sinense, Cymbidium hybridium, Hybrid PLB, Propagation