Abstract:The eggs of Chlamys farreri were activated by ultraviolet irradiated heterogenous sperms of Pacific oyster Crassostrea gigas and the pro embryos were induced by inhibiting extrusion of the second polar body from fertilized eggs with 6 DMAP. Those eggs were treated with different parameters of 6 DMAP which were designed in the method of orthogonal experiment design L9（34）. It was found that the occasion of starting time, the length of the treatment time and the concentration of 6-DMAP were important factors to affect the derivational rate of diploids. The statistic data of the trochophores' chromosomes in the nine groups was analysed with the software SPSS115. Results showed that all the three factors had prominent effect on the derivational rate of diploids; the relationship between the rate of malformed embryos and the rate of diploids was negative correlation and the equation was y=46.632-0.891x (r=-0.813，P＜0.01）. Based on the relationship between derivational rate of diploids and the rate of malformed embryos, in the stated range, it was confirmed that the optimal inducing condition of 6-DMAP for gynogenesis in the C. farreri was that the eggs were to be treated with 6-DMAP at the concentration of 60μg per ml for 25 minutes when of the fertilized eggs expelling first polar body 20% to 25%. In this way, 29.5±5.36% diploidinduction could be got. In this study, the states of poly ploidy yield in the treatment groups were also discussed.
