Abstract: Chinese soft-shelled turtle (Trionyx sinensis) belongs to the group of temperature-dependent sex determination. Here we examined the effects of exogenous 17α-methyl testosterone (MT) and estradiol (E₂) on the sex determination of embryos during the sensitive stage as well as the primary sex characters of young softshelled turtles. The two kinds of hormones were injected into embryos during the sensitive period of sex determination. Results showed that hormones treatment  significantly affected embryo survival rate. The average hatching time of embryos in the E₂ group was 5.5 days earlier than that in the control, while that of the MT group was slightly later than that in the control. Turtles in the MT and E₂ groups were all males and females, respectively, while the ratio of male to female in the control group was 3∶11. Young turtles were fed for 40 days with different concentrations of MT and E₂ after 20 days of domestication. Three treatment groups (25, 50 and 100 mg·kg^-1) for each hormone and a control group were set up. Hormones treatment had no significant effect on the survival rate but promoted the morphological development of young soft-shelled turtles. After 40 days of feeding, the sex ratio (number of male∶number of undetermined sex∶number of female) of the 50 mg·kg^-1 E₂ treatment group changed from 19∶6∶15 to 19∶0∶4. The final female ratio (17.39%) was not significantly different from the control group (16.67%), but the proportion of females in the 25 mg·kg^-1 E₂group and the 100 mg·kg^-1 E₂ group was 0. The sex ratio (number of male∶number of undetermined sexnumber of female) of the MT treatment groups were 9∶0∶0, 19∶0∶0 and 8∶0∶0 respectively, all of which were males, with the primary sex characters being more obvious than that of the E₂ group and control.

Key words: karst, Praxelis clematidea, meta analysis, invasive plant, diversity, linear mixed effect model.