Objective The purpose of this experiment is to explore the optimal induction conditions for inducing triploidy of Siniperca scherzeri using cold shock method.

Method The experiment set three induction time point (TP) (2.5, 4, 5.5 min after insemination), three induction temperatures (T) (2, 4, 6 ℃), and three induction durations (D) (10, 12, 14 min) ,respectively. Nine experimental groups were obtained using the orthogonal experimental table L₉(3⁴), and denoted as P1~P9, respectively, with P0 (S. scherzeri normally developed at 22 ℃) serving as the control (untreated) group .

Result 1) Cold shock had a significant effect on the hatching rate of fertilized eggs in S. scherzeri, with the hatching rate of P0 group was extremely significantly higher than those of other groups (P<0.01). 2) Group P4 (TP 4.0 min, T 2 ℃, D 12 min) exhibited the highest triploid induction rate in S. scherzeri at (83.33±5.77)%, followed by group P5 (TP 4.0 min, T 4 ℃, D 14 min) at (73.33±5.77)% and group P7 (TP 5.5 min, T 2 ℃, D 14 min) at (70.00±0.00)%. The induction rates of group P7 and P5 were not significantly different from that of group P4 (P>0.05), but were significantly higher than those of other groups (P<0.05). While P9 (TP 5.5 min, T 6 ℃, D 12 min) group had the lowest induction rate at only (3.33±5.77)%.3) The interaction among TP, T and D was not significant (P>0.05), but significant interactions existed between each pair of the three factors (P<0.05), and no primary-secondary relationship existed among the three factors. 4) One-way ANOVA showed that the triploid induction rate in S. scherzeri at 4 min after insemination (TP) was significantly higher than those at 2.5 min and 5.5 min after insemination (P<0.05). The triploid induction rate in S. scherzeri at 2-4 ℃ (T) was significantly higher than at 6℃ (P<0.05). The triploid induction rate in S. scherzeri at 12-14 min (D) was significantly higher than at 10 min (P<0.05). 5) The total length and body mass of 6-month-old triploid S. scherzeri showes no significant differences compared with those of diploids (P>0.05).

Conclusion Triploidy can be successfully induced in S. scherzeri by the cold shock method. Using the induction rate as the evaluation index, the suitable conditions for inducing triploidy in S. scherzeri by the cold shock method are as follows: induction time point at 4.0 min after insemination, induction temperature at 2-4 ℃, and induction duration of 12-14 min. The optimal conditions are induction time point at 4.0 min after insemination, induction temperature at 2℃, and induction duration of 14 min.