Triploid Induction of Green Tiger Shrimp, Penaeus semisulcatus (De Haan, 1844) Using Temperature and Chemical Shock

Triploidy in fertilized eggs of Penaeus semisulcatus was induced by temperature and chemical shocks. The eggs, which were obtained from the shrimp broodstock maintained at 29C, were exposed to cold temperature (8, 10, 12, and 14 C) and 6-dimetiloaminopurine (6-DMAP) concentrations (100, 150, 200, and 250 M) for different durations (4, 6, and 8min) 9min after spawning was detected. While the highest triploidy rate of 49.7 +/- 4.5% was obtained with a 200M 6-DMAP concentration for a duration of 8min, the best mean triploidy rate of 45.5 +/- 2.8% for cold shock was obtained at a temperature of 10 C for a duration of 8min. Temperature and 6-DMAP concentration did not have significant effect on triploidy rate (P>0.05) but shock duration had significant effect on triploidy rate for individual cold temperature shock or 6-DMAP chemical shock (P<0.05). Although longer durations of shock agent increased the rates of triploid induction, they generally had an adverse effect on hatching rates in the study.