TRIPLOIDY INDUCTION IN PACIFIC OYSTER CRASSOSTREA GIGAS BY CAFFEINE WITH THERMAL SHOCK

Zygotes of Pacific oyster (Crassostrea gigas) were treated for triploid induction with caffeine (10 mmol/L, 15mmol/L and 20mmol/L) in combination with thermal shocks (at 40 minute post -fertilization) lasting for 5 and 10 minutes. The highest yield of triploids, 41. 5%, was obtained from the treatment with 20 mmol/L caffeine at 34℃ lasting 10 minutes. The triploid levels were less than 30. 0% in other treatments. Triploid indution was more effective in treatment with 15 - 20 mmol/L caffeine at 34 - 38℃ than with lower concentrations of caffeine at temperatures below 32℃. Our results suggest tha triploid induction with caffeine in combination with thermal shocks is less efficient than some other methods reported previously.