The effect of heat shock and timing on the induction of tetraploidy in Catfish, Heteropnestus fossilis

Abstract

ABSTRACTThis research aims to discover the right physiological age of fertilized egg for tetraploid induction and the parameters of heat shock treatment in Heteropnestus fossilis. The heat shock parameters are shock temperature (39°C, 40°C, and 41°C); time at which the shock is initiated (23 to 28 min after fertilization) and for a duration of 1, 2 and 3 min. The confirmations of tetraploid were based on chromosome counting. The result indicates that the window time to start the heat shock treatment for maximum tetraploid induction is 25 to 27 min after fertilization at an ambient water temperature of 27°C. Shock treatment at 40°C and for 2-min duration, stated at 27 min after fertilization has shown highest tetraploid induction, i.e. 28% (p < .05) with 76% survival. Tetraploids form the main source for the induction of higher ploidy levels.