Two tolerant genotypes (BPR-542-6 and NRCDR-02) and two susceptible genotypes (NPJ-119 and RGN-152) were screened at 45±0.5°C on the basis of time taken to 50% seedling mortality. Lipoxygenase, MDA and H2O2 which are indicators of cell membrane damage increased under heat stress in all the genotypes but increase was higher in susceptible genotypes. On recovery, LOX, MDA and H2O2 content decreased in all the genotypes. The activities of antioxidative enzymes viz. SOD, POX, CAT, APX and GR increased under high temperature stress. SOD and CAT started decreasing but activity of POX and GR still...