Evaluation of Seedling Growth and MDA Content of Wheat Genotypes in Relation to Heat Tolerance

Forty wheat genotypes were grown in petriplates at different temperature treatments (25±2, 35±2 and 40±2˚C) to study the effect of heat stress on germination, growth rate and Malondialdehyde content (MDA). Vigor index and Relative Growth Rate (RGR) showed significant reduction with increasing temperature treatments (25±2 to 40±2˚C). Heat tolerant genotypes had higher values of vigor index and relative growth rate than heat sensitive genotypes. Whereas the MDA content of seedling at 35±2 and 40±2 oC were higher as compared to those at 25 oC. The increments of MDA content from 25 to 40 oC were significant for all wheat genotypes. Heat sensitive genotypes accumulated more MDA content due to enhanced lipid peroxidation of membranes than tolerant and moderately tolerant genotypes. The seedling MDA content at higher temperature treatments also showed significant negative correlation with membrane thermostability (r= -0.617 and -0.861 at 35 and 40 oC respectively) across the 40 wheat genotypes indicating that wheat genotypes with lower MDA content tended to show greater membrane thermotolerance.