Effects of freeze and cold stress on certain physiological and biochemical traits in sensitive and tolerant barley (Hordeum vulgare) genotypes

ABSTRACTAn experiment was performed as a split-plot design based on a randomized complete block (RCB) with three replicates. The aim was to explore physiological traits, catalase (CAT) and peroxidase (POD) activity associated with cold and freeze stress in four barley genotypes (two stress-tolerant genotypes and two sensitive genotypes). The genotypes were regarded as sub-plots and five temperature levels (namely 20, 4, 0, −4, −8°C) as main plots. The results revealed that the hydrogen peroxide (H2O2) and malondialdehyde (MDA) content increased through freeze and cold stress from 20 to 4°C. This increase was more in the sensitive genotypes than in the tolerant ones. Subsequent to the increase in lipid peroxidation, the membrane stability index (MSI) decreased, thereby increasing the electrolyte leakage. The sensitive genotypes demonstrated greater reduction in the studied parameters. Upon the increase in the H2O2 content, the antioxidant enzymes CAT and POD also increased in order to collect and prevent H...