Comparison of Physio-Biochemical and Yield Traits in Barley (Hordeum vulgare L.) Germplasm under Terminal Heat Stress Conditions in Northern India

Heat stress is an extremely detrimental stress greatly influencing the crop productivity in Punjab, India. Long-duration barley (Hordeum vulgare L.) varieties are more sensitive to heat injury due to the overlapping of the crop’s reproductive phase and the heat wave. This emphasizes the need to identify key traits conferring heat tolerance to screen and develop heat tolerant barley germplasm. The present field investigation was carried out to compare physio-biochemical traits and yield attributes of nine heat-tolerant (BL1515, BL1729, BL1780, BL1784, BL1786, BL1792, BL1794, BL1797, and IBYT-E24) and three heat-sensitive barley genotypes (BL1723, IBON23, and IBYT-E15) under timely (optimum environment) and late sown conditions (terminal heat stress environment at reproductive stage) during the rabi seasons of 2019–2020 and 2020–2021. The experiment was conducted in factorial randomised block design with four replications. The pooled analysis showed high proline content, membrane stability index and low malondialdehyde content in heat-tolerant genotypes as compared to heat-sensitive genotypes under terminal heat stress conditions. Heat-tolerant genotypes exhibited superior physio-biochemical traits, i.e., primary metabolites and activities of antioxidant enzymes than heat sensitive genotypes. Yield reduction was substantially greater in heat-sensitive genotypes under terminal heat stress conditions than in heat-tolerant genotypes of barley. Thus, it is imperative to select heat-tolerant genotypes which can withstand heat stress and suffer less yield loss. These genotypes may aid in developing mapping populations and deciphering the molecular basis of key heat tolerance genes in barley germplasm.