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<p>Terminal heat stress is a major constraint to wheat production under global climate change, necessitating the identification of key adaptive traits and tolerant genotypes. This study evaluated 13 bread wheat (<i>Triticum aestivum</i> L.) genotypes under optimal and heat-stress conditions, focusing on morphological, physiological, and biochemical traits at the grain-filling stage. Significant genotypic variability was observed across all measured traits, indicating substantial diversity for heat adaptation. Based on the heat susceptibility index, genotypes TAW 119, DBW 187, and HD 2932 were identified as heat-tolerant. These genotypes exhibited minimal reductions in plant height, number of effective tillers, spike length, number of grains per spike, grain weight, and biological yield under stress, which was associated with enhanced scavenging of reactive oxygen species through increased enzymatic and non-enzymatic antioxidant activities. Physiologically, tolerant genotypes maintained higher chlorophyll and carotenoid content, leaf relative water content, membrane stability index, pollen viability, and canopy temperature depression, supporting sustained metabolic activity under heat stress. Biochemical analyses confirmed effective reactive oxygen species scavenging in tolerant genotypes, supported by elevated activities of catalase, ascorbate peroxidase, superoxide dismutase, and peroxidase, along with increased accumulation of proline and other osmoprotectants. Principal component analysis showed that the first two components explained 42.78% and 47.02% of the total variation under optimal and heat stress conditions, respectively, highlighting stronger trait divergence under stress. Biplot analysis identified catalase, ascorbate peroxidase, proline, grain filling rate, days to heading, superoxide dismutase, peroxidase, grain yield per plant, and grain filling duration as key traits contributing to heat tolerance. The identified tolerant genotypes and associated traits offer valuable resources for wheat breeding programs aimed at improving genetic gains and yield stability under high-temperature stress.</p>

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Integrated morpho-physiological and biochemical responses of wheat genotypes to terminal heat stress and their role in determining grain yield

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月7日

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  • Harsh Jainth,
  • Vijay Sharma,
  • Mukul Kumar,
  • Suman Bakshi,
  • Kamaluddin,
  • Pawan Kumar Prajapati,
  • Mohd Irshad Ali,
  • Himani Maheshwari

摘要

Terminal heat stress is a major constraint to wheat production under global climate change, necessitating the identification of key adaptive traits and tolerant genotypes. This study evaluated 13 bread wheat (Triticum aestivum L.) genotypes under optimal and heat-stress conditions, focusing on morphological, physiological, and biochemical traits at the grain-filling stage. Significant genotypic variability was observed across all measured traits, indicating substantial diversity for heat adaptation. Based on the heat susceptibility index, genotypes TAW 119, DBW 187, and HD 2932 were identified as heat-tolerant. These genotypes exhibited minimal reductions in plant height, number of effective tillers, spike length, number of grains per spike, grain weight, and biological yield under stress, which was associated with enhanced scavenging of reactive oxygen species through increased enzymatic and non-enzymatic antioxidant activities. Physiologically, tolerant genotypes maintained higher chlorophyll and carotenoid content, leaf relative water content, membrane stability index, pollen viability, and canopy temperature depression, supporting sustained metabolic activity under heat stress. Biochemical analyses confirmed effective reactive oxygen species scavenging in tolerant genotypes, supported by elevated activities of catalase, ascorbate peroxidase, superoxide dismutase, and peroxidase, along with increased accumulation of proline and other osmoprotectants. Principal component analysis showed that the first two components explained 42.78% and 47.02% of the total variation under optimal and heat stress conditions, respectively, highlighting stronger trait divergence under stress. Biplot analysis identified catalase, ascorbate peroxidase, proline, grain filling rate, days to heading, superoxide dismutase, peroxidase, grain yield per plant, and grain filling duration as key traits contributing to heat tolerance. The identified tolerant genotypes and associated traits offer valuable resources for wheat breeding programs aimed at improving genetic gains and yield stability under high-temperature stress.