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<p>The development of novel and improved wheat cultivars is optimally based on the variability present at the genetic level. This variability drives inheritance of key characteristics and enables the selection of superior plant types with tolerance against extreme environmental conditions such as terminal heat stress. A panel of 60 wheat accessions, representing diverse geographical origin, was evaluated over two years (2020 and 2021) in two replications. The study revealed extensive genetic variability linked to tolerance against high-temperature stress. Mean performance of all the traits declined under late sown conditions, particularly grain yield was reduced drastically from 14.47 to 8.99&#xa0;g per plant (37.9% decline). Moderate GCV and PCV were recorded for grain yield per plant, canopy temperature depression and grain filling rate under normal and stress conditions. Grain yield per plant and thousand grain weight showed good synergy in combination of high heritability with genetic advance as per cent of mean. Genetic characterization using molecular markers confirmed significant diversity among accessions. Principal component analysis revealed that the first two principal components accounted for 72.1% of the variance. The 60 accessions were analyzed for population genetic structure employing the molecular marker data. The population range from K = 2 to K = 10, with 5 replications per K showing the highest peak at K = 4. Heat susceptibility index for grain yield per plant identified accessions 24, 5, 14, 56, 47, 51, 16, and 38 as highly heat tolerant due to minimal yield reduction. Based on stress tolerance indices, accessions 5, 14, 24, 47, and 56 exhibited low values across multiple indices—including stress susceptibility percentage, percent yield reduction, relative stress index, and heat susceptibility index—while concurrently demonstrating high heat tolerance efficiency (HTE; 88.48–96.69%). Such accessions were identified as relatively stable and better performing under both conditions and can prove to be potentially useful for hybridization and future climate tolerant breeding programmes.</p>

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Exploring genetic diversity and stress adaptation in bread wheat (Triticum aestivum L.) under terminal heat stress

  • 期刊论文

  • 发表日期：

    2026年7月10日

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  • Shivani Upadhyay,
  • Sushma Tiwari

摘要

The development of novel and improved wheat cultivars is optimally based on the variability present at the genetic level. This variability drives inheritance of key characteristics and enables the selection of superior plant types with tolerance against extreme environmental conditions such as terminal heat stress. A panel of 60 wheat accessions, representing diverse geographical origin, was evaluated over two years (2020 and 2021) in two replications. The study revealed extensive genetic variability linked to tolerance against high-temperature stress. Mean performance of all the traits declined under late sown conditions, particularly grain yield was reduced drastically from 14.47 to 8.99 g per plant (37.9% decline). Moderate GCV and PCV were recorded for grain yield per plant, canopy temperature depression and grain filling rate under normal and stress conditions. Grain yield per plant and thousand grain weight showed good synergy in combination of high heritability with genetic advance as per cent of mean. Genetic characterization using molecular markers confirmed significant diversity among accessions. Principal component analysis revealed that the first two principal components accounted for 72.1% of the variance. The 60 accessions were analyzed for population genetic structure employing the molecular marker data. The population range from K = 2 to K = 10, with 5 replications per K showing the highest peak at K = 4. Heat susceptibility index for grain yield per plant identified accessions 24, 5, 14, 56, 47, 51, 16, and 38 as highly heat tolerant due to minimal yield reduction. Based on stress tolerance indices, accessions 5, 14, 24, 47, and 56 exhibited low values across multiple indices—including stress susceptibility percentage, percent yield reduction, relative stress index, and heat susceptibility index—while concurrently demonstrating high heat tolerance efficiency (HTE; 88.48–96.69%). Such accessions were identified as relatively stable and better performing under both conditions and can prove to be potentially useful for hybridization and future climate tolerant breeding programmes.