Abstract
Heat stress is one of the abiotic stresses that cause a significant reduction in barley yield. Climate change will increase the number of heatwaves, which will result in more deterioration in the agricultural sector. Therefore, understanding the physiological changes that occur in the plant to tolerate heat stress is very important. A collection of 60 Egyptian spring barley genotypes has been tested for heat stress under field conditions. To quantify the changes in yield-related traits and the grain-reserve parameters as indicators for heat tolerance, several traits were scored. The causative genes that regulate the variation of all traits of interest were identified via single-marker analysis using 16,966 single nucleotide polymorphisms (SNP). Heat stress reduced yield-related traits, while some physiological traits (chlorophyll index, soluble carbohydrates, amino acids, and proline contents) increased. The genotypes were classified into four classes, A, B, C, and D, based on a reduction in grain yield per spike (GYPS) of 10%, 20%, 30%, and 40%, respectively. The physiological aspects were extensively studied in each group. The tolerant genotypes (class A) retained high yield-related traits as well as high reserved metabolites relative to the sensitive class D. The single-marker analysis and gene annotations revealed that the most effective markers and genes resided on chromosomes 1H and 4H. One of these markers, S4_250499621, was found to be associated with increased proline content, increased chlorophyll content, and decreased reduction in grain yield per spike and thousand kernel weight. This study is a part of our extended evaluation of this collection under various abiotic stresses at different developmental stages to develop climate-resilient crops.
Highlights
Food security is one of the most pressing global issues, with recent global climate change, which adversely affects plant development and yield
For grain yield per spike (GYPS), the genotypes were normally distributed under both conditions
Most the other traits showed a normal distribution under both conditions; control and heat stress (Figure S2)
Summary
Food security is one of the most pressing global issues, with recent global climate change, which adversely affects plant development and yield. Mainly heat waves, the expected rise in average day temperature or shift to warmer seasonal temperatures will substantially reduce crop productivity and quality. Barley is very vulnerable to high temperatures, leading to poor plant growth, plant development, and lower productivity. Winter-season climate changes globally often have short-term cool periods and longer warm periods. Plants grown in these conditions could be subjected to heat stress, during the reproductive. Lobell et al [2] suggested that increasing the average daily temperature by a few degrees would cause considerable reductions in grain yield.
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