Document Type : Research Paper
Authors
1
Agronomy and Plant Breeding Department, Faculty of Agriculture, Yasouj University, Yasouj, Iran.
2
Agronomy and Plant Breeding Department, Faculty of Agriculture, Yasouj University, Yasouj, Iran; Department of Genetics and Plant Breeding, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.
3
Dryland Agriculture Research Institute (DARI) of Gachsaran, Gachsaran, Iran.
10.22034/jppb.2026.69702.1392
Abstract
Objective: One of the most important factors limiting the yield of a crop, including barley, is water-deficit stress during critical stages of growth. Water-deficit stress reduces barley yield and associated traits, compared to optimal conditions. Previous studies have reported that drought stress significantly increases the activity of antioxidant enzymes. This study aimed to identify water-deficit-stress-tolerant barley genotypes by assessing some morphological and enzymatic traits.
Methods: In this study, the tolerance of 18 barley genotypes to water-deficit stress was evaluated based on some morphological and enzymatic traits. Two field experiments were conducted in a randomized complete block design with three replications: one under optimal irrigation and the other under limited irrigation, where water was withheld at the 50% flowering stage (Zadok`s 10.5.2). Following, some enzymatic and agronomic characteristics were measured, including catalase (CAT) and peroxidase (POD) activity, 1000-grain weight, number of tillers, spike length, number of grains per spike, plant height, biomass and grain yield. For the measured traits, genetic coefficient of variation, phenotypic coefficient of variation, and heritability were estimated. Also, cluster analysis was conducted to group genotypes under both water-deficit stress and normal conditions. In addition, the stress tolerance index (STI) was calculated to identify water-deficit-stress tolerant genotypes.
Results: The effect of genotype was significant for all traits, except for POD and CAT. Also, water-deficit stress significantly affected the plant height, biomass, grain yield, peroxidase, and catalase. However, the interaction between genotypes and irrigation conditions was significant only grain yield and biomass. According to analysis of variance of the data, the estimates of genetic coefficients of variation, and cluster analyses, there was appreciable variation among the barley genotypes for most of the traits measured in this experiment, The Genotypes 12 and 17 exhibited a higher biomass and grain yield in both normal and water-deficit stress conditions. The Genotypes 6, Mahour, 8, 3, and 4 showed the highest STI values than the rest of the genotypes; however, their grain yield was much lower than the Genotypes 12 and 17 in both normal and water-deficit stress conditions, and may only be used to exploit their drought-tolerance genes in breeding programs. Enzyme activity analysis suggested that CAT is a more reliable indicator than POD in alleviating the adverse effects of the water-deficit stress. Also, CAT exhibited higher genetic coefficient of variation and heritability than POD under both conditions. The number of grains per spike showed noticeably higher heritability values than grain yield under both normal and water-deficit stress conditions. Also, a high heritability was observed for1000-grain weight under stress conditions. Thus, indirect selection for the grain yield through the number of grains per spike and 1000-grain weight may be useful in segregating generations under water-deficit stress conditions, and through the number of grains per spike in normal conditions.
Conclusion: According to our results, the Genotypes 12 and 17 can be recommended for future evaluation in breeding programs under normal and water-deficit stress conditions. The Genotypes 6, Mahour, 8, 3, and 4 had the highest STI values but lower grain yield than the Genotypes 12 and 17. To exploit their drought-tolerance genes, it may be useful to cross them with the better-yielding Genotypes 12 and 17 to facilitate the development of high-yielding and drought-tolerant barley lines.
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