Document Type : Research Paper
Authors
1
Ph.D. Student, Department of Plant Production and Genetics, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
2
Professor, Department of Plant Production and Genetics, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
3
Research Assistant Professor, Department of Crop and Horticultural Science Research, Fars Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Darab, Iran
4
Research Assistant Professor, Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
10.22124/cr.2025.29400.1847
Abstract
Introduction
Barley (Hordeum vulgare L.) is one of the world’s most important cereal crops, adapted to a range of abiotic stresses, particularly drought, salinity, and cold. Because it is primarily cultivated under arid and semi-arid conditions, therefore this study aimed to select genotypes tolerant to terminal-drought stress based on morpho-phenological traits and to identify traits those traits most closely associated with grain yield.
Materials and methods
In this study, 17 promising barley genotypes and four control genotypes (Including varieties of Auxin, Golchin and Norooz and promising line WB-99-10) were evaluated under two irrigation regimes (non-stress and terminal drought stress conditions) in a randomized complete block design with three replications over two cropping seasons (2002-2024) at the Darab Agricultural Research Station. Drought stress was applied by stopping irrigation at the spike emergence stage. The measured traits included of grain yield, number of spikes per square meter, number of grains per spike, grain weight per spike, thousand grains weight, length of grain filling period, spike length, awn length, plant height, number of days to heading, number of days to maturity, grain filling rate, the number of rows of spikes, type of awn, spike harvest index and spike fertility index. Principal component analysis (PCA) and cluster analysis were used to grouping of genotypes, and the silhouette index was used to optimally evaluate groups.
Research findings
Analysis of variance revealed significant differences among genotypes for all traits in both conditions, indicating substantial genetic diversity. Under non-stress conditions, genotypes 4, 21, and 20 yielded the highest grain yields (6406, 6343, and 6310 kg ha-1, respectively), whereas under drought stress genotypes 4, 20, and 16 led with 5122, 4849, and 4717 kg ha-1. Drought stress caused the greatest relative declines in grain yield (24.6%), grain filling rate (22.6%), thousand grain weight (13.7%) grain weight per spike (13.5%), and spike weight (12.5%). Correlation analysis showed positive, significant associations between grain yield and days to maturity, grain-filling rate, spike harvest index and spike fertility index under both irrigation regimes, identifying them as reliable selection indices for drought tolerance. PCA grouped genotypes into three main clusters in each environment. However, silhouette index diagram classified all genotypes into two and four groups under stress and non-stress conditions, respectively. Based on cluster analysis under non-stress conditions, genotypes 9, 12, 13, 17, 18 and 19 were placed in group one and the other genotypes in group two. Under drought stress conditions, genotypes 12, 13 and 19 were placed in group one, genotypes 9, 17 and 18 in group two, genotypes 11 and 21 in group three and the other genotypes in group four.
Conclusion
In summary, PCA results were similar in the two irrigation regimes and most of the superior genotypes were in group two. PCA identified traits of days to maturity, grain-filling rate, grain yield, spike harvest index and spike fertility index as robust selection criteria under both stress and non-stress conditions. Based on cluster analysis under stress conditions, genotypes in group four were among the superior genotypes and had higher values than the total mean in terms of grain yield, grain filling rate, grain filling period, days to maturity, number of grains per spike and spike fertility index. Comparison of the selected genotypes in both cluster analysis and PCA methods showed strong agreement in the grouping of genotypes. Overall, genotype 4 is recommended as the top candidate for breeding programs targeting drought tolerance.
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