Genetic variability and trait associations in bread wheat (Triticum aestivum L.) genotypes under drought-stressed and well-watered conditions

Abstract

AbstractDrought is one of the most important yield-limiting abiotic stresses threatening wheat production and productivity. Development of wheat genotypes with enhanced grain yield under drought-stressed conditions depend on the extent of genetic variation present for drought tolerance-related traits. This study was carried out to determine the level of genetic variation and associations of yield and yield attributing traits among 196 bread wheat genotypes under drought-stressed and well-watered conditions. The genotypes were evaluated under greenhouse and field conditions and phenotyped for yield and yield-related traits. The genotypes varied significantly for the traits under both conditions. Grain yield ranged from 2.13 to 3.74 t ha−1 and from 2.52 to 5.06 t ha−1 under drought-stressed and well-watered conditions, respectively. Under both conditions, variances due to genotype were higher than environment and genotype × environment interaction variances for all the traits. Estimates of phenotypic coefficient of variation (PCV) were higher than genotypic coefficient of variation (GCV) for all the traits under both conditions, with both PCV and GCV being highest for kernel weight spike−1 and lowest for spike fertility. Under both conditions, broad-sense heritability estimates ranged from moderately high to very high, accompanied with high genetic advance as a percentage of the mean. Fertile spikelets spike−1, one thousand kernel weight, kernel weight spike−1, biomass yield and harvest index manifested high positive genotypic and phenotypic correlations and positive direct effects on grain yield under both conditions. The first five principal components accounted for 78.4% (well-watered) and 76.0% (drought-stressed) of the variation among the genotypes. The 196 genotypes were delineated into six major clusters under both water conditions, with clusters 3 (well-watered) and cluster 5 (drought-stressed) containing genotypes with the highest ability to tolerate drought stress. Genotypes Alidoro, Bolo, Dinknesh, ETBW8491 and ETBW172938 had high stable yields under both conditions. The identified traits and genotypes were drought tolerant and could be exploited to develop novel genotypes for drought stress tolerance.