Identification of Drought Tolerant Genotypes in Barley using Quantitative Tolerance Indices

The most important factor limiting plant growth in rainfed conditions is water, and since most of the land in Iran is located in arid and semi-arid regions, determining the relative drought tolerance in crops is of particular importance. By evaluating the genotypes of each plant that are able to provide relatively acceptable yield under low water conditions, they can be grown with more confidence in arid and semi-arid regions.

In order to investigate the effect of drought stress and selection of drought tolerant genotype in barley, 15 different genotypes under two conditions of normal irrigation and rainfed conditions in randomized complete block design with four replications in 2020-2021 in Khairabad and Khodabandeh research stations Of Zanjan province were studied.

The results of combined analysis showed that there was a significant difference between genotypes in terms of grain yield between normal irrigation and rainfed conditions and rainfed conditions reduced grain yield by more than 50% compared to normal irrigation conditions. Under normal irrigation conditions, the highest yields belonged to G3, G10 and G11 genotypes, respectively, and under rainfed conditions, despite the lack of significant differences between genotypes, the highest yields belonged to G3, G6 and G2 genotypes, respectively. There was a significant difference between the studied genotypes in terms of all quantitative indices of drought tolerance (except YI and SNPI) as well as yield under stress. Correlation analysis of indices with yield under normal irrigation and rainfed conditions showed that there was a significant correlation between MP, STI, GMP, MSTI2, HM and RDY indices with yield under normal irrigation and rainfed conditions. Correlation of indices with yield under normal irrigation and rainfed conditions showed that there was a significant correlation between MP, STI, GMP, MSTI2, HM and RDY indices with yield under normal irrigation and rainfed conditions. Principal component analysis based on indices showed that the first component and second components explain 79.95% and 14.049% of the total changes. The bioplate diagram of the components showed that genotypes G1, G2, G3, G9, G10, G11, G12 and G13 were in the positive part of the first component diagram and these genotypes had good adaptation in normal irrigation conditions. Among these genotypes, G2, G3 and G13 genotypes were in the positive part of the second component diagram, so these genotypes can be introduced as high-yield genotypes in both irrigated and rainfed conditions. Cluster analysis showed that G1, G2, G3, G9, G10 and G11 genotypes were in the same group and these genotypes can be considered as drought tolerant genotypes in terms of calculated indices.

There was a significant correlation between MP, STI, GMP, MSTI2, HM and RDY indices calculated with yield under normal irrigation and rainfed conditions. Therefore, these indices can be used to select stress-tolerant genotypes. Grouping of barley genotypes based on calculated quantitative and qualitative indices showed that G2, G3 and G13 genotypes were identified as superior genotypes in full irrigation conditions and the most tolerant barley genotypes to low water stress.