Volume 16, Issue 49 (4-2024)                   jcb 2024, 16(49): 17-31 | Back to browse issues page

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Asadi1 A A, Amini A, Babaie T, Eivazi A R, Qudsi M. (2024). Identification of Genotypes Tolerant to Drought Stress in Wheat using Quantitative Indices in Different Regions of Iran's Cold Climate. jcb. 16(49), 17-31. doi:10.61186/jcb.16.49.17
URL: http://jcb.sanru.ac.ir/article-1-1463-en.html
Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization, AREEO, Karaj- Iran
Abstract:   (383 Views)
Extended Abstract
Introduction and Objective: Yield under stress conditions has never been an accurate criterion for selecting drought-tolerant genotypes, and the goal of preparing drought-tolerant cultivars has always been to create cultivars that relatively tolerate stress better compared to other genotypes and in the same agricultural conditions, they show less yield loss. In most studies, only the seed yield is considered for the field selection of crops, while some researchers believe that in order to be more efficient in breeding compatible and superior cultivars in arid and semi-arid regions, the indicators that are effective in identifying the stability of cultivars under drought stress conditions should be identified and used them as selection index in addition to seed yield, therefore, the relative uield status of genotypes in drought stress conditions and water conditions is a starting point for identifying and selecting genotypes for improvement in dry environments. In semi-arid regions where the distribution of rainfall is not proportional, the yield potential in stress conditions is not considered the best criterion for drought tolerance, but in addition to yield stability, the comparison of yield in stress and optimal conditions is a more suitable criterion for the reaction of genotypes to moisture stress. Due to the fact that most of the studies related to indicators in crop species and especially wheat are done only in one place and one year and finally in a specific environment and the results are generalized to all environments and the variable effects of year and place are not taken into account in the calculation of indicators. In this regard, this research was carried out to evaluate the genotypes of autumn wheat in terms of drought tolerance, to select the best drought tolerance indices and to identify drought stress tolerant cultivars in different regions of the country's cold climate.
Material and Methods: In this research project, 20 genotypes under normal irrigation and water deficit conditions in the form of randomized complete block design (RCBD) with three replications in the research stations of Karaj, Mashhad, Miandoab and Arak, in the crop years of 2017-2018 and 2018-2019 were investigated. In order to investigate the drought tolerance of the genotypes, different tolerance and stress sensitivity indices were determined for the genotypes under investigation and the genotypes were grouped based on the sensitivity and tolerance to drought by each of these indices. Principal component analyzing was also used in order to summarize the data and draw a diagram based on the first two components and identify the desired indicators. Finally, biplot analysis was used to group genotypes and indices based on drought tolerance criteria.
Results: Stress decreased the Yield of genotypes, but the amount of reduction was different in different genotypes. The average grain yield for all genotypes under normal irrigation conditions and drought stress at the end of the season was 7.002 and 5.215 tons per hectare, respectively, which showed that the stress conditions caused a decrease of about 25% in grain yield compared to normal irrigation conditions. The environmental and agricultural conditions of different regions and the studied years caused differences in the estimated indices so that the ranking of genotypes changed based on different indices in different years and regions therefore, it is better to carry out studies on stress tolerance indices in several places and several years so that the process of functional changes of different cultivars and genotypes is correctly determined and as a result, there is more confidence in the calculated tolerance and sensitivity indices. Genotypes G4, G2, G16 and G5 showed higher yield in both conditions. STI, MP, GMP, MSTI1, MSTI2, YI, HM, and RR had a positive and significant correlation with grain yield under normal and stress conditions, and therefore, they can be used for more favorable selection of drought tolerant genotypes.  Principal component analysis showed that indicators can be grouped using the first two components. The first principal component explained 53.16% of the changes in the total data and had a positive and significant correlation with yield in normal and stress conditions as well as MP, STI, GMP, YI, MSTI1, MSTI2, HM and RDY indicators. Due to the high correlation of this component with yield under normal and stress conditions, this component was named as the yield potential component under normal and stress conditions. The second estimated component justified 42.33% of the total data changes and showed a positive and significant correlation with yield in normal conditions and SSI, TOL, ATI, SSPI and RR indices. It seems that this component is able to identify genotypes that have high yield under stress conditions. Biplot analysis showed that HM, MP, STI, MSTI1, MSTI2, GMP, RDY, YI, and SNPI indices had a positive and high correlation with performance under stress and normal conditions. So that the sharp angles between these indices showed their positive and very high correlation with each other. RDI and YSI indices had a negative correlation with performance in normal conditions and RR, SSI, TOL and SSPI indices had a negative correlation with performance in stressful conditions.
Conclusion: In order to achieve varieties resistant to drought stress by using indices, in order to prevent the mutual effects of the environment in the genotype, the experiments should be carried out in many years and places so that the effects of the environment in the calculated indices can be reduced and more reasonable results can be obtained. Finally, G4, G2, G16, G5 and G17 genotypes can be selected as genotypes with high performance under normal and stress conditions.

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Type of Study: Research | Subject: Special
Received: 2023/02/26 | Revised: 2024/04/17 | Accepted: 2023/06/7 | Published: 2024/04/17

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