EVALUATION OF DROUGHT‑TOLERANT WHEAT VARIETIES FOR SUSTAINABLE CROP PRODUCTION

Abstract

Globally drought stress destroys production of wheat and it has resulted into the search of resilient genotypes with improved physiological and molecular adoptions. Twenty genotypes of bread wheat (synthetic hexaploid wheat lines, moderate drought and severe drought) were evaluated using a well watered environment, moderate drought environment and severe drought environment in this study, randomized complete block design was used. Close assessment of photosynthetic parameters, biochemical indicators, agronomic traits, expression of genes and genetic parameters revealed that synthetic hexaploid wheat genotypes significantly outperformed conventional cultivars in severe drought situations. The net photosynthesis rates, water content of the samples and stability of the cell membranes in the synthetic hexaploid lines of wheat was more than the susceptible checks. Antioxidant enzyme activities (catalase, peroxidase and superoxide dismutase) were also two to three times higher in the synthetic hexaploid wheat lines and the quantity of malondialdehyde developed was significantly less, which was a reduced level of oxidative damage. Molecular analysis showed that synthetic hexaploid wheat genotypes are highly upregulated by drought-responsive genes with TaDREB1A and TaLEA3 genes having over a dozen and fifteen folds more active expression, respectively. Half-diallel analysis indicated that most of the major drought-tolerant phenotypes are majorly additively inherited with the narrow-sense heritability values always being in the moderate to high range. Therefore, synthetic hexaploid wheat genotypes had significantly increased grain yield under extreme stress of drought and had the greatest stress tolerance index and the lowest stress susceptibility index. The principal component analysis revealed the relative water content, grain yield and catalase activity to be the most discriminatory of drought resistance. We conclude that the synthetic hexaploid wheat lines are more adaptive to drought as far as their physiological, biochemical and genetic adaptations and its strategic use in breeding programs is the brightest future of wheat in water-limited environment.