DROUGHT STRESS EFFECTS ON RESISTANT GENE EXPRESSION, GROWTH, AND YIELD TRAITS OF WHEAT (TRITICUM AESTIVUM L.)

Abstract

The study comprised two experiments that were carried out for two consecutive years (2019–2020 and 2020–2021) at the Agricultural Research Station, Babil Governorate, Iraq. In the first experiment, seven wheat (Triticum aestivum L.) cultivars, viz., Iraq, Ezz, Abba-99, Furat, Sham-6, N-70, and Tamoz, were studied for most drought- tolerant genes in 2019–2020. During this year, three drought-tolerant wheat cultivars, i.e., Iraq, Tamoz, and Abba-99, were selected having the most drought-tolerant genes. In the second experiment, the three selected drought-tolerant wheat cultivars under three different drought stress conditions (D-1, D-2, and D-3) were studied during 2020–2021 in a randomized complete block design (RCBD) with three replications using a split-plot arrangement. The study aimed to determine the impact of drought effects on the expression of drought-resistant genes, growth, and yield traits in wheat. The results showed that wheat cultivars differed in their possession of drought-resistant genes (ABC4, GPAT, GBSS1, and umc1283), and the bands appeared in cultivars, Iraq, Tamoz, and Abba-99, while the rest of the four cultivars had lost one or two genes. Cultivar Iraq was distinguished as the most drought-tolerant genotypes, by having an increased relative expression of genes, ABC4 and GPAT, compared with other cultivars. The D-3 - drought stress condition caused a significant reduction in the biological and grain yield, and harvest index, with a decrease of 38.85%, 12.60%, and 29.83%, respectively. Cultivar Iraq was the least affected for plant height, flag leaf area, tillers meter2, biological and grain yield, and harvest index when increasing drought severity, and these traits decreased by 16.96%, 24.08%, 44.17%, 28.08%, 15.10%, and 15.29%, respectively. Results authenticated wheat cultivars differed in the expression of drought-resistant genes, and drought resistance is largely controlled by genes.