GENETIC VARIABILITY AND INHERITANCE OF PHYSIOLOGICAL AND YIELD TRAITS IN UPLAND COTTON UNDER DIVERSE WATER REGIMES

Abstract

Water scarcity during the flowering and ripening stages disrupts physiological processes in crop plants. The recent study on cotton genotypes and their F1 hybrids under two different water regimes (nonstress and stressed conditions) took place in 2018–2020 at the Institute of Genetics and Experimental Biology, Academy of Sciences, Tashkent, Uzbekistan. In optimum and controlled water regimes, the cotton genotypes received irrigation four times, using 4800-5000 m3/ha water. However, under stress conditions, the genotypes received only two irrigations, using 2800-3000 m3/ha water. Comparing the optimum water regime with the water stress conditions, chlorophyll ‘b’ in plant leaves decreased by 3.0% to 46.7% and 1.1% to 26.2% in the parental cultivars and their F1hybrids, respectively. With water deficit conditions, the carotenoid content increased from 8.5% to 39.1% and 2.1% to 44.2% in plant leaves of parental cultivars and their F1hybrids, respectively, compared with the optimal water condition, which indicates how cotton genotypes protect themselves from water scarcity by varying magnitudes of carotenoids in plant leaves. The use of decreased levels of chlorophyll ‘a’ and ‘b’ and increased levels of carotenoids aided the inhibition of oxidants during photooxidation under drought conditions. The F1 hybrids viz., Listopad × Farovon (62.2±0.9 g.), F1 Kupaysin x Elastik (55.8±1.2 g.), F1 Listopad × Kupaysin (55.7±0.2 g.) produced higher seed cotton yield, which might be due to their resistance to drought conditions, as well as heterosis. These promising populations proved suitable for developing drought-tolerant cotton genotypes in future breeding programs.