Investigation of Suitable Osmolytes for Enhancing Cotton Plant Adaptation to Drought Scenarios and Improving Water Use Efficiency

The study aimed to investigate the impact of Glycine Betaine (GB), Salicylic Acid (SA), and Ascorbic Acid (AsA) on the yield and quality of cotton plants during the 2021 and 2022 growing seasons at Harran University’s experimental fields in Şanlıurfa, Turkey. The research employed a split-plot design with three replications. Main plots were assigned for chemical applications (GB, SA, and AsA), while subplots were designated for different irrigation levels (IW₁: Kp;1.00, IW₂: Kp;0.75, and IW₃: Kp;0.50). The study revealed that crop evapotranspiration varied between 400 to 728 mm in 2021 and 489 to 841 mm in 2022. The application of GB, SA, and AsA increased irrigation water productivity, especially under drought stress (DS) conditions, indicating the potential to enhance water productivity in cotton plants. DS resulted in significant reductions in various parameters such as plant height, shoot fresh weight, shoot dry weight, SPAD values, boll number, boll weight, cotton yield, ginning outturn, and 100-seed weight. However, the application of GB, SA, and AsA led to statistically significant (P ≤ 0.05) increases in these parameters under DS. Contrary to this, the application of GB, SA, and AsA did not have a statistically significant effect on ginning outturn and 100-seed weight under DS. GB, SA, and AsA applications demonstrated effectiveness in enhancing drought tolerance in cotton. These applications can help reduce yield losses in cotton production under drought conditions. Importantly, by conserving water and preventing yield losses, they offer valuable support to the textile industry.