Improving Tolerance of Cotton (Gossypium barbadense L.) to Water Deficit by Salicylic Acid and Proline

Amidst global climate change and the disruption of ecological equilibrium, water deficit stress emerges as one of the foremost abiotic constraints affecting cultivated crops, particularly cotton. Therefore, it is essential to study the effect of prolonging irrigation intervals on plant growth, physiological, biochemical and internal anatomical structure parameters of cotton plants Gossypium barbadense L. cv. Super-Giza 94. Prolonging irrigation intervals (every 30 and 45 days) decreased plant height, dry weight, leaf area, relative water content, chlorophyll pigments content or yield as well as fiber quality. On the other side, in cotton plants exposed to water deficit increased endogenous proline content. The combined application of Salicylic acid (SA) and proline effectively alleviated oxidative stress by enhancing antioxidant enzymatic activity, which was more pronounced compared to when they were applied separately. Thicker and wider stem and leaf tissues as well as xylem vessels were noticed by SA, proline and their interaction under water deficit stress conditions. The plant height, leaf area, chlorophyll pigments, relative water content, yield, and fiber quality were improved through the foliar application of SA and proline, either individually or in combination. This approach shows promise for promoting sustainable agriculture in demanding environmental conditions.