Chitosan-mediated Physiological and Biochemical Regulation Enhances Water Deficit Stress Tolerance in Sugarcane

Abstract

Sugarcane is highly sensitive to water deficit stress during its formative stage, leading to substantial reductions in cane and sugar yields. Recently, the use of the biopolymer chitosan in plants has attracted attention for its growth-stimulating activity and its ability to activate stress defence mechanisms. This study examines the effects of foliar application of chitosan versus potassium chloride (KCl) on sugarcane cv. Co 86032, focusing on physiological, biochemical, yield, and juice quality traits under water deficit, with three replications in a randomised block design, providing valuable insights into their relative impacts. Water deficit stress during the formative phase (90-160 DAP) significantly suppressed osmoregulation, resulting in a 52.0% decrease in the number of millable canes (NMC) and cane yield. However, chitosan application significantly enhanced enzyme activity, leading to increases of 45.0%, 29.0%, and 72.0% in SOD, CAT, and POX activities, respectively, compared to the unirrigated control (UIC) during the formative phase. Chitosan treatment also significantly reduced lipid peroxidation by 53.0%, which is involved in osmoregulation. This improvement significantly improves leaf water status and chlorophyll content, helping the plant tolerate stress. Furthermore, chitosan application improved several productivity-related traits, including internode number, number of millable canes, and cane yield, by 31.0%, 26.0%, and 7.0%, respectively, compared with the unirrigated control. The findings demonstrate that chitosan is more effective than potassium chloride in mitigating water-deficit stress by regulating physiological and biochemical processes, thereby improving sugarcane growth and productivity under moisture-limited conditions.