Evaluation of salinity stress tolerance through physiological and biochemical responses in different genotypes of Curcuma longa L.

Abstract:

Salt stress poses a significant threat to turmeric (Curcuma longa L.) cultivation, particularly in regions with saline soils or poor irrigation water quality. This study investigated the biochemical and physiological responses of different C. longa genotypes exposed to increasing NaCl concentrations (0, 50, 100, 150, and 200 mM) in pot experiments to identify salt-tolerant genotypes and understand their adaptive mechanisms. Subsequently, stress indicators including malondialdehyde (MDA), hydrogen peroxide (H?O?), proline content, and antioxidant enzyme activities (superoxide dismutase, catalase, and ascorbate peroxidase) were evaluated. Results revealed genotype-specific responses to salinity, with distinct patterns of oxidative stress accumulation and activation of antioxidant defenses. Higher NaCl concentrations induced a significant increase in lipid peroxidation and reactive oxygen species (ROS) accumulation across all genotypes, though the magnitude varied significantly. Proline accumulation served as a crucial osmo-protectant; tolerant turmeric genotypes showed increased accumulation under a threshold stress concentration (150 mM). The antioxidant enzyme system exhibited differential activation patterns, while the Rajendra Sonia and Prathiba genotypes showed robust enzymatic activity even under severe stress. Turmeric plants grown under NaCl (150 mM) concentrations showed significantly reduced plant height, number of leaves and shoot fresh and dry weight. These findings provide valuable insights into the physiological basis of salt tolerance in C. longa, enabling the identification of salt-tolerance genotypes for cultivation in salt-affected areas or for breeding programs aimed at developing stress-resilient genotypes.

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