Foliar application of chitosan nanoparticles loaded with Shilajit modulates biochemical response in wheat under salinity stress

Abstract

Salinity is a major abiotic stress that limits plant growth and productivity, particularly in arid and semi-arid regions. This study presents a novel nano-biotechnological approach to improving salt stress tolerance in wheat (Triticum aestivum L.) through the foliar application of chitosan nanoparticles loaded with Shilajit (Shilajit@CNPs). Shilajit@CNPs were synthesized and characterized using dynamic light scattering, FTIR spectroscopy, and scanning electron microscopy; their release behavior was also evaluated. Wheat plants exposed to 100 mM NaCl were treated foliarly with 100 ppm Shilajit@CNPs every five days for one month. The treatment improved growth, physiological performance, and photosynthetic pigment content while reducing lipid peroxidation, as indicated by a decrease in malondialdehyde levels (from 0.07 to 0.05 mu mol g- 1 fresh weight). Total phenolic content increased, and antioxidant capacity was enhanced by up to 15 %, based on free radical scavenging activity. Furthermore, key antioxidant enzymes were significantly activated, with catalase, ascorbate peroxidase, and superoxide dismutase activities increasing by 29 %, 25 %, and 90 %, respectively, compared to salt-stressed plants. Overall, this formulation, merging traditional bioactives with nanoscale delivery, represents an untested strategy in the context of salinity stress management in wheat. These findings underscore its potential as a sustainable solution to enhance crop resilience in salt-affected environments.