INFLUENCE OF NANO-SILICON AND NANO-CHITOSAN ON GROWTH, ION CONTENT, AND ANTIOXIDANT DEFENSE ENZYME OF TWO CITRUS ROOTSTOCKS UNDER SALINITY CONDITIONS

Abstract

Nanoparticle foliar spray is a new and effective approach for improving seedling growth and survival under adverse conditions such as salt stress. The current study was conducted to investigate the impact of commercial silicon dioxide (SiO2), SiO2 nanoparticles (SiO2 NPs), commercial chitosan (CS), CS nanoparticles (CS NPs) on growth, proline, antioxidant defense enzyme, and ions content in One-year-old for sour orange (Citrus aurantium, L.) and Volkamer lemon (Citrus volkameriana) rootstocks grown under salinity stress. Foliar spray of SiO2, SiO2 NPs, Chitosan, and Chitosan NPs with a concentration of 50 ppm was applied at two NaCl concentrations (0, 50 mM). Vegetative growth, including plant height, stem diameter, leaf area, roots, and total fresh and dry weights, were determined. The findings demonstrated that salinity adversely affected plant growth. Salt-stressed plant leaves exhibited a greater activity of peroxidase (POD) and proline content when compared to the control treatment. Na+ and Cl- ions accumulated in leaves of salinized plants. Nano-Silicon dioxide and Nano-chitosan achieved a significantly increased of full vegetative growth parameters and antioxidant defense enzyme. Nano treatments decreased Na+ and Cl- ions content in the leave tissue. As a result, both SiO2 NPs and CS NPs are employed as part of a combined approach to increase the growth indices of citrus plants, especially achieving a significant impact in alleviating salinity stress.