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

Nanoparticle foliar spray is a new approach and effective for improving seedling growth and survival with 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. In the current study, a foliar spray of bulk SiO2, SiO2 NPs, Chitosan, and Chitosan NPs with a concentration of 50 ppm was applied at 0 and 50 mM of NaCl concentrations. Vegetative growth was determined, including plant height, stem diameter, leaf area, roots, and total fresh and dry weights. The findings demonstrated that salinity adversely affected plant growth. Salt-stressed plant leaves exhibited greater peroxidase (POD) activity and proline content than the control treatment, and Na+ and Cl- ions accumulated in the leaves of salinized plants. Nano-Silicon dioxide and Nano-chitosan significantly increased full vegetative growth parameters and antioxidant defense enzymes. Nano treatments decreased Na+ and Cl- ions content in the leaf tissue. Finally, as a result 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.