Zinc oxide nanoparticles for sustainable agriculture: A tool to combat salinity stress in rice (Oryza sativa) by modulating the nutritional profile and redox homeostasis mechanisms

The use of nanoparticles (NPs) as an amendment to reduce salt toxicity has gained much attention. Keeping in mind, this research work was done to evaluate the effect of zinc oxide NPs (ZnO-NPs) to mitigate the salt stress in rice (Oryza sativa) plant. Rice plants were subjected to salt stress (150 mM of NaCl) at 15 days of sowing through the soil. ZnO-NPs were characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) and were applied foliar at concentration of 100 mg/L for five consecutive days (26–30 DAS). The results confirmed the salt toxicity and reduced shoot length (27 %), root fresh weight (31 %), SPAD chlorophyll (29 %), net photosynthetic rate (24 %), and nitrogen (N), phosphorus (P), potassium (K) and zinc (Zn) uptake by 9 %, 11 %, 13 % and 17 % respectively, while salinity increased the activity of antioxidant enzymes, proline, hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) content in rice plants. However, in plants grown under salt stress, foliar application of ZnO-NPs significantly improved growth, photosynthesis, nutrient uptake and antioxidant enzymes activity. Beside, ZnO-NPs reduced salinity-induced oxidative stress by lowering H₂O₂ and MDA content. Therefore, our research showed that ZnO-NPs is useful and efficient in encouraging growth and lessening salinity stress in rice plants.