Influence of Zinc Oxide Nanoparticles to Regulate the Antioxidants Enzymes, Some Osmolytes and Agronomic Attributes in <i>Coriandrum sativum</i> L. Grown under Water Stress

Climatic variations adversely affect the limited water resources of earth which leads to water stress and influences agricultural production worldwide. Therefore, a novel approach has been introduced to improve the tolerance against water stress in herbaceous nature medicinal plants such as <i>Coriandrum sativum</i> by the usage of nanotechnology (foliar applied nanoparticles of ZnOx) coupled with the application of water deficit irrigation. This is an alternative water saving strategy that proved to be efficient to mitigate the <i>Coriandrum sativum</i> tolerance against water stress regimes for sustainable yield production through the activation of antioxidant system. Thus, the phenomena of green synthesis have been deployed for the formation of Zinc oxide nanoparticles (ZnOx NPs) from the leaf extract of <i>Camellia sinensis</i> L. and zinc acetate dihydrate was used as precursor. Different techniques have been used for the thorough study and confirmation of ZnOx NPs such as UV-vis spectroscopy (UV-vis) X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Elemental dispersive spectroscopy (EDS). The prepared ZnOx NPs exhibit hexagonal wurtzite crystal nature has an average size of 37 nm with high purity. These ZnOx NPs have been further studied for their role in amelioration of water stress tolerance in <i>Coriandrum sativum</i> in a pot experiment. Two levels of water stress regimes were employed, IR75 (moderate) and IR50 (Intense) to evaluate the behavior of plant compared to full irrigation (FI). Results showed that under water stress regimes, the 100 ppm of prepared NPs stimulate the antioxidant system by increasing the activity of catalases (CAT), super oxidases (SOD) and ascorbate peroxidase (APX) enzymes and found the maximum at IR50, while the concentration of malondialdehyde (MDA) decreased due to increase in activity of antioxidative enzymes. Furthermore, chlorophyll content and amount of proline also enhanced by the foliar application of prepared ZnOx NPs under moderate water stress (IR75). The results suggested that all the investigated agronomic attributes significantly increased, including plant biomass and economic yield (EY), compared to non-treated ZnOx NPs plants, except for the number of primary branches and LAI. Further, the 100 ppm of prepared ZnOx NPs have great potential to improve water stress tolerance in <i>Coriandrum sativum</i> by improving the antioxidant enzymes activity that enhance agronomic attributes for high crop productivity that require further research at transcriptomic and genomic level.