The Effects of Zinc Oxide Nanoparticles on Drought Stress in Moringa peregrina Populations

Introduction: Moringa peregrina (Forssk.) Fiori, is a nutritionally and medicinally important desert tree, which is constantly exposed to drought stress. This study was accomplished to alleviate the adverse effects of drought stress on M. peregrina populations through the foliar application of zinc oxide nanoparticles (ZnONPs) by monitoring some physiological and biochemical alterations. Methods: Moringa peregrina seeds were collected from the Southeast of Iran in 2014. Fourteen days after germination, the seedlings were subjected to drought stress by withholding watering until 50% field capacity (FC), followed by spraying 0.1% and 0.05% ZnO-NPs and no spraying (as control). Results: The changes of sodium (Na), potassium (K), chlorophylls, total phenolic content (TPC) as well as antioxidant activity under drought stress condition varied based on M. peregrina populations. Drought stress significantly reduced chlorophylls content, while it enhanced TPC and antioxidant activity. ZnO-NPs treatment significantly inhibited chlorophylls degradation under drought stress conditions. It also enhanced chlorophyll content in wellwatered plants. Moreover, it was revealed that TPC and antioxidant activity of M. peregrina populations significantly increased in response to foliar application of ZnONPs in both droughtstressed and unstressed plants. Conclusion: Our results suggested that ZnO-NPs spray can augment drought tolerance of different populations of M. peregrina subjected to water deficit condition.