The Effect of Zinc Oxide Nanoparticles (ZnO NPs) on Vigna mungo L. Seedling Growth and Antioxidant Activity

Aim: The purpose of this study was to test the phytotoxicity effect of ZnONPs on Vigna mungo L. seedling growth and antioxidant activity. Methods: Vigna mungo L. Seeds were treated with to a wide range of ZnO NPs ranging 5 to25mg/100ml for 8hours. Vigna mungo seeds that were soaked in ZnO NPs solution were sown in pots (20 cm × 40 cm) filled with red soil and a layer of coco peat. The effect of ZnO NPs on morphological, biochemical and antioxidant activity in Vigna mungo L. plants was investigated after 15,30,45 and 60 days. Results: The impact of ZnO NPs on plant growth characteristics and biochemical changes in Vigna mungo L. plants was investigated after 15,30,45 and 60 days. The ZnONPs exposure significantly enhanced germination percentage by 111.3% but root length (75.25%), shoot length (89.81%), number of leaves (91.66%), length of leaves (76%), width of leaves (67.27%), fresh weight of plant (27.96%) and dry weight of plant (28.23%) decreased in the treated plants after 60 days exposure to 25mg/100ml compared to the untreated control. Interestingly, treated plants after 60 days exposure to 25mg/100ml increased significantly the chlorophyll (115.0%), reducing sugars (244.4%), total sugars (212.72%) protein (181.8%). Treatment to Vigna mungo L. seeds with ZnONPs has been found to induce the activities of antioxidant enzymes such as Guaiacol peroxidase, Glutathione Reductase, Catalase and increase in the ascorbic acid and hydrogen peroxide contents. TEM images revealed that the aggregated ZnO NPs to be deposited inside the seed. Conclusion: Vigna mungo seeds treated with different concentrations of ZnO NPs showed decreased root growth and increased germination index, shoot and leaf growth. There was a significant change in Glutathione reductase, Guaiacol peroxidase and Catalase activity and ascorbic acid and hydrogen peroxide of Vigna mungo exposed to ZnONPs. Aggregated nanoparticles penetration into the intracellular region of the seed was observed.A complete study on the toxic effects of ZnO NPs can help significantly in the safe disposal of ENPs for the reduction of adverse effects in both environmental and agricultural systems.