Effective use of zinc oxide nanoparticles through root dipping on the performance of growth, quality, photosynthesis and antioxidant system in tomato

The objective of the study was to explore the effect of zinc oxide nanoparticles (ZnO-NPs) through root treatment on growth biomarkers, photosynthetic traits, activities of carbonic anhydrase and various antioxidant enzymes as well as the yield of tomato plants. 20 days old seedlings of tomato (cv. PKM-1) were dipped in double distilled water (control), 10, 50, 100 or 200 ppm of ZnO-NPs for 15, 30 or 45 min, respectively. At the stage of 45 and 60 days after sowing (DAS), the plants developed from ZnO-NPs (10 ppm for 30 min) showed improved growth and photosynthetic attributes, enhanced activity of various antioxidant enzymes (e.g., catalase, peroxidase and superoxide dismutase) and higher accumulation of proline and protein content over the non-treated plant. The fruits number and yield in ZnO-NPs treated plants (10 ppm; 30 min) were higher whereas ascorbic acid was lower than the non-treated plant. These fruits possessed higher levels of beta-carotene and lycopene content. The root dipping with 10 ppm for 30 min of ZnO-NPs was found to be best for most of the evaluated parameters.