Abstract
In the past decade nanomaterials (NMs) have emerged as important tools for manipulating growth and yield of crop plants. Of these NMs, nano-titanium dioxide (nano-TiO2) has been shown to play various roles in growth and development of crop plants under abiotic stresses. Present work was carried out to evaluate the role nano-TiO2 in the protection of plants against water stress (WS) and to select the best of nano-TiO2. The results show that WS caused a significant reduction in growth attributes, chlorophyll (Chl) content, leaf relative water content (LRWC) and activity of nitrate reductase (NR) enzyme. Whereas, an increase was noticed in reactive oxygen species (ROS), carbonic anhydrase (CA) activity, electrolyte leakage, and lipid peroxidation in water stressed plants. In addition, plants under WS also showed an increase in the activities of antioxidant enzymes and accumulation of proline (Pro) and glycine betaine (GB) content. However, application of nano-TiO2 (5, 10, 15, and 20 mg L-1) to water-stressed plants further enhanced the activities of antioxidant enzymes, CA activity, and Pro and GB content. Nano-TiO2-induced increase in ROS, CA, Pro and GB resulted in a decrease in ROS level, electrolyte leakage and lipid peroxidation leading to increase in LRWC, Chl content, NR activity and growth of the plants. Furthermore, an additional increase in the level of nano-TiO2 to 25 mg L-1 could not alleviate water stress and showed adverse effects.