Response of Maize Seedlings to Silicon Dioxide Nanoparticles (SiO 2 NPs) under Drought Stress.

Recently, the use of nanofertilizers has received a great deal of attention in managing plants under biotic and abiotic stresses. However, studies that elucidate the role of silicon dioxide nanoparticles (SiO 2 NPs) in regulating maize tolerance to drought stress are still at early stages of development. In this study, plants that were treated with SiO 2 NPs (0.25 g/L as foliar spray) displayed considerable improvement in the growth indices, despite being subjected to drought stress. In addition, the action of SiO 2 NPs led to a considerable rise in the levels of chlorophylls, proline, cell membrane integrity, leaf water content, and antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (G-POX)). In contrast, an inverse trend was seen in the oxidative injury, the total amount of soluble sugars, and the activity of ascorbate peroxidase (APX). At the same time, carotenoids were unaffected in SiO 2 NPs-treated and non-treated plants under drought stress. The results of the molecular investigation that was conducted using qRT-PCR showed that the relative expression of the D2 protein of photosystem II ( PsbD ) was elevated in SiO 2 NPs-treated plants in response to drought stress, while the expression of the osmotic-like protein ( OSM-34 ) and aquaporin ( AQPs ) was downregulated in SiO 2 NPs-treated plants in response to drought stress. This research could pave the way for further investigations into how SiO 2 NPs boost plant resistance to drought stress.