Response of Maize Seedlings to Silicon Dioxide Nanoparticles (SiO₂NPs) 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 (SiO₂NPs) in regulating maize tolerance to drought stress are still at early stages of development. In this study, plants that were treated with SiO₂NPs (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 SiO₂NPs 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 SiO₂NPs-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 SiO₂NPs-treated plants in response to drought stress, while the expression of the osmotic-like protein (OSM-34) and aquaporin (AQPs) was downregulated in SiO₂NPs-treated plants in response to drought stress. This research could pave the way for further investigations into how SiO₂NPs boost plant resistance to drought stress.