Mechanistic Insights on Physiological, Biochemical, and Metabolite Profiling of Oryza Sativa Grown Under Drought Stress: A Strategic Coping Mechanism of Silicon Oxide Nanoparticles Treatment

Abstract

Climate change is increasing the frequency of droughts, posing a significant threat to crop yields, particularly for drought-sensitive species like rice (Oryza sativa). Drought stress adversely impacts the physiological and biochemical functions of plants, ultimately resulting in lower productivity. This study aims to fill the knowledge gap concerning effective approaches to alleviate drought-induced damage and boost productivity in rice. We hypothesize that the application of silicon oxide nanoparticles (SiO2-NPs) can enhance drought tolerance in rice by influencing its physiological and biochemical responses. To evaluate this hypothesis, rice plants were cultivated under well-watered and drought-stressed 20% of polyethylene glycol (PEG; MW 6000) conditions using a completely randomized design (CRD) with four replications. The results revealed that applying various concentrations of SiO2-NPs (50 mg/L, 100 mg/L, and 200 mg/L) significantly improved growth and enhanced key physiological and biochemical traits such as protein content, photosynthetic rate, stomatal conductance, chlorophyll content, and antioxidant activity. It also significantly elevated Fv/Fm levels by 29%, 22%, and 16% respectively by 50 mg/L, 100 mg/L, and 200 mg/L concentrations of SiO2-NPs. Activity of several key antioxidant enzymes: superoxide dismutase (SOD) by 41%, 35%, and 33%, catalase (CAT) by 38%, 33%, and 31%, peroxidase (POD) by 47%, 41%, and 37%, and proline content by 29%, 26%, and 24%, under drought stress, respectively. Moreover, SiO2-NPs (50 mg/L, 100 mg/L, and 200 mg/L) alleviated drought-induced oxidative stress by reducing hydrogen peroxide (H2O2) level by 28%, 21%, and 15% and malondialdehyde (MDA) level by 31%, 23%, and 18%, respectively, compared to control plants. Furthermore, SiO2-NPs increased the concentration of total free amino acid (TFAA) and total soluble sugar (TSS) along with nitrogen (N), phosphorus (P), and potassium (K). The results of this study indicated that different concentrations (50 mg/L, 100 mg/L, and 200 mg/L) of SiO2-NPs could improve plant resistance and lessen the negative effects of drought stress. The post-harvest performance and reproductive stage of drought-stressed rice treated with SiO2-NPs require more research.