Unveiling the Ameliorative Effects of Soil-Mediated Nano-Biochar and Calcium Oxide Nanoparticles on Drought Tolerance in Oryza Sativa: Insights into Biochemical Responses, Reactive Oxygen Species, Photosynthetic Pigments and Nutrient Homeostasis

Abstract

This study investigates the synergistic effects of calcium oxide nanoparticles (CaO NPs) and nano-biochar (nano-BC) on drought-stressed rice (Oryza sativa), a combination that has not been extensively explored in previous research. While individual applications of NPs or BC have been studied, the concurrent use of CaO NPs (as foliar spray) and nano-BC (as soil amendment) offers a novel integrative approach for enhancing drought resilience. The study demonstrates that, this combined application significantly mitigates drought-induced damage, as evidenced by improvements in physiological and biochemical traits. Notably, the treatment enhanced net photosynthetic rate (P-N) by 96.46%, stomatal conductance (gs) by 93.75%, and total soluble sugar (TSS) by 95.22% compared to drought-stressed plants. It also improved protein content, nitrogen accumulation, and transpiration rate. Additionally, reductions of 56% in malondialdehyde (MDA) and 59% in hydrogen peroxide (H2O2) indicate alleviation of oxidative stress. These findings provide new insights into the potential of nanomaterial-based interventions for sustainable rice cultivation under water-limited conditions, offering a promising strategy to improve crop resilience in the face of climate change.