Reducing drought stress in rice (Oryza sativa L.) through silicon-induced improvements in photosynthetic pigments, leaf gas exchange, biomass, and antioxidant activities

Drought impacts sustainable crop production by disrupting the fundamental metabolic processes of plants leading to reduced photosynthesis, leaf gas exchange, and oxidative damage. Silicon can mitigate the negative consequences of water stress. In a field experiment in 2020 and 2021, we applied silicon foliar spray to rice (Oryza sativa L.) genotypes at different growth stages (tillering, panicle initiation, 50% flowering, and milky stage) to determine how silicon can enhances water stress tolerance. Almost all measured parameters increased with silicon across the rice genotypes. When compared with control, silicon-treated plants had higher total chlorophyll (increased by 13.12% in genotype US-312 in 2020; and 11.3% in genotype 27P63 in 2021) and contents of chlorophyll a (increased by 11.2% in US-312) and chlorophyll b (increased by 11.5% in 27P63), total dry matter (increased by 23.53% in genotype IIRRH-143), photosynthetic rate (increased by 15.0% in genotype US-312), total dry matter (increased by 23.53% in genotype IIRRH-143), stomatal conductance (increased 28.34% in genotype 27P63 and 19.35% in genotype US-312), and transpiration rate (increased 3.97% in genotype DRR Dhan-48 at flowreing; 7.77% in genotype IIRRH-143 by 7.77% at anthesis). Intercellular CO2 concentration and proline content was also enhanced with silicon application. Intercellular CO2 concentration increased 25.83% in genotype IIRRH-143, and proline content increased 37.95% in genotype DRR Dhan-48 in 2020, and increased 33.72% in genotype US-314 in 2021. The antioxidant superoxide dismutase was also increased. Our findings show that silicon application alleviated the adverse effects of drought stress, and may be a strategy for mitigating drought stress for rice production in water-deficit conditions.