European Journal of Sustainable Agroecosystems

Background: Drought is one of the most severe abiotic stresses limiting rice (Oryza sativa L.) productivity in rainfed and water-deficient environments, with increasing intensity under climate change. Although silicon (Si) and potassium (K) independently enhance drought tolerance through different physiological and biochemical mechanisms, their combined effects remain insufficiently investigated.
Methods: A conceptual evaluation was conducted to assess the individual and combined effects of Si and K nutrition on drought tolerance in rice. A pot- and field-based factorial experiment was designed using two irrigation regimes (well-watered and drought stress at 50% field capacity) and four nutrient treatments (control, Si, K, and Si + K) arranged in a randomized complete block design. Physiological traits, antioxidant enzyme activities, nutrient-use efficiency, and grain yield were comparatively evaluated.
Results: Drought stress significantly reduced relative water content, photosynthetic rate, stomatal conductance, and grain yield while increasing malondialdehyde accumulation and reactive oxygen species. Silicon application improved leaf water status and minimized non-stomatal photosynthetic limitations, whereas potassium enhanced osmotic adjustment and stomatal regulation. The combined Si + K treatment produced the greatest improvement by restoring relative water content and photosynthetic activity, enhancing superoxide dismutase, catalase, and ascorbate peroxidase activities, reducing lipid peroxidation, and increasing potassium, nitrogen, and phosphorus use efficiency. Consequently, the integrated treatment maintained higher panicle fertility, harvest index, and grain yield under drought conditions than either nutrient applied alone.
Conclusion: Integrated silicon and potassium nutrition provides synergistic protection against drought-induced physiological, biochemical, and productivity losses in rice. The combined application of Si and K represents an effective climate-smart nutrient management strategy that can complement drought-tolerant cultivars and water-efficient irrigation practices to improve the resilience and sustainability of rice production under increasing water scarcity.