Physiological and Biochemical Responses of Rice Genotypes to Drought and Industrial Pollution under Changing Climatic Conditions

Abstract

Rice (Oryza sativa L.) is one of the world's most important food crops, yet its productivity is increasingly threatened by climate change-induced drought and industrial pollution. Water scarcity coupled with contamination of agricultural soils by heavy metals adversely affects plant growth, photosynthetic efficiency, nutrient uptake, and grain yield. The present investigation evaluated four rice genotypes for their physiological, biochemical and morphological responses under drought and industrial pollution stress at the industrial region near Tilda, Sarona Chhattisgarh. The experiment consisted of four treatments comprising well-watered control, drought stress, industrial pollution stress (heavy metal-contaminated soil), and combined drought plus industrial pollution stress. Physiological parameters including SPAD chlorophyll content, canopy temperature, relative water content, photosynthetic rate, transpiration rate, stomatal conductance, chlorophyll pigments, and carotenoids were evaluated during the active vegetative stage. The results revealed considerable variation among genotypes in their tolerance to combined stress conditions. Rice genotypes Poornima, Indira Barani Dhan 1 and Samleshwari maintained significantly higher chlorophyll content, photosynthetic rate, stomatal conductance, and relative water content compared with susceptible cultivars such as Mahamaya, Rajeshwari and Swarna. Combined drought and industrial pollution caused substantial reductions in chlorophyll content (18–32%), photosynthetic rate (35–55%), transpiration rate (30 45%), and relative water content (20–35%), while leaf temperature increased by 3–6°C. Heavy metal stress further intensified oxidative damage through chlorophyll degradation and reduced carbon assimilation. The identified tolerant genotypes exhibited better physiological adjustment and maintained greater biomass accumulation under combined stress conditions. These findings provide valuable information for breeding climate-resilient and pollution-tolerant rice cultivars suitable for sustainable agriculture under changing environmental conditions.