Effect of Cadmium on the Growth and Physiology of Paddy (Oryza sativa L.) Plants

Abstract

Cadmium (Cd) pollution in agricultural soils has emerged as a critical environmental concern, particularly for rice cultivation, due to its detrimental effects on plant development, physiological functions, and overall productivity. Since rice is an essential meal for a large percentage of people worldwide, it is crucial to comprehend how the plant reacts to cadmium stress in order to ensure food security for sustainable agriculture. This study investigates the physiological and growth responses of three widely cultivated Indian rice varieties—IR64, Swarna, and BPT 5204—under varying levels of cadmium exposure (0, 1, 2, and 3 mg/L). The objective is to analyze how these cultivars respond to different concentrations of Cd, with particular attention to growth parameters, cadmium accumulation in plant tissues, dry biomass, tolerance index, and nutrient uptake efficiency.The experimental results indicate that Cd exposure leads to a dose-dependent reduction in plant growth and physiological performance in all three rice varieties. Significant declines were observed in dry weight and overall plant vigor, particularly at higher Cd concentrations. However, notable differences were recorded in the degree of tolerance among the cultivars. Among the tested varieties, BPT 5204 showed comparatively greater resilience to Cd toxicity, exhibiting less reduction in dry weight and higher tolerance index values across the tested concentrations. In contrast, IR64 proved to be more vulnerable, with considerable buildup of Cd in both shoots and roots, accompanied with severe growth restriction. Additionally, cadmium stress disrupted the nutritional balance and further hampered plant growth and metabolism by negatively affecting the uptake of vital minerals like potassium (K), phosphorus (P), and nitrogen (N). The interference of Cd with nutrient transport mechanisms suggests a critical interaction that exacerbates toxic effects of heavy metals. Pattern of Cd accumulation also varied among the varieties, with higher concentrations typically sequestered in roots rather than shoots, indicating a possible defence mechanism to restrict Cd translocation to aerial parts and grains.This varietal variation in response to cadmium exposure has significant implications for rice breeding and crop improvement programs. Identifying and promoting cultivars with intrinsic tolerance mechanisms can be an effective strategy for mitigating the effects of Cd-contaminated environments. The results of this study highlight the need for more research into creating stress-resilient rice cultivars and offer significant insights regarding physiological & biochemical underpinnings of cadmium tolerance in rice. Future breeding programs can improve the sustainability and security of rice production in areas impacted by Cd by combining physiological screening with molecular & genetic techniques.In conclusion, the differential responses of IR64, Swarna, and BPT 5204 to cadmium stress highlight the potential for varietal selection in improving crop performance under heavy metal stress. Such efforts are essential for safeguarding agricultural productivity and protecting human health from heavy metal accumulation in food crops.