Effect of cadmium on seed germination and seedling growth of five rice (oryza sativa l.) cultivars toxic effects of heavy metal on early growth and tolerance of five rice cultivars

Objectives: Cadmium ion (Cd2+) is a ubiquitous toxic heavy metal in the environment and presents a potential threat to human health via the food chain through plant root uptake systems. Cadmium (Cd) is extremely toxic metal and reduces plant growth. Therefore, this study was conducted to evaluate the effect of various Cd levels on seed germination and seedling growth of five rice cultivars (Co-7, Co-2, Co-6, Paiyur and Vbn-2). Methods: Seeds of Oryza sativa were germinated in glass Petri-dishes of 200 × 30 mm diameter lined with blotting paper. 75 seeds were placed in each petri-dish. Petridishes were irrigated with 25, 50, 75, and 100 ppm concentrations of Cd. A control was moistened with ten milliliters of distilled water. Results: All the rice varieties are survived up to 100 ppm. Co-7 performed better under Cd stress (62%) while Vbn-2 had poor performance (84.4%) and other varieties such as Paiyur, Co-6 and Co-2 maximum decrease in percent germination 79.3%, 75.8 and 67.2 at 100 ppm Cd compared to control. Growth parameters like root length, shoot length, fresh weight of the root and shoot decreased with increasing concentration of Cd. However, among the varieties, minimum decrease in growth parameters was observed in Co-7. Conclusions: From these results it is evident that Co-7 could germinate well on soils contaminated with Cd, however, more studies are required to signify its effects on growth and yield of rice.