Effects of tea application on cadmium, phosphorus, and iron accumulations in rice (Oryza sativa L.) seedlings

To decrease the cadmium (Cd) uptake in rice and study the relationships of phosphorus (P), iron (Fe), and Cd uptakes in rice, the effects of four different tea types (green, black, dark, and white teas) on the P, Fe, and Cd accumulation in rice seedlings were studied. The results showed that only the black and dark teas increased the biomass of rice seedlings. The application of green, black, dark, and white teas increased the photosynthetic pigment content to some extent. Only the black tea increased the shoot P content, and the black, dark, and white teas increased the shoot Fe content. Compared with the control, only the black and dark teas decreased the shoot Cd content by 9.51% and 25.02%. Correlation and gray relational analyses showed that the root Cd content, soil pH value and soil exchangeable Cd concentration were the most closely associated with the shoot Cd content. The principal component and cluster analyses also showed the top three close cluster categories with shoot Cd content were root Cd content, soil exchangeable Cd concentration, and soil pH value. These findings indicate that the application of black and dark teas can promote the growth and decrease the Cd uptake of rice.