Interaction of Cd and five mineral nutrients for uptake and accumulation in different rice cultivars and genotypes

Pot experiments were conducted on 20 rice cultivars of different genotypes and origins by adding 100 mg/kg of cadmium (Cd) to soil. The aim was to investigate the effects of Cd on the dry matter accumulation and grain yield of different rice cultivars, the differences among rice cultivars and genotypes in Cd uptake and translocation, the interactions between Cd and five mineral nutrients Fe, Zn, Mn, Cu and Mg in response of the uptake and translocation in rice plant. The results showed that the effects of Cd on rice growth and development were variety dependent; some cultivars were strongly tolerant to soil Cd stress, while others were very sensitive. Differences existed among the cultivars for Cd uptake and distribution in rice plants, but the differences were not necessarily related to rice genotypes. Cd concentrations fell rapidly from roots to brown rice along rice plants, so the concentrations of Cd were very low in brown rice compared with other parts of rice plants. The effects of Cd on the concentrations of the mineral nutrients in the rice roots and leaves were mostly significant, however, the results varied with metal elements, rice plant organs and growing stages. Under soil Cd stress, the variations of the grain and straw yield of the cultivars were not correlated with the changes of any mineral nutrient in the rice plant. The regression analysis showed that, for their concentrations in roots and leaves, significant positive correlations between Cd and Fe, Cd and Zn, Cd and Cu existed, but no significant correlation between Cd and Mg, and the relationship between Cd and Mn varied with the organs of rice plant. These results suggested that rice cultivars differed greatly in growth and development responses to Cd and in absorption and translocation of Cd, Fe, Zn, Cu, Mn and Mg. The effects of Cd on the five mineral nutrients were not the main causes of the inhibition of Cd on rice growth and development. The interactions of Cd and Fe, Zn, Cu are synergetic in uptake and translocation from root to shoot by rice plants. (C) 2003 Elsevier Science B.V. All rights reserved.