Growth and tissue composition of rice grown in soil treated with inorganic copper, nickel, and arsenic

Abstract

Arsenic (As), copper (Cu), and nickel (Ni) are known to be toxic to plants. To evaluate their two and three way interaction effects on growth and tissue composition of rice (Oryza sativa L.), a short‐term greenhouse experiment was conducted. Four levels of As, three levels of Cu, and three levels of Ni were added to soil, alone and in all possible combinations, in a completely randomized block design. The biomass and Cu, Ni, and As concentrations of both shoots and roots were determined after rice was grown under flooded conditions for 57 days. As indicated by the analysis of variance, both shoot and root biomass were significantly decreased by the application of Ni, Cu, and As. Over the ranges of metal application rates used in this study, the effects of Ni, Cu, and As on the growth of rice plants were not independent of each other. In terms of toxicity to rice, a synergistic interaction existed between Cu and Ni while those between Ni and As, and Cu and As were antagonistic. A quadratic polynomial model adequately represented the effects of soil applied Cu, Ni, and As on rice growth. Plant tissue concentrations of Ni and Cu were also described by quadratic models, and the coefficients in these models clearly indicated that Cu and Ni competed with one another for uptake by rice. The presence of As enhanced the concentration of Cu and Ni in rice tissue. Tissue As concentration was a second order function of applied As and was not affected by addition of the other elements to the soil.