EFFECT OF LANTHANUM ON RICE PRODUCTION, NUTRIENT UPTAKE, AND DISTRIBUTION

ABSTRACT

Split root solution culture experiments were conducted to study the effects of the rare earth element lanthanum (La) on rice (Oryza sativa) growth, nutrient uptake and distribution. Results showed that low concentrations of La could promote rice growth including yield (0.05 mg L⁻¹ to 1.5 mg L⁻¹), dry root weight (0.05 mg L⁻¹ to 0.75 mg L⁻¹) and grain numbers (0.05 mg L⁻¹ to 6 mg L⁻¹). High concentrations depressed grain formation (9 mg L⁻¹ to 30 mg L⁻¹) and root elongation (1.5 mg L⁻¹ to 30 mg L⁻¹). No significant influence on straw dry weight was found over the whole concentration range except for the 0.05 mg L⁻¹ treatment. In the pot and field experiments, the addition of La had no significant influence on rice growth.Lanthanum had variable influence on nutrient uptake in different parts of rice. Low concentrations (0.05 mg L⁻¹ to 0.75 mg L⁻¹) increased the root copper (Cu), iron (Fe), and magnesium (Mg), and grain Cu, calcium (Ca), phosphorus (P), manganese (Mn), and Mg uptake. High concentrations (9 to 30 mg L⁻¹) decreased the grain Ca, zinc (Zn), P, Mn, Fe and Mg, and straw Ca, Mn, and Mg uptake. With increasing La concentration, root Zn, P, Mn, Cu, and Ca concentrations increased, and grain Ca and Fe, and straw Mn, Mg, and Ca concentrations decreased. Possible reasons are discussed for the differences between the effects of La in nutrient solutions and in pot and field experiments.

ACKNOWLEDGMENTS

The authors thank Ms. Margaret Cargill, Dr. Patrick O'Connor, and Professor Andrew Smith, from Adelaide University, for their helpful comments on the draft of this paper. This project was supported by the National Natural Science Foundation of China (Grant No. 29890282) and the Foundation of Ecological Experimental Station of Red Soil, The Chinese Academy of Sciences.