Phosphorus Alleviation of Cadmium Phytotoxicity*

A hydroponic study was conducted under controlled environmental conditions to determine the effect of phosphate addition on cadmium (Cd) toxicity to soybeans (Glycine max L. Cutiva perron) plants. Three-week-old soybean plants previously grown on perlite for two weeks and additional seven days on ‘Hoagland’ nutrient solution without Cd supply were transferred to solutions containing either 0, 0.075 or 0.15 mg Cd L−1. Each of these Cd treatment received either 0.4, 0.6, or 0.8 M phosphorus (P) as KH2PO4 and the seedlings were grown for additional 33 d. Results of this study indicated that irrespective of Cd level in the growing solution, phosphate addition alleviated Cd toxicity in soybean. The addition of as little as 0.4 M phosphate alleviated biomass reductions induced by 0.075 mg Cd L−1. The alteration in tissue Cd concentrations brought about by phosphate addition may reveal an antagonistic effect between P and Cd.