Abstract: A hydroponic study was conducted on the root growth, nutrient uptake,and root extracts and exudates of soybean and rice under aluminum (Al) stress. The results showed that low Al (10 μmol·L^-1) stimulated the seed germination and root growth of soybean, but had no obvious promotion effects on rice. Al stress increased the P uptake, but decreased the K, Ca and Mg uptake by both soybean and rice. Rice accumulated less Al and more P than soybean. When exposed to Al stress, the soluble protein content in soybean and rice roots increased, soluble phenol decreased, while soluble sugar increased first and decreased then. The citrate content in soybean roots decreased obviously under Al stress. Compared with soybean, rice accumulated more soluble protein and phenol and less citrate, but no difference was observed in soluble sugar content. Al increased the exudation of citrate and soluble protein, phenol and sugar from soybean roots. Under Al stress, soybean roots possessed a higher cation exchange capacity than rice roots. It was suggested that soybean and rice had different physiological responses to Al stress. The Al tolerance of rice was probably associated with its higher P uptake and lower cation exchange capacity than soybean, while root exudates had no significant correlation with its Al tolerance.

Key words: iron, cadmium, interaction, rice, lipid peroxidation, antioxidative enzyme.