Relative Toxicities of Inorganic Aluminum Complexes to Barley

Abstract The inorganic forms of Al in the soil solution that decrease plant growth in acid soils have not been clearly identified. Therefore, we examined the effects of Al and its complexes with F ‐ and SO 2‐ 4 on the root elongation of barley ( Hordeum vulgare ) in nutrient solutions containing 3333 µmol Ca L −1 and 6 µmol B L −1 at pH 4.5. The anions were chosen because of their presence in the soil solution at levels sufficient to complex Al. The toxicity of 0 to 100 µmol Al L −1 was studied in the presence of 0 to 10 µmol F ‐ L −1 or 0‐3300 µmol SO 2‐ 4 L −1 . The elongation of roots of barley seedlings was correlated with Al 3+ concentrations but not with total soluble Al or Al complexed with F ‐ and SO 2‐ 4 . This could be one of the reasons why measurements of labile Al using complexing agents have not always been successful at distinguishing between Al‐toxic and nontoxic soils.