Amelioration of aluminum toxicity by pretreatment with phosphate in aluminum-tolerant rice cultivar

The phytotoxicity of aluminum.(Al) in relation to preculture with phosphates was examined in the rice cultivar Arkansas fortuna. In plants precultured with phosphates, Al did not inhibit shoot growth, while Al retarded shoot growth in plants precultured without phosphates. In contrast, Al inhibited root elongation, irrespective of the presence of phosphates in the preculture solution. A large proportion of the Al in roots was in unknown, insoluble forms. In phosphate-precultured plants, Al deposition was slightly increased, presumably due to the formation of aluminum phosphates in the roots, and phosphor-us levels in shoots were markedly increased. Binding with phosphates may ameliorate the toxicity of Al when it enters the shoots and account for the uninhibited shoot growth in the presence of Al in plants precultured with phosphates.