Differential Response to Al-Toxicity of Two Populations of Avena sterilis L.

Negative correlation between Al concentrations and root and shoot growth was detected in two populations of Avena sterilis L. investigated [one from a bauxite area (1) and the other (2) from a pasture area]. Al solubility and Al content of plant tissue depend on pH levels of nutrient solution. Population-1 although in all treatments contained greater amounts of Al in its roots, was grown better than population-2, suggesting that population-1 is more tolerant than population-2. Al content of shoot and root of both populations was greater at pH 10.0 than at pH 4.5, a fact that may indicate that Al ions in alkaline medium are preferentially absorbed than Al ions in acid medium. The better growth of both populations observed in all Al concentrations at pH 10.0, where Al content of plant tissues was greater, may indicate that Al forms predominant in acid nutrient medium are more harmful than Al forms in alkaline nutrient medium.