Evaluation of the aluminium-induced root growth inhibition in isolation from low pH effects in Glycine max, Pisum sativum and Phaseolus vulgaris

The interaction between proton and aluminium toxicities was examined in soybean (Glycine max L.), pea (Pisum sativum L.) and bean (Phaseolus vulgaris L.). Accurate characterization of genotype Al-sensitivity in solution culture experiments, employing a continuous Al-exposure, required response definition at both growth-enhancing and growth inhibiting activities. Essentially, this involved multiple controls to account for the interactive effects. Experiments measuring growth during a recovery period in Al-free solution were more successful in distinguishing genotypic response to Al, especially in species demonstrating high H+-sensitivity. The time, concentration and basal solution dependencies of the characteristic genotype response for the three species examined were consistent with the hypothesis that responses of genotypes may be predicated upon conditions emphasizing irreversible (cell division) effects. Cell extension effects, however, appear to be rapid, largely-reversible and often not different between differentially Al-sensitive genotypes growing in a complete nutrient solution.