Attenuation of the toxic effects of aluminium by organic acids in rice cultivars.

Soil acidity, specifically the presence of Al ^+ 3 at toxic levels for most crop plants, is one of the main factors limiting agricultural production. However, the relationship between organic acid exudation and its direct influence and magnitude on aluminium tolerance in rice plants remains poorly elucidated in the literature. In order to verify the complexing effect of organic acids on Al, trials were carried out with rainfed rice seedlings of the Comum Branco and Caiapó varieties, under controlled growth conditions, in addition to evaluating the exudation of organic acids and possible changes in their internal root contents as a function of Al. It can be concluded that citric acid was effective in mitigating the toxic effects of Al³⁺ on the root system of the evaluated rice cultivars. In the absence of aluminium, malic acid promoted an increase in root length. The cultivar Comum Branco exhibited a greater tolerance to Al³⁺ compared to Caiapó, which may be associated with its higher exudation and accumulation of organic acids in the roots. These results suggest that the action of these mechanisms contributes to the greater aluminium tolerance observed in this cultivar.