Phosphorus nutrition alleviates manganese toxicity in Lolium perenne and Trifolium repens

Phosphorus (P) nutrition has been suggested to play a role in the alleviation of manganese (Mn) toxicity in some higher plant species. However, there are few reports on the role of P in regulating Mn accumulation by forage species. We studied the effect of P nutrition on Mn toxicity in Lolium perenne L. and Trifolium repens L. An increase in Mn concentration in root and shoot tissues was associated with an increase in both P supply and P tissue concentrations. Nevertheless, in both forage species, especially white clover, plant-growth inhibition caused by Mn excess was decreased with increasing P additions. Moreover, the carboxylate exudation that had increased in response to high Mn was gradually reduced by increasing P supply. We suggest that P supply may have a beneficial effect in reducing the severity of Mn toxicity in forage species.