Effect of aluminium on nitrate uptake and assimilation in maize roots

The mechanism by which aluminium influences the ion uptake is still poorly understood. In this study the effects of Al on nitrate uptake, nitrate redu ctase and P-ATPase activity were measured in maize roots exposed to Al for different time period. In short-time experiments (Al-treatment lasting for 1 h) root growth, nitrate uptake as well as nitrate reductase activity have not been influenced by Al. Long-term experiments (Al-treatment lasting for 24 h) significantly reduced the root growth, nitrate uptake, and P-ATPase activity. At the same condition the nitrate reductase activity was slightly inhibited in apical parts of roots while stimulation was observed in root parts more distant from the root apex. The differences found out in our exp eriments support the prevalent view that Al may influence the ion flux by d ifferent mechanisms the extent of which is time dependent.