Effect of manganese on cadmium toxicity in maize seedlings

The interaction of manganese with cadmium (Cd) toxicity was studied on maize plants grown in hydroponics. Man ganese supplied as MnSO 4 clearly alleviated the toxic effect of cadmium on the root growth of maize seedlings. The magnitude of alleviation was dose dependant and total abolition of 10µM Cd toxicity on root growth was observed at Mn/Cd ratio of 20:1. The 12 h pre-treatment with 10 µM Cd was generally toxic for nitrate uptake and reduction (both determined in Cd-free media). The beneficial effect of 100 µM Mn on this toxicity was confirmed for the low-affinity nitrate uptake system, but on the other hand, Mn alone seems to be slightly toxic for high affinity nitrate uptake system and on the nitrate reductase activity.