The effect of increased manganese concentrations on shoot growth, leaf chlorophyll content, Chl. ‘a/b’ ratio and catalase activity in seedlings of four Amaranthus species (A. polygamus, A. oleracia, A. viridis and A. gangeticus) were examined inorder to evaluate Mn tolerance, the treatments comprised of five Mn levels (0.2 to 6.0 mmol) in nutrient solutions and three exposure times (24, 48 and 72h). A. polygamus and A. oleracia were found as Mn-sensitive and A. viridis and A gangeticus as Mn-tolerant.
