PHYSIOLOGICAL AND BIOCHEMICAL-CHANGES IN YOUNG MAIZE PLANTS UNDER IRON-DEFICIENCY .2. CATALASE, PEROXIDASE, AND NITRATE REDUCTASE ACTIVITIES IN LEAVES

Young maize plants, grown hydroponically, were supplied with different amounts (7.5, 0.75, 0.15, 0.075, and 0 mg Fe/L) of iron (Fe). At 14, 21, and 28 days, in vitro activities of catalase, peroxidase and nitra te reductase in leaves were determined. Strong and complete Fe deficie ncy resulted in decreased enzyme activities. Under moderate Fe deficie ncy-often a restoration of the normal activity after an initial reduct ion-was observed. The rapidity and the degree of reaction to Fe defici ency depended on the enzyme. The ratio peroxydase/catalase activity ca n not be applied as a reliable tool for diagnosis of Fe deficiency.