Zinc uptake by rice, as affected by metabolic inhibitors and competing cations

Absorption of Zn by 14-day-old intact rice seedlings was studied in short-term uptake experiments. Severe retardation of Zn absorption by various metabolic inhibitors indicated that an active process prevails at Zn concentrations often found in soil solutions. Several cultivars all showed similar sensitivity to the metabolic inhibitor 2,4-dinitrophenol (DPN). At concentrations of 10−4 M, both FeCl2 and MnCl2 depressed Zn uptake in roots and translocation to shoots; uptake was depressed to a lesser extent with Ca. Although Mg reduced uptake by the roots, translocation to the shoots was enhanced. These results suggest that high solution concentrations of reduced Fe and Mn which develop in paddy culture may be related to Zn nutrition. This information could assist in predicting Zn deficiency and may explain correction of Zn deficiency by draining flooded rice fields.