Micronutrient Uptake and Mobility Within Corn Plants (Zea mays L.) in Relation to Phosphorus‐induced Zinc Deficiency

Abstract Corn plants ( Zea mays L.) were grown in greenhouse pots on calcareous soil known to be low in available Zn. Phosphorus was applied to soil at rates of 0 to 520 ppm with concomittant addition of Zn decreasing from 40 to 0 ppm—in inverse concentration. Zinc deficiency occurred at high P and low Zn. Maximum growth occurred at 130 ppm P and 2.5 ppm Zn applied. Distribution of Zn, Fe and Mn among leaf, stem and root tissue indicated that P and Zn fertilization had altered the mobility of these micronutrients within the plant. Mobility of Fe and Mn was increased by high P and low Zn. Zinc mobility varied opposite to that of Fe and Mn. Applied P reduced Zn concentration in tissue but not uptake per plant. DTPA‐extractable Zn in soil was not decreased by P applied, but did increase with Zn applied. DTPA‐extractable Fe and Mn increased at high levels of applied P. Zinc‐deficient plants accumulated a large excess of Fe. Interference from excess Fe is suggested as contributing to physiological malfunction within Zn‐deficient corn plants.