Zinc fertilizer placement affects zinc content in maize plant

Adequate zinc (Zn) in maize (Zea mays L.) is required for obtaining Zn-enriched grain and optimum yield. This study investigated the impact of varying Zn fertilizer placements on Zn accumulation in maize plant. Two pot experiments with same design were conducted to investigate the effect of soil Zn heterogeneity by mixing ZnSO4 center dot 7H(2)O (10 mg Zn kg(-1) soil on an average) in 10-15, 0-15, 25-30, 0-30, 30-60 and 0-60 cm soil layers on maize root growth and shoot Zn content at flowering stage in experiment-1, and assessing effects on grain Zn accumulation at mature stage in experiment-2. In experiment-1, Zn placements created a large variation in soil DTPA-Zn concentration (0.3-29.0 mg kg(-1)), which induced a systemic and positive response of root growth within soil layers of 0-30 cm; and shoot Zn content was increased by 102 %-305 % depending on Zn placements. Supply capacity of Zn in soil, defined as sum of product of soil DTPA-Zn concentration and root surface area at different soil layers, was most related to shoot Zn content (r = 0.82, P < 0.001) via direct and indirect effects according to path analysis. In experiment-2, Zn placements increased grain Zn concentration by up to 51 %, but significantly reduced the grain Zn harvest index from 50 % by control to about 30 % in average. Matching the distribution of soil applied Zn with root by Zn placement was helpful to maximize shoot Zn content and grain Zn concentration in maize.