PHOSPHORUS AND ZINC INTERACTIONS AND THEIR RELATIONSHIPS WITH OTHER NUTRIENTS IN MAIZE GROWN IN CHELATOR-BUFFERED NUTRIENT SOLUTION

Maize (Zea mays L.) is common in potato (Solanum tuberosum L.) cropping systems and is especially susceptible to zinc (Zn) deficiency, possibly related to induced potato demand for high phosphorus (P). Three chelator-buffered nutrient solution experiments were evaluated for maize response to establish ranges of deficient, sufficient, and excessive Zn and P and to evaluate interactions. Zinc concentrated in roots and manganese (Mn) accumulated in shoots as P increased, but only 32 mu M P produced significantly lower shoot Zn than other treatments and there was not a decline in shoot Zn at high P levels. Deficient Zn levels promoted excessive P uptake. Root Mn increased dramatically above 0.05 mu M Zn, peaked at 20 and 40 mu M Zn, and then declined at higher solution Zn levels. The P-Zn interaction in maize may be explained by the combined impacts of increased available P on Zn precipitation in roots and increased Mn in shoots.