Phophorus, Zinc, and Manganese Interactions in Hydroponically Grown Maize.

Maize (Zea mays L.) is commonly included in rotation with potato (Solanum tuberosum L.), a species with relatively high phosphorus (P) nutritional requirements. Evidence shows high P levels may induce zinc (Zn) deficiency and consequently cause interactions with other micronutrients. Two experiments, with either variable levels of Zn or P, were conducted to study sufficient, deficient, and toxic levels of P and Zn on Zn efficient (35F38) and Zn inefficient (35T06) maize hybrids. Using hydroponic techniques, maize plants were grown for 18 days and then analyzed for dry weight and nutrient concentrations. Variable Zn and P solution levels generally resulted in significant maize dry matter yield differences in identifiable ranges of deficiency, sufficiency, and toxicity. Results showed Zn precipitation in roots and Mn increase in shoots as application of P increased. However, in this study only the first increment of P (32 µM P) reduced maize Zn shoot content below that of the control (8 µM P). Increasing levels of Zn above 20 µM resulted in reductions of P in both shoots and roots while concurrently resulting in higher Mn levels. Root Mn increased dramatically above 0.05 µM Zn, peaked at 20 and 40 µM Zn, and then declined at higher solution Zn levels. Observations comparing the two hybrids partially explained differences in susceptibility to Zn deficiency in the field. The P-Zn interaction in maize may be explained by the combined impacts of Zn precipitation in roots and increased Mn in shoots.