How Much Phosphorus Uptake Is Required for Achieving Maximum Maize Grain Yield? Part 2: Impact of Phosphorus Uptake on Grain Quality and Partitioning of Nutrients

Abstract

Previous studies have shown that excess phosphorus (P) uptake by maize can lead to a decreased grain yield. Part one of this study demonstrated that maize experienced luxury consumption of P in three phases of P uptake. The objective of this work was to further explore how P uptake indirectly impacts the uptake of other nutrients and their translocation within the plant to explain the yield penalty associated with luxury P consumption. Three maize hybrids were grown under optimal conditions using sand-culture hydroponics for precise control of the root environment. Plants were grown to maturity with six different P concentrations followed by biomass and nutrient partitioning analysis of various maize parts. All non-P nutrients achieved maximum grain content at P uptake levels that coincided with the maximum grain yield, while the partitioning of K, Mg, Mn, B, N, S, and Fe into other non-grain tissue continued with further P uptake. With luxury P consumption beyond the point corresponding with maximum grain yield, the N, S, Fe, Cu, and Zn grain content significantly decreased along with the grain yield. With luxury P consumption, Cu, Zn, and Fe accumulated in the roots. Grain production with luxury P uptake may have been limited by P-inhibited translocation of Cu, Zn, and Fe from roots to grain. This decrease in translocation did not prevent further non-grain tissue growth since those nutrients were not as limiting as they were for grain. Data suggest that these micronutrients limited protein production, which was evident from the decrease in grain N and S content and concentration that coincided with the decrease in grain yield concomitant with luxury P uptake.