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

Authors: Penn, Chad; CAMBERATO, JAMES - Purdue University; WIETHORN, MATTHEW - Purdue University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2023
Publication Date: 1/14/2023
Citation: Penn, C.J., Camberato, J., Wiethorn, M. 2023. 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. Agronomy Journal. 13(1). Article: 258. https://doi.org/10.3390/agronomy13010258.
DOI: https://doi.org/10.3390/agronomy13010258

Interpretive Summary: Previous research has shown that excess phosphorus (P) uptake by corn can lead to decreased grain yield. Such uptake represents both an agronomic and resource-use inefficiency. This study was conducted to investigate the mechanism by which luxury consumption of P by corn decreases yield, and how it impacts the quality of the grain and partitioning of all other nutrients. Corn was grown indoors by a sand-culture hydroponics method for precise control of environment and nutrient bio availability. Six different P treatments were applied in order to achieve a range in P uptake. Plants were grown to full maturity, harvested and separated into roots, stem, leaf, cob, tassel, husk, and grain. Biomass and nutrient content was measured for each plant part. Uptake of all nutrients increased with P uptake. Content of all non-P nutrients in grain reached a maximum at maximum grain yield. Further P uptake beyond that point resulted in decreased grain content of N, S, Fe, Cu, and Zn, coinciding with decreased grain yield. However, all nutrients except for Cu and Zn continued to increase in total content among non-grain plant parts except for Cu and Zn, which accumulated in the roots. Therefore, luxury consumption of P decreased grain yield and quality, including protein, which occurred due to inhibited translocation of Cu and Zn from roots to grain. Depending on soil Cu and Zn fertility, excess P fertilization may limit corn grain yield and quality.

Technical Abstract: Previous studies have shown that excess phosphorus (P) uptake by maize can lead to decreased grain yield. We demonstrated that maize experienced luxury consumption of P in a three-step series of P uptake. The objective of this work was to further explore how P uptake indirectly impacts uptake of other nutrients and their translocation within the plant to explain the yield penalty associated with P luxury consumption. All non-P nutrients achieved maximum grain content at P uptake levels that coincided with maximum grain yield, while partitioning of K, Mg, Mn, B, N, S, and Fe into other non-grain tissue continued with further P uptake. With P luxury consumption beyond the point of maximum grain yield, N, S, Fe, Cu and Zn grain content sig-nificantly decreased along with grain yield. With luxury P consumption, Cu, Zn, and Fe accumu-lated in the roots with further P uptake beyond the 580 mg plant required for achieving maximum grain yield. 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. We hypothesized that those micronutrients limited protein production, which was evident from the decrease in N and S grain content and concentration that coincided with the decrease in grain yield concomitant with luxury P uptake.