Effect of Elevated [CO₂] on Assimilation, Allocation of Nitrogen and Phosphorus by Maize (Zea Mays L.)

ABSTRACT

To estimate the effect of elevated [CO₂] on nitrogen (N) and phosphorus (P) dynamics and productivity in summer maize, a field experiment was conducted in open-top chambers (OTCs) at different [CO₂] (550 μmol/mol, T1; 750 μmol/mol, T2 and a control, CK) in Nanjing in Jiangsu Province, China. The results showed that maize total N and P accumulation were 13.23–66.56% higher in the elevated [CO₂] treatments than in the CK plots during the jointing, anthesis and maturity stages. There was only a significant difference in total N accumulation between the T2 treatment and CK at maturity (P < 0.05). However, rising [CO₂] decreased the N and P concentrations in each biomass fraction. Elevated [CO₂] increased the amounts of N and P translocation, resulting in the contribution of translocated N to grain N. Similarly, rising [CO₂] increased N and P translocation efficiencies, N or P harvest index, and N or P utilization efficiency based on grain yield and N or P utilization efficiencies based on biomass in both growing seasons. In addition, elevated [CO₂] significantly increased aboveground biomass at three stages, including 4.73–12.34% at maturity. The grain yields of summer maize increased by 21.28% and 29.07% in the two elevated [CO₂] plots. Furthermore, spike numbers, kernels per spike and 100-grain weight were increased by elevated [CO₂] treatments. Kernels per spike and grain yield showed obvious differences between elevated [CO₂] treatments and CK (p < 0.05).

KEYWORDS:

• Grain yield
• nitrogen
• open-top chambers (OTCs)
• phosphorus
• Zea mays L.

Acknowledgments

The authors acknowledge experimental helps provided by Xie Chenyu and Tang Huichun. This study was supported by the Natural Science Foundation of China (41205087) and Special Fund for Meteorological Scientific Research in the Public Interest (201506055), We also acknowledge the funding support provided by the Priority Academic Development Program for Jiangsu Higher Education Institutions (PAPD).