Coordinating postanthesis carbon and nitrogen metabolism of hybrid rice through different irrigation and nitrogen regimes

Yongjian Sun, Yuanyuan Sun, Fengjun Yan, Yue Li, Yuxia Wu, Changchun Guo, Peng Ma, Guotao Yang, Zhiyuan Yang, Jun Ma*

Agronomy  Journal（IF=1.683），2020，10（8）:1187

https://www.mdpi.com/2073-4395/10/8/1187/htm

Abstract

We sought to explore the role of postanthesis carbon and nitrogen (C-N) metabolism of hybrid rice in increasing yield and nitrogen utilization efficiency (NUE). We used the ¹³C and ¹⁵N dual-isotope tracer method and physiological/biochemical analysis and established different irrigation and nitrogen fertilization (W-N) regimes to investigate the relationship of C-N metabolism characteristics, yield, and NUE. The results showed that W-N regimes had significant effects on postanthesis absorption and translocation of N and photosynthate, yield and NUE. Aerobic irrigation combined with the N fertilization regime 30% base, 30% tillering, 40% booting was the best W-N coupling regime for rice yield and NUE increase. The regime enhanced flag leaf photosynthesis rate and the activities of ribulose 1,5-diphosphate carboxylase/oxygenase (RuBPCase), glutamine synthetase (GS), and other key enzymes of C-N metabolism, and improved the total accumulations of photoassimilates (0.97–21.57 mg ¹³C plant⁻¹) and N (1.55–23.36 mg ¹⁵N plant⁻¹), respectively. Correlation analysis showed that, under the W-N interaction, C-N metabolism enzymes promoted the positive synergistic effect between ¹³C and ¹⁵N accumulation in panicles (r = 0.825). In addition, the change in C/N ratio can be used as an indicator of the simultaneous improvement in yield and NUE in hybrid rice.