Effect of nitrogen application levels on photosynthetic nitrogen distribution and use efficiency in soybean seedling leaves

Binbin Qiang; Weixin Zhou; Xingjie Zhong; Chenye Fu; Liang Cao; Yuxian Zhang; Xijun Jin

doi:10.1016/j.jplph.2023.154051

Effect of nitrogen application levels on photosynthetic nitrogen distribution and use efficiency in soybean seedling leaves

J Plant Physiol. 2023 Aug:287:154051. doi: 10.1016/j.jplph.2023.154051. Epub 2023 Jul 9.

Authors

Binbin Qiang¹, Weixin Zhou¹, Xingjie Zhong¹, Chenye Fu¹, Liang Cao², Yuxian Zhang³, Xijun Jin⁴

Affiliations

¹ School of Agronomy, Heilongjiang Bayi Agricultural University, Daqing, 163000, China.
² School of Agronomy, Heilongjiang Bayi Agricultural University, Daqing, 163000, China; National Multigrain Engineering and Technology Center, Daqing, 163000, China.
³ School of Agronomy, Heilongjiang Bayi Agricultural University, Daqing, 163000, China; National Multigrain Engineering and Technology Center, Daqing, 163000, China. Electronic address: zyx_lxy@126.com.
⁴ School of Agronomy, Heilongjiang Bayi Agricultural University, Daqing, 163000, China; National Multigrain Engineering and Technology Center, Daqing, 163000, China. Electronic address: shaoxiang1979@163.com.

PMID: 37481898
DOI: 10.1016/j.jplph.2023.154051

Abstract

Background: Nitrogen nutrition is strongly associated with crop growth and development. Nitrogen application level affects leaf size as well as nitrogen content and distribution, and thus affects photosynthetic nitrogen-use efficiency (PNUE) and yield. In this study, soybean varieties "Jinyuan 55" and "Keshan 1" were treated with nitrogen as urea at: N0, 0 kg hm^-2; N0.5, 60 kg hm^-2; N1, 120 kg hm^-2; and N1.5, 180 kg hm^-2. We compared the effect of nitrogen level on plant morphology, biomass, photosynthetic physiology, nitrogen distribution, PNUE, and other soybean seedling leaf characteristics.

Results: Maximum carboxylation and electron transfer, net photosynthetic rates, and PNUE of both soybean varieties showed initial significant increases with increasing nitrogen application rate and subsequent stabilization. PNUE, carboxylation system components, electron transport components, and non-photosynthetic system distribution ratios in the photosynthetic system increased and subsequently decreased with increased nitrogen application rate. The nitrogen ratio between carboxylation and electron transport systems was positively correlated with PNUE in both soybean varieties. The nitrogen ratio in light-harvesting and non-photosynthetic systems showed a linear negative correlation with PNUE.

Conclusions: Overall, an appropriate nitrogen level maintained a high photosynthetic nitrogen ratio, whereas low- or high-nitrogen conditions increased or decreased the nitrogen ratio in non-photosynthetic and photosynthetic systems, respectively, thus decreasing the PNUE and photosynthetic capacity. Moreover, increased nitrogen application rate led to a decreased nitrogen ratio in the light-harvesting system and an increased nitrogen ratio of electron transport and carboxylation systems. Our results provide a theoretical basis for optimizing leaf nitrogen distribution, determining optimum nitrogen levels, and promoting soybean seedling growth.

Keywords: Leaf nitrogen content; Nitrogen distribution; PNUE; Photosynthetic system; Soybean seedlings.

MeSH terms

Biomass
Glycine max
Nitrogen*
Photosynthesis / physiology
Plant Leaves
Seedlings*

Substances

Nitrogen