Leaf Color Chart-Based Nitrogen Management Affects Rice Enzyme Activities and Maintains Soil Nitrogen Balance

Jichao Tang, Wenxuan Zhang, Xi Niu, Chengfang Li, Cougui Cao, Dongliang Xiong, Ying Zhang, Jianhua Qu, Bin Wang and Tianqi Liu ()
Additional contact information
Jichao Tang: School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China
Wenxuan Zhang: School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China
Xi Niu: School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China
Chengfang Li: MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China
Cougui Cao: MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China
Dongliang Xiong: MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China
Ying Zhang: School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China
Jianhua Qu: School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China
Bin Wang: Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China
Tianqi Liu: School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China

Agriculture, 2025, vol. 15, issue 17, 1-21

Abstract: Real-time nitrogen (N) management based on the leaf color chart (LCC) is considered a potential alternative to traditional farmer practices. However, its physiological mechanisms for enhancing rice N utilization and its effects on paddy field N balance remain unclear. We aimed to elucidate the potential enzymatic mechanisms underlying LCC’s influence on rice N use and quantify the impact of LCC on paddy field N balance. In 2022 and 2023, a single-factor randomized block design experiment was conducted during the rice planting season. Four N treatments: no N (ONF), farmers’ conventional practices + urea [FNR] as the control, LCC + urea [SSNM1], LCC + controlled-release urea [SSNM2] were administered. Rice yield and N uptake were positive correlations with nitrate reductase (NR), glutamine synthetase (GS), glutamate-pyruvate transaminase (GPT), glutamate-oxaloacetate transaminase (GOT) and glutamate dehydrogenase (GDH) activities, which were higher under SSNM1 and SSNM2 compared with FNR, but were negative correlation with proteinase activity. Moreover, SSNM1 and SSNM2 increased rice yield by 9.2% and 9.4%, N uptake by 15.4% and 15.3%, and N use efficiency by 46.9% and 65.0%, and reduced reactive N losses by 46.2% and 66.7%, respectively. The annual net soil N inputs under FNR, SSNM1, and SSNM2 were 12.6, 8.9, and 4.2 kg N ha −1 , respectively. LCC-based N management increased N uptake and rice yield by enhancing the activities of NR, GS, GPT, GOT, and GDH while reducing protease activity. Moreover, LCC maintained soil N supply capacity even with reduced nitrogen fertilizer application.

Keywords: leaf color chart; nitrogen fertilizer; reactive nitrogen losses; nitrogen balance; enzyme activity (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2025
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/2077-0472/15/17/1861/pdf (application/pdf)
https://www.mdpi.com/2077-0472/15/17/1861/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jagris:v:15:y:2025:i:17:p:1861-:d:1738668

Access Statistics for this article

Agriculture is currently edited by Ms. Leda Xuan

More articles in Agriculture from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().