ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Nutrition
Nitrogen Use Efficiency of Flue‑Cured Tobacco Genotypes: Physiological Basis and Relative Contributions of Nitrogen Uptake and Utilization
Weiguo YE 1
Jia Lei 2
Xianyun Zhong 2
Changyue Qi 1
Najam Ud Din 1
Yuanyuan Wang 1
Huaiyuan Li 1
Jianjun Chen 1
Shiyuan Deng 1
1. South China Agricultural University, Guangzhou, China
2. China Tobacco Guangdong Industrial Co Ltd, Guangzhou, China
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Abstract
Understanding the physiological processes that regulate nitrogen uptake efficiency (NUpE), nitrogen utilization efficiency (NUtE), and nitrogen use efficiency (NUE) in crops is essential for developing nitrogen-efficient varieties. We conducted a two‑year field study (2021–2022, Shixing, southern China) comparing three flue‑cured tobacco genotypes (Yunyan 87, Yueyan 97, K326) under two nitrogen application rates: traditional (150 kg ha⁻1) and reduced (105 kg ha⁻1, −30%). Across both rates, the high‑NUpE genotypes (Yueyan 97, K326) showed substantially greater root biomass, length, surface area, volume, vigor, bleeding sap and nitrate flow rates, and higher activities of key N ‑metabolism enzymes than low‑NUpE Yunyan 87. These root and physiological traits were positively correlated with nitrogen uptake efficiency, indicating that they are major correlates of NUpE and may contribute to its variation. Compared with Yunyan 87 and K326 (both low‑NUtE genotypes), Yueyan 97 (a high‑NUtE genotype) exhibited a significantly lower respiratory rate despite a lower net photosynthetic rate. This pattern is consistent with higher NUtE being associated with a balance between net photosynthesis and respiration that favors reduced respiratory consumption. Path analysis indicated strong conditional associations of both NUpE and NUtE with NUE across genotypes. While path coefficients do not imply causality, the results suggest that jointly improving NUpE and NUtE may be a promising avenue for achieving high yield and improved NUE in flue-cured tobacco. In conclusion, this study identifies physiological traits that are strongly associated with NUpE and NUtE in flue-cured tobacco and provides insights to guide future efforts aimed at enhancing NUE in this crop.
Summary
Keywords
flue‑cured tobacco, Genotype, nitrogen uptakeefficiency (NUpE), Nitrogen use efficiency (NUE), nitrogen utilization efficiency (NUtE)
Received
18 October 2025
Accepted
19 February 2026
Copyright
© 2026 YE, Lei, Zhong, Qi, Din, Wang, Li, Chen and Deng. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Jianjun Chen; Shiyuan Deng
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