## 4 Conclusions  
In this study, the effect of magnesium regulation on volatile compounds and odor characteristics of tea tree leaves was analyzed, and the results showed (Figure 7) that magnesium regulation significantly changed the content of volatile compounds in tea tree leaves, especially terpenids, esters, and heterocyclic compounds. After magnesium regulation, the characteristic volatile compounds that changed significantly in tea tree leaves were mainly 15 kinds, and their contents showed an increasing trend with the increase of magnesium ion concentration. Among them, heptyl formate and t-geraniol played a key role in distinguishing between different concentrations of magnesium ions. After magnesium regulation, the characteristic volatile compounds of tea tree leaves mainly  
Figure 6: Effect of magnesium regulation on odor characteristics and their intensities in tea tree leaves. Note: ML: Mg\({}^{2+}\) concentration 0 mmol/L; MM: Mg\({}^{2+}\) concentration 0.4 mmol/L; MH: Mg\({}^{2+}\) concentration 0.8 mmol/L; (**A**) Odor analysis of characteristic volatile compounds of tea tree leaves under magnesium regulation; (**B**) Intensity analysis of odor characteristics of tea under magnesium regulation.  
exhibited five types of odor characteristics, such as fruity, green, floral, pungent, woody, and burnt, the intensities of which all showed a significant upward trend with the increase of magnesium concentration, especially floral, fruity, and green. In conclusion, magnesium is beneficial to enhancing the synthesis of volatile compounds in tea leaves and the intensity of odor characteristics such as floral, fruity, and green. This study provides an important theoretical basis for the application of exogenous magnesium ions to regulate the growth of tea trees and improve the aroma quality of tea leaves.  
**Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/foods14061043/s1](https://www.mdpi.com/article/10.3390/foods14061043/s1)]([https://www.mdpi.com/article/10.3390/foods14061043/s1](https://www.mdpi.com/article/10.3390/foods14061043/s1)), Table S1. Raw data of volatile compounds in tea leaves.  
**Author Contributions:** J.Y.: Writing--original draft, Conceptualization, Funding acquisition, Visualization, Methodology. Q.W.: Writing--original draft, Methodology, Data curation, Formal analysis. Y.W., W.C. and J.G.: Methodology, Validation, Writing--original draft. Q.Z., B.Z. and Q.L.: Data curation, Methodology, Validation, Writing--review & editing. X.J.: Writing--review & editing, Funding acquisition, Resources. J.W.: Methodology, Writing--review & editing. H.W.: Writing--review & editing, Project administration, Supervision, Resources, Funding acquisition, Conceptualization. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was supported by Natural Science Foundation of Fujian Province (2024)J01861, 2024N0009, 2024J01866); Youth Science and Technology Talent Project of Education Department of Guizhou Province (KY 2022-153); Construction of First-Class Undergraduate Specialty (Tea Science) in Fujian Province (SIZY2019004); Nanjing City Science and Technology Plan Project (NP2021 KTS06, NP2021 KTS05, N2021Z012); Innovation and Entrepreneurship Training Program for College Students (202411312002); and Wuyi University Horizontal Research Program (2023-WHFW-017).  
Figure 7: Effect of magnesium regulation on characteristic volatile compounds and odor characteristics of tea tree leaves.