During the production of Wuyi rock tea, withering and fermentation play a crucial role in the primary processing of the tea, greatly influencing the development of its distinct taste characteristics. In this study, Rougui (Camellia sinensis) was selected as the research object to investigate the effects of withering and fermentation on metabolites and taste characteristics in tea leaves. The findings revealed that a total of 1249 metabolites were detected in Rougui leaves at various processing stages, of which only 40 key metabolites were significantly altered. The process of withering and fermentation is crucial to increase the content of organic acids, plumerane, alkaloids, nucleotides and derivatives, amino acids and derivatives, and free fatty acids in the leaves of Rougui and to decrease the content of saccharides, phenolic acids, flavonols, flavones, and flavanols, which in turn enhances the mellowness, fresh and brisk taste, and aroma of tea and attenuates the saccharides, bitterness, and astringency. Withering and fermentation had the greatest effect on the bitterness and astringency of Rougui taste characteristics, followed by mellowness. It can be seen that withering and fermentation were extremely important for the development of Rougui’s special taste characteristics. The present study provides important support for optimizing Rougui processing and the formation of its special taste characteristics.

To investigate the impact mechanism of different fertilization modes on the rhizosphere soil microecology of Camellia sinensis (C. sinensis), this study adopted 100% chemical fertilizer (HCF), 100% organic fertilizer (HOF), 2/3 chemical fertilizer + 1/3 organic fertilizer (HTC), 1/2 chemical fertilizer + 1/2 organic fertilizer (HHOC), and 1/3 chemical fertilizer + 2/3 organic fertilizer (HTO) applied to C. sinensis. In May 2025, samples were collected for measurement and analysis. The results showed that the combination of organic–inorganic fertilizers (especially HTO) significantly increased the content of available nutrients in the soil while maintaining a high pH value, organic matter, and total nutrient content. Microbial community analysis showed that the key microbial groups sensitive to different fertilization responses were Thauera, Zoogloea, and Ceratobasidium. Functional prediction revealed that HCF significantly enriched nitrogen respiration and plant pathogenicity functions, while HOF treatment resulted in a decreased relative abundance of sequences related to pathogenesis. The results of structural equation modeling and path intensity analysis indicated that there was a significant synergistic effect among key microbial communities, which strongly drove their functional expression. The enhancement of these functions resulted in a decrease in soil pH, total soil nutrient content, and available nutrient content. The combination of organic and inorganic fertilizers could optimize the microbial community structure, balance its functional expression, and alleviate the effects caused by single fertilization. This study preliminarily explored the effects of different fertilization modes on the rhizosphere soil microbial community and nutrient transformation of C. sinensis, providing a reference for the subsequent application of organic–inorganic fertilizers in C. sinensis planting.

Magnesium plays an important role in regulating the growth and quality of tea trees. However, the effect of magnesium regulation on changes in the aroma quality of tea tree leaves remains unknown. In this study, the volatile compounds of tea leaves under different magnesium concentrations were determined to obtain the characteristic volatile compounds that changed significantly and their odor characteristics and to explore the effect of magnesium regulation on the aroma quality of tea leaves. The results showed that magnesium significantly enhanced the content of 15 characteristic volatile compounds in tea tree leaves, especially heptyl formate and t-geraniol. The 15 characteristic volatile compounds mainly showed five kinds of odor characteristics, such as fruity, green, floral, pungent, woody, and burnt; magnesium regulation critically increased floral, fruity, and green odor characteristics. This study lays an important foundation for the application of exogenous magnesium ions to regulate tea aroma quality.

Magnesium (Mg) ions play a crucial role in the growth and development of tea plants (Camellia sinensis). In this study, the ion kinetic method was used to analyze the effect of ions from various elements on the Mg ion uptake rate in two tea plant varieties (Rougui and Shuixian). Additionally, Mg ion content and the expression intensity of CsMGT5 gene in the tea plant’s root system were measured to further understand how different elemental ions affect Mg ion uptake and accumulation. The results revealed that while the trends in the effects of different elements on Mg ion uptake were similar in both Rougui and Shuixian roots, the magnitude of these effects was lower in Rougui and higher in Shuixian. In the presence of only Mg ions in the solution, the tea plant’s root system exhibited the highest intensity of CsMGT5 gene expression, the fastest uptake rate of Mg ion, and the highest Mg content. Conversely, the presence of nitrogen, phosphorus, and potassium ions alone reduced CsMGT5 gene expression, Mg ion uptake rate, and Mg content in the tea plant’s root system. However, differences in the impact of these three elements on Mg ion uptake and accumulation were not statistically significant. In addition, with the increase in the types of added ions, the Mg ion uptake rate by tea plants gradually declined, indicating a decreasing demand, with Mg accumulation showing a downward trend. Statistical analysis of correlations showed that CsMGT5 gene expression in the tea plant’s root system positively regulated the maximum uptake rate of Mg ion (I_max value, 0.94 **). The I_max value negatively regulated Mg ion content in solution (C_min value, −0.94 **), and the C_min value negatively regulated Mg ion content in the tea plant’s root system (−0.95 **). In conclusion, the presence of different elemental ions significantly influenced the uptake and accumulation of Mg ions in tea plants, with the magnitude of this effect intensifying as the number of elemental types increased. A positive correlation was observed between the capacity for Mg ion uptake and accumulation capacity in the tea plant’s root system and the expression intensity of the CsMGT5 gene within the root system. This study offers valuable insights and serves as an important reference for leveraging Mg to regulate tea plant growth in practical agricultural applications.

Space-induced mutation is a novel approach in tea plant breeding, but its effect on processing-induced aroma formation remains unclear. This study analyzed the dynamic changes in VOCs during the processing of space-induced mutants of Dahongpao tea. The results showed that processing significantly reshaped the VOC profile, with the fermentation stage exerting the greatest impact and terpenoids serving as the major contributors. Seven characteristic VOCs (α-phellandrene, β-phellandrene, d-sylvestrene, iso-geraniol, seudenone, hexyl benzene, and nerol) were identified and a transformation network linking floral, green, woody, almond, and fruity attributes was constructed. Molecular docking revealed that VOCs exhibiting green, woody and almond characteristics could form strong binding interactions with more than 100 olfactory receptors, whereas those with floral and fruity characteristics bound to fewer receptors. This finding indicates that during the processing, the first three odor characteristics may be perceived more prominently. Overall, this study provided a theoretical basis for the aroma evaluation of space-induced mutant tea.