Rock zones have an important influence on the yield and quality of Wuyi rock tea. In this study, OPLS-DA combined with machine learning was used to analyze the effects of different rock zones and tea tree varieties on the physicochemical properties of rhizosphere soil, the growth of the tea tree and the quality of the tea leaves using tea trees in different rock zones. The results showed that rock zones had significant effects on rhizosphere soil physicochemical indexes, soil enzyme activities, tea tree growth and tea quality indexes, while there was little difference between different tea tree varieties. The interaction analysis showed that the physicochemical indexes of rhizosphere soil in different rock zones significantly affected tea quality, while also affecting growth indexes. The main indexes affecting tea yield and caffeine content were soil pH, available nitrogen, total phosphorus, total nitrogen and available phosphorus, while the main indexes affecting tea quality were available potassium, organic matter, total potassium, protease, polyphenol oxidase and urease. Analyses of PCA, OPLS-DA models and KNN and ANN machine learning showed that different rock zones could be effectively distinguished from each other with 100% accuracy, while different tea varieties had little difference and could not be distinguished. TOPSIS analysis found that the physicochemical indexes most affected by rock zone were available nitrogen, available potassium and sucrose, and the quality indexes most affected by rock zone were tea polyphenols and theanine. The growth index most affected by rock zone was tea yield. It was evident that the key difference between tea trees in different rock zones was yield and quality, with high yields in continent zones, and good quality in semi-rock zones and rock zones. This study provides a crucial foundation for tea-plantation management, the artificial regulation of tea yield and the quality of different rock zones of Wuyi rock tea.

Aviation mutagenesis is a breeding method for the rapid selection of superior plant varieties. In this study, rhizosphere soil chemical indexes, soil enzyme activities, and soil metabolites were measured in Dahongpao tea trees with aviation mutagenesis (TM) and without aviation mutagenesis (CK). The main soil metabolites distinguishing TM and CK and their relationships with soil chemical indexes and soil enzyme activities were analyzed and obtained. The results showed that there was no significant change in the rhizosphere soils’ pH of TM tea trees compared to CK (p = 0.91), while all other chemical indexes of TM were significantly higher than CK (p < 0.05). In addition, the activities of enzymes related to soil nutrient cycling such as urease, protease, sucrase, acid phosphatase and cellulase, and enzymes related to soil antioxidants such as superoxide dismutase, catalase, peroxidase, and polyphenol oxidase were significantly increased (p < 0.05) in the rhizosphere soils of TM tea trees compared to CK. Soil metabolite analysis showed that the main soil metabolites distinguishing CK from TM were carbohydrates, nitrogen compounds, and amines. Of these, carbohydrates and nitrogen compounds were significantly positively correlated with soil chemical indexes and soil enzymes, whereas amine was significantly negatively correlated with soil chemical indexes such as organic matter, total nitrogen, total potassium, available nitrogen, available phosphorus; amine showed significant negative correlation with soil enzymes such as catalase, peroxidase, polyphenol oxidase, and urease. It can be seen that aviation mutagenesis is conducive to improving the ability of tea tree rhizosphere aggregation and transformation of soil nutrients, increasing the total amount of soil nutrients and the content of available nutrients, which is more conducive to promoting the uptake of nutrients by the tea tree, and thus promoting the growth of the tea tree.

Soil acidification is a major environmental issue facing tea plantations in China. However, the molecular mechanisms by which acidification affects tea plant growth through rhizosphere microbial functional proteins remain unclear. In this study, tea plantation soils with different pH gradients were selected. Tea plant growth indicators, soil available nutrient contents, microbial abundance, and microbial physiological indicators were comprehensively measured, and metaproteomics was employed to analyze soil protein composition, functions, and microbial origins. The results showed that as soil pH increased from 3.54 to 5.37, the leaf chlorophyll content, leaf area, hundred-bud weight, and yield of tea plants were all significantly increased (p < 0.05). Soil available nitrogen, phosphorus, and potassium contents, as well as microbial biomass carbon, nitrogen, and phosphorus, also significantly increased in parallel. The abundances of bacteria and actinomycetes increased with rising pH, whereas fungal abundance decreased. A total of 6558 soil proteins were identified by metaproteomics, among which 236 were characterized as signature proteins (VIP > 1). Functional enrichment analysis revealed that proteins significantly upregulated with increasing pH were mainly enriched in pathways such as cysteine and methionine metabolism, galactose metabolism, and glycerophospholipid metabolism, with sulfur-containing amino acid metabolism contributing as much as 88.31%. Microbial source tracking indicated that Bacillus and Burkholderia were the primary contributors to these signature proteins; their abundances were significantly higher in the pH 5.37 treatment than in the low-pH treatment, with contribution rates of 100% and 43.73%, respectively. Partial least squares structural equation modeling (PLS-SEM) further revealed that signature microorganisms sequentially promoted microbial physiological indicators, nutrient availability, and tea plant growth by positively influencing the abundance and function of signature proteins. In conclusion, increasing soil pH to 5.37 can enhance the nutrient cycling capacity in the rhizosphere and increase tea yield. This phenomenon is closely related to the increase in the number of Bacillus and Burkholderia species, as well as the enhancement of key pathways such as sulfur-containing amino acid metabolism. This study provides molecular targets and a theoretical basis for the ecological remediation of acidified tea plantation soils.

Wuyi rock tea quality in different rock zones differs significantly, and it is of great significance for the development of the rock tea industry to deeply reveal the mineral nutritional basis of its quality formation. In this study, the rhizosphere soils, root systems and leaves of tea trees from 180 tea plantations in different rock zones were collected, to explore the migration pattern of elements in the “soil and root system-leaf” of tea trees in different rock zones. The results showed that the contents of tea polyphenols, theanine, and caffeine were significantly higher in the authentic zone than in the semi-rock zone and the continent zone, with all three quality indices exhibiting a consistent decreasing trend from ZY to BY to ZC, and their mean values in ZY were approximately 1.2-fold and 1.4-fold higher than those in BY and ZC, respectively. The ability of the root system of tea trees in different rock zones to enrich Mn, P and S, their translocation from roots to leaves, and their accumulation in leaves directly affected tea quality. Using four machine learning approaches based on enrichment coefficients of key elements, the classification accuracy for the three rock zones reached 100%. The above conclusions were further verified by hydroponic experiments with Mn, P or S treatments, which confirmed that P exerted the strongest influence on tea quality, followed by S, with Mn showing the smallest effect. This study reveals the mineral nutrient basis for the formation of rock tea quality and lays an important theoretical foundation for the elemental directed regulation of Wuyi rock tea quality.

Mineral elements affect tea nutritional and flavor quality, but systematic research on their dissolution behavior and links to volatile and taste profiles in Dahongpao tea is lacking, as is evidence regarding contribution to mineral intake for different populations. In this study, nine Dahongpao teas were brewed five times. Eleven elements were measured by inductively coupled plasma mass spectrometry (ICP-MS) with first-order kinetic fitting; volatile profiles were analyzed by electronic nose and taste attributes by electronic tongue; the contribution of tea infusions to dietary reference intakes was estimated from Chinese Dietary Reference Intakes (2023). The results showed that electronic nose analysis revealed distinct variation in volatile compound classes among the nine samples, with broad range and sulfur–organic compounds showing the highest response intensities. Electronic tongue analysis showed clear differences in taste profiles, particularly in astringency, umami, and sweetness, across the nine samples. Regarding dissolution behavior, Mg had the highest dissolution rate (67.24–70.94%), while Fe, Ca, K, and Zn were below 10%; dissolution followed first-order kinetics and total dissolved amounts correlated with total contents except for Fe. Network analysis integrating element data with volatile and taste profiles demonstrated that Mg and Mo contents were positively correlated with multiple volatile classes (e.g., sulfur–organic, broad range), while Ca, Mg, and Fe dissolution rates significantly correlated with richness and aftertaste-A, and Mo inversely correlated with sourness and saltiness. Contribution assessment showed that only Ca, K, Mg, and Se could be marginally supplemented, but the tea amounts needed far exceeded typical intake. In summary, element dissolution in Dahongpao tea is co-regulated by brew count and total content, with complex element–flavor interactions. Tea is not a primary mineral source; consumption should be individualized by age and physiological status.

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.