Tea plant is an acidophilic plant, and soil pH has an important effect on the absorption and enrichment of elements, tea plant growth and quality. In this study, rhizosphere soils and leaves of tea plants from 30 tea plantations were collected to determine soil pH and multi-element content of soil and leaves of tea plants, to obtain and validate key elements that are enriched by pH affecting tea plants, and to analyze the effects of pH on the growth and quality of tea plants. The results showed that soil pH significantly affected the enrichment of 15 elements by tea plants, and the enrichment coefficients of 11 elements (C, Mg, Si, N, P, Mn, Sr, Cd, S, Ca and Sb) tended to increase significantly with the increase of soil pH, while the opposite was true for the other four elements (Cu, Rb, Ba and Al). TOPSIS analysis showed that soil pH had the greatest effect on tea plant enrichment of seven elements, namely N (100%), Mn (43.32%), C (39.22%), P (27.66%), Sr (15.30%), Mg (13.41%) and Ba (10.47%). Pot experiments with tea seedlings also verified that soil pH significantly affected the enrichment of tea leaves for seven key elements. Moreover, with the increase of soil pH, the growth indexes, photosynthesis indexes and quality indexes of tea seedlings showed a significant upward trend. Interaction analysis showed that the enhanced enrichment of N, Mn, C, P, Sr and Mg by tea plants was beneficial to increase the photosynthetic capacity of tea plants, promote the growth of tea plants and improve the quality of tea leaves. This study provides an important theoretical basis for the cultivation and management of tea plants.

In order to fully comprehend the impact of soil acidification on the quality of tea, further analyses are essential and are of the utmost importance to the cultivation of tea trees and the simultaneous enhancement of tea quality. In May 2022, Tieguanyin tea trees planted in soils with different pH levels were selected as the research object of this study to analyze the effect of soil pH on the soil chemical index, soil fertility and the aroma quality of tea leaves. The results showed that the organic matter content, cation exchange capacity and the available nitrogen, available phosphorus and available potassium contents in the rhizosphere soil of the tea trees decreased significantly with decreasing soil pH levels (5.32–3.29), while the total nitrogen, total phosphorus and total potassium contents did not change significantly. The results of an aroma quality analysis showed that the aroma of the Tieguanyin tea was mainly floral, and the formation of floral odor characteristics was mainly derived from geraniol. The results of an interaction network analysis showed that the soil chemical indexes were significantly positively correlated with geraniol and floral aromas except for the total phosphorus and total potassium contents. In conclusion, with a decrease in the pH of soil, the soil’s cation exchange capacity, organic matter content and available nutrient content showed decreasing trends which, in turn, hindered the synthesis of geraniol and reduced the floral odor characteristics of tea leaves.

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.