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Background: Intercropping, especially with legumes, as a productive and sustainable system, can promote plants growth and improves the soil quality than the sole crop, is an essential cultivation pattern in modern agricultural systems. However, the metabolic changes of secondary metabolites and the growth in tea plants during the processing of intercropping with soybean have not been fully analyzed. Results: The secondary metabolomic of the tea plants were significant influence with intercropping soybean during the different growth stages. Especially in the profuse flowering stage of intercropping soybean, the biosynthesis of amino acids was significantly impacted, and the flavonoid biosynthesis, the flavone and flavonol biosynthesis also were changed. And the expression of metabolites associated with amino acids metabolism, particularly glutamate, glutamine, lysine and arginine were up-regulated, while the expression of the sucrose and D-Glucose-6P were down-regulated. Furthermore, the chlorophyll photosynthetic parameters and the photosynthetic activity of tea plants were higher in the tea plants-soybean intercropping system. Conclusions: These results strengthen our understanding of the metabolic mechanisms in tea plant's secondary metabolites under the tea plants-soybean intercropping system and demonstrate that the intercropping system of leguminous crops is greatly potential to improve tea quality. These may provide the basis for reducing the application of nitrogen fertilizer and improve the ecosystem in tea plantations. [ABSTRACT FROM AUTHOR]

Ancient tea plants black tea (ATBT) has outstanding sweet-mellow taste, but what contributes to its quality remains unclear. We tested 36 freeze and 9 finished tea sampled from five processing stages for ATBT by electronic tongue (ET), high performance liquid chromatography, and gas chromatography-tandem mass spectrometry. ET and chromatographic data revealed variation of sensory characteristics and chemical compounds among the five processing steps of ATBT. Through the correlation analysis and principal component analysis, it was concluded that ester-catechins and soluble sugars content in tea leaves had significant effect with the bitterness and sweetness in tea infusions (p < 0.05). Catechins, theaflavins, soluble sugars, and ET signals was considered an important information for determining the processing steps, and it had an impact on the taste of the tea infusions. These findings indicated that accurate processing control is effective approach to maintaining chemical constituents of contributes to taste quality in ATBT. [Display omitted] • The changes of taste metabolites during ATBT processing were firstly revealed. • Monosaccharides contribute to the sweet taste of ATBT. • Theaflavins contribute to the mellow taste of ATBT. • Ester-catechin was negatively correlated with the sweetness of the tea infusion. [ABSTRACT FROM AUTHOR]