Effects of Different Fertilization Patterns on the Content of Quality Indices and the Formation of Aroma Characteristics of Tea Leaves

Fertilization is a necessary measure in the cultivation and management of the tea bush, and the use of different fertilizers significantly affects the quality of tea leaves. In this study, 100% chemical fertilizer (CF), 100% organic fertilizer (OF), and 50% chemical fertilizer + 50% organic fertilizer (COF) were used to analyze the effects of different fertilizer treatments on the quality indices and volatile component compositions of tea leaves. The results showed that COF treatment significantly increased the content of water extract, tea polyphenols, theanine, free amino acids, and soluble sugar, but decreased the content of total flavonoids and caffeine, indicating that COF treatment has an advantage in improving the overall quality of tea leaves. Analysis of volatile components showed that different fertilizer treatments significantly affected the content of eleven characteristic metabolites in tea bush leaves, of which four characteristic metabolites were most abundant under CF treatment, eight under OF treatment, and only one under COF treatment. The odor characteristics and their intensity analyses showed that the 11 characteristic volatile components mainly exhibited three types of odor characteristics, such as woody, green, and floral, of which OF treatment enhanced woody and green intensities, while CF treatment enhanced floral intensity. Taken together, different fertilizer treatments could regulate the quality indices and volatile components of tea leaves, while the use of chemical fertilizers or organic fertilizers alone was conducive to enhancing the intensity of individual special odor characteristics in tea leaves. Overall, the combination of chemical fertilizers and organic fertilizers was more conducive to the improvement of tea quality. This study provides a theoretical basis for optimizing the fertilization strategy of tea bushes to improve tea quality.