Aroma Rather than Taste Quality Exerted a More Pronounced Response to Organic Fertilizer Substitution in a Tea Garden: A Case Study on the Yellow Tea Quality

The warm and smooth taste, combined with the pleasant sweet aroma, are unique quality characteristics of Pingyang Huangtang (PYHT) tea. However, the potential to refine the quality through agricultural practices remains poorly explored. In this study, a one-year field experiment was conducted in the core production region of PYHT tea to assess the impacts of organic fertilizer substitution on tea quality. The experiment consisted of three fertilization regimes: T0 (pure chemical fertilizer), T1 (chemical fertilizer with rapeseed cake), and T2 (chemical fertilizer with newly organic fertilizer). Through sensory evaluation, determination of major biochemical components, and GC-MS analysis of aromatic compounds, combined with multivariate statistical methods, results showed that varied fertilization treatments significantly affected the aroma quality of PYHT tea, as indicated by T2 scoring the highest, surpassing the T0 and T1 scores, whereas no significant differences were observed in appearance, taste, liquor color, infused tea, or total score. Compared with chemical fertilization, organic fertilizer substitutes significantly reduced the total content of ammonia acids, a change primarily attributed to the decrease in the Thea, Arg, and Val levels, while the tea polyphenols and caffeine had no significant differences among treatments. GC-MS and multivariate analysis identified five key volatiles as octan-1-ol, linalool, geraniol, benzeneacetaldehyde, and δ-cadinene that differentiated the tea samples’ aroma profile. The distinct abundance patterns of these compounds are likely responsible for a fresher and more pronounced floral style of T2 tea, compared to the slightly less fresh floral notes of T0 tea and the stuffy floral expression of T1 tea. In summary, the research findings offer actionable guidelines for fertilizer application to PYHT tea production, improving aroma quality and increasing its overall market value.