Soil nutrient deficiency decreases the postharvest quality-related metabolite contents of tea (Camellia sinensis (L.) Kuntze) leaves.

The long-term cultivation of tea plants without fertilization can severely decrease yield, but it remains unclear whether this soil nutrient deficiency affects tea quality. In this study, tea plants (Camellia sinensis (L.) Kuntze) cultivated in unfertilized soil for 11 years were analyzed. The soil nutrient deficiency down-regulated protochlorophyllide oxidoreductase-encoding gene expression, which adversely affected chlorophyll biosynthesis, ultimately leading to leaf etiolation. Because of decreased synthesis and increased degradation in response to nutrient deficiency, l-theanine content decreased to 11.4% of the control level, which increased the phenol-ammonia ratio and decreased taste quality. Soil nutrient deficiency also decreased the abundance of many aroma compounds (e.g., green leaf volatile, linalool and its oxides, and methyl salicylate). Thus, nutrient deficiency adversely influences tea color, taste, and aroma. This study provides researchers and tea growers with important information regarding the effects of soil nutrient deficiency on tea quality and the rational fertilization of tea gardens.