Effects of geographic locations and topographical factors on secondary metabolites distribution in green tea at a regional scale

To understand the effects of geographic locations, cultivation altitude, slope, and aspect on secondary metabolites in tea leaves, 78 tea samples were randomly collected from Southern Jiangsu region, China, and catechins, caffeine, and free amino acids were examined. The results showed that samples from the farther north had higher contents of TC, EGCG + GCG, ECG + CG and the ratios of ETC to NTC, while had lower contents of free amino acids, leading to more bitterness and astringency taste in tea. Furthermore, more free amino acids were accumulated in tea cultivated in hilly areas due to shorter sun exposure time and lower intensity than plain areas with the rotation of the earth formed a natural shade management effect, whereas more TC in plain areas. Principal Component Analysis (PCA) grouped the 78 tea samples into three clusters and further confirmed that tea samples from a similar geographical environment exhibited a similar constituent of major secondary metabolites. These results might be useful for providing references to regional tea plantation planning, tea plantations location selection and geographical environment management.