Comprehensive evaluation of 47 tea [Camellia sinensis (L.) O. Kuntze] germplasm based on entropy weight method and grey relational degree

China has the most abundant tea resources in the world. In oder to scrutinize superior accessions suitable for popularization and planting, the quality characteristics of distinctive tea resources were analyzed by examining their key evaluation indexes and comprehensive evaluation methods. In this study, 29 indexes of 47 tea germplasms were detected, including agronomic characters, chemical compositions, quality of green tea and stress resistance. The key evaluation indexes were selected by factor analysis and cluster analysis, whereas the weight value of the indexes was determined by analytic hierarchy process (AHP) and entropy weight method. Furthermore, the comprehensive evaluation of tea varieties was carried out by grey correlation degree and entropy weight method. Our results showed that drastic differences of character indexes existed among tea varieties, and the 29 character indexes demonstrated complex information overlapping with each other. After simplification, 12 key evaluation indexes, namely score of green tea quality, total free amino acids, growth potential, water extract, yield, epigallocatechin gallate (EGCG), epigallocatechin (EGC), one bud one leaf stage, insect resistance, germination density, bud leaf color, and gallic acid (GA) were chosen. The weight value of each index was also determined. Since the rank of some varieties in these two evaluation methods was different, based on the comprehensive evaluation results of grey correlation degree method and entropy weight method, it was more rational to combine these two evaluation methods in selecting superior varieties. Consequently, nine excellent tea varieties were selected. This study not only provides an innovative method for comprehensive evaluation of tea resources, but also an approach to promote genetic improvement of the selected excellent tea varieties.