A comprehensive evaluation of pea germplasm resources based on cluster analysis and grey relational analysis

Abstract Pea (Pisum sativum L.) is an economically important legume crop. Due to the growingly improved living standard and the dietary diversity, there is an increasing demand for peas and sprouts year by year, which makes it imperative to screen high-quality pea varieties. In this study, 34 pea varieties were collected for germination treatment, and their sprouting and functional characteristics were investigated. The results showed that the epicotyl length and output ratio of pea sprouts ranged from 3.54 ~ 20.66 cm and 0.91 ~ 3.03, respectively. The total phenolic content (TPC), total flavonoid content (TFC), 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free radical scavenging capacity and ferric reducing antioxidant power (FRAP) varied widely, ranging from 2.33 ~ 4.61 mg GAE/g DW, 7.14 ~ 13.54 mg RUT/g DW, 46.67 ~ 65.65 µM TE/g DW and 14.95 ~ 31.26 mM Fe2+/g DW, respectively. Significantly high linear correlation coefficients were reported among TPC, TFC, ABTS, and FRAP of pea sprouts. Compared with ungerminated pea seeds, sprouts had richer phenolic content and superior antioxidant capacity. Principal component analysis (PCA) extracted three principal components with a total cumulative contribution rate of 84.50%. Hierarchical clustering analysis was carried out based on the extracted three principal components, and the obtained dendrogram divided pea varieties into four categories. The best-performing variety was evaluated by grey relational analysis as 9618-2, with an associate degree of 0.819. The high-quality pea varieties selected by cluster analysis and grey relational analysis were basically the same. Overall, the germinated varieties 9618-2, Dingwan 4, Dingwan 8, Baiwandou, Taiwanxiaobaihua, Chengduzhushawan, Dingwan 5, Caoyuan 224 were superior sources of natural antioxidants.