Pea (Pisum sativum L.) is the fourth leading legume crop in the world, and its demand is increasing. In this study, the morphological characteristics (seed shape, seed surface, seed coat color, hilum color, cotyledon color, 100-seed weight and color values), 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) of 75 pea cultivars were investigated. Results showed rich genetic diversity and a wide range of phenolic contents and antioxidant activities. Sixteen varieties enriched with phenolic contents and high antioxidant activities were screened out. A significant correlation was reported among color values, TPC, TFC, ABTS and FRAP. Principal component analysis (PCA) extracted four principal components with a total cumulative contribution of 81.29%. Hierarchical cluster analysis based on the four extracted principal components resulted in a dendrogram dividing the peas into three groups. In addition, dark pea seeds have potential as a functional food in addition to their traditional role in providing dietary protein and fibre. This study provided a scientific basis for the breeding of pea varieties, development of new products and improvement of pea resource utilization.

Flavonoids are thought to participate in protection of the photosynthetic apparatus against photoinhibition under excessive light. Flavone glycoside, scutellarin, is a main active ingredient extracted from Erigeron breviscapus, the plant used in Chinese medicine. Shade-developed leaves of E. breviscapus were transferred from shade to full sunlight to quantify a relationship between the concentration of leaf scutellarin and tolerance to high radiation stress or the recovery from photoinhibition. The maximal quantum yield of PSII photochemistry showed a diurnal fluctuation in both shaded and sunlit leaves throughout the day. It indicated dynamic photoinhibition in the leaves of Erigeron, i.e., higher photoinhibition at solar noon and lower one in the morning and late afternoon. The sun-developed leaves reached the higher scutellarin content and values of nonphotochemical quenching coefficient with a lower degree of photoinhibition than the shadedeveloped leaves. When the shade-developed leaves were transferred to full sunlight, the content of scutellarin was declining continuously for 10 d and then was increasing for 15 d. After 50 d, all leaves became the sun-developed leaves with their scutellarin contents of about 138.5 ± 5.2 mg g -1 (dry mass, DM) which was significantly higher than that of the shade-developed leaves [107.8 ± 9.8 mg g -1 (DM)]. During acclimatization, the degree of photoinhibition was negatively correlated with the scutellarin content. Our results demonstrated a synchronous fluctuation between the flavonoid content and degree of protection against photoinhibition.