Effects of nitrogen nutrition on content of calycosin in different cultivars of peanut (Arachis hypogaea L.)

Peanut is not only an important economic crop but also considered to be as a kind of functional food. However, the presence of calycosin, a bioactive isoflavonoid, in peanuts is still unknown. In this study, calycosin was firstly identified in leaves, needles and pods of four peanut cultivars examined including Yuanza 9102 (P1), Kainong 176 (P2), Zhuhua 2 (P3) and Yuhua 23 (P4). Moreover, the effects of three nitrogen fertilization levels (N0: 0 kg/ha, N1: 75 kg/ha, N2: 150 kg/ha) on calycosin accumulation in leaves, needles and pods of four different peanut cultivars at DAF30, DAF60 and DAF90 were investigated. The results showed that calycosin content varied from 0.87 to 718.83 mu g/g FW in peanut and the relatively higher calycosin content was found in leaves, followed by needles and pods. Furthermore, calycosin contents in leaves of all four peanut cultivars at DAF60 were higher than that at DAF30 and DAF90, respectively. Calycosin accumulation in needles and pods at DAF90 was more than that at DAF30 and DAF60. In addition, the optimal combination for the highest calycosin yields in the leaves, needles and pods were P1 under N1 (75 kg/ha) at DAF60, P2 under N2 (150 kg/ha) at DAF60 and P2 under N1 at DAF90, respectively.