Leaf senescence and physiological characters in different adzuki bean (Vigna angularis) cultivars (lines)

摘要

The relation of leaf senescence and its physiological characters at different flower internodes from flowering to maturing, the aging mechanisms of adzuki bean leaf, the intrinsic yield-forming mechanisms and theoretical basis for high-yield breeding and production of adzuki beans were examined in a field experiment on high-yielding (2000-75 and JiHong 9218) and low-yielding (HongBao1 and WanXuan1) adzuki bean varieties. All adopted in the summer planting ecological region of China, were grown in 2008 and 2009, and their leaf physiological characters, such as chlorophyll content, net photosynthetic rate (Pn), superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities, and malondialdehyde (MDA) content. The results indicated that the chlorophyll contents, Pn, SOD and CAT activities gradually decreased from 15 days after the varieties flowered to maturing, but their POD activities and MDA contents gradually increased when leaves senescence started. Leaf senescence initiated from the low internodes and gradually moved toward to the upper internodes after the plants flowered. Compared with low-yielding varieties, high-yielding varieties maintained higher chlorophyll contents, Pn, SOD and CAT in the late stages, and thus resulting significantly higher grain yields. The overall data indicated that yield is positively correlated with leaf chlorophyll and Pn, as well as SOD and CAT activities and negatively associated with POD activities and MDA accumulation at the late growth stage. Therefore, effective inhibition of leaf senescence or prolonging the functional period of leaves at the late growing stage plays an important role in raising yield.