[Effects of light quality on leaf senescence and endogenous hormones content in grapevine under protected cultivation]

Abstract

Two grape varieties 'Italia' and 'Centenial seedless' cultured in protected and delayed cultivation were used as experimental materials to study the effects of red and blue light quality on chlorophyll content, net photosynthetic rate, and endogenous hormone content during leaf senescence. The results showed that the chlorophyll content and net photosynthetic rate of the grapes were significantly enhanced in the red light treatment. Although the content of endogenous GA₃ was decreased, an increase in abscisic acid (ABA) content and a decrease of total content of zeaxanthin (ZR) were obviously slowed, which led to the significant increase in value of (GA₃+ZR)/ABA, delaying leaf senescence. In prophase of leaf senescence, the chlorophyll contents, net photosynthetic rate and (GA₃+ZR)/ABA of the grapes were lower in the blue light treatment than those in the control, and the leaf senescence in the blue light treatment was accelerated. At late stage of leaf senescence, the chlorophyll content, net photosynthetic rate and (GA₃+ZR)/ABA in the blue light treatment were gradually higher than those in the control, and the leaf senescence was delayed to a certain extent. The plant endogenous hormone auxin (IAA) promoted leaf growth and development in prophase of leaf senescence and accelerated leaf aging in late stage of leaf senescence. The leaf senescence rate of 'Italia' was slower than that of 'Centenial seedless'. In conclusion, our experiment suggested that red light was the best on delaying leaf senescence and prolonging the functional period of leaves.

Keywords: endogenous hormone; leaf senescence; light quality.