Abstract:45Ca2+ absorption by plasma membrane vesicles isolated from maize (Zea mays L. ) leaves cultured in vitro was assessed to investigate the relationships among hormone changes, transmembrane Ca2+ flux and lipid peroxidation during leaf senescence. The results suggested that the possible process of leaf senescence in spring maize followed a sequence of endogenous hormonal change then transmembrane Caa + flux which further led to lipid peroxidation, with consequent degradation of chlorophyll and protein.