Essay On Senescence

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2. SENESCENCE AND POSTHARVEST PHYSIOLOGY OF CUT FLOWERS Senescence is a highly ordered, endogenously controlled, active degenerative developmental process that culminates in the death of a cell, tissue, organ or organism (Nooden and Leopold, 1978). Senescence, a genetically regulated process, is largely oxidative in nature involving a general degradation of the cellular structures and the mobilization of the products of degradation to other parts of the plants. The process is mainly characterized by the visual symptoms as the loss of chlorophyll and other pigments, colour change, dessication and abscission. Cellular and molecular events contributing to these visual symptoms include cessation of photosynthesis, disintegration of organelle structures, intensive degradation of chlorophyll, loss of…show more content…
The central senescence process seems to begin in the nucleus with the synthesis of RNA’s, which in turn, are used to make certain proteins in the cytoplasm, ultimately resulting in the alteration of plasma membrane…show more content…
Senescence may be monocarpic or polycarpic. In monocarpic senescence, the whole organism dies at the same time, following a reproductive phase e.g. most crop plants. In polycarpic senescence, organs are lost several times in a season or over several years and the organism passes through repeated reproductive phases as is the case with most horticultural perennial crops. However, in both the cases, the senescence is continuous at organ or cell level (Nooden, 1988a; Voleti et al., 2000). Leopold (1961, 1980) has classified senescence of higher plants into three major types: population senescence (e.g. annual plants); organism or individual plant senescence and determinate organ senescence (e.g. leaves, fruits, flowers, petals,
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