The purpose that is served for survival of the species is the accumulation of sufficient food resources in the mother plant to optimize seed fill so new seedlings will be competitive . Some seeds require a period of cold temperature before they will germinate. This can be supplied artificially by allowing the seed to take up water, then storing the imbibed seed in the cold for several weeks. Similarly, some bulbs will only produce flowers after being stored in cool temperatures for a given length of time. Senescence Senescence is the death of a plant or plant part .
Senescence is a natural part of the life cycle of plants.
It is not just the cessation of growth, but a metabolically active process involving the redistribution of the internal resources of the plant . Leaf senescence that leads to the beautiful display of fall color is triggered by decreasing daylength and cool night temperatures , and involves the mobilization of nutrients and breakdown of proteins in the leaves . These nutrients are removed to the roots for storage , and the leaf that is shed consists primarily of structural materials such as cell walls. The stored nutrients are reused in the spring to support new growth . The yellow and orange carotenoid pigments seen in the fall are revealed when chlorophyll is broken down .