Question

how is photoperiodism an adaptation for plant?

Answer 1

Plants respond to environmental conditions by both adaptation and acclimation. Adaptation consists of heritable modifications in structures or functions that increase the probability of an organism surviving and reproducing in particular environment. Acclimation refers to nonheritable modifications caused by exposure of an organism to changing environment, and is based on the structural and physiological plasticity of the plants. Plasticity is unique feature of plants that has been suggested to have significance as an integral part of the mechanisms by which plants (a) control reproductive effort and (b) capture resources from their environments,The present distribution of higher plants is reflection ofan evolutionary adaptation to environmental conditions. The first photosynthetic organisms evolved about 2500 million years ago and free oxygen based respiration developed some 2000 million years ago. From this perspective, the appearance offlowering plants 130 million years ago is rather recent event. The present vegetation of Nordic countries evolved even more recently, about 12 000-15 000 years ago. Plant growth arises from the production of dry matter through energy metabolism and morphological development. Both of these main processes are notably affected by environmental conditions and are subjected to adaptation and acclimation. The main emphasis here is on developmental adaptations of plants; the adaptation of dry matter production is limited to some brief comments only. In annual plants this is related to the rate of development and to the timing ofreproduction. In perennial plants growing under northern conditions, adaptation of phenology, growth cycle, to the annual climatic cycle is of primary importance.As will be shown here, adaptation of these developmental processes is mainly based on responses to photothermal conditions. The physiological and certain genetic aspects of adaptation