Plant Physiology

Plant physiology is the functioning of plants. This can be studied at several levels of complexity and organization, as indicated by such terms as metabolic physiology, cellular physiology, or whole-plant physiology. The aim of the current text is to give an account of the physiology of flowering plants mainly from the whole plant or organismal point of view. Moreover, since an organism functions within its environment, and by virtue of its physiological activities continuously interacts with its environment, plant–environment interactions are emphasized throughout the book. But many plant life processes are carried out at the level of the individual cell, even of the individual organelle. Physiological processes of plants can therefore be described only to a limited degree without reference to activities at the cellular or subcellular level. (Physiology of Flowering Plants).

Plant Water Relations

WATER PLAYS A CRUCIAL ROLE in the life of the plant. For every gram of organic matter made by the plant, approximately 500 g of water is absorbed by the roots, transported through the plant body and lost to
the atmosphere. Even slight imbalances in this flow of water can cause water deficits and severe malfunctioning of many cellular processes. Thus, every plant must delicately balance its uptake and loss of water. This balancing is a serious challenge for land plants. To carry on photosynthesis, they need to draw carbon dioxide from the atmosphere, but doing so exposes them to water loss and the threat of dehydration.