Plant physiology

Plant physiology

That branch of plant sciences that aims to understand how plants live and function. Its ultimate objective is to explain all life processes of plants by a minimal number of comprehensive principles founded in chemistry, physics, and mathematics.

Plant physiology seeks to understand all the aspects and manifestations of plant life. In agreement with the major characteristics of organisms, it is usually divided into three major parts: (1) the physiology of nutrition and metabolism, which deals with the uptake, transformations, and release of materials, and also their movement within and between the cells and organs of the plant; (2) the physiology of growth, development, and reproduction, which is concerned with these aspects of plant function; and (3) environmental physiology, which seeks to understand the manifold responses of plants to the environment. The part of environmental physiology which deals with effects of and adaptations to adverse conditions—and which is receiving increasing attention—is called stress physiology.

Plant physiological research is carried out at various levels of organization and by using various methods. The main organizational levels are the molecular or subcellular, the cellular, the organismal or whole-plant, and the population level. Work at the molecular level is aimed at understanding metabolic processes and their regulation, and also the localization of molecules in particular structures of the cell but with little if any consideration of other processes and other structures of the same cell. Work at the cellular level often deals with the same processes but is concerned with their integration in the cell as a whole. Research at the organismal level is concerned with the function of the plant as a whole and its different organs, and with the relationships between the latter.

Research at the population level, which merges with experimental ecology, deals with physiological phenomena in plant associations which may consist either of one dominant species (like a field of corn) or of numerous diverse species (like a forest). Work at the organismal and to some extent the population level is carried out in facilities permitting maintenance of controlled environmental conditions (light, temperature, water and nutrient supply, and so on). See Plant metabolism, Plant respiration, Physiological ecology (plant)