Crop yield is determined by plant growth and partitioning of biomass to marketable parts of plants. Both growth and partitioning are affected by developmental stages of crops. Knowledge of physiological processes of growth, development, and partitioning into yield components is necessary for a basic understanding of maximizing crop yield. It is important first to define growth. Growth refers to biomass accumulation and can be measured by leaf area, shoot, root, and total weights, or plant height, and these can be used to compare within cultivars or between cultivar means (McCauley, 1990). The term growth also applies to quantitative changes that occur during development and may be defined as an irreversible change in the size of cells, organs, or whole organisms (Wareing and Phillips, 1981). Wilhelm and McMaster (1995) defined growth simply as irreversible increases in physical dimension of individuals or organs with time. Therefore, examples of growth are irreversible lengthening of leaf blade tissue or increases in leaf area. In agriculture, where the purpose of most enterprises is to convert solar energy into dry matter, an equally useful definition of growth is increased dry weight. Growth is affected by environmental factors such as climate, soil, and plants themselves. Growth is sometimes confused with development. These two terms are interrelated but different.