There are a number of essential conditions which all organisms, both plants and animals, require to grow. These are known as growth factors. Plants, for example, require sunlight, water, and carbon dioxide in order to perform photosynthesis. They require nutrients such as nitrogen, phosphorus, and various trace elements in order to form tissues. The environment in which the plant is growing does not contain a unlimited supply of these growth factors. When one or more of them is present in levels or concentrations low enough to constrain the growth of the plant, it is known as a growth limiting factor. The rate or magnitude of the growth of any organism is controlled by the growth factor that is available in the lowest quantities. This concept is analogous to the saying that a chain is only as strong as its weakest link.

These factors limit...