Light is the key environmental factor which strongly affects the form and function of plants with changing quality and quantity. Light quantity specifically within the PAR range (Photosynthetic Active Radiation, 400-700 nm) directly affects photosynthesis, at low light intensities the rate of light dependent reactions increases proportionally up to a level when photosynthesis is limited by other factors then the rate of photosynthesis levels out. Light quality e.g. the red to far-red ration (730/660nm) is known to affect plant morphology and the light beyond the PAR range may also strongly affect the heat fluxes of the leaf and thus the leaf temperature. Detailed and continues monitoring of the light environment is thus one of the basic requirements in plant experiments.
The description of the light as environmental parameter is based on the publication by Poorter at all 2012.
Nobel, P. S. (2005). Physiochemical and Environmental Plant Physiology. San Diego Academic press Inc.Hardcourt Brace Jovanovich.
Poorter, H., et al. (2012). "The art of growing plants for experimental purposes: a practical guide for the plant biologist." Functional Plant Biology. 39: 821-838