Plant Production in Relation to Foliage Illumination

Abstract

The intensity of light received by plants can be specified in terms of its extinction with depth in the foliage. Various light-extinction functions are introduced to specify the light received by plants with different patterns of foliage development (viz. standard exponential, best exponential, and ideal). The implications of these extinction functions are discussed and the production associated with each foliage type is studied as a function of leaf area index, LAI (the ratio of leaf area to ground area). The concepts of optimum LAI and ceiling LAI are considered in relation to these foliages. It is shown that, contrary to what has previously been thought, a foliage in which the bottom leaves are at compensation point is not necessarily at optimum LAI. It also becomes possible to reconcile conflicting views on the relationship between optimum LAI and ceiling LAI.