The Light Composition of Solar and Sky Spectra Available to Plants

Abstract

Using a 5—band spectral light meter the spectral energy of light available to plants was measured under several different environmental conditions including bright sunshine, sky light, twilight, light from cloudy skies, and light within leaf canopies of varying densities. Increased haziness or decreased both the ultraviolet and the blue energy in sky light. A closed crop canopy transmitted a high proportion of far red energy.