Spectral transmittance properties of several greenhouse construction and shading materials were determined by measuring the quantity and quality of solar radiation transmission on non-clouded (sunny) days at solar noon. Spectral transmittance parameters included photosynthetic radiation (400–700 nm) and photomorphogenic radiation (660 nm (red light), 730 nm (far-red light), and 400–500 nm (blue light). Light available for photosynthesis was measured as photosynthetic photon flux density (PPFD) and photosynthetic radiation (PI). Photomorphogenic radiation was measured as far-red/red (FR/R) and blue light. Greenhouse construction materials included glass, chambered acrylic, chambered polycarbonate, and inflated plastic film. Various shade materials of different colors were evaluated. Photosynthetically active radiation transmission of construction materials ranged from approximately 95% transmission of direct sunlight with Exolite to less than 50% with tinted Lexan. Far-red/red values of shade materials ranged from 0.94 for Enduro Green to 5.58 for Cravo LS-7.
2Graduate Student, Associate Professor, and Assistant Professor, Resp.