Light interception by a row crop of glasshouse peppers

Abstract

Commercial crops of glasshouse cucumbers, peppers and tomatoes are normally trained into a highly artificial canopy of parallel hedgerows for easy access combined with effective interception of incident light. This study of a sweet pepper canopy with the plants in north-south rows shows that: (a) interception of light increased from a low value at planting to about 92% at maturity in early June and remained at this level throughout the fruiting period which coincided with high daily light integrals, (b) under overcast skies, light transmission beneath the rows was about a quarter of that in the intervening gaps, (c) under clear skies, transmission of light by the canopy varied with solar azimuth, increasing to over 20% around noon and falling to a minimum of about 2% a few hours away from noon, (d) interception of light differed little between the two cultivars and training systems examined, (e) the amount of light incident on the sides of the canopy in this large glasshouse was relatively unimportant, at...