The separate phases of fruiting and vegetative growth in the red raspberry make it difficult to describe the plant canopy and its light interception.
Because of the juxtaposition of fruiting cane and primocane the initial light environment of primocane is low but improves as the primocanes grow through the fruiting cane canopy.
Fruiting cane architecture generally exhibits increased lateral lenght towards the base of the canopy, while fruit production falls.
The growth and development of both cane phases may be related to the light environment experienced by each phase. Experiments which remove or restrict the vegetative phase suggest that heavy self shading of fruiting canes by primocanes in current production systems leads to a reduction in actual yield compared to potential yield as indicated by flower numbers.
It is suggested that greater emphasis should be placed on light interception characteristics when considering new management techniques and when breeding new cultivars.