Beneficial Spectral Characteristics of Red and Black Raspberry Plants (Rubus idaeusandRubus occidentalis)

Raspberry naturally occurs in association with trees as a forest border species, thus is ideally adapted for species-diverse agroforestry systems. In spite of thriving in relatively low solar radiation environments, some red (European) and black (North American) raspberry (Rubus idaeus L. and Rubus occidentalis L.) plant surfaces are highly reflective, both species on leaf abaxial surfaces and black raspberry on cane surfaces. Cane surface color varies from green to red. The objective of this study was to quantify plant spectral characteristics in order to assess their potential ecological significance. Leaf reflectance and transmittance were determined using a spectroradiometer with integrating sphere and regulated light source. Reflected irradiance from leaves and canes was measured under natural sunlight with a microscopic lense attachment. Reflectance of abaxial leaf surfaces was 4.3 and 5.3 times greater than abaxial leaf surfaces for red and black raspberry, respectively. This amounted to 2...