Trial manufacture of simple integrated tube-type pyranometer by phycoerythrin and measurements of transmittance of solar radiation in crop canopies

摘要

A simple integrated tube-type pyranometer was constructed using phycoerythrin from seaweed pigment. The most sensitive waveband of phycoerythrin was 550-560 nm, which was in the photosynthetically active radiation range. The acrylic tubes (outside diameter, 22 mm. length, 100 cm) were coated with white paint except for a strip 15 mm in width, and phycoerythrin was put into the acrylic tube. In outdoor measurements, the tube-type pyranometer showed a positive correlation between the transmittance ofphycoerythrin (%) and the measured accumulated solar radiation (MJ m-2), but the slope of the linear equation was different in summer and winter. In an artificial climate room, the relationship between the transmittance of phycoerythrin and the accumulated solar radiation could be approximated by a quadratic equation at every temperature. The accumulated solar radiation could be estimated outdoors using the transmittance of phycoerythrin and the mean air temperature during measurements.