SIMULTANEOUS ASSESSMENT OF PHOTOSYNTHETICALLY ACTIVE AND ULTRAVIOLET SOLAR RADIATION

‡To whom correspondence should be addressed. 1 A new dosimetric package for assessing solar radiation affecting photosynthesis in the visible and ultraviolet wavebands in plant canopies has been developed and tested. The package consists of several detectors sensitive to various wavebands between 290 and 700 nm. For photosynthetically active radiation (PAR), the dosimeter was calibrated for exposures in terms of photosynthetically active photons between 0.003 and 0.38 mol m-2. The package allows simultaneous assessment of the irradiances across the visible and ultraviolet wavebands. Over a plant canopy, the biologically effective ultraviolet radiation varied by approximately a factor of 2 compared to a variation by approximately a factor of 14 in the photosynthetic photon flux density