A METHOD FOR EVALUATION OF UV AND BIOLOGICALLY EFFECTIVE EXPOSURES TOPLANTS

This paper presents a method for evaluating the UV and biologically ef fective exposures to a plant canopy during the irradiation of soybean with supplemental levels of UV radiation in a greenhouse study, The me thod employs four materials as dosimeters that allow evaluation of the UV spectra, The exposures evaluated at three growth stages were less by factors of 0.44, 0.49 and 0.56 compared to the ambient exposures, A t the end of the irradiation period, the ambient biologically effectiv e exposure for generalized plant response was higher by 180% compared to that calculated over the canopy. This is the magnitude of the error in UV studies that provide the ambient exposure as a measure of the U V incident on the plant, Additionally, the difference between the ambi ent and canopy exposures varied during the growth stages, These result s indicate that the dosimetric technique applied to evaluating the UV exposures over a plant canopy is a more accurate representation of the UV exposure incidence on a plant than any obtained by measuring the a mbient exposures only.