A Method for Evaluation of UV and Biologically Effective Exposures to Plants

Abstract

This paper presents a method for evaluating the UV and biologically effective exposures to a plant canopy during the irradiation of soybean with supplemental levels of UV radiation in a greenhouse study. The method 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. At the end of the irradiation period, the ambient biologically effective 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 UV incident on the plant. Additionally, the difference between the ambient and canopy exposures varied during the growth stages. These results 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 ambient exposures only.

An estimation of biological hazards due to solar radiation

“…Its sensitivity at 340 nm is about 1000 times that of polysulphone [14]. The development and testing of the method has been previously described [16,13,14]. The dosimeter materials employed in the spectrum evaluator are polysulphone, nalidixic acid (NDA), 8-methoxypsoralen (8MOP) and phenothiazine [13].…”

Dosimetric measurement of the visible and UV exposures on field grown soybean plants

“…This provided a zero irradiance at approximately 292 nm (Parisi et al, 1996). Both the Mylar and CA filter material were pre-solarised for eight hours prior to wrapping around the lamps.…”

Dosimeter for measurement of UVA exposures

“…In this application, the UVA transmission of the mylar is known to reduce as a result of exposure to UV. Over a period of a week, the UV transmission is approximately halved due to degradation of the mylar 24 . In the current application, the exposure period will be less than this and of the order of half a day to one day.…”

“…The mylar film has been previously employed in UV irradiation research to remove the UVB wavelengths from UVB lamps [24][25][26] . The transmission of the mylar filter as measured in a spectrophotometer (model 1601, Shimadzu Co., Kyoto, Japan) is provided in Figure 2.…”