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

Abstract

This paper describes a dosimeter system for measuring both the PAP (photosynthetically active photons) (400-700 nm) and ultraviolet-B (UVB) (280-320 nm) exposures in the supplemental UVB irradiation of field grown soybean (Glycine max [L.] Merr.) plants. At the V2 growth stage, the dosimeters positioned at the same position and orientation as the trifoliate leaves of the plants that were measured received 12 to 38% more PAP and 5 to 82% more UVB than the unifoliate leaves. For the crop maturity stage, the plants exposed to high levels of UV irradiance (high UV treatment) received approximately 40% more UVB on a horizontal plane at the top of the plant canopy compared to the control group of plants (control treatments). For the other measurement sites over the plants that were orientated at 45 degrees to the vertical in the north, south, east and west directions, the additional amount of UVB for the supplemental treatment compared to the corresponding sites for the plants in the control treatments varied between -39% and 37%, due predominantly to the shading provided by the other plants. Furthermore, the supplemental UVB changed the natural partitioning of UVB and PAP and the ratio of PAP to UVB over the plants. All these variations to the UVB and PAP over the plant canopy cannot be predicted by exposure measurement in the wavebands on a horizontal plane. Consequently, for the case of the complex topography of plants, the dosimeters described in this paper have the advantage of allowing the exposures to be measured simultaneously at multiple sites that are at any orientation.

Effects of supplementary ultraviolet-B irradiance on maize yield and qualities: a field experiment

“…Commonly, the control treatment was one in which there was no exposure to UV-B and consequently, the environmental complex in these studies was artificial and the results obtained may not precisely simulate the field conditions (11). The studies of plants to enhanced UV-B radiation under field conditions are very important to an assessment of the responses of natural ecosystems to this stress factor (19,20). The present study reports the growth and yield responses of a maize crop exposed to enhanced UV-B radiation under field conditions.…”

Solar UV exposures measured simultaneously to all arbitrarily oriented leaves on a plant

“…Previous research has measured the UVB to the canopy of a small plant by deploying polysulphone dosimeters that were 3 cm x 3 cm in size, on thin metal rods to allow measurement of the UVB over a plant canopy [11]. Polysulphone has a similar UVB sensitivity to a variety of action spectra associated with plant growth or effects and can provide as much information as other broadband sensors when the exposures are weighted according to the appropriate action spectrum.…”

“…In order to measure the solar UV radiation to plant leaves, the use of dosimeters has been investigated. Dosimeters have been employed to measure the UV exposures (from 280 nm to 320 nm) to a plant canopy in both greenhouse and field studies [7,11]. The dosimeters employed in these studies were based on the polymer polysulphone [12] and were each approximately 3 cm x 3 cm in size.…”

Effects of Suplementary Ultraviolet‐B Irradiance on Maize Yield and Qualities: A Field Experiment¶

“…Commonly, the control treatment was one in which there was no exposure to UV‐B and consequently, the environmental complex in these studies was artificial and the results obtained may not precisely simulate the field conditions (11). The studies of plants to enhanced UV‐B radiation under field conditions are very important to an assessment of the responses of natural ecosystems to this stress factor (19,20). The present study reports the growth and yield responses of a maize crop exposed to enhanced UV‐B radiation under field conditions.…”