Field Study of the Interaction between Solar Ultraviolet-B Radiation and Drought on Photosynthesis and Growth in Soybean

Abstract

Soybean, Glycine max (L.) Merr. cv Essex, plants were grown in the field in a 2 x 2 factorial design, under ambient and supplemental levels of ultraviolet-B (UV-B) radiation (supplemental daily dose of 5.1 effective kilojoules per square meter) and were either well-watered or subjected to drought. Soil water potentials were reduced to -2.0 megapascals by the exclusion of natural precipitation in the drought plots and were maintained at approximately -0.5 megapascal by supplemental irrigation in well-watered plots. Plant growth and gas exchange characteristics were affected under both drought and supplemental UV-B radiation. Whole-leaf gas exchange analysis indicated that stomatal limitations on photosynthesis were only significantly affected by the combination of UV-B radiation and drought but substrate (ribulose bisphosphate) regeneration limitations were observed under either stress. The combined effect of both drought and UV-B radiation on photosynthetic gas exchange was a reduction in apparent quantum efficiency and the rapid appearance of biochemical limitations to photosynthesis concomitant with reduced diffusional limitations. However, the combination of stresses did not result in additive effects on total plant growth or seed yield compared to reductions under either stress independently.Reductions in global stratospheric ozone column thickness of 1.7 to 3.0% from 1969 to 1986 have recently been reported with seasonal reductions of up to 50% over the Antarctic (21). Such reductions are projected to result in increased solar UV-B2 radiation reaching the earth's surface. UV-B radiation has been shown to reduce plant biomass, leaf area, and photosynthetic capacity in soybean (Glycine max [L.] Merr.), and its '

Response of barley seedlings to water deficit and enhanced UV-B irradiation acting alone and in combination

“…In the experiment on black mustard (Brassica nigra) and turnip (Brassica rapa) both moderate soil WD (drought) and UV-B radiation at the levels of 6 and 17 kJ m -2 day -1 had detrimental effects on plant growth indices, but the effect of WD was much stronger than that of UV-B (Conner and Zangori 1998). A stronger effect of severe WD (PEG -2.0 MPa) than that of UV-B (13.6 kJ m -2 day -1 ) on dry matter of aboveground parts was found in soy (Glycine max) (Sullivan and Teramura 1990). Conversely, a higher dose of UV-B (49 kJ m ) caused more severe reduction of fresh matter of aboveground parts than stress factors applied separately (Tian and Lei 2007).…”

Interaction of Elevated Ultraviolet-B Radiation and CO2 on Productivity and Photosynthetic Characteristics in Wheat, Rice, and Soybean

“…For example, approximately half of the 300 species and cultivars tested for sensitivity to UV-B radiation show a decrease in production and/or photosynthesis (20), while 9 to 120% increases in economic yield have been projected with a doubling of present CO2 levels (10). These response differences may also be modified by changes in microclimate (15,18). It is reasonable, therefore, to anticipate that sensitivity to concurrent increases in CO2 and UV-B radiation may also be dependent upon species and cultivar, and modified by microclimate.…”

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

“…Lamps were filtered with either 0.13 mm polyester (spectrally equivalent to Mylar Type S) film (control or CK treatment), which absorbs nearly all radiation below 316 nm, or 0.13 mm Kodacel CTA (Eastman Kodak Company, Rochester, NY) for supplemental UV-B irradiance. The Kodacel films are cellulose triacetate materials with similar spectral properties to the more commonly used cellulose diacetate (24,25) in the ultraviolet-A (320-400 nm) region but with somewhat greater transmittance in the shortwave UV-B waveband (Fig. 1).…”