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1981, Effects of supplemental UV-B radiation on growth and leaf photosynthetic reactions of soyhean (Glycine max). -Physiol. Plant. 52: 353-362.Experiments were conducted under greenhonse conditions to investigate the effects of enhanced UV-B radiation (280 to 320 nm) OB height, fresh and dry weights, leaf chlorophyll and carotenoids, CO^ uptake rates, and Hill activity in soybean {Glycine max L. cv. Bragg). Plants were exposed for 6 h continuously from midmorning to midafternoon each day to UV-B radiation which was provided by Westinghouse FS-40 sun lamps filtered with 0.127-mm cellulose acetate film (UV-B enhanced) or 0.127-mni Mylar S film (UV-B Mylar control). Three different UV-B enhanced radiation levels were tested: 1.09 (treatment T,), 1,36 (treatment T^), and 1.83 (treatment T3) UV-B sun equivalent units (UV-BJ. where 1 UV-B5^" = 15.98 mW-m"^ of solar UV-B obtained by applying EXP -[(i-265)/21]^ a weighting function that simulates the DNA absorption spectrum, to the UV-B lamp systems. These UV-B levels correspond to a calculated decrease in stratospheric ozone content of 6%, 21%, and 36% for treatment T,, T^, and T3, respectively. Daily exposure of soybean plants to UV-B radiation significantly decre,ased height, fresh and dry weights, leaf chlorophyll and carotenoid contents, and CO3 uptake rates. Leaf pigment extracted in 80% acetone from UV-B-treated soybean plants showed considerable increase in absorption in the wavelength region of 330 to 400 nm with increased UV-B radiation levels. Chloroplast preparations from leaves of Tj and T3 plants showed significant reductions in Hill reaction measurements.