|Field Study of the Interaction between Solar Ultraviolet-B Radiation and Drought on Photosynthesis and Growth in Soybean.
Sullivan, J. H. ;
Teramura, A. H. ;
|Maryland Univ., College Park. Dept. of Botany.;Corvallis Environmental Research Lab., OR.
|SCIENTIFIC-8044 ;CONTRIBA-4997; EPA-R-812150-02-0; EPA/600/J-90/490;
Ultraviolet rays ;
Farm crops ;
Field tests ;
Plant growth ;
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Soybean, Glycine max (L.) Merr. cv Essex, plants were grown in the field in a 2x2 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. 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.