Author
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Ziska, Lewis |
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Submitted to: Weed Research
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/1/2012 Publication Date: 1/28/2013 Citation: Ziska, L.H. 2013. Observed changes in soyabean growth and seed yield from Albutilon theophrasti competition as a function of carbon dioxide concentration. Weed Research. 53:140-145. Interpretive Summary: Increasing atmospheric carbon dioxide, projected to reach 1000 parts per million (ppm) by the end of the current century by some estimates, may differentially stimulate the growth of desired crop plants, and undesired weed species. This may, in turn, significantly reduce crop yields as weeds are recognised globally as the greatest limitation to crop production. To determine how rising levels of carbon dioxide impact crop weed competition, we examined soybean and a troublesome weed, velvetleaf, at current and projected increases in CO2 (ambient and ambient + 250 ppm). In a weed-free condition, elevated CO2 resulted in significant stimulations in soybean seed yield and associated components, including pod number. At an approximate density of 6 plants per square meter, velvetleaf resulted in a significant (-40%) reduction in soybean seed yield. Although significant differences in seed yield reduction by velvetleaf were observed as a function of year, the relative decrease in seed yield with velvetleaf biomass did not differ in response to carbon dioxide concentration. Although careful weed management will be necessary if CO2 induced increases in seed yield for soybean are to be achieved, these data suggest that soybean seed yield may be more resilient in competition with velvetleaf as a function of rising atmospheric levels of carbon dioxide. This research will be of benefit to land managers, growers, and weed scientists. Technical Abstract: Soybean (Glycine max) was grown at ambient and at projected levels of atmospheric carbon dioxide (+250 µmol mol-1 above ambient) with and without the presence of a weed (velvetleaf, Albutilon theophrasti Medic.) to quantify the potential effect of rising atmospheric carbon dioxide concentration [CO2] on weed crop interactions and potential yield loss in soybean over a two year period. In a weed-free condition, elevated [CO2] resulted in significant stimulations in soybean seed yield and associated components, including pod number. At an approximate density of 6 plants m-2, velvetleaf resulted in a significant (-40%) reduction in soybean seed yield. Although significant differences in seed yield reduction by velvetleaf were observed as a function of year, the relative decrease in seed yield with velvetleaf biomass did not differ in response to [CO2]. Although careful weed management will be necessary if CO2 induced increases in seed yield for soybean are to be achieved, these data suggest that soybean seed yield may be more resilient in competition with velvetleaf as a function of rising atmospheric levels of carbon dioxide. |
