Submitted to: International Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 9, 2002
Publication Date: N/A
Interpretive Summary: It has been widely recognized for some time that air pollution, particularly ground level ozone can inhibit the growth and yield of important agriculture plants such as soybean. However, no data are available on the response of weeds to similar ozone levels. One weed which is important both agronomically and in regards to public health is ragweed, which is found both in city environments (where ozone concentration is high) and in agricultural fields in the country. To quantify the extent to which elevated ozone limits growth and reproduction, ragweed was grown from germination to floral initiation at control (carbon filtered, 15.8 nL O3 L-1 air) and treatment levels (63.5 nL O3 L-1 air) of tropospheric ozone. Data from this study indicate that ragweed is insensitive to ozone levels up to four times that of the control treatment. This suggests that: (1) Differential sensitivity between crops and weeds to ozone would favor the weed with subsequent losses in crops, and (2) That higher ozone levels associated with city environments do not limit the growth of ragweed in urban areas.
Technical Abstract: Although the sensitivity of growth and yield in response to ground level ozone has been determined for a variety of agronomic crops and trees, little information is available for weedy species. Common ragweed (Ambrosia artemisiifolia) is recognized both as a common agricultural weed and the principle source of pollen for fall allergies in the U.S. To quantify the extent to which elevated ozone limits growth and reproduction, ragweed was grown from germination to floral initiation at control (carbon filtered, 15.8 nL O3 L-1 air) and treatment levels (63.5 nL O3 L-1 air) of tropospheric ozone. By 48 days after sowing, during floral initiation, no significant differences in total plant biomass or floral biomass were observed as a function of ozone concentration. Analysis of leaf area ratio, relative growth rate and net assimilation rate at approximately 10 day intervals during early vegetative growth also did not demonstrate any significant effect of ozone. Data from this experiment indicate that ragweed was insensitive to ozone levels up to 4 times that of the CF control, and suggests that elevated ozone levels associated with urban environments probably do not limit the growth or reproductive development of ragweed.