Effect of elevated atmospheric carbon dioxide on the allelopathic potential of common ragweed

Background: Allelopathy has been suggested as one potential mechanism facilitating the successful colonisation and expansion of invasive plants. The impacts of the ongoing elevation in atmospheric carbon dioxide (CO₂) on the production of allelochemicals by invasive species are of great importance because they play a potential role in promoting biological invasion at the global scale. Common ragweed (Ambrosia artemisiifolia var. elatior), one of the most notorious invasive exotic plant species, was used to assess changes in foliar mono- and sesquiterpene production in response to CO₂ elevation (389.12 ± 2.55 vs. 802.08 ± 2.69 ppm). Results: The plant growth of common ragweed significantly increased in elevated CO₂. The major monoterpenes in the essential oil extracted from common ragweed leaves were β-myrcene, dl-limonene and 1,3,6-octatriene, and the major sesquiterpenes were β-caryophyllene and germacrene-D. The concentrations of 1,3,6-octatriene (258%) and β-caryophyllene (421%) significantly increased with CO₂ elevation. Conclusions: These findings improve our understanding of how allelochemicals in common ragweed respond to CO₂ elevation.