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.The authors would like to acknowledge Dr. Samsik Kang (College of Pharmacy, Seoul National University) and Dr. Jonghee Kim (Department of Biology, Gyeongnam University) for the technical advice and supportive discussion and Dr. Changsuk Kim (National Institute of Agricultural Science and Technology) for the seed collection. This work has been supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT)(2018R1C1B6005351). We are grateful to NRF (2016R1D1A1A02937049, 2017096A001719BB01) for the financial support

Effect of heavy metals on establishment of common ragweed «(Ambrosia artemisiifolia L.)» and ground cover legumes in roadside edges

Poor establishment of supplement ground cover (i.e. Trifolium species) has led to unsuccessful turf-recruitment and creating empty niches near pavement edges of major roadways and highways in southern Québec, Canada. The resulting empty niches are frequently occupied by dense monocultures of Ambrosia artemisiifolia. Due to its adverse impacts on agroeconomy and public health, understanding ecological cause(s) associated with A. artemisiifolia's successful establishment along roadside edges will help us to control this problematic weeds and prevent its dispersal into nearby agricultural and urban areas. Surface soils adjacent to major roads and highways commonly contain heavy metals at phytotoxic levels. We hypothesized that during early establishment stage higher metal tolerance of A. artemisiifolia compared to the current cover legume (Trifolium spp.) may cause its successful establishment along roadside edges. Growth chamber experiments investigated germination and early seedling behaviors of four test species (Ambrosia artemisiifolia, Coronilla varia, Lotus corniculatus, and Trifolium arvense) exposed to Zn, Pb, Ni, Cu, and Cd. All metal additions hindered the seedling growth of all test species, and the inhibitory effect was greater on the belowground growth than the aboveground growth. The germinability and seedling survival of T. arvense were inhibited by the studied metals, whereas those of A. artemisiifolia were tolerant to the metal additions. Low levels of Pb and Ni promoted germination initiation of A. artemisiifolia. While sensitive to Cu and Cd, the germinabilities of L. corniculatus and C. varia were tolerant to the other metals. The germinability of L. corniculatus was more tolerant of Zn, Pb, and Ni than that of C. varia. The seedling survivals of L. corniculatus and C. varia were not affected by the metal additions, except for Ni and Cu. In addition to the interspecific comparisons, germination and early seedling responses to metals (Zn, Pb, Ni, Cu, and Cd) between the agriculture and roadside populations of A. artemisiifolia were compared under laboratory condition. Germinability and early seedling behaviours of the two A. artemisiifolia populations had similar responses to heavy metal additions. However, there was population-specific difference in germination rate, suggesting that this variation might arise from different maternal environmental factors between the two source populations. A field experiment was conducted to verify the establishment potential of the test species near roadside edges along a heavy metal gradient. Seedling emergence of T. arvense was negatively correlated with Zn, Pb, and Cu concentrations, while emergence of A. artemisiifolia was positively correlated with these metal elements. Similar to A. artemisiifolia, the emergence of L. corniculatus was positively related with the metal contents, but no correlation was found for C. varia. The present research project outlines a potential mechanism that may drive the successful establishment of A. artemisiifolia along roadside edges. Based on the findings from the laboratory and field studies, A. artemisiifolia establishment along roadside edges appears to be caused by its higher metal tolerance relative to T. arvense. Because its metal tolerance and establishment potential was similar to A. artemisiifolia, L. corniculatus could be an alternative supplement ground cover for effective turf-recruitment and control of A. artemisiifolia along edges of highways in southern Québec. This study provides integrated roadside ground cover management strategy for controlling A. artemisiifolia, supporting turf-recruitment and stabilizing disturbed soil near pavement edges of high traffic roadways, which may eventually alleviate economic burdens (involving health care, roadside maintenance, and agricultural production) on society.L'implantation difficile de couvre-sol (i.e. Trifolium spp.) conduit à l'échec de la végétation herbacée et crée des surfaces libres en bordure des routes principales dans le sud du Québec. Ces niches exemptes de végétation sont colonisées par une monoculture d'Ambrosia artemisiifolia. La connaissance des facteurs écologiques responsables du succès de l'A. artemisiifolia le long des routes permettra de lutter contre cette mauvaise herbe en raison de ses effets sur l'agroéconomie et la santé publique et d‘empêcher sa dispersion dans les zones agricoles et urbaines. Les sols en bordure des routes principales contiennent des métaux lourds à des niveaux phytotoxiques. Nous émettons l'hypothèse que l'établissement de populations d'A. artemisiifolia le long des routes est relié à un seuil de tolérance plus élevé aux métaux lors des premiers stades végétatifs comparativement aux légumineuses (Trifolium spp.). La germination et le développement de plantules de quatre espèces (A. artemisiifolia, Coronilla varia, Lotus corniculatus et Trifolium arvense) en présence de diverses concentrations de Zn, Pb, Ni, Cu, et Cd ont été évalués en chambre de croissance. Tout ajout de métaux a entravé la croissance des plantules de toutes les espèces et l'effet inhibiteur était plus important sur la croissance racinaire que sur la croissance aérienne. La germination et la survie des plantules de T. arvense étaient sensibles aux métaux étudiés, tandis que ceux d'A. artemisiifolia ne l'étaient pas. De faibles concentrations de Pb et Ni ont augmenté le taux de germination d'A. artemisiifolia. Bien que sensibles au Cu et Cd, la germination de L. corniculatus et C. varia n'était pas affectée par les autres métaux. La germination de L. corniculatus était plus tolérante au Zn, Pb, et Ni que celle de C. varia. La survie des semis de L. corniculatus et C. varia n'a pas été affectée par les ajouts de métaux, à l'exception du Ni et Cu. La germination et le développement de plantules d'A. artemisiifolia provenant d'une population agricole et d'une population routière ont été évalués en présence de diverses concentrations de métaux (Zn, Pb, Ni, Cu et Cd) en laboratoire. L'apport de métaux sur la germination et le développement des plantules étaient similaires entre les deux populations. L'origine des populations a eu un effet sur le taux de germination, ce qui suggère que d'autres facteurs environnementaux d'origine maternelle puissent induire des différences spécifiques aux populations. Un essai a été mené in situ pour tester le potentiel d'établissement des espèces à l'essai en bordure de routes selon un gradient de métaux. L'émergence des plantules de T. arvense a été corrélée négativement avec Zn, Pb, et Cu, tandis que celle d'A. artemisiifolia était positivement corrélée avec ces mêmes métaux. Tout comme A. artemisiifolia, l'émergence de L. corniculatus était positivement corrélée avec les teneurs en métaux, mais il n'y a aucune corrélation pour C. varia. Cette étude décrit des mécanismes qui peuvent potentiellement conduire au succès de l'implantation d'A. artemisiifolia le long des routes. En s'appuyant sur les résultats en laboratoire et in situ, l'implantation d'A. artemisiifolia le long des routes semble être relié à un seuil de tolérance plus élevé aux métaux par rapport à T. arvense. Puisque la tolérance aux métaux et le potentiel d'implantation de L. corniculatus étaient semblables à ceux d'A. artemisiifolia, L. corniculatus peut être un couvre-sol complémentaire pour la mise en place de végétation herbacée et pour le contrôle d'A. artemisiifolia en bordure de routes dans le sud du Québec. Cette étude propose une méthode de gestion de couvre-sol pour contrôler A. artemisiifolia, maintenir une végétation herbacée et stabiliser le sol perburbé en bordure des routes principales. Ceci peut éventuellement alléger le fardeau économique (tels les soins de santé, l'entretien routier, et la production agricole) sur la société

Tricotelydenous giant ragweed (Ambrosia trifida L.).

In this short communication we report the observation of a tricotelydenous giant ragweed (Ambrosia trifida L.) individual. In contrast to the normal dicotelydenous pattern of phyllotaxy, this individual was observed to express three axillary meristems at each node that intersected the main stem at angles of 120 degrees.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author