Rea Maria Hall1,3, Harry Bein2, Bettina Bein-Lobmaier2, Gerhard Karrer3, Hans-Peter Kaul1 and Johannes Novak2
1Department of Crop Science; University of Natural Resources and Life Science Vienna, Austria
2Institute of Animal Nutrition and Functional Plant Compounds, University of Veterinary Medicine Vienna, Austria
3Department of Integrative Biology and Biodiversity Research; University of Natural Resources and Life Science Vienna, Austria
Ambrosia artemisiifolia L. (Asteraceae) known as common ragweed is an annual herbaceous species native to North America and is not only a troublesome agronomic weed but actually one of the most important inducers of pollen allergy. Due to its plasticity, it is highly adaptive behavior in terms of habitat requirements, growing conditions, herbicide tolerance and resistance in combination with its extremely high reproductive power, the importance of common ragweed as an agricultural weed and promoter of allergies will increase further.
Following the “enemy release hypothesis”, the invasiveness of non-native species such as common ragweed can result from a loss of natural competitors due to the production of chemical compounds by the non-native species that unfavorably affect native communities. In this case, native plants may not be able to tolerate compounds released by non-native plants which have not co-evolved in the same environment. In particular, the genus Ambrosia produces and releases several types of organic compounds, which have a broad spectrum of biological activities and which could be major drivers in the successful invasion and competition process of common ragweed.
We aimed to (i) asses the chemical profile of the aboveground biomass of common ragweed, using four different extracts (i.e. H2O, hexane extract, methanol extract and essential oil) which was prepared and analysed for their content substances, and (ii) determine the effects of different concentrations of these substances on germination and seedling development of three different crops (soybean, wheat, and rapeseed), native weedy species (Chenopodium album, Senecio vulgaris, and Arabidopsis thaliana) and on common ragweed itself. This was implemented as a laboratory experiment.
Results showed a range of 58 different compounds in the aboveground biomass of which many of them could be identified as growth inhibitors and/or neurotoxines. Accordingly, germination as well as seedling development was signficantly influenced by the chemical compounds in the extracts. The highest inhibitory effect on germination of crops, native weedy species, as well as common ragweed was observed with essential oils; the higher their concentration, the higher the effect. A second run of this trial in a greenhouse should further reveal (iii) the interaction effect of different substrate types and the extracts. The aim is to test if various substrates retard or promote the effectiveness of the chemical compounds on germination and/or seedling growth of the same plant species used in the laboratory experiment. The findings of this study can contribute in the development of new sustainable agricultural management approaches and can serve as basis for further research in a broad field of plant science, e. g. plant protection.