1Dept. of Environmental and Agricultural Sciences, Faculty of Agriculture, University of Perugia, 06121 Perugia, IT, Email: firstname.lastname@example.org
Recently, allelopathy is exploited as a weed control tool in order to reduce the use of herbicides and improve weed management strategies, both in the integrated and organic farming systems. Interesting results were obtained by selecting allelopathic crop types, using allelopathic cover crops and developing herbicides from allelopathic compounds. Herbicides derived from allelopathic compounds may have new target sites, important in managing herbicide resistance. Many weed species have been observed to have allelopathic activity. In particular, A. vulgaris was found to have allelopathic properties, although available results are few and without practical relevance. The aims of this study were to evaluate allelopathic potential of different plant tissues of A. vulgaris and their activity against wheat (T. aestivum) and L. multiflorum, one of the main crop in Italy and its most problematic weed respectively, due to resistance to ACCase inhibiting herbicides.
Allelopathic potential of A. vulgaris was determined under laboratory, greenhouse and field conditions. Petri dishes experiments were carried out with leaves, stems and rhizomes aqueous extracts of A. vulgaris (0, 5, 10, 17.5 and 25% w/v concentrations) in order to compare their effect on seed germination and growth of Sinapis alba, used as test species. Subsequently, aqueous extracts of aerial biomass (stems + leaves) of A. vulgaris were applied in Petri dishes and pots bioassays against wheat and L. multiflorum. A field experiment was carried out in a winter wheat crop using aqueous extract of A. vulgaris (20% w/v) alone or in mixture with chlorsulfuron for weed control in pre-emergence treatments. Allelopathic extract was prepared from plants of A. vulgaris harvested at the flowering stage in an infested field. Air-dried tissue was ground to fine powder and extracted for 24 h in distilled water at room temperature. The obtained extract was filtered through filter paper. Germination percentage, radicle and hypocotyls lengths were determined in Petri dishes bioassays, fresh and dry weight of plants were recorded in pots bioassays. Data were subjected to a non-linear regression analyses by using a dose-response model and the ED levels were derived.
ED levels showed that the extracts from rhizomes and stems had a similar inhibitory effect on seed germination, radicle and hypocotyls length of S. alba and lower than leaves extract. The extract of aerial biomass did not affect germination and growth of T. aestivum, but inhibited seed germination and growth of L. multiflorum. These results were confirmed by field experimental data that showed as aqueous extract of A. vulgaris alone, in pre-emergence applications, obtained a weed efficacy of 50% and 75% against L. multiflorum and Veronica hederifolia, respectively. Pre-emergence treatments with A. vulgaris aqueous extract + chlorsulfuron gave higher weed control levels than chlorsulfuron alone. A. vulgaris is characterized by allelopathic potential with higher activity in leaves than rhizomes or stems. Aqueous extract of A. vulgaris aerial biomass showed to be effective against L. multiflorum also in pre-emergence applications in field. These results seem to support the possibility to use A. vulgaris allelopathic potential in practical relevance, in order to reduce the use of herbicides and improve the management of herbicide resistant weeds.