Allelopathic effects of invasive woody plant species in Hungary

Abstract

Allelopathy may play an important role in the invasion success of adventive plant species. The aim of this study was to determine the allelopathic potential of invasive woody plant species occurring in Hungary. Juglone index of fourteen invasive woody plant species in Hungary was determined by the method of Szabó (1997), comparing the effects of juglone and substance extracted of plant species with unknown allelopathic potential on the germination rate, shoot length and rooth length of white mustard (Sinapis alba L.) used as receiver species. Results have proven a more or less expressed allelopathic potential in case of all species. The juglone index at higher concentration extracts (5 g dry plant material extracted with 100 ml distilled water) of almost every studied species approaches to 1 or is above 1, this means the effect of the extracts is similar to juglone or surpasses it. In terms of juglone index, the allelopathic potential of false indigo (Amorpha fruticosa L.), tree-of-heaven (Ailanthus altissima (Mill.) Swingle) and hackberry (Celtis occidentalis L.) were the highest. Besides these species the treatment with the extracts of black walnut (Juglans nigra L.), black cherry (Prunus serotina Ehrh.) and green ash (Fraxinus pennsylvanica MARSH. var. subintegerrima (Vahl) Fern.) reduced extremely significantly the germination rate, shoot and root length, compared to the control.