TY  - JOUR
A1  - Moravcová, Lenka
A1  - Pyšek, Petr
A1  - Jarošík, Vojtěch
A1  - Zákravský, Petr
T1  - Potential phytotoxic and shading effects of invasive Fallopia (Polygonaceae) taxa on the germination of dominant native species
T2  - NeoBiota
N2  - Two species of the genus Fallopia (F. sachalinensis, F. japonica, Polygonaceae) native to Asia, and their hybrid (F. ×bohemica), belong to the most noxious plant invaders in Europe. They impact highly on invaded plant communities, resulting in extremely poor native species richness. The low number of native species in invaded communities points to the possible existence of mechanisms suppressing their germination. In this study we assessed, under laboratory conditions, whether there are phytotoxic effects of the three Fallopia congeners on seed germination of three target species: two native species commonly growing in habitats that are often invaded by Fallopia taxa (Urtica dioica, Calamagrostis epigejos), and Lepidium sativum, a species commonly used in allelopathic bioassays as a control. Since Fallopia taxa form dense stands with high cover, we included varying light conditions as an additional factor, to simulate the effects of shading by leaf canopy on germination. The effects of aqueous extracts (2.5%, 5.0%, and 0% as a control) from dry leaves and rhizomes of the Fallopia congeners on germination of the target species were thus studied under two light regimes, simulating full daylight (white light) and light filtered through canopy (green light), and in dark as a control regime. Rhizome extracts did not affect germination. Light treatments yielded inconclusive results, indicating that poor germination and establishment of species in invaded stands is unlikely to be caused by shading alone. However, we found a pronounced phytotoxic effect of leaf extracts of Fallopia taxa, more so at 5.0% than 2.5% extract concentration. Fallopia sachalinensis exerted the largest negative effect on the germination of Urtica dioica, F. ×bohemica on that of C. epigejos, and F. japonica had invariably the lowest inhibitory effect on all test species. The weak phytotoxic effect of F. japonica corresponds to the results of previous studies that found this species to be generally a weaker competitor than its two congeners. Although these results do not necessarily provide direct evidence for allelopathic effects in the field, we demonstrate the potential phytotoxic effect of invasive Fallopia taxa on the germination of native species. This suggests that allelopathy may play a role in the impact of Fallopia invasion on species diversity of invaded communities.
KW  - Allelopathy
KW  - canopy shading
KW  - leaf and rhizome extracts
KW  - light regimes
KW  - phytotoxicity
KW  - plant invasions
KW  - Reynoutria
Y1  - 2011
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/32115
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-321150
SN  - 1314-2488
IS  - 9
SP  - 31
EP  - 47
ER  -