Determination of allelopathic effect of some invasive weed species on germination and initial development of grain legume crops

Abstract

During the 2006-2007 period, the allelopathic effect of cold water extracts from Amaranthus retroflexus L., Chenopodium album L., Erigeron canadensis L. and Solanum nigrum L. on seed germination and initial development of Glycine max L., Pisum sativum L. and Vicia sativa L. was studied under laboratory conditions in the Institute of Forage Crops, Pleven. It was found that: water extracts from fresh and dry biomass of A. retroflexus, Ch. album, E. canadensis and S. nigrum had an inhibitory effect on seed germination of G. max, P. sativum and V. sativa, the inhibition rate for the extracts from fresh biomass varying from 28.8 to 81.5% and for the extracts from dry weed biomass it was from 26.8 t? 89.2%; The values of LC50 varied from 13.5 t? 72.2 g l-1 for the extracts from fresh biomass and from 7.0 t? 84.1 g l-1 for the extracts from dry weed biomass and they could be conditionally grouped in the following ascending order: A. retroflexus < S. nigrum < E. canadensis <Ch. album and for extracts from dry biomass: A. retroflexus < E. ?anadensis < Ch. album < S. nigrum; P. sativum was the most sensitive to the allelopathic effect of the extracts from fresh and dry weed biomass - LC50 varied from 13.5 t? 21.6 g l-1, followed by V. sativa - LC50 from 26.0 t? 11.7 g l-1 and G. max had relatively the lowest sensitivity - LC50 was from 46.6 t? 56.7 g l-1.