Allelopathic Activity of Plant Species From Asteraceae and Polygonaceae Family on Lettuce

The allelopathic potential of extracts from nine plants species belonging to Asteraceae and Polygonaceae family was evaluated on germination and early growth of lettuce. Water extracts from dry biomass of different plant parts in concentration of 5% were examined under laboratory bioassay in Petri dishes. Among species of Asteraceae family, the highest germination and seedlings growth inhibition was observed with annual fleabane (Erigeron annuus) leaf extract which reduced all parameters for 100%. Similarly, common sow thistle (Sonchus oleraceus) and common tansy (Tanacetum vulgare) also exhibited considerable negative effect. Germination of lettuce was not greatly affected when extracts from Polygonaceae plant species were applied, however significant inhibition of root and shoot length as well as fresh seedling biomass was recorded, especially in treatments with black bindweed (Fallopia convolvulus).