INHIBITORY EFFECTS OF LAVENDER, ABSINTHIUM AND WALNUT ON GERMINATION AND SEEDLING GROWTH OF Convolvulus arvensis, Portulaca oleracea AND Triticum aestivum

One means of reducing utilization of herbicides is allelopathic effect that is found in some plant species. therefore, allelopathic effects of different doses (0, 5, 7.5 and 9 g dried leaves/plot) of walnut, lavender and absinthium on germination and seedling growth of convolvulus arvensis, portulaca oleracea and triticum aestivum were evaluated in greenhouse conditions. this study was conducted in a factorial experiments based on a randomized complete design with three replications in 2012. the experimental treatments included amounts of allelopathic plants that were mixed with 2 kg soil in each pot. shoot dry weight, shoot fresh weight, root dry weight, root fresh weight, seedling height, leaf number and germination percent were measured. results showed that main effects of allelopathy on shoot fresh and dry weight, root dry weight and seedling height were significant (p<0.05). lavender had more reducing effects than walnut and absinthium on all traits. dose had significant effect on all parameters and higher doses (7.5 and 9 g/plot) were more effective. in general, results showed that all allelopathic plants reduced shoot fresh weight of portulacaoleracea significantly and 9 g/plot of walnut and absinthium had significant reducing effect on convolvulus arvensis. allelopathic plants had significant effect on shoot fresh and dry weight, root fresh and dry weight and seedling height of triticumaestivum and not significant effect ongermination percentage. it can be concluded that the allelopathic effect of lavender disrupted the germination and seedlings of portulacaoleracea by producing allelopathic chemicals.