allelopathic effects of medicinal plants of lemon balm, lemon verbena and bitter apple on seed germination and early seedling growth characteristics of wild mustard weed

allelopathy refers to the chemical inhibition or stimulation of one species by another which could influence on the growth or germination of other plant and used in control of weed in agricultural practices. in this sense in order to study the possibly allelopathic effects of lemon balm, bitter apple and lemon verbena medicinal plants on control of wild mustard weed, a laboratory experiment was arranged based on completely randomized design (crd) in three replications at laboratory of mehrgan institute during 2014.  in this study, effects of different aqueous extracts and essential oils of mentioned medicinal plants compared with control treatments. evaluated values were germination rate, germination percentage, radicle length, shoot length, fresh and dry weight of radicle and shoot. results showed that essential oil of lemon verbena at 600 mg/l concentration had more meaningful effect on germination percentage and germination rate of wild mustard. our results also indicated that aqueous extract of these plants had stimulating effect on weed seed development, while some essential oils treatments had an inhibitory effect on this weed seeds development.