Effects of Essential Oils of Thyme and Sweet Marjoram on Seed Germination and Growing of Some Weeds

In order to find alternative methods to chemical control of weeds, essential oils with the doses of 0.5, 1, 2, 4, 8, 16 and 32 μl/petri dish of thyme (Origanum syriacum L.) and sweet marjoram (O. majorana L.) were used for germination studies on Amaranthus retroflexus L. (redroot pigweed), Portulaca oleracea L. (common purslane), Physalis angulata L. (cutleaf groundcherry), Echinochloa colonum (L.) Link. (barnyard grass) and Solanum nigrum L. (black nightshade). In addition, the same essential oils with the dosages of (1%, 2%, 4%, 8% and 16% were applied for growing studies on the same weeds. As average, both plants’ essential oils inhibited the weed germination more than 50% and especially S. nigrum and P. angulata were inhibited in high ratios. Both P. oleracea and S. nigrum’s growth were inhibited more than 50% by the essential oils