Allelopathic Effects on Seeds Germination of Lactuca Sativa L. Seeds and Antibacterial Activity of Thymus Capitatus Essential Oil from Zintan-Libya Flora

The present study was amid to evaluate the essential oil composition of Thymus capitatus and its allelopathy effects on seeds germination of Lactuca sativa L., based on germination assay, also antibacterial activity was tested against to bacteria species ( Salmonella gallinarum and E. coli ) using the disc diffusion method.                The oil analysis by GC-MS, showed that the main class was oxygenated monoterpenes with percentage (87.61 %), while hydrocarpons monterpend represented by (10.46 %) of the total oil, and the dominated compounds were carvacrol (68.19 %), thymol (12.29 %) and p-cymene (3.25 %) respectively. The allelopathy effect based on germination assay, where we used three essential oil concentration (0.5 µl/ml, 1 µl/ml, 2 µl/ml) showed that the activity increase with the increase of the oil concentration and the inhibition percent (IP) reached  96.66 % and germination percentage (GP) 3.4  % at the maximum concentration (2µl/ml) compared with control which was  only water IP  0 % and GP (100%). In the case of antimicrobial activity the oil showed activity better than positive control (Gentamycine) against the two bacteria species and diameter of the clear zone around the discs were (35 mm, 32mm, 15 mm) for S. gallinarum , E. coli and positive control respectively.