Allelopathic effects of rhizome aqueous extract of Cynodon dactylon L. on seed germination and seedling growth of Legumes, Labiatae and Poaceae

Allelopathic effects of aqueous extract of rhizomes of Cynodon dactylon L. were studied on seed germination and seedling growth of three legume crops (Phaseolus vulgaris L., Pisum sativum L., and Vicia faba L.), three Labiatae species (Thymus vulgaris L., Melissa officinalis L., and Mentha spicata L.), and two species of Poaceae (Avena fatua L., Sorghum halepense L.). Seed germination of all Labiatae species was completely inhibited at treatments more than 2% rhizome extract of Cynodon dactylon but in other species, except Phaseolus vulgaris, complete failure of seed germination was recorded only at treatments more than 6% in Vicia faba and Sorghum halepense and 10% in Pisum sativum and Avena fatua. Seed germination of Phaseolus vulgaris was not completely inhibited but it was low at high concentration of the extract. The extract had strong inhibitory effect on root elongation of seedling in legums and Labiatae to shoot elongation in Poacae. Rhizomes of Cynodon dactylon may be a source of natural herbicide against Sorghum halepense which will help to control invasive plants.