study on the effect of orchard grass (dactylis glomerata l.) allelopathy on germination and seedling growth of alfalfa (medicago sativa l.)

in order to identification of allelopathic compounds and investigation of the effect of aerial part extract of orchard grass on germination and seedling growth of alfalfa an experiment conducted as completely randomized design with four replications at university of mohaghegh ardabili, iran. treatments were concentrations of orchard grass extracts including 0, 25, 50, 75, and 100%. radicle and plumule length, fresh weight of seedling, percentage and rate of germination were measured. results showed that with increasing extract concentration there was a reduction trend in all studied traits (except of seedling fresh weight and plumule length which increased at lower concentrations and then declined). the highest content of allelopathic substances related to phenolic compounds (7.98 and 13.91 mg in root and shoot, respectively). plumule length and seedling fresh weight increased at the concentrations between 23 to 26% and after then reduced sharply and prevented completely at 100% concentration. all the traits reached to zero at 100% concentration. orchard grass allelopathic substances inhibited the germination and growth of alfalfa seeds at higher concentrations.