Allelopathic Effects of Bunium persicum and Cuminum cyminum Essential Oils on Seed Germination of some Weeds Species

In order to investigate the allelopathic effects of the essential oils of Bunium persicum and Cuminum cyminum, this research conducted in two separate experiments to find out the effects of different essential oils concentration of Bunium persicum (200, 500, 700, 1000 and 2000 ppm) and Cuminum cyminum (100, 300, 500, 700 and 1000 ppm) on germination activity of Bromus tectorum, Centura ovina and Descurainia sophia. Each experiment was conducted in RCBD with 4 replications. Results showed that germination percentage of all the weeds were high in control plots(96.67, 73 and 96.67 respectively). Germination of Centura ovina and Bromus tectorum were completely inhibited by Bunium persicum essential oils at 700 and 1000 ppm respectively. Descurainiaseeds were more sensitive to Bunium persicum essential oils and its germination completely inhibited at 500 ppm. There was no significant difference between 200 ppm and 500ppm of Bunium persicum essential oils as germination percentage of Bromus tectorum as concerned (54% and 44% respectively). Bunium persicum essential oils at 500ppm decreased germination percent of Centura ovina by 25% (from 73% to 48.67%). But 200ppm Bunium persicum essential oils decreased germination percent of Descurainia sophia by 69% (from 96.67 to 27.67). Cuminum cyminum essential oils also affected germination process of all the weeds that were tested in the experiments. Germination of Bromus tectorum, Centura ovina and Descurainia sophia completely inhibited by 2000, 1000 ppm and 500 ppm, respectively. Concentration increasing of Cuminum cyminum essential oils from 100ppm to 1000ppm decreased germination percent of Bromus tectorum, Centura ovina and Descurainia sophia by 46.67%, 51% and 53 % respectively. In respect to germination rate data showed that all the treatments decreased germination rate and it decreased from 11.25, 4.14, 17.5 seed/day in control plot to zero in treated seeds with Bunium persicum essential oils. Germination rate of Bromus,Centura and Descurainia were also affected by Cuminum cyminum treatments and it decreased from 18.77, 5.82 and 13.6 in control plot to zero respectively. It was concluded that Bunium persicum and Cuminum cyminum essential oils as an allelopathic agents for the weeds control should be a good agent for organic culture.