Effects of the application of vermicompost and nitrogen fixing bacteria on quantity and quality of the essential oil in dill (Anethum graveolens)

Abstract

The main objective of this study was to determine the effects of vermicompost and nitrogen fixing bacteria on the quantity and quality of essential oil in dill essential oil content in seed, essential oil yield and carvone content, limonene content and dillapiole content in essential oil. The experiment was carried out at the Hamand Research Station of Damavand in 2011. Vermicompost (0, 4, 8 and 12 ton/ha) and nitrogen fixing bacteria, mixture of Azotobacter chroococcum and Azospirillum lipoferum (non-inoculated, inoculated seeds and inoculated seeds + spray on the plant base at stem elongation stage) were used as the effecting parameters. The present results have shown that the highest essential oil content in seed and carvone content in essential oil and the minimum dillapiole content in essential oil were obtained after applying 4 ton/ha vermicompost. The maximum essential oil yield was obtained after applying 8 ton/ha vermicompost. Nitrogen fixing bacteria also showed significant effects on essential oil content, essential oil yield and carvone content in essential oil. The maximum essential oil content and carvone content were obtained by using the nitrogen fixing bacteria once. The highest essential oil yield was obtained by using the nitrogen fixing bacteria twice. Key words: Dill, vermicompost, Azotobacter, Azospirillum, essential oil.