evaluation of symbiosis with mycorhizzal on yield, yield components and essential oil of fennel (foeniculum vulgare mill.) and ajowan (carum copticum l.) under different nitrogen levels

in order to investigate the effects of mycorrhiza symbiosis and different nitrogen levels on yield, yield components and essential oil content and yield of fennel (foeniculum vulgare mill.) and ajowan (carum copticum l.), a field experiment was arranged in a factoriel based on a randomized complete block design with three replications at the agricultural research station, ferdowsi university of mashhad during growing season 2009-2010. the first and the second factors were inoculation with mycorrhiza (with and without inoculation) and nitrogen levels as urea (0, 50 and 100 kg.ha-1), respectively. inculated soil with 200 g mycorrhiza (glomus intraradaices) was applied at planting time. urea was used in two stages such as plating time and one month after that. ceriteria such as yield components (including number of branch, umbel, umbellet, seed and seed weight), biological and seed yield, harvest index and essential oil content and yield of fennel and ajowan were measured. results showed that yield components, seed yield, biological yield, harvest index, essential oil content and yield of fennel and ajowan were affected by mycorrhiza and nitrogen level. mycorrhiza increased fennel and ajowan seed yield (with 35 and 85%, respectively) and essential oil content (with 34 and 30%, respectively). the highest and the lowest 1000-seed weight of fennel and ajowan obsevered in inoculation (2.9 and 0.3 g) and control (2.1 and 0.2 g), respectively. nitrogen improved all growth characteristics and decreased essential oil content. there were not significant differences between mycorrhiza and nitrogen interaction. inoculation with mycorrhiza enhanced root development and hence availability of nutrients, particularly phosphorus. also, nitrogen is the cause of increasement of photosynthesis rate and duration which promote growth and yield, but it declined essential oil content of two species.