Evaluation of integrated management of organic manure application and mycorrhiza inoculation on growth criteria, qualitative and essential oil yield of hyssop (Hyssopus officinalis L.) under Mashhad climatic conditions

In order to study impacts of organic manure levels and inoculation with mycorrhiza fungi on growth, quantitative and qualitative yield of hyssop (Hyssopus officinalis L.), a field experiment was conducted as factorial based on a randomized complete block design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad, during two growing seasons of 2009-2010 and 2010-2011. Mycorhiza inoculation (with and without inoculation) and five levels of organic manure as decomposed cow manure (zero, 10, 20, 30 and 40 t.ha-1) were considered as treatments. Plant height, canopy diameter, leaf to shoot ratio, shoot dry weight, essential oil content and essential oil yield of hyssop were measured and calculated accordingly. The results showed that the simple and interaction effects between organic manure and mycorrhiza were significant (p≤0.01) on plant height, canopy diameter, leaf to stem ratio, shoot dry weight and essential oil content and yield of hyssop. By increasing organic manure level from zero to 30 t.ha-1 enhanced shoot dry weight and essential oil yield of hyssop up to 127 and 43%, respectively. Whereas by increasing organic manure level up to 40 t.ha-1 improved these traits up to 12 and 24%, respectively. Mycorrhiza inoculation enhanced shoot dry weight and essential oil yield up to 19 and 14%, respectively. The second year, growth of hyssop plants due to suitable establishment and more availability of nutrients were higher than the first year. Organic manure enhanced growth and yield of hyssop due to availability of nutrients and improvement in soil characteristics. Mycorrhiza inoculation promoted growth and yield of this valuable medicinal plant because of root development and nutrient availability particularly phosphorus.