The effect of plant growth promoning rhizobacteria and vermicompost on quality traits of druge marigold (Calendula officinalis L.)

In order to investigate the effects of different levels of vermicompost and nitroxin on the qualitative properties of medicinal plant marigold (Calendula officinalis L.), an experiment was conducted as factorial based on a completely randomized design with four replications in the greenhouse of Gonbad-e-Kavos University during 2014-2015. The first factor was vermicompost fertilizer treatment at six levels (0%, 10%, 20%, 40%, 70% and 100%) and the second factor was biological nitroxin fertilizer at two levels of inoculation (25 ml/kg soil) and no inoculation with nitroxin. The results of analysis of variance showed that the effects of nitroxin, vermicompost and their interaction on all traits studied were significant. However, the total phenol content was only significant in the vermicompost treatment. The results showed that the highest total phenol content, chlorophyll a, and total chlorophyll were obtained in 10% vermicompost treatment with nitroxin inoculation. The highest chlorophyll b content was related to 10% vermicompost treatment without nitroxin inoculation. The highest nitrogen content in the plant and catalase content were obtained from 100% vermicompost treatment with nitroxin inoculation, and 100% vermicompost without nitroxin inoculation, respectively. The highest amount of essential oil was obtained from 100% vermicompost treatment with nitroxin inoculation and the lowest was obtained from control treatment without nitroxin inoculation. According to the results, 100% and 70% vermicompost with nitroxin inoculation could be suggested as a suitable treatment for the production of marigold essential oil.