Evaluation quantitative, qualitative traits and elements adsorption of lemon verbena (Lippia ‎citriodora L.) under biochar, vermicompost and plant growth promoting rhizobacteria ‎

The Lippia genus which has over than 200 species and Lippia citriodora L. is medicinally important. In order to evaluate the quantitative and qualitative characteristics and elements of Lippia citriodora L. under the influence of plant growth promoting rhizobacteria (PGPR), vermicompost and biochar, a factorial experiment was conducted in a randomized complete block design with 3 replications in the Research Institute of Forests and Rangelands, Alborz Research Station in field conditions, was implemented in 2017 on one-year seedlings. The  first factor included factors: vermi-compost at three levels (0, 6 and 12 ton/ha), the second factors was biochar  at three levels (0, 5 and 10 ton/ha) and the thirs factor was plant growth promoting rhizobacteria at two levels (non-inoculation and inoculation with combination of Azotobacter chroococcum strain 5, Azospirillum lipoferum strain OF and Pseudomonas putida). Comparison of means demonstrated that the highest essential oil percentage (0.86 %) was acquired from control treatment and the highest essential oil yield with 3.74 kg/ha was observed in treatment 12 ton/ha vermicompost, 10 ton/ha biochar and inoculation with plant growth promoting rhizobacteria. The highest Fe (377.06 ppm) was observed in 12 ton/ha vermicompost, 10 ton/ha biochar and non-inoculation. Generally, application of 6 ton per hectare vermicompost, 10 ton per hectare biochar and PGPRs on Lippia citriodora can improve yield and qualitative traits of the plant through increasing growth, developing root and better absorbing water and nutrients from soil.