To evaluate the effect of vermicompost, plant growth promoting bacteria and humic acid on growth and essence of basil an experiment was conducted in agriculture research field of Islamic Azad University, Karaj, Iran. The treatments were including; plant growth promoting bacteria (inoculation and non inoculation), vermicompost (application and non application), humic acid (non application, seed treated and foliar application) applied in the form of factorial experiment based on randomized complete block design. The results depicted that inoculation of PGPRs and application of vermicompost significantly affects almost the measured trait except for wet dry weight, leaf area and treatments were in the different statistical group. Whereas, seed treated of humic acid was superior to spraying it or to control. The highest wet and dry yield, essence yield and chlorophyll a, b and a+ b was observed in the interaction between PGPRs and vermicompost, indicating the synergistic effect. The interaction between PGPRs and humic acid led to the highest essence percentage, essence yield and plant height. Regarding to the replacement of chemical fertilizers with biologic fertilizers, it seems that applying biofertilizers, vermicompost and humic acid can decrease the use of chemical fertilizers and their negative effect. In addition they may play an important role to obtain the purposes of sustainable agriculture.
