Effect of Vermicompost and Spent Mushroom Compost on the Nutrient and Essential Oil Composition of Basil (Ocimum basilicum L.)

A pot-based experiment was conducted on the medicinal plant basil following a completely randomized design in the research farm of the Iran. Experimental treatments included supplementing the basic plant growth medium, a mixture of three parts soil and one part sand, with zero (control treatment), 10,20,30,40 and 50 % volume ratios of vermicompost and washed and unwashed spent mushroom compost (SMC). Macronutrients including nitrogen, phosphorus, potassium and calcium and micronutrients such as iron, zinc, manganese and copper have been measured in the shoots of basil grown under above conditions. Essential oil of basil was extracted by Clevenger's hydro-distillation apparatus and the ingredients of the essential oil have been identified using a gas chromatograph (GC) and a gas chromatography-mass spectrometry instrument (GC-MS). The results of micro and macronutrient contents in the shoot of basil showed the effectiveness of organic fertilizers (vermicompost and SMC) leading to an increase in those contents in plant. Organic fertilizers, when present in the plant growth medium, led to a higher nutrient content compared to the control treatment. The best results have often been achieved in vermicompost treatment. Increases in the major essential oil ingredients resulted from the elevated levels of vermicompost, and SMC. The highest concentration of myrsine (0.87), 1,8-cineol (10.98) and sabinene (0.37) were found in the plants grown in a growth medium supplemented with 50 % of washed SMC which represented an increase of these compounds by 102 %, 96 %, and 116 % compared to the control treatment, respectively.