effects of biofertilizers on morphological traits of tarragon

in order to investigate the effects of plant growth promoting rhizobacteria (pgpr) inoculation on the morphological traits of tarragon a factorial pot experiment, based on completely randomized design with four replications, were conducted in research field of horticulture department of mohaghegh ardabili university in 2010 - 2011. treatments consisted of inoculation with three species of rhizobacteria namely azotobacter, azosperillium, pseudomonas suspension in single and combination applications of these bacteria which included azotobacter- azosperillium, azotobacter – pseudomonas, azosperillium-pseudomonas, azotobacter- azosperillium-pseudomonas and control (without inoculation), which were applied as rhizome inoculation and foliar spraying. results revealed that inoculation of tarragon plants with plant growth promoting rhizobacteria had significant effect on growth parameters. the highest value for traits such as the number of stem branches and rhizome and leaf number were obtained by foliar application of azosperillium – pseudomonas combination and combined form of three mentioned rhizobacteria. rhizome inoculation of azotobacter - azosperillium combination caused increases in plant height and rhizome dry weight in comparison with control. in general, results of this investigation indicated that inoculation with plant growth promoting rhizobacteria caused increases in growth indices of tarragon plants by enhancing root growth and development by providing favorable conditions for plant growth with respect to supplying better condition for water and nutritional elements  absorption from soils.