The effect of growth promoting bacteria (GPB) and mycorrhizal fungi on seedling emergence, early eestablishment and growth of alfalfa (Medicago sative) under salinity stress condition.

In order to study the effects of growth promoting bacteria (GPR) and mycorrhizal fungi on seedling emergence, establishment and growth of two ecotypes alfalfa under salinity stress condition, an experiment was conducted in greenhouse of college of agriculture and natural resources, University of Tehran in summer 2011. The experiment was arranged as a factorial with three replications. Experimental treatments including: three levels of salinity stress (0 (S0)and 120 (S 2) µm), two levels of alfalfa cultivars (Bami and Yazdi) and eleven levels of Bio-treatments. The bio-treatments were four growth promoting rhizobacteria (Azetobacter, Azospirillum, Pseudomonas and Sinorhizobium meliloti) along with mycorrhizain single form, four different double integrated forms of Sinorhizobium meliloti with other bio- treatments as well as a quintuplet form of all bio- treatments. The results indicated that applying salt stress significantly decreased seedling emergence, establishment and alfalfa biomass. The descending trend in control treatment was more than that of treated seeds. Appling bacterial priming especially pseudomonas priming and compiled treatments played an important role in moderating the negative effects of salinity on measured traits. With respect to the results of this study, it seems that plant growth promoting bacteria and mycorrhiza by an improvement in water and nutrient absorption, improve plant growth in salinity stress condition.