Effect of Seed Inoculation with Plant Growth Promoting Rhizobactria on Dry Matter Remobilization of Spring Barley at Different Levels of Nitrogen and Phosphorus Fertilizers

In order to investigate the effect of plant growth promoting rhizobacteria on yield and dry matter remobilization of spring barley at different levels of nitrogen and phosphorus fertilizers, an experiment was conducted in two years at the Research Farm of Islamic Azad University, Ardabil branch, during 2009-2010 and 2010-2011 crop seasons. The combination of nitrogen fertilizer at three levels (0, 40 and 80 kg N/ha as urea) and phosphorus fertilizer (0, 30 and 60 kg P₂O₅/ha) were factorially assigned to the main plots and seed inoculation with plant growth promoting rhizobacteria at four levels (no inoculation, seed inoculation with Azotobacter chorchorum strain 5, Azosprilium lipoferum strain OF and combination of Azotobacter + Azosprilium) were assigned to the subplots. The results showed that with increase in N and P rates and seed inoculation with plant growth promoting rhrizobacteria, total remobilization of dry matter from plant and from stem and their contribution to grain filling decreased. The highest dry matter remobilization and contribution to grain yield were observed at the control levels of the experimental factors. The maximum grain yield, 1000 grain weight, number of grains per ear, number of tillers per plant, biological yield and harvest index were obtained in the plots which had received the highest rates of N and P fertilizers and seed inoculation with both Azosprilium and Azotobacter. The minimum of these parameters were obtained in plots without application of experimental factors. Based on the results, it was concluded that application of the highest rate of nitrogen and phosphorus (80 kg N.ha^-1 and 60 kg P.ha^-1) in seed inoculation with Azospirillum and Azotobacter can be recommended for profitable barley production in the study area.