Influence of Plant Growth Promoting Rhizobacteria on Alfalfa, Medicago sativa L. yield by Inoculation of a Preceding Italian Ryegrass, Lolium multiflorum Lam

This study was conducted to test the hypothesis that plant growth promoting rhizobacteria (PGPR) can promote the growth of Italian ryegrass, Lolium multiflorum Lam. as well as the growth and nodulation of subsequent alfalfa, Medicago sativa L. In a pot experiment, the influence of PGPR on yield and nitrogen content of Italian ryegrass and alfalfa was studied with the aim to improve their growth and provide effective alfalfa nitrogen fixation under unfavourable soil conditions. Plants were inoculated with seven strains belonging to Sinorhizobium meliloti, Azotobacter spp. and Enterobacter sp. A beneficial effect on yield and N-assimilation in Italian ryegrass was obtained due to the inoculation of the plants with Azotobacter vinelandii and some Sinorhizobium meliloti strains. In addition, Italian ryegrass seed inoculation with particular rhizobial strains the year before alfalfa growing provided abundant nodulation and better growth of alfalfa.