Seed inoculation with plant growth promoting rhizobacteria enhances photosynthesis and yield of runner bean (Phaseolus coccineus L.)

Growth promoting potential of two rhizobacterial strains positive for phosphorous solubilization and siderophore production (S4) and for indoleacetic acid production (S7) was assessed on runner bean plants cultivated in organic crop system. Seed inoculation with rhizobacterial strains resulted in an increase of photosynthetic activities, water-use efficiency and chlorophyll content. The positive effect exerted by the two rhizobacterial strains was more pronounced during vegetative and early flower setting stages. Also S4 + S7 treatment significantly increase the grains yield with 27.58%. The results indicate that co-inoculation produced a more pronounced influence, while inoculation alone showed a lower effect, probably due to a synergistic effect between rhizobacterial inoculated strains. Our results suggest that S4 and S7 strains may be utilized as biofertilizer for vegetable production in sustainable and organic agricultural systems. (C) 2012 Elsevier B.V. All rights reserved.