Potential for enhancing lentil (Lens culinaris) productivity by co-inoculation with PSB, plant growth-promoting rhizobacteria and Rhizobium

Rhizobia in association with a legume host have the exceptional ability to form root nodules. Free living microorganisms, especially the plant growth-promoting rhizobacteria are known to promote Rhizobium efficiency by different mechanisms. Field experiments were conducted to assess the effect of co-inoculation of Rhizobium leguminosarum bv. viciae, phosphorus-solubilizing bacteria and plant growth-promoting rhizobacteria on symbiotic parameters, growth and yield of lentil. Seeds of lentil (Lens culinaris Medikus) variety LL 699 were treated with the three inoculants singly and in combination and sown following randomized block design in three replications. Results revealed that PGPR with rhizobial inoculation enhanced nodulation, growth and yield (19.8nodules/plant, 70.6mg nodule dry weight/plant, 1 605kg/ ha) as compared to Rhizobium alone (17.8nodules/plant, 64.3mg/plant and 1 546kg/ha resp.) and non-inoculated control (13.9nodules/plant, 47.7mg/plant and 1 401kg/ha resp.). Treatment comprising Rhizobium +PSB was found to be at par with Rhizobium inoculation alone in terms of nodulation and yield. However, the response was more prominent when all the three microorganisms were applied in combination, higher nodule biomass (16.7%) and yield (5%) was recorded over that with Rhizobium inoculation alone. Although PSB alone did not show any positive effect on symbiotic parameters and yield, however in conjunction it seemed to assert a synergistic effect. The results imply that co-inoculation with Rhizobium, PSB and PGPR is a beneficial approach for improving the nodulation, growth and yield of lentil.