Laboratory and field performance of some soil bacteria used as seed treatments on Meloidogyne incognita in chickpea
AbstractExperiments were conducted under in vitro and field conditions to assess the efficacy of the soil bacteria Bacillus subtilis, Pseudomonas fluorescens, P. stutzeri and Paenibacillus polymyxa for controlling the root knot nematode, Meloidogyne incognita, in chickpea, Cicer arietinum, in India. The bacterial strains tested solubilized phosphorous under in vitro and soil conditions and produced indole acetic acid, ammonia and hydrogen cyanide in vitro. Both pure culture and culture filtrates of the bacteria reduced egg hatching and increased juvenile mortality of the nematode. Under field conditions, seed treatment (at 5 ml/kg seed) with cultures containing 1012 colony forming units/ml of P. fluorescens and P. stutzerisignificantly increased yield and root nodulation of chickpea. Inoculation with 2000 juveniles of M. incognita/spot (plant) caused severe root galling and decreased the yield of chickpea by 24%. Treatment with P. fluorescens suppressed gall formation, and treatment with P. fluorescensor B. subtilis suppressed reproduction and soil populations of M. incognita. However, the suppressive effects of the two bacteria on the nematode were less than that of fenamiphos. In nematodes infested plots, only treatments with P. fluorescens increased the yield (14%) compared to fenamiphos, being 31% above the untreated nematode control. Paenibacillus polymyxa and P. stutzeri increased the yield over that of the control and were on par with fenamiphos treatment. Rhizosphere populations of all bacteria increased over the course of experiment irrespective of the nematode treatment. Seed dressing with P. fluorescens appears to be a handy and cost effective treatment to control the nematode and increase yield of chickpea.