Effect of certain phosphate solubilizing bacteria on root-knot nematode disease of mungbean

M. R. Khan

Department of Plant Protection, Aligarh Muslim University, Aligarh 202 002, India

e-mail: mrkhan777in@yahoo.co.in

Abstract

Bacillus subtilis, B. polymyxa, Pseudomonas fluorescens and P. stutzeri were cultured on nutrient broth and were applied on the seeds of mungbean at 5ml/kg of seeds along with the rhizobium. The seeds were sown in microplots (3x1.5m) where nematode suspension (1500 second stage juveniles of Meloidogyne incognita/kg soil) had already been added or not added. Three microplots which were randomly distributed in the field were maintained for each treatment. In the plots without nematodes, plants showed better growth with significantly improved yield, especially with P. stutzeri. Root-nodulation was significantly increased due to the treatments of P. stutzeri or B. polymyxa compared to uninoculated control. Inoculation with the nematode caused severe galling on roots and decreased the yield of mungbean by 23.8%. Application with P. fluorescens or B. subtilis suppressed the gall formation, reproduction and soil population of M. incognita. The nematicidal effect of the PSMs was considerably less than the fenamiphos treatment (at 2g/kg seed). Rhizosphere population of all PSMs tested was significantly increased over time irrespective of nematode presence or absence. Application of P. fluorescens suppressed the nematode pathogenesis and increased the yield of mungbean by 30.9% that was greater than the nematicide treatment (16.7%).