Evaluation of biocontrol potential of fluorescent Pseudomonas associated with root nodules of mungbean

Abstract

Thirty two isolates of fluorescent Pseudomonas and sixteen rhizobia were isolated from the root nodules of mungbean (Vigna radiata) collected from the experimental fields of Karachi University. Pseudomonas and rhizobia were characterized for their plant growth promoting and biocontrol potential through the determination of in vitro activity against root rotting fungi viz., Macrophomina phaseolina, Fusarium solani, Fusarium oxysporum and Rhizoctonia solani and nematicidal activity against the second stage juveniles of Meloidogyne javanica. Pseudomonas isolates NAFP-19, NAFP-21, NAFP-22, NAFP-27, NAFP-31 and NAFP-32, and rhizobial isolates NFB-102, NFB-103, NFB-107 and NFB-109 inhibited the growth of all the test fungi and showed maximum nematicidal activity against second stage juveniles of M. javanica. Strains of Pseudomonas (NAFP-19, NAFP-31 and NAFP-32) and rhizobia (NFB-103, NFB-107 and NFB-109) used as a soil drench significantly reduced root rot disease under screen house condition and thereby enhanced plant growth and yield in mungbean. In field plot experiments, mixed or separate application of NAFP and rhizobia showed effective control of M. phaseolina and F. oxysporum with some protection from F. solani and R. solani.