Effect of Cell Concentrations of Four Strains of Rhizobacteriunl, Pseudomonas fluorescens on Hatching and Mortality of Root-Knot Nematode, Meloidogyne incognita

Effect of four strains (Pf 1–12, Pf 1–20, Pf 2–1 and Pf-ws) of P. fluorescens using cell suspension concentrations (10⁶, 10⁷, 10⁸, 10⁹ and 10¹⁰ cells/ml) on the hatching and mortality of root-knot nematode, M. incognita was investigated in vitro. Results indicated that the bacterial cell concentrations of all the four strains significantly reduced hatching and increased mortality at each level of concentration compared to control (distilled water). However, strain Pf 2–1 caused relatively higher inhibition of hatching and higher mortality of second stage juveniles of M. incognita. After 72h, lowest hatching of 13.2% was observed at concentration of 10¹⁰ cells/ml. Similarly, the maximum mortality (49.8%) of second stage juveniles was observed after 72h at concentration of 10¹⁰ cells/ml. The reduced hatching and increased mortality of second stage juveniles of M. incognita were positively correlated with bacterial concentrations and exposure periods.