EVALUATION OF RHIZOBACTERIA EFFECTS ON THE ACTIVITY OF ROOT-KNOT NEMATODE, Meloidogyne incognita, UNDER GREENHOUSE AND LABORATORY CONDITIONS

The effect of several rhizobacteria isolates on activity of root-knot nematode, Meloidogyne incognita, was studied under laboratory and greenhouse conditions. Initially, 52 rhizobacteria isolates from the rhizosphere of cucumber, eggplant and tomato plants and their inhibitory effects on egg hatching and mortality of the second stage juveniles (J2s) were investigated in vitro. Then, nine most effective isolates were selected and identified by biochemical and morphological tests. Using filtered culture of five isolates of Pseudomonas fluorescens and one isolate of P. putida, Bacillus subtilis, B. brevis, and Serratia sp., caused 35-48% reduction in egg hatching and 32.2-48.8% increase in the mortality of J2s. The inhibitory effects of the isolates on nematode activity and growth indices of tomato cv. Early Urbana were evaluated under greenhouse conditions. Treatment of the sterilized and non-sterilized field soil and mixture of sand and field soil (3:1 ratio) with suspension of 10⁸CFU ml-1 bacteria and four eggs and J2s of nematode (per g soil) significantly reduced nematode reproduction factor and increased the growth indices of tomato plants. The results showed that nematode indices were reduced more in non-sterilized soil, compared to sterilized soil. The isolates of P. putida, P. fluorescens PF19 and Bacillus subtilis were the most effective isolates in reduction of nematode population.