Effect of some plant growth-promoting rhizobacteria strains on root-knot nematode, Meloidogyne incognita, on tomatoes

Root-knot nematode, Meloidogyne incognita, is one of the main problems in vegetable-growing regions, decreasing yield quality and quantity worldwide. Root-knot nematode management tactics mostly involve chemical control which is a threat to the environment, consequences to human health. Biological control of nematodes is considered to be one of the best alternatives to the chemical control. In this study, the effect of some bacterial isolates against M. incognita was determined on tomato in the greenhouse. The trial was designed as a randomized complete block, consisting of 15 plant growth-promoting rhizobacteria (PGPR) strains and 2 control groups (−, +) with 10 replications, total of 170 pots. Two days after transplanting the bacteria-treated tomato (Solanum lycopersicum cv. 56-56 F1) seedlings in the sterile soil in pots, the plants were inoculated with 1000 eggs or J2s of M. incognita/pot. At the end of a 90-day plant-growing period, isolate ZHA90 of Bacillus pumilus decreased plant root galling which, in turn, increased plant height, shoot fresh and dry weight, and root fresh weight. Isolates ZHA296 and ZHA178 of Paenibacillus castaneae reduced the number of egg masses and root galling with no effects on plant growth compared to the control (+). While the isolate ZHA17 of Mycobacterium immunogenum increased plant height and shoot fresh weight, ZHA57 of the same bacterium enhanced significantly only plant height. Results indicated that among 15 bacterial strains studied, ZHA296 and ZHA178 of P. castaneae and ZHA17 and ZHA57 of M. immunogenum were identified as the promising biocontrol agents for the future nematode management tactics.