اثر بازدارندگی باکتری CHA0 Pseudomonas fluorescensو عصاره‌ی آبی برخی گیاهان بر نماتد ریشه‌گرهی (Meloidogyne javanica) در گیاه گوجه‌فرنگی

Root-knot nematodes which have worldwide distribution and lots of host plants are one of the major limiting factors affecting plant growth. Pseudomonas fluorescens CHA0 (Pf) have the potential for controlling the root-knot nematodes. There is an interest to use eco-friendly nematicides such as different plant extracts, instead of chemical pesticides. In the present study, an isolate of Pf and different concentrations of two plants extracts, namely Datura stramonium and Myrtus cominus were investigated on egg hatching and larval mortality of M. javanica under laboratory conditions. After determination of the LC30, LC50 and LC70 values of each extract, seeds of tomato cv. Early-Urbana were planted in plastic pots containing 2kg of steam-sterilized soil mixture. Four leaf stage seedlings of tomato were treated with 20 ml of Pf suspension at a concentration of 108 CFU/ml, as soil drench. One week after treatment, they were inoculated with 4000 eggs and second stage juveniles of M. javanica and simultaneously were treated with 100 ml of selected concentrations viz. 1.1, 1.4 and 1.8% (W/V) of D. stramonium and also selected concentrations viz. 1.8, 3 and 5.2% (W/V) of M. cominus were added to the soil. The in vitro experiment was conducted as a completely randomized design (CRD) and in vivo experiment as a factorial in completely randomized design with four replicates. Plant growth as well as nematode population indices were evaluated 60 days after inoculation. Results showed that plant extracts in combination of Pf increased the growth of plants and decreased the nematode indices. The treatment with combination of Pf and leaf extract of D. stramonium at the rate of 1.8% or M. cominus at the rate of 5.2%, was the most effective treatment. As compared to control, the reduction in number of eggs per root system as well as the reproductive factor, respectively was 68 and 45%, reduction in number of galls per root system, respectively was 64 and 33% and reduction in number of egg masses, respectively was 65 and 43%.