بررسی اثر بازدارندگی متابولیت های باسیلوس علیه نماتد ریشه‌گرهی خیار (Meloidogyne javanica) در شرایط آزمایشگاهی

One of the most important pathogens affecting greenhouse cucumber cultivation is root-knot nematodes (Meloidogyne). Due to their broad host range, high adaptability to various climatic conditions, and high reproduction rate. Using chemical compounds to control nematodes might be considered a common method to mitigate their damage. However, with the increasing public awareness regarding the environmental hazards and adverse effects of nematicides, there is a growing demand for organic products. Among these, the genus Bacillus represents the largest group of biocontrol agents, to the extent that nearly half of the commercial formulations of biological control agents on the market are comprised of Bacillus isolates. In this research, the effect of six strains collected from the Plant Pathology Laboratory of the Faculty of Agriculture at Ferdowsi University of Mashhad, including Ba1, Ba2, Ba12, Ba15, JR16, and Tolr-MA, were evaluated for their efficacy against Meloidogyne javanica root-knot nematodes under laboratory conditions, focusing on their production of nematicidal volatile and non-volatile compounds. To assess non-volatile metabolites, bacterial supernatant at concentrations of 100% and 10% was directly exposed to second-stage juvenile of (J2s) nematodes in a petri dish over a 48-hour period. The bacterial suspension was prepared by high-speed centrifugation and filtration to remove bacterial cells. In the evaluation of volatile metabolites, three-compartment petri dishes were used. For this purpose, M. javanica second-stage juveniles, bacterial supernatant, and activated carbon as an adsorbent for volatile compounds and confirmation of nematicidal effects were employed. In all laboratory tests, after a specified period, the mortality rate of 100 J2s in bacterial treatments was compared to the control (P < 0.05). Results indicate that the Tolr-MA strain showed the highest mortality rates of 87.5% and 65.5% at 100% and 10% concentrations respectively, followed by the Ba2 strain with 80.5% and 73% in the non-volatile metabolite test. In the volatile metabolite assessment, similar to the previous evaluation, the Tolr-MA recorded 89.99% and the Ba2 85.35% as the best performance.