Evaluation of Biocontrol Agents Against Root-Knot Nematode (Meloidogyne incognita) in Cucumber (Cucumis sativus) Under Greenhouse Conditions

Root-knot nematode (Meloidogyne incognita) is a significant challenge in cucumber (Cucumis sativus L.) production under protected cultivation systems. This study aimed to evaluate the effects of four microbial biocontrol agents (Trichoderma asperellum, Beauveria bassiana, Fusarium proliferatum, and Bacillus mojavensis) on cucumber growth and root gall formation. Two greenhouse experiments (spring and summer 2023) were conducted using potted plants inoculated with 100 g of nematode-infected soil. All treatments improved seed germination compared with the untreated control, particularly B. mojavensis and T. asperellum. During vegetative growth, F. proliferatum and B. mojavensis produced higher biomass in the spring experiment, while T. asperellum enhanced root development. Treatment with T. asperellum reduced root galling by 45% in the spring and 31% in the summer experiment, although these differences were not statistically significant. In the chemotaxis assay, the different microbial biocontrol agents showed variation in the chemotaxis index (CI), ranging from 0 to 0.12 among treatments. Overall, microbial treatments mainly enhanced plant growth under nematode stress, while effects on root galling were limited.