Deciphering the Biocontrol Potential of Trichoderma asperellum (Tv1) Against Fusarium-Nematode Wilt Complex in Tomato.

The study assessed Trichoderma spp. as a biocontrol agent for managing wilt-nematode complex in tomato crops, aiming to mitigate yield losses. Fusarium sp. and Meloidogyne sp. were isolated from infected plant samples and confirmed molecularly and morphologically as Fusarium oxysporum f.sp. lycopersici and Meloidogyne incognita. Four Trichoderma spp. procured from the Department of Plant Pathology, Tamil Nadu Agricultural University, India were identified molecularly as Trichoderma asperellum (Tv1), Trichoderma asperelloides (Tasd1), Trichoderma harzianum (Th1), and Trichoderma koningiopsis (Tk1) utilizing ITS and TEF1 primer pairs. Among them, Tv1 effectively inhibited the mycelial growth of pathogen isolates. Furthermore, crude metabolite of Tv1 exhibited similar effects. The mortality rate of M. incognita J2s ranged from 90.48% to 100% after 24-72 h of incubation and inhibition percentage of egg hatching reached 90.20%. The shoot length, root length, fresh weight, and dry weight of the tomato plants treated with Tv1 conidia were increased. In a pot experiment, Tv1 treatment reduced disease incidence by 64.57%, comparable to carbendazim treatment (82.32%). Tv1-treated plants had fewer root galls, egg masses, and J2s per 100 g of roots than the inoculated-untreated control plants. The root-knot index (RKI) was significantly lower in plants treated with carbafuran (1.98 ± 0.047) and Tv1 (3.06 ± 0.086) than in control (4.47 ± 0.109). The bio-control efficiency of Tv1 against M. incognita was 21.04%, and the nematodes' reproductive factor (RF) declined to 0.53 in Tv1 treatment group. Based on the findings above, it was established that Tv1 effectively controlled nematode populations and wilt disease when applied in soil.
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