Experimental Materials

Seeds of tomato ‘Ginobili’ (a cultivar sensitive to TFCRR) were purchased from Qingdao Wufeng Fruit and Vegetable Development Co. Ltd. (Qingdao, China).

The symbiotic AMF F. mosseae (Fm), R. intraradices (Ri), PGPR B. subtilis PS1-3 (Bs), and P. fluorescens PS2-6 (Pf) were obtained from the Institute of Mycorrhizal Biotechnology, Qingdao Agricultural University (QAU), China. Spores, mycorrhizal root segments, and culture media of AMF were employed as inocula with inoculation potential units determined following the method of Liu and Luo (1994).

The aforementioned PGPR species were inoculated into nutrient broth (3 g beef extract, 10 g peptone, 5 g NaCl, and distilled water to 1,000 ml) and cultured on a rotating shaker at 30°C for 3 days. The PGPR fermentation broth was diluted to 1 × 10⁸ CFU/ml for inoculation.

Trichoderma virens 140012 (Tv), T. harzianum 140015 (Th), and the TFCRR pathogen F. oxysporum f. sp. radicis-lycopersici (Fo) were provided by the College of Plant Medicine, QAU. The Trichoderma spp. were inoculated onto potato dextrose agar (PDA) medium and incubated at 28°C for 10 days. The pellets were filtered, washed, resuspended, and diluted to 1 × 10⁵ CFU/ml for inoculation. Fo was cultured on PDA plates for 5–7 days and a conidia suspension was prepared. The solution was diluted to 10⁷ conidia/ml, stored at 4°C, and inoculated within 24 h.

Nutrient broth and PDA were used for isolation and culture of bacteria and fungi, respectively.

Peat (0–6 mm grade; Pindstrup Mosebrug A/S, Ryomgård, Denmark) was sterilized (121°C for 1 h). The chemical characteristics of the peat were pH 6, electrical conductivity 40 mS/m, NO₃^–-N 70 g/m³, NH₄⁺-N 50 g/m³, P₂O₅ 140 g/m³, K₂O 240 g/m³, MgO 23 g/m³, B 0.4 g/m³, Mo 2.04 g/m³, Cu 1.7 g/m³, Mn 2.9 g/m³, Zn 0.9 g/m³, and Fe 8.4 g/m³. The 2.5-L pots were surface-sterilized before filling with the peat.