Abstract
A low-scale Food Waste Compost (FWC1), characterized by optimal physic-chemical parameters and high organic matter percentages, was used as a fertilizer and a bio-stimulant for vegetable plants. Groups of treated plants were inoculated with active juveniles of root-knot nematodes to detect the effect on plant defense. Optimal amounts of compost mixed with soil increased plant biomass 30% compared to untreated plants. Moreover, when plants were inoculated, treated roots contained about 50% less sedentary forms (SFs) of nematodes and a lower reproduction rate of the parasites than untreated plants. Although the performance of FWC1 as defense activator was similar to other microbiome-generating commercial formulations, the compost was found to be the best fertilizer in both un- and inoculated plants. Diffuse root colonization by arbuscular mycorrhizal fungi (AMF) was observed after treatments with FWC1. FWC1 water extracts did not show any toxic effect on living nematode juveniles. Expression of the marker gene of immune response PR4b was found to be 3-5-fold higher in the roots of inoculated plants treated with FWC1 with respect to untreated plants, thus indicating that FWC1 primes plants against RKNs (root-knot nematodes, Meloidogyne incognita (Kofoid White) Chitw). Data are reported to associate immunization of plants with mycorrhization occurring in FWC1-treated plants. The proposed compost is indicated as having optimal performance both as a bio-fertilizer and a bio-stimulant.