Variety specific differential response to commercial PGPR and probiotic inocula in vegetable plant production

A co-operative (company, university) effort to develop a commercial PGPR-based product for sustainable production of orchard and field vegetable plants is described. Marketed probiotic microbial treatments were applied to all plants as follows: PGPR, arbuscular mycorrhizal fungi (AMF), mix of PGPR and AMF, control. Inoculation tests were performed both in microcosms (years 2002 and 2003) and in open fields (years 2003 and 2004), in conventional and organic systems, on a total of ten plant species (mostly vegetables), and up to two varieties. Plant productivity was affected by probiotic inocula according to species, and results were confirmed by molecular counts of microorganisms in the rhizospere. A clear tendency was detected for correlation between plant variety and probiotic inocula. This is in agreement with recent findings of other Authors and our own (Picard et al., this workshop), which are driving PGPR commercial research to the plant variety/genotype level.