Arbuscular mycorrhizal fungi and plant growth-promoting pseudomonads improve yield, quality and nutritional value of tomato: a field study.

The aim of this work was to assess the effects of plant-beneficial microorganisms (two Pseudomonas strains and a mixed mycorrhizal inoculum, alone or in combination) on the quality of tomato fruits of plants grown in the field and subjected to reduced fertilization. Pseudomonas strain 19Fv1T was newly characterized during this study. The size and quality of the fruits (concentration of sugars, organic acids and vitamin C) were assessed. The microorganisms positively affected the flower and fruit production and the concentrations of sugars and vitamins in the tomato fruits. In particular, the most important effect induced by arbuscular mycorrhizal (AM) fungi was an improvement of citric acid concentration, while bacteria positively modulated sugar production and the sweetness of the tomatoes. The novelty of the present work is the application of soil microorganisms in the field, in a real industrial tomato farm. This approach provided direct information about the application of inocula, allowed the reduction of chemical inputs and positively influenced tomato quality.