Effects of microorganisms on the growth and the development of tomato crops

Plant biostimulants (natural compounds and microorganisms) when added into the rhizosphere stimulate natural processes such as nutrient uptake, nutrient efficiency, biotic and/or abiotic stress tolerances, and crop quality. Since '90 Sicilian growers, involved in cold greenhouse vegetable production, started to grown cherry and round cluster tomatoes and they reached high economic incomes focusing their attention to improve yield and the qualitative traits of the product. Their productions are widespread among thousands of greenhouses throughout the Southermost Sicilian coastline. The peculiar climatic conditions (high exposure to the sun, salinity of irrigation water and a low frequency of winter-spring frost) favor vegetable crops especially for tomato production. The aim of this work was to evaluate the effects of some microorganisms (mycorrhizas and bacteria) on the germination in vitro on the growing process both, in nursery and in the greenhouse, growing systems. The in vitro trials were performed in petri dishes, monitoring the biostimulant activity in promoting the tomato seed germination in relation to three water solution doses (0, 1.5 and 3 g L-¹) of two biostimulant products provided by Itaka Crop Solution Company: Maxy Root and 3KO. The same experimental factors were considered for the in vivo experimental trials. Seeds of the tomato cultivars/rootstocks were sown in cellular trays and the plantlets were grown in a specialized vegetable nursery on March and they finally transplanted in a traditional greenhouse on May in Vittoria (Ragusa province). The effects of the different doses of the two-biostimulant products utilized were evaluated by the main bio-morphological parameters related to the growth and the development of the plant. Some tomato cultivars/rootstocks showed interaction among the experimental factors for some parameters (shoot length, shoot number, and root dry weights, fruits harvesting, number and weight of fruit) compared to the control. Some results were observed by the germination trials showing the effects of the biostimulants utilized to increase root efficiency and to promote plant growth.