Initial development of lettuce in vermicompost at higher trichoderma doses

ABSTRACT The study aimed to evaluate the initial development, as well as, the chemical characteristics of lettuce plants grown in substrate with high concentrations of bioagent (trichoderma). A completely randomized design with four replicates was used. The treatments, applied to a substrate composed of a blend of vermicompost and commercial substrate, were established by the following doses of the commercial product ICB Nutrissolo Trichoderma: T1) 0.0; T2) 1.0; T3) 2.0; T4) 4.0; T5) 8.0 and T6) 16.0x1011 conidia kg-1 of product. After inoculation, the substrate was placed in trays, where 50 lettuce seeds were sown on each replication. Plants were thinned after emergency stabilization, maintaining ten seedlings per tray. At 28 days after sowing, the characteristics percentage and emergence speed index, leaf area, fresh and dry leaf biomass, volume, length and surface area of the root were evaluated. We also determined the chemical characteristics of the leaves. The percentage of seed germination and the emergence speed index were lower at doses higher than 4.0x1011 conidia kg-1 of the biological product. All the studied doses influenced negatively in shoot and root development of the plants. The percentage of nutrients in the leaves was higher in treatments with ICB.