Promoção do crescimento e da produtividade de alface americana pelo emprego de cepas comerciais de Trichoderma spp

Abstract

The fungus Trichoderma comprises as essential for the sustenance of the soil in its formation, in the nutrient cycling and decomposition of the organic matter acting in the crop growth and productivity. The objective of this work was to evaluate four strains of Trichoderma spp. (Trichoderma harzianum IBLF 006 WP, Trichoderma harzianum IBLF 006 SC, Trichoderma harzianum ESALQ 1306 and Trichoderma asperellum URM 5911) in the seedlings growth promotion on laboratory and in the yield of American lettuce on field. Thus, lettuce seeds cv. Astra were treated with 2 mL of Trichoderma suspension (2.5 x 108 conidia mL-1 per 100 g of seeds) and submitted to the laboratory growth assay until 7 days after sowing (DAS). Each treatment had 200 seeds (four Gerboxes containing 50 seeds), arranged in a completely randomized design (DIC). For the field experiment, it was carried out the furrows opening which received 5 x 107 conidia mL-1 with the aid of a hand sprayer, followed by the seedlings transplanting (4 to 6 leaves) of American lettuce cv. Mauren and harvest at 40 days after transplanting. Each treatment comprises in four experimental plots (1.2 x 1.2 m with 16 plants) arranged in randomized blocks (RBD). In both experiments a control without Trichoderma application was included, and the evaluations were: shoot length (SL), root length (RL), total length (TL), fresh shoot mass (FSM), fresh root mass (FRM), total fresh mass (TFM), dry shoot mass (DSM), dry root mass (DRM), total dry mass (BIO), shoot mass ratio (SMR), root mass ratio (RMR) and shoot/root ratio (S/R). The germination percentage (GP) was evaluated in the laboratory assay, while in the field experiment it was evaluated the height (H), stem diameter (SD), head diameter (HD), number of leaves (NL) and yield (PROD). The T. harzianum strain ESALQ 1306 provided the better growth of American lettuce in the laboratory assay, which was confirmed in the field experiment, whose productivity (50.2 t/ha) was superior to the other strains (41.38 to 44.23 t/ha) and the control (30.18 t/ha)