ABSTRACT
Brazil has many important native species, which includes Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby, however, the growth of this species is inhibited in soils with low boron contents, or excess boron, which causes phytotoxicity. Applications of strains of Trichoderma spp. increase the plants' tolerance to abiotic stresses, including tolerance to low or excess levels of nutrients such as boron (B). Thus, the objective of this work was to evaluate plant development and the effect of strains of Trichoderma spp. in Schizolobium parahyba var. amazonicum seedlings grown under different boron rates. A randomized block experimental design was used, with a 4×5 factorial scheme, consisting of 4 strains of Trichoderma spp. and 5 B rates (0, 0.5, 1.0, 1.5, and 2.0 mg dm-3), with seven replications, in greenhouse. Plant height, stem diameter, fresh and dry mass, leaf, stem and total were evaluated at 120 days after emergence. The stains of Trichoderma spp. and B rates presented significant interaction for all evaluated variables, decreasing phytotoxicity. The strain IBLF006WP (T. harzianum) showed a higher capacity of increasing the plants' tolerance to boron, followed by URM5911 (T. asperellum). However, the beneficial effect of increasing this tolerance with the application of these strains is only feasible for soils with high contents of this micronutrient in the soil.