Biofertilización con hongos micorrízicos en pastos del género Urochloa en un suelo ácido de baja fertilidad

Objective: To evaluate the response to biofertilization with arbuscular mycorrhizal fungi of four grass species of the genus Urochloa, cultivated on a low-fertility acid soil in the Manacas Savanna region, Cuba. Materials and Methods: Twelve different treatments were evaluated, generated from the combination of four grass species and three mycorrhizal inoculants. The used species were Urochloa brizantha cv. Marandú, Urochloa decumbens cv. CIAT 606, Urochloa híbrido cv. 36087 Mulato II and Urochloa híbrido cv. BR02/1752 Yacaré. The mycorrhizal inoculants were formulated with the arbuscular mycorrhizal fungi strains Funneliformis mosseae, Glomus cubense and Rhizoglomus irregulare, respectively. In addition, a control group, without inoculation, was included. The experiment was carried out according to a randomized block design, with a 4 x 4 factorial arrangement and four replications. The total duration was three years. The evaluated variables were: frequency and intensity of mycorrhizal colonization, number of spores in the rhizosphere, macronutrient concentrations (NPK) in aerial biomass, participation of inoculants in nutrition and dry mass yield. Results: There was no interaction between inoculation with arbuscular mycorrhizal fungi strains and grass species for the measured variables. The inoculation factor treatments showed differences among themselves. The highest values of frequency and intensity of mycorrhizal colonization, number of spores in the rhizosphere, nutrient concentrations in the biomass and participation of the inoculants in the nutrition and yield of the grasses were reached with F. mosseae, whose effect was maintained up to two years after the inoculants were applied. Conclusions: Biofertilization with F. mosseae is effective in improving the nutritional status and yields of grasses of the genus Urochlola, grown on a low-fertility acid soil.