Abstract:

The objective of this study was to evaluate the biofertilizers effect in Panicum maximaum (cv. Mombaza) and Brachiaria brizantha tropical grasses production. Microorganisms were obtained in rhizosphere of plants. To establish an effective symbiosis with native strains of Azospirillum, Azotobacter and mycorrhizal fungi, experiments were carried out in greenhouse and field. The biofertilizers used in greenhouse were combined (CC), semisolid medium Nitrogen free with malate as nitrogen source (NFB), Azotobacter (azot) and Azospirillum (Azos). For mycorrhizal fungi, 6 treatments were used: T1-control, T2-fertilized, T3-brown spore, T4-honey spore, T4-black spore and T5-commercial spore. The microorganism used in field were those that showed effectivity in greenhouse. The treatments in field were T1: control, T2: inorganic fertilizer, T3: Azospirillum + Azotobacter, T4: mycorrhizal and T5: commercial biofertilizer. The variables evaluated were dry weight (DW), radicular weight (RW), radicular volume (RV), stem diameter (SD) and total height (TH). Results for B. brizantha indicate differences (P≤0.05). Application of Azospirillum + Azotobacter (T3) favored the development of the height of the plant and the diameter of the stem. The commercial biofertilizer (T5) increased the production of dry matter with 0.99 kg/m2. In respect with P. maximum (cv. Mombaza) grass, they were not detected significative differences (P≥0.05) between treatments, however, the biological results showed that inorganic fertilizer (T2) increased the dry matter production with 1.34 kg / m2 in comparison with Azospirillum + Azotobacter (T3) that showed 0.72 kg / m2.

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