Efeitos da densidade populacional da braquiária sobre as características fisiológicas e produtivas do milho e da forrageira em consórcio

• Autor(a) principal: Silva, Daniel Valadão
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1240
• topic: Plantas forrageiras; Urochloa; Brachiaria; Milho; Densidade de Semeadura; Integração lavoura-pecuária; Forage plants; Urochloa; Brachiaria; Corn; Sowing density; Integrated crop-livestock; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The maize intercropping with brachiaria is one of the main techniques for refurbishment or renovation of degraded pastures and straw formation to direct seeding. An important aspect in the implementation of this system is the crops competition by growth factors (light, water and nutrients), which if not controlled properly can derail economic cultivation. Thus, knowledge of the physiological, nutritional and productive crop intercropping aspects is essential to obtain adequate techniques for these species management. In this sense, the objective of this research was to evaluate the effects of different densities of Urochloa Brizantha on the physiological, nutritional and productive characteristics of corn and forage cultivate in intercropping. For this, two field experiments were conducted in a randomized complete block design with four replications. In the first experiment, treatments have been the planting corn with eight densities of brachiaria (0, 8, 9, 12, 14, 15, 17 and 23 plants m-2) and at 60 days after planting the intercropping (DAP) evaluated the nutritional efficiency of corn. The second experiment evaluated the maize intercropped with eight brachiaria densities (0, 5, 7, 8, 9, 10, 12 and 15 plants m-2), being determined at 60 DAP, the physiological characteristics of crops [stomatal conductance (Gs), photosynthetic rate (A), transpiration rate (E) and water use efficiency (EUA)]. In the two years the grain yield and dry matter production of brachiarias were evaluated at 160 DAP. The increased density of the U. Brizantha resulted in a linear reduction of the levels of nitrogen, phosphorus, calcium and magnesium and Gs, A and E of corn plants, however without changing the content of potassium and sulfur and the EUA. The physiological characteristics of brachiaria were negatively impacted by shading corn. These results reflected directly in the the species productivity, and the high plant densities brachiaria (above 8 plants m-2) maize productivity is reduced by 25%, while the forage has its biomass decreased by approximately 85% compared to its monoculture. Increased planting density of U. Brizantha linearly increased dry matter forage with negative effects on ear weight, grain weight and number of grains per corn ear in the two years of evaluation. The grain yield was negatively affected in population densities above the 14 and 8 plants m-2 when sown manually in the planting corn or planted to a depth of 2 cm, respectively. At higher densities, the brachiaria plants can reduce the efficiency of the corn harvest. The conclusion was that the magnitude of the effects on the physiological, nutritional and productive characteristics of maize is dependent on U. Brizantha population density, while the physiological and productive characteristics depend on the forage crop (intercropping or monoculture) system.