Funcionalidade das micorrizas arbusculares em cafezais agroecológicos

• Ano de defesa: 2011
• Autor(a) principal: Tavares, Rodrigo de Castro
• Orientador(a): Cardoso, Irene Maria
• Banca de defesa: Andrade, Felipe Vaz , Pereira, Olinto Liparini
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Solos e Nutrição de Plantas
• Departamento: Fertilidade do solo e nutrição de plantas; Gênese, Morfologia e Classificação, Mineralogia, Química,
• País: BR
• Palavras-chave em Português: Sistemas agroflorestais; Fungos micorrízicos arbusculares; Agroecologia
• Palavras-chave em Inglês: Agroforestry systems; Arbuscular mycorrhizal fungi; Agroecology
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/1624

The Zona da Mata of Minas Gerais is a region that historically has suffered severe soil degradation and loss of native forest. In this environment, the soils tend to beundernourished and alic, eutrophic soils occurring only in the lower parts of the relief. The deep weathering mantle and associated to topography favors the loss of nutrients. In this region, the fragmentation of the properties is accompanied by a very unequal distribution of resources, where small farmers do not have enough land for reproduction of the family unit. The culture of coffee (Coffea arabica L.) is one of the main productive activities in the region, practiced on hillside soils, mainly by small farmers. In this context, the deployment of the systems based on agroecological principles in an alternative that allows for soil conservation and maintenance of local biodiversity. In 1994 farmers in the municipality of Araponga Forest zone mining chose to combine the production of the coffee with environmental sustainability, giving rise to the idea of coffee production in agroecological, agroforestry or the sun coffee. The agroecological systems are management with low use of chemical fertilizers, no use pesticides, the untilled soil and with an emphasis on nutrient cycling. In agroforestry systems (SAF), unlike the system to sun coffee (PS) the inclusion of the tree component, prioritizing the use of native Atlantic Forest and or fruit. After the consolidation of these agroecosystems (18 years) and several studies have as its theme: carbon stocks organic phosphorus in the soil, indicators of physical, chemical and biological water flow, nutrient cycling and plant species diversity, there is the need to assess the functionality of key organizations such systems, such as mycorrhizal fungi (AMF). These microsymbionts perform several functions that are critical to the perpetuation of these ecosystems. The action of AMF is attributed often to the increase in the volume of soil explored by the host plant, increases the absorption of water and nutrients. However, other benefits are conferred on the mycorrhizal plants, such as protection against root pathogens, tolerance to attack by herbivores, salinity, phytotoxic elements such as aluminium (Al) or heavy metals. Furthermore, the network mycelial fungi is important in the structure and carbon (C) input of the soil (hyphae and glomalin). Glomalin is a hydrophobic glycoprotein produced by the AMF and accumulates in the soil concentrations in mg per g-1. This glycoprotein remains for years or decades in the soil, with stays of 6-42 years. The dynamics of glomalin in the soil is still unclear, however, factors such as management of agricultural areas, the availability of host species, nutrient balance of plants, nutrient availability, levels of CO2 in the atmosphere and the soil physical and chemical attributes of the soil can affect the stocks of this protein, especially those that alter the abundance and diversity of AMF. The aim of this study was to evaluate the dynamics of glomalin in areas of Zona da Mata of Minas Gerais. And yet, the transfer of chemical signals between plants connected by hyphae of AMF. To assess the dynamics of glomalin in the soil were selected three family farms (An, Ro e Fe), which grow coffee (Coffea arabica L.) in the region of Araponga-MG. In each farm was sampled the soil from one an agroforestry system (SAF) and sun coffe system (PS). As a reference, sampled the soil is of a secondary native forest (MN) representative of the region and within the areas of Atlantic Forest. Were taken from four composite samples of soil between the rows of planting and near the basal third of the canopy of coffee at different depths. We analyzed the levels total glomalin (GT) and easily extractable glomalina (GFE), total organic carbon (COT), total nitrogen (NT), carbon glomalin (CG), the nitrogen of glomalin (NG), the levels of glomalin on aggregate classes (4-2, 2-1 and 1 to 0.5 mm in diameter), geometric mean diameter (DMG), mean weight diameter (DMP) of aggregates stability index (ASI), labile carbon (CL) and carbon not labile (CNL), bulk density (Ds), clay content, water-dispersible clay (ADA), mycorrhizal colonization of coffee, pontaneous species, tree species of agroecosystems, and roots extracted from s the ground, number of spores of AMF, weight of roots, pH, available P, sum of bases (SB), total cation exchange capacity (CTCtotal) and effective (CTCefetiva), exchangeable aluminum (Al3+) and potential acidity (H + Al). Finally, to demonstrate the connection between plants of hyphae of an AM signal and the transfer plants built between a double system of vessels connected. The results indicated that agroecosystems with coffee Zone Mata de Minas Gerais have high stocks of glomalin. The AMF they contribute significant amounts of organic C and N in the soil as glomalin. Aggregates of larger diameter have higher levels of glomalin. Some physical, chemical and biological soil affect the levels of glomalin. The agroforestry systems can contribute to increase the restoration of the levels of glomalina, but this will depend on system characteristics, such as age, type and quality of individual trees. In a study of coffee, the introduction of tree component in an area adjacent to an agroecological sun coffee, with the same history of degradation, resulted in higher stocks of glomalin in the soil. In signal transduction, it was found that the technique of double pot proper is connected to note the induction of plant defense indirectly connected via the network mycelial AMF.