Navegando por Autor "MAIA, Rodrigo da Silva"

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Acesso aberto (Open Access)
Colonização micorrízica arbuscular em floresta secundária na Amazônia sob remoção de serrapilha e irrigação do solo
(Universidade Federal do Pará, 2010) MAIA, Rodrigo da Silva; VASCONCELOS, Steel Silva; http://lattes.cnpq.br/0719395243841543
We evaluate the effect of alteration of availability of substrate (litterfall) and water about the arbuscular mycorrhizal colonization and chemical attribut of soil in Secondary Forest in the eastern Amazon. The percentagem of mycorrhizal colonization (PMC) was analyzed in apogeotropic roots and roots present in the surface 0-10 cm layer of soil, spore density, glomalin production and physico-chemical attributes of soils in four plots of treatment to litter removal, four plots of irrigation treatment and four control plots. The plots measuring 20 m x 20 m. In each plot was collected four single samples of soil and roots divided into four areas. The results showed that litter removal reduced significantly the PMC in roots, but had no effect on spore density. The litter removal decreased availability of nitrogen and organic carbon in soil, but there was no influence of reduced availability of nutrients in the soil for mycorrhizal colonization. The Glomalin which is produced by hyphae of arbuscular mycorrhizae, and is aggregated with soil organic matter was also reduced by litter removal. The irrigation treatment did not affect the PMC, and spore density in soil and did not affect the availability of nutrients. The study allowed to show that changes in land cover can cause serious damage to the plant-fungus symbiosis.
Acesso aberto (Open Access)
Colonização micorrízica e disponibilidade de fósforo no solo em sistemas agroflorestais com palma de óleo na Amazônia.
(Universidade Federal do Pará, 2020-01-20) MAIA, Rodrigo da Silva; VASCONCELOS, Steel Silva; http://lattes.cnpq.br/0719395243841543; https://orcid.org/0000-0003-2364-8822
Phosphorus (P) is considered the most expensive and limiting nutrient for agricultural production in the tropics, due to the limitations of phosphate reserves and adsorption phenomenon. In the Amazon agricultural production may be limited by 90% due to P deficiency. In recent decades the introduction of monocutives, such as oil palm (Elaeis guineensis) in the state of Pará, has caused changes in land use, affecting nutrient availability and environmental dynamics. In this context, the insertion of oil palm into an alternative soil management model and conservationists such as the Agroforestry System (AS), can help reduce dependence on imported P, ensure greater use of P in the soil through organic sources and increase plant uptake through arbuscular mycorrhizae symbiosis. However, there is little information on the contribution of AS to P availability and mycorrhizal colonization in perennial crops like an oil palm in tropical agrosystems, especially in the Amazon. The aim of this study was to evaluate the labile and moderately P (organic and inorganic) fractions in soil and arbuscular mycorrhizal colonization in oil palm planted in biodiverse and monoculture agroforestry systems in the Brazilian Amazon. The P fractions were determined by sequential extraction method described by Hedley and mycorrhizal colonization was evaluated by intersection magnification method. Mycorrhizal colonization was generally 3.5 times higher in oil palm cultivated in Agroforestry in relation to monoculture and Agroforestry did not differ from monoculture in the supply of labile P and have a larger pool of moderately labile P in the soil. The results of the study showed that the adoption of Agroforestry Systems in oil palm cultivation in the Amazon is a promising practice to increase mycorrhizal colonization in this species and represents a type of advantageous management for the supply of available P and for the maintenance of P reserves compared to monoculture.
Acesso aberto (Open Access)
Frações de fósforo e simbiose micorrízica em floresta secundária em resposta a disponibilidade de água e nutrientes na Amazônia oriental
(Instituto Nacional de Pesquisas da Amazônia, 2015-09) MAIA, Rodrigo da Silva; VASCONCELOS, Steel Silva; CARVALHO, Claúdio José Reis de
The availability of soil nutrients (especially phosphorus) and soil water strongly influence mycorrhizal symbiosis in forest ecosystems. The aim of this study was to evaluate the impact of litter removal and increased soil moisture availability on the spore density and mycorrhizal colonization of apogeotropic and non-apogeotropic roots of a secondary forest stand in eastern Amazonia. We determined the percentage of mycorrhizal colonization of apogeotropic and non-apogeotropic (0-10 cm soil depth) fine roots (diameter ≤ 2 mm), spore density, glomalin concentration, and soil phosphorus availability. Litter removal did not reduce soil phosphorus availability. The spore density was not affected by litter removal. In general, the variables varied on a seasonal basis, except the mycorrizal colonization of non-apogetropic roots and glomalin concentration, but were not affected by irrigation. Mechanical damage to the apogeotropic root system, inherent to the fortnightly litter removal, may have contributed to decrease mycorrhizal colonization of both apogeotropic and non-apogeotropic roots and, consequently, soil glomalin. Our results suggest that the reduction of soil cover may have negative impact over the fungus-plant symbiosis.