Camila Pinheiro Nobre

Fungos micorrízicos arbusculares em sistema de aléias no Estado do Maranhão, Brasil

Alley cropping systems may be a solution for land use in tropical regions. How land use is connected to mycorrhizal arbuscular fungi (AMF) is poorly understood, especially in the tropics. The aim of this study was to evaluate the influence of leguminous trees in an alley cropping system in regard to the infectivity and diversity of native AMF species in Sao Luis, Maranhao, Brazil. Soil samples were collected in an experimental area of the Universidade Estadual do Maranhao (UEMA) - Sao Luis, in two seasons (July/2006 and April/2007), two distances (0 m and 0.5 m) from the trunk of three leguminous trees (Leucaena leucocephala, Clitoria fairchildiana e Acacia mangium), and in a control area 0-20 cm deep. Soil samples were used to evaluate the infectivity of AMF, density and diversity of glomerospores. The alley cropping systems increased the infectivity of AMF which varied according to the leguminous tree species, raining season and distance from trees. Sixteen AMF species of five genera were identified in the area, and Scutellospora was the most representative genus.

Production of native arbuscular mycorrhizal fungi inoculum under different environmental conditions.

In order to obtain an arbuscular mycorrhizal fungi (AMF) native inoculum from Sierra de Moa and determine the most appropriate conditions for its big scale production, four light and temperature combinations were tested in three plant species (Calophyllum antillanum, Talipariti elatum and Paspalum notatum). Growth and development parameters, as well as the mycorrhizal functioning of the seedlings were evaluated. The natural light treatment under high temperatures (L-H) was the most suitable for the growth and development of the three plant species, showing the highest total biomass values, mainly of root, and a positive root-shoot ratio balance. This treatment also promoted higher values of root mycorrhizal colonization, external mycelium and AMF spore density. A total of 38 AMF species were identified among the plants and environmental conditions tested. Archaeospora sp.1, Glomus sp.5, Glomus brohultii and G. glomerulatum were observed in all the treatments. The L-H condition can be recommended for native inoculum production, as it promotes a better expression of the AM symbiosis and an elevated production of mycorrhizal propagules.

Acaulospora endographis (Glomeromycetes), a new fungus with a complex spore wall

A new acaulosporoid fungal species characterized by glomerospores with a complex ten-layered wall structure and uniquely ornamented fourth layer (outer wall layer OWL4) found in impacted areas of the Amazon Forest and cultivated areas of the Atlantic Forest in Brazil is described as Acaulospora endographis.

Biostimulation of inoculation with Glomus proliferum and application of humic acid in the in vitro growth of Lunularia cruciata

In this study, we evaluated the growth of the liverwort Lunularia cruciata, inoculated or not with the arbuscular mycorrhizal fungi (AMF) Glomus proliferum (15 spores per Petri dish), in Strullu-Romand Variant (SRV) medium modified and enriched with humic acid (HA) at different concentrations (0, 20, 40 and 80 mg C L−1), as well as the sporulation of the AMF. We assessed the absolute growth rate (AGR) and relative growth rate (RGR) at inoculation, as well as at 7, 14, 21, 28, 43, 52 and 60 days after inoculation (DAI), whereas we assessed sporulation at 25, 43, 60 and 70 DAI. The main determinant of L. cruciata growth was the presence of AMF. With and without G. proliferum inoculation, respectively, the AGR peaked at 39 and 42 DAI, and the RGR was 0.0474 and 0.0387 cm2 cm−2 d−1. Doses of 20 and 80 mg C L−1 of HA had a positive influence on the growth of L. cruciata. With and without HA, respectively, the AGR peaked at 38 and 39 DAI, and the RGR was 0.0484 and 0.0422 cm2 cm−2 d−1. The sporulation of G. proliferum, which was as high as 199 spores plate−1, was influenced by HA, especially at 20 and 80 mg C L−1.

Diversity of Arbuscular Mycorrhizal Fungi in an Amazon Environment after Mining

At the Brazilian Amazon forest, studies were carried out to estimate the community of arbuscular mycorrhizal fungi (AMF), from this it was used a bioassay of dilutions of samples collected from preserved and regenerated areas after bauxite extraction. To regenerate areas, tree species were introduced and samples were taken after 2, 6, 12, and 16 years, the spores obtained were compared to those obtained by direct extraction and the number of species recovered from the bioassay was significantly higher. Therefore, the species founded after different periods regeneration was similar to the ones from the native forest. Since the early years of revegetation, the number of rare species was high with strong dominance of G. macrocarpum. Among older communities this high dominance decreased while at the same time, there was an increase in the number of individuals from other AMF species, concluding that the number of species did not change with the age of the revegetation.

Arbuscular mycorrhizal fungi associated with the babassu palm (Attalea speciosa) in the eastern periphery of Amazonia, Brazil

Babassu, Attalea speciosa (Arecaceae) is a ruderal palm native to Amazonia, which turned dominant in frequently burned lands throughout the ‘arc of deforestation’ and other degraded lands, in extreme cases attaining complete dominance. This study investigated arbuscular mycorrhizal fungi (AMF) as one possible explanation for the outstanding ecological success of this exceptional palm. We explored the relationships between the babassu palm and native arbuscular mycorrhizal fungi and babassu effects on the AMF richness and mycorrhizal inoculum potential (MIP) in the eastern periphery of Amazonia. For this purpose, we sampled topsoil (0-20 cm) at the onset of the rainy season from a 5-year-old secondary forest regrowth (SEC) area with three levels of babassu dominance (sites with 10, 50 and 70% babassu biomass shares), and at three distances (0, 2.5 and 4 m) from isolated babassu patches within a degraded pasture (PAS), both with five replications per treatment. Glomerospore density varied from 100 to 302 per gram of soil, 56% higher in SEC than PAS. We identified a total of 16 AMF species, with dominance of Acaulospora (six species) followed by Glomus (three species). AMF richness increased with babassu dominance in SEC sites, and reduced with distance from babassu patches within the PAS. The colonization rate of babassu roots was higher in SEC than in PAS, whereas MIP was similar in both areas and without treatment differences. Our study points to strong mycorrhizal association of the babassu palm as a potential mechanism for its outstanding ecological success in degraded lands.