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Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

PERLATTI, Fabio. Diversidade de fungos micorrízicos arbusculares em solo de agroecossistemas do semiárido cearense. 2010. 90 f. Dissertação (Mestrado em ecologia e recursos naturais)- Universidade Federal do Ceará, Fortaleza-CE, 2010. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-05-20T17:24:42Z No. of bitstreams: 1 2010_dis_fperlatti.pdf: 5400626 bytes, checksum: 9bd98bd19b20780205753aaa6376e61b (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-05-27T20:14:18Z (GMT) No. of bitstreams: 1 2010_dis_fperlatti.pdf: 5400626 bytes, checksum: 9bd98bd19b20780205753aaa6376e61b (MD5) / Made available in DSpace on 2016-05-27T20:14:18Z (GMT). No. of bitstreams: 1 2010_dis_fperlatti.pdf: 5400626 bytes, checksum: 9bd98bd19b20780205753aaa6376e61b (MD5) Previous issue date: 2010 / Arbuscular Mycorrhizal Fungi - AMF are key organisms in natural ecosystems and agroecosystems, as being responsible for a symbiosis that occurs in more than 80% of terrestrial vascular plants. Work in mutualism with plants, helping them with less mobile nutrient uptake, increase the absorption of water, protect them against diseases and are strongly influenced by agricultural practices and environmental changes. This study evaluated the influence of chemical parameters of soil, climate variation in two seasons and four different agroecosystems of tropical fruit trees (cashew- Anacardium occidentale, coconut - Cocos nucifera and soursop - Annona muricata), with the diversity of AMF compared with an area of native forest adjacent to plantations, considering the hypothesis that these factors change the community composition of these fungi. Samples were collected at depth of 0-20 cm in the rainy (April/2009) and dry season (October/2009) and used ecological indexes as a way of evaluating changes in the systems and periods. In total were identified 35 different morphotypes of spores and chemical parameters of the soil indicated that pH was negatively correlated with the average density of spores, Mg with the species richness and Zn with both. The average density of spores was negatively influenced by agroecosystems, because the highest values were found in the forested area in both periods, and except for the coconut (Cocos nucifera L.) crop, all the others had a significant increase in between the periods. Species richness was found to be stable, with only the soursop culture (Annona Muricata) different compared to other systems in the rainy season. During the dry season no differences being detected in richness. The relative abundance indicates greater dominance in the communities during the rainy season and relative frequency shows the prevalence of species of the genus Glomus on all systems. The highest diversity, as measured by the Shannon- Wiener index, indicated that the soil under coconut had the highest values in both periods. There was a general increase in diversity comparing the rainy with the dry season. The dominance assessed by the Simpson index corroborates the results obtained by relative abundance, demonstrating that in the rainy season the concentration of dominance was higher in all systems. The similarity analysis using the Bray-Curtis index shows that the dry season has made the systems more similar, since they showed higher values in this period. Cluster analysis based on similarity index shows that despite the richness of abundance variations, the systems were also grouped in both periods. The soursop formed an isolated group, the area of forest was more similar to the old cashew culture. The other cluster was formed by the coconut culture and the new cashew plantation. Results of the study allowed concluding: agricultural activities have changed the community composition of AMF in relation to the native forest; the coconut agroecosystem had the highest biodiversity of AMF among all the systems evaluated; the species of the genus Glomus were the most abundant in agroecosystems and natural ecosystem; there were differences in community composition and diversity of fungi in between the rainy and dry season; and the diversity of AMF spores in soil did not correlate with the tropical fruit tree’s infective capacity. / Os Fungos Micorrízicos Arbusculares - FMA são microrganismos chave tanto em agroecossistemas como em ecossistemas naturais. São responsáveis por uma simbiose que ocorre com a maioria das plantas vasculares. Atuam em mutualismo com as plantas, auxiliando-as na absorção de nutrientes pouco móveis no solo, além de aumentar a absorção de água e protegê-las contra patógenos, sendo fortemente influenciados por práticas agrícolas e variações ambientais. Neste trabalho avaliaram-se as influências de parâmetros químicos do solo, períodos do ano e quatro diferentes agroecossistemas com fruteiras tropicais (cajueiros - Anacardium occidentale (2 pomares), coqueiros - Cocos nucifera, e gravioleiras - Annona muricata), na diversidade de FMA em comparação com uma área de mata nativa adjacente aos plantios, partindo da hipótese de que estes fatores alteram a composição da comunidade desses fungos. Foram coletadas amostras de solo na profundidade de 0-20 cm, no período chuvoso (abril/2009) e seco (outubro/2009), e utilizados índices ecológicos como forma de avaliar as alterações entre os sistemas e os períodos. No total foram identificados 35 diferentes morfotipos de esporos de FMA. Entre os parâmetros químicos do solo, o pH mostrou-se negativamente correlacionado com a densidade média de esporos, o Mg com a riqueza de espécies e o Zn com ambos. A densidade média de esporos foi influenciada negativamente pelos agroecossistemas, pois os maiores valores foram encontrados na área de mata em ambos os períodos, e exceto pela cultura do coqueiro, todas as outras tiveram aumento significativo no período seco. A riqueza de espécies de FMA mostrou-se estável, sendo que apenas a gravioleira apresentou diferença em relação aos outros sistemas no período chuvoso. Já no período seco não houve diferença na riqueza entre os sistemas, sendo detectado um aumento na riqueza de espécies, comparado ao período chuvoso. A abundância relativa indicou uma maior dominância nas comunidades no período chuvoso, e a freqüência relativa demonstra a prevalência de espécies do gênero Glomus em todos os sistemas. A maior diversidade de FMA foi constatada no solo cultivado com coqueiro. Houve um aumento generalizado da diversidade no período chuvoso comparada com o período seco. A dominância avaliada pelo índice de Simpsom corrobora os resultados obtidos pela abundância relativa, demonstrando que no período chuvoso a concentração de dominância foi maior em todos os sistemas A análise de similaridade, utilizando o índice de Bray-Curtis, demonstra que o período seco tornou os sistemas mais similares, uma vez que apresentaram maiores valores nesse período. A análise de agrupamento baseada no índice de similaridade demonstra que, apesar das variações de riqueza de abundância, os sistemas foram agrupados igualmente em ambos os períodos. A gravioleira formou um grupo isolado, enquanto a área de mata mostrou-se mais similar a cultura do cajueiro velho. O outro agrupamento foi formado pelo coqueiral e a plantação de cajueiro novo. Os resultados deste estudo permitem concluir: as atividades agrícolas alteraram a composição da comunidade de FMA em relação à mata nativa; o agroecossistema cultivado com coqueiro apresentou a maior biodiversidade de FMA dentre os sistemas avaliados; as espécies do gênero Glomus foram mais abundantes tanto nos agroecossistemas como no ecossistema natural; houve diferença na composição e na diversidade da comunidade de fungos entre o período chuvoso e seco; e a diversidade de esporos de FMA no solo, não se relacionou com a capacidade infectiva nas fruteiras.

The fairy circles are an intriguing and unexplained feature of the pro-Namib in Namibia and northwestern parts of South Africa. The presence of hundreds of almost circular patches where no plants grow were first mentioned in scientific literature in 1971 and since then scientists have tried to find an explanation for the origin of these circles. Although there are many hypotheses regarding the origin of these circles not one of these can explain the existence of these circles satisfactory. In this study several aspects of the fairy circles were investigated to improve the characterization of the phenomenon. Total element analysis of the soil from the different microhabitats (inside the circle, on the edge of the circle and between the circles, referred to hereafter as the matrix) and at different depths in these microhabitats were performed by inductively coupled plasma mass spectrometry (ICP-MS) and analyzed by principal component analysis (PCA). No patterns emerged regarding the concentration of the elements in the respective microhabitats. The occurrence of vesicular arbuscular mycorrhizae (VAM) in the roots of plants collected from the different microhabitats was also investigated. It was shown that VAM occurred in most of the roots of plants collected in the matrix and on the edge but no VAM were found in plants collected inside the circles. The succulent plant Euphorbia damarana has also been implicated in the origin of the circles. The presence of germination inhibiting compounds in this species was investigated. No such compounds were found. The extracts of it inhibited the growth of radicles of lettuce seeds at a concentration of 25 mg/ml. Bio-assays were also performed on soil collected in the different microhabitats using a dominant grass of the area, Stipagrostis uniplumis, as bioindicator. The fresh an dry shoot mass of plants harvested from soil collected on the edge and in the matrix grew much better than the shoots grown in soil collected from the inside of the circles (p = 0.0007). The dry shoot mass showed the same trend as the fresh shoot mass. The fresh root mass showed a marked increase in the roots collected from soil on the edge of circles when compared to plants grown in soil collected from the inside and the matrix (p = 0.013). There was a significant difference in the length of shoots measured in plants grown in the soils collected from the different microhabitats with the shoots measured from plants grown in the soil collected from the edge showing stimulation in growth when compared to the plants grown in soil from the matrix and inside the circles (p = 0.00004). The difference in shoot length between grasses grown in soil collected from the edge and the matrix was also significant (p = 0.00004) with the edge samples showing a stimulation in growth. / Dissertation (MSc)--University of Pretoria, 2008. / Plant Science / unrestricted

Mycorrhizae have been used in restoration for decades. However, studies assessing the use of mycorrhizae in Bromus tectorum-invaded areas of the Great Basin are limited. Two greenhouse pot experiments were conducted to assess the role of mycorrhizae in sagebrush restoration. The first objective (Chapter 2) was to determine the response of Pseudoroegneria spicatum, Elymus elymoides, and B. tectorum to mycorrhizal symbiosis by altering phosphorus, density, species, presence of mycorrhizae and water levels in a 5 factor design. To assess the mycorrhizal response, a variety of morphological and physiological traits were measured, such as tissue P concentration, specific root length, specific leaf area, carbon isotope discrimination, etc. The effects of the different treatment combinations were analyzed using ANOVA. The second objective (Chapter 3) was to determine the role of different inocula in competition between the three grasses. Species, density, and inoculum type were altered in a 3 factor design. Inoculum was cultured on Allium plants. The effect of locally cultured inoculum on the species was compared to the effect of commercial inoculum. The response of each species to mycorrhizae with different species compositions and densities was assessed. Morphological measurements were used to determine each species response to the different factor combinations. The effects of the different treatment combinations were analyzed using ANOVA. This research provides land managers with information regarding the efficacy of using local versus commercial inocula and whether they should use mycorrhizae in restoring their systems.

No description available.

Effects of fungi and overstory composition on tree seedling survival and growth were investigated in closed canopy upland forests in the coastal plain of South Carolina. Seedlings of Quercus alba, Cornus florida and Pinus taeda were planted in the understory of two forest types -naturally regenerated hardwood and planted pine. Fungal species composition and biomass were experimentally manipulated with a treatment of the fungicide captan. In contrast with other studies conducted in different systems (sand dune, grassland, and old field), the effects of soil fungi were minor in a closed canopy forest. Only Q. alba showed a significant response to the fungicide (p < 0.05) treatment with increased growth. Overstory composition had no significant effect on growth or survival for any of the species. Both of the commercially desirable species (Q. alba and P. taeda) had reasonable survival ( @ 60%). Both also maintained positive, though modest, growth. This suggests that an advance regeneration pool could be established successfully by artificial regeneration. / Master of Science

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

Podocarpus cunninghamii is an endemic New Zealand conifer that, in pre-human times, formed extensive forest communities across the eastern South Island high country. Anthropogenic disturbances have reduced the distribution of Podocarpus cunninghamii communities such that they now exist mainly as small and isolated remnants within a highly modified, predominantly pastoral landscape. Very little is known of the ecology of high country Podocarpus cunninghamii communities, and without this information it is not possible to develop an ecological basis for their restoration. This thesis explores the ecology of Podocarpus cunninghamii in the eastern South Island high country, investigating factors that potentially affect the restoration of Podocarpus cunninghamii within this environment, with special attention paid to the role of arbuscular mycorrhizal fungi (AMF). Field investigations of Podocarpus cunninghamii communities showed that they contain a high degree of floristic and structural variation determined by soil and climatic variables. Analysis of age and size class distributions suggest that Podocarpus cunninghamii has more than one regeneration strategy, and can regenerate within intact forest following the opening of small canopy gaps or can undergo large-scale recruitment following catastrophic disturbance. Field and glasshouse experiments investigating growth and nutrient responses of Podocarpus cunninghamii to different AMF inoculants found that Podocarpus cunninghamii responses are dependent on both AMF type and grass competition. Finally, investigation of Podocarpus cunninghamii carbon stocks showed that they are less than that of other New Zealand forest types, but are greater than that of grazed pastures. Successful restoration of high country Podocarpus cunninghamii communities will require the incorporation of associated species based on local environmental conditions, and will also need to allow for disturbance processes. AMF may have an important role to play in restoration by reducing seedling production times and by increasing the competitiveness of Podocarpus cunninghamii when in competition with exotic grasses.

Em busca de melhorar a eficiência do uso de fontes de fósforo (P) e viabilizar o aumento da absorção deste nutriente, objetivou-se com este trabalho determinar as mudanças promovidas por plantas de cobertura, associadas à fontes fosfatadas de solubilidade distintas, na colonização por fungos micorrízicos arbusculares (FMA), como também avaliar as mudanças promovidas na disponibilidade de frações de P no solo e na eficiência de uso do P pelas coberturas. O delineamento adotado foi de blocos ao acaso, em esquema fatorial 5x3, com quatro repetições. Foram utilizadas quatro plantas de cobertura: milheto (Pennisetum glaucum), braquiária (Brachiaria ruziziensis), guandú-anão (Cajanus cajan) e crotalária (Crotalária juncea), além do controle (pousio);Duas fontes de P: fosfato natural reativo Bayóvar e superfosfato simples, além de um tratamento controle (sem fosfato),. Avaliou-se a colonização micorrízica por FMA e densidade de esporos no solo em três épocas, correspondendo à estação chuvosa e seca de 2013 e a estação chuvosa de 2014. Avaliou-se também a produção de massa seca e o acúmulo de P pelas plantas. No final do segundo ano, analisou-se o fracionamento de P do solo. A colonização radicular foi mais influenciada nas épocas chuvosas. A presença das plantas de cobertura proporcionou maior colonização micorrízica e densidade de esporos na época chuvosa. As aplicações de fontes fosfatadas não influenciam a densidade dos esporos, enquanto que as plantas de cobertura, principalmente o guandú e a braquiária, apresentaram aumento no número de esporos. Apesar de não aumentar as frações lábeis do P no solo, a utilização de plantas de cobertura proporcionou maior ciclagem do nutriente. Os fosfatos não influenciaram a massa seca nem o acúmulo de P, sendo que houve efeitos das plantas de cobertura na massa seca e no acúmulo de P na parte aérea, com destaque para o milheto e a braquiária. / In order to improve the use efficiency of phosphorus sources and enable a higher absorption of this nutrient, this research aimed to determine the changes promoted by cover crops and phosphorus sources of different solubility in the colonization by arbuscular mycorrhizal fungi (AMF), as much as the availability of P fractions in the soil and the use efficiency of P by the cover crops. A complete randomized block design was adopted, in a 5x3 factorial scheme, with four replications. For the first factor were used four cover crops: millet (Pennisetum glaucum), brachiaria (Brachiaria ruziziensis), pigeon pea (Cajanus cajan) and sun hemp (Crotalaria juncea), including a control (fallow); for the second factor were used the reactive phosphate Bayovar and the simple superphosphate plus a control treatment (no phosphate). It was assessed the AMF colonization, the spore density in the soil in three different times, the rainy and dry seasons in 2013, and the rainy season in 2014. At the end of 2014, it was also evaluated the amount of the fractioned P in the soil. The root colonization was more influenced in rainy season. The presence of cover crops provided greater mycorrhizal colonization and spore density in the rainy season. The applications of phosphate sources did not influence the spores density. However, the cover crops, mainly pigeon pea and brachiaria, showed an increase in the number of spores. The use of cover crops did not increase the labile fractions of P in the soil, Nevertheless they provided greater cycling of this nutrient. Phosphates did not influence the dry matter or the accumulation of P. Interestingly, the dry matter and P accumulation in shoots was influenced by the kind of cover crops, being higher for millet and brachiaria.