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Previous issue date: 2015-02-27 === Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES === The evaluation of toxicity caused by aluminum (Al) trees used in urban forestry is of great importance for the development of seedlings and plantings in appropriate conditions. The tree species Bauhinia variegata L. is commonly used in urban afforestation, requiring knowledge of their nutritional requirements and conflicts related to the presence of trees on the streets, for example, interference in the electricity distribution networks. Pruning is the main practice management done on trees planted in the streets. Optimizing the pruning process can generate benefits such as less frequent pruning, lower cost and higher efficiency, especially for the energy sector. The objectives of this study were to evaluate the influence of Al in the development of Bauhinia variegata seedlings, and analyze the effectiveness of different types of pruning cut with or without the use of Al, in order to reduce shoots. This study was developed in two stages, resulting in two chapters. The first, directly related to mineral nutrition, with the study aimed to investigate the effects of Al toxicity on growth and root development. Experiments were performed in simple and complete nutrient solution and in acid soil substrate. The second chapter presents the study to assess the effectiveness of different types of pruning cut made in adult plants of Bauhinia variegata, with and without the use of Al as a growth inhibitor. The results indicated that this species is sensitive to the toxicity of Al from the concentration of 50 ?M, being observed decrease in root growth rate and relative root elongation. The critical dose to paralyze Al root growth were 151,48 ?M of Al in simple nutrient solution and 388,72 ?M of Al in complete nutrient solution. Al caused increase in the diameter of the roots of seedlings from the concentration at 400 ?M solution. The application of limestone in acid soil favored the growth of plants of Bauhinia variegata, resulting in higher dry matter weight values of root and shoot dry mass weight. When pruning was held close to the trunk and Al application shoots were not observed until the last evaluation at 210 days after pruning. In pruning held close to the trunk without Al application occurred shoots. In the cuttings leaving stump 20 and 40 cm, with or without the application of Al occurred shoots === A avalia??o da toxidez causada pelo alum?nio (Al) em ?rvores utilizadas na arboriza??o urbana ? de grande import?ncia para o desenvolvimento de mudas e plantios em condi??es adequadas. A esp?cie arb?rea Bauhinia variegata L., ? comumente utilizada na arboriza??o de urbana, sendo necess?rio o conhecimento das suas exig?ncias nutricionais e dos conflitos relacionados ? presen?a das ?rvores nas ruas, como, por exemplo, a interfer?ncia nas redes de distribui??o de energia el?trica. A poda ? a principal pr?tica de manejo realizada nas ?rvores plantadas nas ruas. A otimiza??o do processo de podas pode gerar benef?cios como menor frequ?ncia de podas, menor custo e maior efici?ncia, especialmente para o setor el?trico. Os objetivos deste trabalho foram avaliar a influ?ncia do Al no desenvolvimento de mudas de Bauhinia variegata, e analisar a efici?ncia de diferentes tipos de corte em poda associado ou n?o ao uso de Al, de modo a diminuir brota??es. Estes estudos foram desenvolvidos em duas etapas, resultando assim em dois cap?tulos. O primeiro, relacionado diretamente ? nutri??o mineral, com o estudo direcionado ? investiga??o dos efeitos da toxidez do Al no crescimento e desenvolvimento de ra?zes. Foram realizados experimentos em solu??o nutritiva simples e completa e em substrato de solo ?cido. O segundo cap?tulo apresenta o estudo de avalia??o da efici?ncia de diferentes tipos de corte em podas realizadas em plantas adultas de Bauhinia variegata, com e sem a utiliza??o de Al como inibidor de crescimento. Os resultados indicaram que esta esp?cie ? sens?vel ? toxidez do Al a partir da concentra??o de 50 ?M, sendo observada diminui??o na taxa de crescimento radicular e na elonga??o radicular relativa. As doses cr?tica de Al que paralisaria o crescimento radicular foram de 151,48 ?M de Al em solu??o nutritiva simples e de 388,72 ?M de Al em solu??o nutritiva completa. O Al provocou aumento do di?metro das ra?zes de mudas a partir da concentra??o em solu??o de 400 ?M. A aplica??o de calc?rio em solo ?cido favoreceu o crescimento de plantas de Bauhinia variegata, resultando em maiores valores de peso de massa seca de raiz e peso de massa seca de parte a?rea. Quando a poda foi realizada rente ao tronco principal e com aplica??o de Al n?o foram observadas brota??es at? a ?ltima avalia??o, aos 210 dias ap?s a poda. Na poda realizada rente ao tronco principal sem aplica??o de Al ocorreram brota??es. Nas podas deixando toco de 20 e 40 cm, com ou sem aplica??o de Al, ocorreram brota??es.
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