-Brazil is a major producer and exporter of beef in the world, 90% of the production is made in pasture and 85% of cultivated pastures in the country are Brachiaria sp. With a growing livestock industry in the recent years, several forage plant diseases became significant importance for causing losses in pasture productivity and quality. This study aims at quantifying the species of fungi associated with seeds and their frequency in forage plants from tropical regions of Brazil. Assays were performed considering: incidence, pathogenicity and seed-seedling transmission of fungi associated with seeds. Therefore, 28 lots of forage species seeds produced in the harvest of 2010-2011 were used. Fourteen genera of fungi associated with seeds were found, among which Bipolaris sp., Phoma sp., and Curvularia sp. had pathogenic potential. It was possible to note that Bipolaris sp., is prejudicial to forage seedlings of Brachiaria, Panicum and Crotalaria. Bipolaris sp. and Curvularia sp. have an average of seed-seedling transmission of 100% and 90%, respectively.
O objetivo deste estudo foi avaliar os efeitos dos óleos essenciais C. nardus, E. citriodora e composto citronelal da germinação associada à micoflora e milho inicial da planta (Zea Mays) nas doses de 5, 10 e 15% para todos os testes. A cultivar de milho utilizada foi XGN5320 e o delineamento experimental foi inteiramente casualizado. Após a aplicação de doses definidas, a germinação foi avaliada no papel do germiteste na DBO. A avaliação da fitotoxicidade foi realizada em plantas cultivadas em vasos com aplicação direta nas plantas e nos sintomas observados 48 e 96 horas após a aplicação. Também avaliamos o tamanho das mudas e raízes. A matéria seca foi obtida após essas partes permanecerem na circulação forçada de ar dos gases. O efeito na micoflora das sementes foi observado pelo método Blotter. Os resultados mostraram que os óleos utilizados não eram seletivos para plantas de milho, causando danos graves no desenvolvimento inicial de fitotoxicidade dos mesmos, com consequente redução na massa seca e no comprimento da parte aérea (P <0,05). Os óleos inibiram dramaticamente os fungos transmitidos pelas sementes, Aspergillum ssp inibindo satisfatoriamente. e levado à incidência de Colletotrichum, Fusarium e Penicillium zero, com a dose mais alta (15%), indicando toxicidade para esses microrganismos. No entanto, mostrou atividade alelopática, afetando dramaticamente a germinação das sementes.
Essential oils are alternative to control pathogenic agents, agricultural pests and weeds, with the use of pesticides in agriculture has been an important tool in the control of many pathogenic microorganisms and plants to increase production, but the indiscriminate use of these chemicals has negatively affected the environment and human health. It has been researched lately, demand for new plants with metabolic molecules such as terpenes, alkaloids and phenolic compounds, in effect; bioinsecticide, biofungicide bioherbicida and plants that can replace chemicals or with low or no residual power and reduce the impact to environment, this manuscript aims to give a comprehensive explanation on the importance of essential oils and their secondary metabolites in plant defense. The use of plants with insecticidal properties, fungicide and herbicide, shows a high potential of this tool in the management of pests, diseases and weeds. For the final insertion and safe botanical products in agriculture, however, more studies are still needed.
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