-(Do recalcitrant seeds really exist?). In the 70's, seeds were divided into two categories: recalcitrant and orthodox. In the 80's, it was necessary to create an intermediate category; from the 90's onwards, a gradient between orthodox and recalcitrant categories has been considered by several authors. Currently, the terms orthodox and recalcitrant are appropriate just for technological purposes, not for scientific studies. It seems that the differences between recalcitrant and orthodox seeds lie only on the maturity stage in which they are detached from the mother plant, the recalcitrant ones in a very immature stage. This implies that little progress should be expected to expand the storability of these recalcitrant seeds with the application of any treatment after harvesting. Efforts shall be focused on amplifying the maturation period of these seeds by keeping them linked to the mother plant until the maturation process has been completed. Key words: conservation, desiccation tolerance, maturation, seed storage RESUMO -(Sementes recalcitrantes realmente existem?). Na década de 1970, as sementes foram divididas em recalcitrantes e ortodoxas. Na década de 1980, foi necessário criar a categoria das intermediárias e, a partir de 1990, um gradiente entre as categorias ortodoxas e recalcitrantes tem sido considerado por vários autores. Atualmente, os termos ortodoxa e recalcitrante são apropriados apenas para fins tecnológicos, não para estudos científicos. As diferenças entre sementes recalcitrantes e ortodoxas parecem residir apenas no estádio de maturidade no qual se desprendem da planta mãe, as recalcitrantes em uma fase muito imatura. Isso implica que pouco progresso deve ser esperado para expandir a capacidade de armazenamento com a aplicação de qualquer tipo de tratamento após a colheita dessas sementes recalcitrantes. Esforços devem ser voltados para ampliar o período de maturidade das sementes, mantendo-as ligadas à planta-mãe até que o processo de maturação tenha sido concluído. Palavras-chave: armazenamento, conservação, maturação, tolerância à dessecação
RESUMO -(Gramíneas do cerrado: carboidratos não-estruturais e aspectos ecofisiológicos). As gramíneas reúnem características que as destacam como grupo evoluído e diversificado de plantas. Possuem desempenho fotossintético eficiente em diversas condições, são eficientes na produção e dispersão de diásporos, possuem sistema radicular fasciculado, além de produzirem estolhos e rizomas. O conjunto destes atributos faz com que gramíneas sejam apropriadas para a recomposição de áreas degradadas, atuando como pioneiras na sucessão ecológica. Se de um modo isto possibilita vantagem na ocupação de áreas em seu habitat original, por outro podem ser atributos que incrementam o grau de invasibilidade de uma espécie em outro ambiente. A composição de carboidratos não-estruturais e a alta produção de biomassa são discutidas visando fornecer subsídios para utilização das vantagens adaptativas das gramíneas em programas de manejo de reservas naturais. Palavras-chave: gramíneas, carboidratos não-estruturais, cerrado, invasão de reservas biológicasABSTRACT -(Grasses of the cerrado: non-structural carbohydrates and ecophysiological aspects). Grasses combine characteristics that distinguish them as an evolved and diversified group of plants. They present an efficient photosynthetic metabolism under several conditions, as well as a high production and spreading of diaspores. Besides their fasciculate roots, some species can present stolons and rhizomes. Together, such attributes make grasses appropriated for the recovery of degraded areas, acting as pioneers in the ecological succession. However, if these characteristics enable grasses to occupy areas in their original habitat, they also increase their ability of invading other environments. Non-structural carbohydrates composition and high biomass production are discussed aiming at providing subsidies for the use of those adaptive advantages in programs for conservation of natural reserves.
No abstract
The use of inulinases provides an alternative way to obtain fructose syrup through the hydrolysis of inulin. The objective of this work was to study the production, characterization and application of an inulinase from Pseudozyma sp CCMB 300 isolated from Brazilian semi-arid region. The higher production of inulinase in a medium containing 0.86 g L-1 yeast extract and 14.54 g L-1 glucose using response surface methodology (RSM). This statistical method was also used to access the optimum pH (8.28) and temperature (54ºC) for fermentative inulinase production. The results showed that the inulinase has potential for inulin hydrolysis, where a conversion yields of roughly 87.39 % for an initial concentration of inulin of 1% (w/v).
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