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SUMMARYThe contents and composition of fructans in underground organs (rhizophores) of Vernonia herbacea (Veil.) Rusby, a perennial herb native to the Brazilian cerrado, were analyzed at different phenological stages, Fructopolysaccharides were always present in higher concentrations than oligosaccharides but variations in amounts of both fractions occurred together, A marked decline in total fructan and an increase in free fructose were observed between sprouting and fiowering, suggesting the occurrence of hydrolysis in association with the growth of new aerial shoots and flower development. There were higher amounts of total fructan at the end of summer and at dormancy, alternating with lower amounts at early dormancy. In spite of these variations the mean molecular mass of the fructo-polysaccharides remained nearly constant throughout the cycle, except for the higher value found in vegetative plants at the end of summer. The maintenance of the mean molecular mass of fructo-polysaccharides in the flowering phase concurrent with a marked reduction in total fructans suggests a peculiar mechanism of depolymerization in this plant, while the variation pattern found for fructan contents over the phenological cycle points to their role as reserve compounds in Vernonia herbacea.

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Caesalpinia echinata seeds stored in laboratory environmental conditions lose their viability in one month whilst under low temperatures germination is maintained for 18 months of storage. These seeds are tolerant to desiccation, keeping their viability up to 0.08 gH 2 O.gDW -1 . Since soluble carbohydrates are believed to be involved with desiccation tolerance and seed storability, the aim of this work is to analyze the content and composition of soluble carbohydrates in C. echinata seeds during storage in paper bags (PB) and glass flasks (GF) at laboratory room (RT) and cool (CT) temperatures. In freshly harvested seeds, total soluble carbohydrates comprised approximately 10% of the dry weight, decreasing to ca. 8% over 18 months of storage at RT. In seeds stored at CT, sugars varied differently decreasing initially and being restored at the end of the analysis period. The main neutral sugars in seeds from all treatments were sucrose, fructose and glucose. Raffinose and stachyose were present as traces. Free myo-inositol and other cyclitols were also detected. The main tendency observed was the variation in levels of both glucose and fructose in relation to sucrose, the highest levels of monosaccharides which were found in seeds stored at CT. The values of glucose and fructose were practically constant in seeds stored in paper bags for 18 months at CT, decreasing consistently in the other treatments, mainly at RT. Sucrose contents remained relatively stable. Changes in soluble sugars during storage suggest that the loss of germinability of seeds of C. echinata could be associated with low levels of glucose and fructose in relation to sucrose.Keywords: seed longevity, desiccation tolerance, pernambuco, soluble sugars, cyclitols. RESUMO Modificações nos carboidratos solúveis durante o armazenamento de sementes de Caesalpinia echinata LAM. (pau-brasil), uma leguminosa arbórea da Mata Atlântica em risco de extinçãoSementes de Caesalpinia echinata (pau-brasil) perdem a viabilidade em um mês quando armazenadas no ambiente de laboratório, enquanto a capacidade germinativa é mantida quando armazenadas sob temperturas baixas. O presente trabalho teve como objetivos analisar o conteúdo e a composição dos carboidratos de sementes de C. echinata armazenadas em câmara fria (CT) e em temperatura ambiente do laboratório (RT), em duas embalagens distintas (permeável e impermeável), visando a avaliar o envolvimento desses compostos com a capacidade germinativa das sementes. Os resultados mostraram que os carboidratos solúveis são constituídos principalmente de sacarose, glicose, frutose, myo-inositol e traços de rafinose e estaquiose, totalizando cerca de 10% da massa seca das sementes. As variações nos carboidratos solúveis foram semelhantes nos dois tipos de embalagem, mas diferentes quanto à temperatura de armazenamento. Em CT, as proporções dos monossacarídeos encontradas nas sementes recém-colhidas foram mantidas por cerca de 18 meses de armazenamento, coincidindo com alta porcentagem de germinação (80%). Nas arma...