Respostas metabolicas e morfo-anatomicas de sementes e plantas de Tabebuia Cassinoides (Lam.) DC (Bignoniaceae) a hipoxia

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

Tabebuia cassinoides (Lam.) De (Bignoniaceae) is an arboreous species that occurs in wampy areas of the seacoast "restinga". To elucidate the adaptive strategies which enable the establishment of this species and the occupation of areas of waterlogged soil by it the fol1owing characteristics were studied: metabolic and morpho-anatomic responses of seeds during germination and of plants under conditions that limited oxygen access. Seeds of this species did not genninate under anoxia or when under total submersion, remaining viable under these conditions for 15 and 20 days respectively. Wing seeds reached 100% of germination while floating on the water surface, an essential capacity to overcome this initial stage in flooded environments. ln relation to the metabolism of the seeds we observed an acceleration of glycolysis with high production of ethanol, lactate and malate, the first one produced in higher amount. The root system or T cassinoides plants presented higher levels of ethanol only in the first days of flooding. The presence of intercel1ular spaces and the induction of aerenchyrna formation under flooding allow oxygen transport from the shoot to the roots maintaining an aerobic respiration. These characteristics and the capacity to oxidise the rizosphere are responsible for the survival and vigorous growth of plants while flooded and for their success in an environment which restricts the presence of the majority of the species

ASSUNTO(S)

sementes germinação ecofisioloogia plantas

ACESSO AO ARTIGO

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