Marta Bruno Loureiro

Caracterização morfoanatomica e fisiológica de sementes e plântulas de Jatropha curcas L. (Euphorbiaceae)

Jatropha curcas L., conhecida popularmente como pinhao-manso, e uma especie encontrada em quase todas as regioes intertropicais do planeta. Possui sementes oleaginosas de importância medicinal e economica, sendo apontada atualmente como promissora fonte de materia-prima para a producao de biocombustiveis. Os objetivos deste trabalho consistiram em identificar as diferentes fases do processo de germinacao, descrever e ilustrar a morfologia de sementes e plântulas de Jatropha curcas L. e os aspectos anatomicos das sementes, relacionando as mudancas que ocorrem nos tecidos durante as fases de embebicao. Para a analise morfologica das sementes e plântulas, observaram-se os detalhes externos e internos. Para o estudo das fases de germinacao, foi realizado um ensaio para avaliar o comportamento das sementes durante a embebicao; para a analise anatomica, foram preparadas lâminas permanentes com cortes das sementes apos 0, 4, 24 e 72 h de embebicao. As sementes de Jatropha curcas L. sao endospermaticas, elipticas e anatropas com tegumento glabro, possuindo poros e fissuras em sua superficie. Os cotiledones sao foliaceos, com formato cordiforme e nervuras trinervias. A germinacao e do tipo fanerocotiledonar, epigea. Anatomicamente, as sementes sao albuminosas, sendo o tegumento constituido de celulas parenquimaticas, vacuoladas e poligonais com feixes vasculares e celulas esclereficadas. O endosperma e composto por celulas poliedricas ricas em substâncias de reserva, principalmente lipidios. Durante as fases de germinacao, observaram-se alteracoes no acumulo de grânulos de amido presentes no endosperma, bem como mudancas na organizacao dos seus feixes vasculares.

Revisão: Jatropha curcas L.: aspectos morfofisiológicos e químicos

Jatropha curcas L. (physic nut) is an oleaginous plant species and the oil extracted from its seeds presents multiple applications for use by local communities, in addition to its potential application in different industrial sectors, amongst which the biodiesel industry, thus constituting one more source of raw materials within the inventory of useful oleaginous species. The morphophysiological and physicochemical aspects are of great importance when there is interest in the prospection of plant species aiming at their domestication and commercial exploitation. The aim of this study was to carry out a review of the state of art concerning J. curcas by compiling studies on its morphophysiological characterization and on the chemical composition of its seeds, thus generating information that could help in the exploitation of the production and cultivation potential of this species, so as to subsidize studies that propitiate this crop and its sustainable commercial exploitation. The morphological knowledge available concerning J. curcas allows for an accurate understanding of its biological cycle. However, physiological studies still need to be developed for a better understanding of its behavior, particularly in terms of storage, the optimum conditions for germination and the production of seedlings, as well as it behavior under adverse conditions, such as excessive sunlight, water restriction and high temperatures, amongst others. The description of the chemical composition, characterization of the toxic compounds and existing anti-nutritional factors in the seed would provide information that could support the production and commercial exploitation of J. curcas. However, animal studies and tests should be carried out to confirm the commercial applications with greater confidence.