Morphoanatomical description and germination of Merremia tomentosa (Choisy) Hall. / DescriÃÃo morfo-anatÃmica e germinaÃÃo de Merremia tomentosa (Choisy) Hall

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Merremia tomentosa is a medicinal plant native from the cerrados and rupestrian fields, belonging to the family Convolvulaceae, of the genus Merremia, utilized in folk medicine as a blood depurative. The present work was conducted with the purpose of doing a morphoanatomical description and the germination of M. tomentosa. The botanical material was collected on the Serra do Macaia (Macaia Range), Lavras town, MG, in the period of February 2007 to April 2008. The morphoanatomical characteristics were studied by means of morphological boards and photos of the plant and cross sections of the leaf, stem and root of the seedling. The moisture content of the seeds, influence of light, of temperature and of substrate on germination were evaluated. The in vitro seed germination in different culture media and in the MS medium with a reduction of 50% of salt concentration, added of different concentrations of GA3 was, further, evaluated. For in vitro germination, seed asepsis was performed in running water for 20 minutes, which, afterwards, they were immersed in 70% alcohol (v/v), for 60 seconds and, next, in the solution of 50% sodium hypochlorite (NaOCl) (v/v) for 20 minutes. Later, they were washed three times in distilled and autoclaved water and after inoculation; the seeds were kept in a growth room under irradiance of photons of 36 mmol m-2 s-1, 16-hour photoperiod and temperature of 25Â2ÂC. The evaluation was conducted daily, for 30 days, after inoculation. The completely randomized design was utilized for all the treatments. The data of the germination test were transformed into arcsin (x/100)0,5 and germination velocity rate into (x + 0.5)0,5. The means were compared by the F test or by the Tukey test at 5% of probability (p≤0.05), according to the experiment conducted. The analysis of variance was carried out and the means were compared by utilizing the Sisvar statistical program. In the data of in vitro germination with a concentration of GA3, the results were submitted to the analysis of variance, their being analyzed by the regression test in the Sisvar. From the results obtained, it follows that M. tomentosa is a subshrub of upright, cylindrical stem, penninervate simple leaves, pluricelular tector trichomes of alternate phylotaxy, single , axillary, pentamerous flowers; reduced bract with protuberances in which there is the presence of dialysepalous stellar trichomes; pentamer calyx, small sepals, unequal among one another, two being smaller and three being larger; gamopetalous, pentamer corolla of white coloration; androecium with stamens; bicarpelar gynoecium, with a bilocular supero ovary, with a terminal style, with two fused subglobous stigmas; fruit type capsule normally regular with 4 valves, sometimes irregular, with 2 or 3 valves of coloration ranging from dummy brown to reddish brown when ripe of late and late irregular dehiscence and; black colored seeds, covered by pluricelular tector trichomes, embryo with two leafy cotyledons, green and folded into labyrinth. From the anatomical studies of the seedling, it was found that the epidermis of the abaxial and adaxial face are uniseriate, both with stellar pluricelular tector trichomes, and the mesophyll possesses an hypostomatal dorsiventral arrangement, it presents one or two layers of cells in the palisade parenchyma and two or three layers of cells in the spongy parenchyma and there is the presence of secretory cavities between them, origin of those cavities not being possible to settle, possibly lysigen. For germination, it was found that the seeds have a positive photoblastic behavior. The content of moisture was of 56%, for evaluation of physiological quality. Considering the root protrusion and the appearance of normal seedlings, one should proceed the analysis between sand at 25ÂC or under paper at 30ÂC. In in vitro germination, it is advised to utilize the MS medium with a 50% reduction of concentration of salts added of 1 mgL-1 de GA3.

ASSUNTO(S)

agronomia

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