Caracterização morfo-anatômica da folha e do caule de Brachiaria brizantha (Hochst. ex A. Rich.) Stapf e B. humidicola (Rendle) Schweick. (Poaceae)

Abstract

-(Leaf and stem morpho-anatomical characterization of Brachiaria brizantha (Hochst. ex A. Rich.) Stapf and B. humidicola (Rendle) Schweick. (Poaceae)). The morpho-anatomy of the leaf and stem of B. brizantha and B. humidicola were studied at three plant stratums. The difference among the species and the different stratums were investigated in order to justify the different intensities of consumption that occurs with plant aging. The experiment was carried out in a greenhouse and on plants cultivated in plastic vessels with sterilized sand, receiving nutritive mineral solution. After 70 days, the median leaf of each stratum was collected and divided into limbo and leaf sheath. The same was done to the stem. For the morphological study the total plant height, number of leaves, nodes and sprouts, length and width of blades and sheaths and length and diameter of internodes were measured. For purposes of anatomical characterization the samples were fixed in FAA, embedded in GMA, sectioned in microtome e stained with basic fucsin and Astra blue. The morpho-anatomical studies indicated some parameters that can interfere on tissue digestibility. The species presented different morphology, with shorter and narrower limbo measurements, thereby may affect the accessibility to lower leaves and interfering on the forage consumption. The stem was the fraction with the most variation between species, and showing in B. brizantha a larger stem diameter and thicker culm wall, which make the stem more resistant to apprehension, suggesting a larger number of vascular bundles and, consequently, a high percentage of lignified tissues. Secretory structures were identified below the trichome base cells in the leaf sheaths of B. brizantha, probably as secretory cavities, quite rare in Poaceae and there are no studies about its interference on digestibility and consumption.RESUMO -(Caracterização morfo-anatômica da folha e do caule de Brachiaria brizantha (Hochst. ex A. Rich.) Stapf e B. humidicola (Rendle) Schweick. (Poaceae)). Neste trabalho, caracterizou-se a morfo-anatomia do caule e da folha de Brachiaria brizantha e B. humidicola, em três estratos, objetivando diferenciar tais estratos e espécies, bem como justificar, com estes parâmetros, a diferença de consumo que ocorre nessas espécies com o envelhecimento da planta. O experimento foi conduzido em casa de vegetação, utilizando-se vasos plásticos com areia esterilizada e recebendo solução nutritiva. Aos 70 dias após o corte de uniformização, cada planta foi dividida em três partes (estratos), coletando-se a folha mediana de cada estrato, separando-a em limbo e bainha foliar, e também o entrenó recoberto pela referida bainha. Para o estudo morfológico, foram mensurados a altura total das plantas, número total de folhas, nós e perfilhos, comprimento e largura da lâmina e da bainha foliar, comprimento e diâmetro do entrenó. Para a caracterização anatômica, as amostras foram fixadas em FAA, emblocadas em GMA, seccionadas em micrótomo e coradas com fucsina básica e azul de As...

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Anatomia e morfometria de raízes e folhas de Urochloa brizantha cv. Marandu em diferentes estádios de acometimento da síndrome da morte das pastagens

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