Sistema vascular e atividade cambial em Alibertia concolor (Cham) k. Schum. (Rubiaceae)
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Data
2012-04-27
Autores
Lara, Natalia Oliveira Totti de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A família Rubiaceae é a quarta maior família entre as eudicotiledôneas, possui distribuição pantropical com representantes arbustivos a arbóreos, sendo as regiões sul-americanas aquelas que superam todas as regiões do mundo em diversidade de espécies da família. Em ambientes tão diversos, um conjunto de fatores pode influenciar, direta ou indiretamente, a atividade do câmbio vascular nas espécies arbóreas desses ambientes e consequentemente em seus produtos, o xilema e floema secundários. Assim, este estudo abrange a caracterização do sistema vascular secundário bem como a atividade cambial e a diferenciação celular em relação à fenologia da espécie e às condições climáticas da região. Para tanto, foi escolhida a espécie Alibertia concolor (Cham) K. Schum. (Rubiaceae) por apresentar camadas de crescimento bem demarcadas no lenho, com potencial para análise de atividade cambial e periodicidade de crescimento. Foram realizadas seis coletas em cinco espécimes em área de floresta estacional semidecidual no Jardim Botânico da UNESP, Campus de Botucatu, no ano de 2010. Xilema e floema secundários mostram um paralelismo entre suas características anatômicas. O xilema secundário da espécie apresenta camadas de crescimento demarcadas por faixas marginais de parênquima axial, enquanto que o floema secundário apresentou faixas tangenciais de fibras intercalando as camadas de células vivas do floema. Porosidade difusa foi visualizada nos vasos do xilema secundário e também não foi observada diferença no tamanho dos elementos de tubo crivado no floema secundário quando comparados os floemas inicial e tardio. Os elementos de vaso do xilema secundário possuem placa de perfuração simples e os elementos de tubo crivado, por sua vez, possuem placas crivadas simples. Fibras gelatinosas...
The family Rubiaceae is the fourth largest family between eudicotyledonous. It has a pantropical distribution with shrubs to trees. In South American regions the family surpass all regions of the world in species diversity. In such diverse environments a set of factors can influence, directly or indirectly, the activity of vascular cambium in woody species of this family, and thus their products, the secondary xylem and phloem. The goal of this study was to characterize the secondary vascular system in one of the representative species from Rubiaceae, Alibertia concolor (Cham) K. Schum., its cambial activity and cell differentiation in relation to the phenology of the species and climatic conditions of the region. The species was selected because the growth rings in the wood were well-defined which suggests growth periodicity. We collected periodically samples of five specimens in a semideciduous forest at the Botanical Garden of UNESP, Botucatu, in the year 2010. Secondary xylem and phloem show a parallel between their anatomical characteristics. Marginal bands of axial parenchyma delimits growth rings in the xylem while tangential fiber bands are present in the phloem. Diffuse porosity in the xylem and no difference in the size of sieve tube elements in the phloem. Simple perforation plates in vessel elements, and simple sieve plates in sieve tube elements. Rays are predominantly uniseriate and biseriate in the xylem as well as in the phloem. The species is evergreen, however, there is a remarkable period of growth and sprouting of buds in December. Flower buds and flowering were observed in January-February. The initiation of cambial activity occurred in December, and it was related to the first rains and budding. The ending of cambial activity occurred in February, rainy season, and cambium remained dormant until October. In the... (Complete abstract click electronic access below)
The family Rubiaceae is the fourth largest family between eudicotyledonous. It has a pantropical distribution with shrubs to trees. In South American regions the family surpass all regions of the world in species diversity. In such diverse environments a set of factors can influence, directly or indirectly, the activity of vascular cambium in woody species of this family, and thus their products, the secondary xylem and phloem. The goal of this study was to characterize the secondary vascular system in one of the representative species from Rubiaceae, Alibertia concolor (Cham) K. Schum., its cambial activity and cell differentiation in relation to the phenology of the species and climatic conditions of the region. The species was selected because the growth rings in the wood were well-defined which suggests growth periodicity. We collected periodically samples of five specimens in a semideciduous forest at the Botanical Garden of UNESP, Botucatu, in the year 2010. Secondary xylem and phloem show a parallel between their anatomical characteristics. Marginal bands of axial parenchyma delimits growth rings in the xylem while tangential fiber bands are present in the phloem. Diffuse porosity in the xylem and no difference in the size of sieve tube elements in the phloem. Simple perforation plates in vessel elements, and simple sieve plates in sieve tube elements. Rays are predominantly uniseriate and biseriate in the xylem as well as in the phloem. The species is evergreen, however, there is a remarkable period of growth and sprouting of buds in December. Flower buds and flowering were observed in January-February. The initiation of cambial activity occurred in December, and it was related to the first rains and budding. The ending of cambial activity occurred in February, rainy season, and cambium remained dormant until October. In the... (Complete abstract click electronic access below)
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Palavras-chave
Anatomia vegetal, Rubiacea, Cambio (Botanica), Plant anatomy
Como citar
LARA, Natalia Oliveira Totti de. Sistema vascular e atividade cambial em Alibertia concolor (Cham) k. Schum. (Rubiaceae). 2012. 117 f. Dissertação (mestrado) - Universidade Estadual Paulista Julio de Mesquita Filho, Instituto de Biociências de Botucatu, 2012.