Avaliação sazonal da atividade da fenilalanina amonia-liase e dos teores de fenois e taninos totais em Byrsonima verbascifolia Rich. ex. A. Juss.: uma especie medicinal do cerrado.

• Autor(a) principal: CASTRO, A. H. F.
• Data de Publicação: 2005
• Outros Autores: ALVARENGA, A. A., SOARES, A. M., YOUNG, M. C. M., PURCINO, A. A. C.
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
• Texto Completo: http://www.alice.cnptia.embrapa.br/alice/handle/doc/489112
• topic: Sazonalidade; Cerrado; Murici; Tanino

An experiment was conducted, ever month, from november, 2001 to september, 2002 in order to investigate the influence of seasonal variation of physical environment on gas exchange, on leaf water state, on the phenylalanine ammonia-lyase activity and on the total phenolic and tannin contents of murici,. The used area was a praire with a physionomy of Cerrado stricto sensu, located in Ijaci, south of the State of Minas Gerais. For the evaluation, plants Were selected with an average height of 2.70 +/- 0.21 m and an average basal diameter of 0.15 +/- 0.04 m. Leaf potential at 7 and 12 am and gas exchange at 10 and 12 am was evaluated ever month. The results showed that the leaf water potential was not significant seasonal variations indicating that the plants were in similar water conditions in both dry and rainy seasons. Higher photosynthetic and transpiration rates-were observed during rainy season. The net photosynthesis showed higher in the morning, although no significant variations of transpiration on the evaluating hours were observed. The stomatal conductance reached similar Values in both seasons, suggesting a participation of non-stomatal factors on the seasonal variation observed for the-gas exchange. It. was also observed significant seasonal variations on enzyme activity and total tannins contents. The increase of the phenylalanine ammonia-lyase activity and decrease Of the total tannins contents were characteristic of the dry season. The levels of total phenolics. had not varied significantly during the dry and rainy seasons, while the total tannin contents followed the photosynthetic response of plants, the enzyme activity was much more influenced by environmental conditions.