Atividade da redutase do nitrato, teores de nitrogênio e de carboidratos em cafeeiro influenciados pelo sombreamento e estádio fenológico

• Autor(a) principal: Khouri, Camila Rodrigues
• Data de Publicação: 2007
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4456
• topic: Coffea arabica; Nitrato; Nutrição; Coffea arabica; Nitrate; Nutrition; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The objective was to evaluate the activity of the enzyme reductase of nitrate, contents of nitrogen and carbohydrates in leaves of Arabian coffee plant under different levels of shading and position over the plant, during the phases of development of the fruit. The experiment was lead in fortuitous block-type in the project of subdivided parts, with three repetitions. The parts were constituted by the levels of shading (0%, 16%, 32% and 48%), the subparts for three positions of sampling over the plant and the subpart for six phases of development of the fruit. Samples of 3rd and 4th pair of situated branch leaves in three different positions (apex, 3rd medium and base) of the coffee plant were collected. In each position, leaves were collected in the cardinal points (N, S, W, E) of each plant. To the 12 (post- flowering), 69 (fast expansion), 98 (fast expansion), 137 (seed-filling), 169 (seed-filling) and 199 (maturation) days after anthesis, were determined: activity of nitrate reductase (NR); nitrate contents (NO3-), organic nitrogen (ON), total nitrogen (TN); starch contents (SC), reducing sugars (RS), non-reducing (NRS) and total soluble sugar (TSS). In general, the apex of the coffee plant presented lesser contents of NO3- in the seed-filling and maturation phase of the fruit. The contents of NO3- in coffee leaves were higher in the plants with 48% of shading, during the fruit maturation stage. During the fruit development, independently of the studied shading, the activity of the RN was lesser in the fruit maturation stage. The contents ON and TN, in leaves of the apex, were higher in the stage of fast expansion of the fruit. The carbohydrate contents in coffee plant leaves had increased with the development of the fruit, which SC content was higher in the plants under the full sun, and NRS and TSS contents were higher in the plants under 48% of shading. The results suggest that the shading not only influences the photosynthesis, but also the metabolism of nitrogen. Nevertheless, one expects different answers to the shading in different nitrogen availabilities.