Trocas gasosas e metabolismo antioxidativo em Coffea canephora em resposta ao sombreamento promovido por Hevea brasiliensis

• Autor(a) principal: Caten, ângela Ten
• 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/123456789/4348
• topic: Estresse oxidativo; Coffea canephora; Trocas gasosas; Seringueira; Oxidative stress; Coffea canephora; Gas exchange; Rubber tree; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::FISIOLOGIA VEGETAL

Despite being evolved in shady environments, robusta coffee (Coffea canephora) has been traditionally cropped at full exposure. Currently, there is an increasing trend for growing coffee shrubs under taller trees, thus under some degree of shade. In this study, two clones of robusta coffee, 109A (relatively sensitive of oxidative stress) and 120 (relatively tolerant) were compared in order to explore their physiological responses to light availability, and to examine their plasticities to varying irradiance. The experiment was conducted in the field with rows of rubber trees (north-south orientation) planted perpendicularly to the coffee rows (east-west orientation). The evaluations were carried out in the east, middle and west of the coffee hedgerows. Although their photosynthetic rates were very low, photoinhibition of photosynthesis over the course of the day was not detected, even in the more exposed plants to solar radiation. Generally, regardless of treatments, coffee leaves showed similar abilities to dissipate irradiance through photochemical and non-photochemical processes. Leaf inclination changed over the course of the day in both clones, regardless of leaf water status. Overall, activities of antioxidant enzymes tended to be slightly lower in clone 120 than in clone 109A. However, lipid peroxidation, electrolyte leakage and hydrogen peroxide concentration were all similar irrespective of treatments. It is proposed that shading, as it can contribute to a better plant water status, may be a promising alternative to reduce the amount of water employed in irrigation systems or, alternatively, to increase the water-use efficiency of robusta coffee stands.