Cafeeiros em formação e produção em diferentes níveis de radiação: características morfofisiológicas

• Ano de defesa: 2011
• Autor(a) principal: Baliza, Danielle Pereira
• Orientador(a): Guimarães, Rubens José
• Banca de defesa: Castro, Evaristo Mauro de, Silva, Virgílio Anastácio da, Paiva, Leandro Carlos
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Lavras
• Programa de Pós-Graduação: Programa de Pós-Graduação em Agronomia/Fitotecnia
• Departamento: Departamento de Agricultura
• País: BRASIL
• Palavras-chave em Português: Coffea arabica L.; Ecofisiologia; Sombreamento; Sistemas agroflorestais; Echophysiology; Shading; Agroforestry systems
• Área do conhecimento CNPq: Ciências Agrárias
• Link de acesso: https://repositorio.ufla.br/handle/1/3092

The coffee trees shading has been indicated for regions under unfavorable environmental and management conditions. Currently there is in Brazil a great demand for knowledge about this culture system. The aim was to evaluate the morphological and physiological mechanisms of the formation and production of coffee trees grown under different radiation levels (full sunlight and plastic screens/sombrites with 35, 50, 65 and 90% shade). The first experiment was made with coffee trees in formation phase, the morphological-physiological characteristics and the incidence of cercosporiosis evaluated during the dry and rainy seasons. Under high luminosity and low water availability conditions, the coffee leaves have greater thickness of the cuticle adaxial face. The increase of the radiation availability causes the increase of the leaf thickness and stomata density, besides the reduction of the stomata size of coffee trees in formation phase. These changes potentially favour the photosynthesis process up to the 65% shade level, the 30% shade level being the most recommended. At each 10% increase in the shade level, there is reduction of about 5% in the photosynthesis rate and 10% in the cercosporosis incidence in coffee trees in the formation phase. The second experiment was carried out in crop production phase where the gas exchange characteristics, chlorophyll content, nitrogen content and leaf anatomy in the rainy and dry seasons were evaluated. In coffee trees in production phase the radiation levels change very little in the chlorophyll full content and the a/b chlorophylls proportion. The increase of the radiation availability causes the increase of the leaf thickness and stomata density, besides the reduction in the stomata size of coffee trees in the production phase. These changes potentially favour the photosynthesis process up to 50% shade level, the 20% shade level being the most recommended. The highest photosynthesis rate occurs in 21% and 26% shade levels, under low and high water availability in the soil, respectively.