RESUMO -
INFLUENCE OF DIFFERENT SHADING LEVELS IN PHYSIOLOGICAL BEHAVIOR OF COFFEE CULTIVARS (Coffea arabica L.)ABSTRACT -The objective of this work was to examine the coffee cultivars Acaiá MG 474/19, Catuaí MG 99, Icatu Amarelo MG 3282 and Rubi MG 1192, in relation to parameters such as water potencial, transpiration, leaf surface temperature, stomatic conductance, photosynthesis, internal carbon concentration and PSII photochemical efficiency when submitted to shading levels of 30, 50 and 70% and full sunlight. The evaluations were made in cuttings from these cultivars. The experimental design used was fully randomized with three pots for each treatment. The leaf water potential did not change according to treatments.The photosynthesis, stomatic conductance, transpiration and PSII photochemical efficiency showed significative variations in function of shading levels.
INDEX TERMS:Coffee tree, shading, photosynthesis, water relations.
INTRODUÇÃOAs cultivares recomendadas para o plantio em escala comercial apresentam elevado potencial econômico, que não tem sido explorado adequadamente pela maior parte dos cafeicultores, e para o estabelecimento e plantio, a escolha adequada é um fator que, sem dúvida, pode afetar mais a produtividade.Apesar do grande número de espécies de café existentes, pouco se sabe sobre o potencial comercial que encerram e seu possível aproveitamento nos planos de melhoramento, sendo os países cafeicultores carentes de estudos comparativos (Fazuoli, 1986).1. Parte da dissertação de mestrado do primeiro autor. 2. Engenheiro Agrônomo, MS em Fisiologia Vegetal,
Objetivou-se verificar o efeito da adubação de 100 g de N/ano/planta, em três épocas (outono-inverno, primavera-verão e outono-inverno/primavera-verão) e três modos de aplicação (folha, solo e folha/solo), no desenvolvimento, na produção e na atividade da redutase do nitrato (RN) da cultivar Rubi-MG com quatro anos de idade. A análise conjunta entre o modo e época de aplicação mostra que o padrão de RN não se altera, sendo no frio maior nas raízes e no calor maior nas folhas. O mesmo aconteceu com o padrão de crescimento, rápido na estação quente/chuvosa e lento no período seco/frio. Em função da época de adubação, concluiu-se que, no outono-inverno, deve-se dar preferência pela aplicação na folha ou folha-solo. Esses modos de adubação foram os mais eficientes na retomada do crescimento. Quando as adubações ocorrerem nos dois períodos, qualquer um dos três modos pode ser utilizado. Apesar da inviabilidade de várias pulverizações, eventualmente, uma ou mais pulverizações com KNO3 podem substituir eficientemente a adubação no solo.
The process of soil erosion begins with the removal of native vegetation, which exposes the soil surface to the impact of raindrops, whose kinetic energy causes the destruction of its structure, releasing the different constituents of the texture to be carried by the wind and by the floods. In this sense, the disorderly growth of cities brings serious problems for the urban space, mainly related to subdivisions and waterproofing, which can trigger and / or intensify erosion processes. Thus, this research aimed to characterize, from a geological perspective, three ravines located in the neighborhoods of Colina da Praia (Rav 1), Ribeira de Baixo (Rav 2) and Praia (Rav 3), in the city of Itabira (MG), identifying the factors that favor its development. The analysis of the satellite images allowed to indicate the anthropic interference in these areas, evidenced by the removal of vegetation, opening of lots and streets. As for the geological characterization, it is possible to emphasize the presence of schist rock and granitic-gneiss rock, as well as similar orientations between the direction of ravines 1 and 3 with the fracture planes obtained. Considering the granulometric analysis of soil samples of the three ravines analyzed, it is verified the predominance of soil with medium texture, which commonly has a medium erodibility index. However, the anthropic interference characterized by the removal of the vegetation cover and the opening of road, together with the geological structuring, are factors that contribute, inseparably, to the development of the erosive processes analyzed. The importance of pedological surveys for proper land use planning is emphasized, which will minimize the negative impacts of natural environments.
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