Coffee Science
URI permanente desta seção${dspace.url}/handle/123456789/3355
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Resultados da Pesquisa
Item Inhibition of respiration by light in Coffea arabica(Universidade Federal de Lavras, 2023-12-29) Oliveira, Indira Pereira de; Barbosa, João Paulo Rodrigues Alves Delfino; Saleska, Scott; Pennacchi, João Paulo; Prohaska, NeillDescribing gas exchange between plants and the atmosphere is essential to improve current estimates of fluxes and carbon stocks. Light is directly related to gas exchange; when plants are under low light intensities, there is an increase in photosynthetic quantum yield and, consequently, in respiratory rate. That means there is an apparent inhibition of respiration under high light intensity, a phenomenon known as the Kok effect. Considering the effect of light and leaf age, the aim of this study was to describe the physiological responses of daytime gas exchange related to leaves of different ages in Coffea arabica L. cv. Catuaí Vermelho, seeking to identify leaf respiration inhibition by light. The experiment was conducted at the Universidade Federal de Lavras, Minas Gerais, Brazil. Leaves were measured using an infrared gas analyzer (IRGA; LI- 6400XT, LI-COR, Lincoln, NE, USA) and the fluxes were measured to create a light response curve in “in situ”, thus obtaining photosynthetic parameters, used to estimate light and dark respiration, also the rate of inhibition of leaf respiration by light throughout the leaf age. The assimilation (A_sat) and quantum efficiency did not differ among young, mature, and old leaves, showing that photosynthetic process was not affected by leaf age; however, light and dark respiration were higher in young and mature leaves than in old leaves. Inhibition of respiration by light was similar among leaf ages, assuming the occurrence of inhibition of respiration caused by light (the Kok effect).Item Looking for adjustments to severe drought in coffee: lessons of a rainfall exclusion plot in the Southern Brazil(Universidade Federal de Lavras, 2022-12-29) Silva, Debora Valim da; Naves, Vicente Luiz; Toro-Herrera, Mayra Alejandra; Vieira, Daniel Amorim; Mendonça, Ane Marcela das Chagas; Rambal, Serge; Barbosa, João Paulo Rodrigues Alves DelfinoRainfall exclusion experiments allow us assessing the effects of environmental stresses such as long-term water limitations on both leaf and canopy structural traits. This work aimed to evaluate how leaf anatomical traits and canopy development of productive coffee trees change when submitted to more dry conditions in the southern region of Minas Gerais - Brazil. The experimental plots have been set up in a plantation area in which is growing Coffea arabica L. cv. Mundo Novo- IAC 379-19, in a completely randomized arrangement, composed by three treatments: Control (C) - no gutter system; Control plus roof (Ĉ) and Exclusion system (E). Leaf anatomical and canopy traits were determined within a year at the end of each season: late Spring- 2015 (Sp), and late Summer (Su), late Autumn (Au) and late Winter (Wi) - 2016. During the studied period the rainfall exclusion condition led to a reduction in the relative water content (RWC) of leaves. In the leaf-level, as the dry condition increase, the leaves invested in thicker cuticles, reduced xylem and phloem areas and smaller stomata, especially with the rainfall exclusion. In the canopy-level, there was a remarkable reduction in leaf area index (LAI) especially in the winter as a strategy of reduction of transpiratory area, when the availability of water decreased around 25%. In a context of reduced water availability due to effects of climate change, coffee trees may be able to present modifications at both levels, to cope with the effects of this abiotic stress.Item Spatial-temporal patterns of coffee tree physiology(Editora UFLA, 2019-07) Santini, Paula Tristão; Barbosa, Ronei Aparecido; Almeida, Lorena Gabriela; Souza, Kamila Rezende Dázio de; Barbosa, João Paulo Rodrigues Alves Delfino; Alves, José DonizetiThe ecophysiological parameters of coffee canopy were mapped throughout the day. Therefore, evaluations were carried out in ‘Catuaí Vermelho’ Coffea arabica L., measuring 1.7 meters. A vertical gradient (from the apex to the base of the plant canopy) and a horizontal gradient (plagiotropic branches) were established to analyze different positions of the canopy. Thus, in the vertical direction, four heights were analyzed in the plant: top, upper, middle and lower regions. In the horizontal gradient, the plagiotropic branches were divided into three parts: basal, median and apical. Collection was performed on the east and west sides of the canopy, at four times of the day: 6 a.m., 9 a.m., noon, and 3 p.m., totaling 24 collection points at each time. Gas exchange, photosynthetically active radiation and leaf temperature were evaluated in each of the 24 points of the coffee canopy. The gas exchange characteristics of an individual coffee leaf diverge considerably from other leaves, which require caution when scaling estimates of leaf photosynthesis at the global canopy level. The analysis of some punctual leaves does not serve to discriminate the overall dynamics of a canopy.Item Spatio-temporal variability of carbohydrate and chlorophyll content in the coffee canopy(Editora UFLA, 2019-07) Santini, Paula Tristão; Almeida, Lorena Gabriela; Souza, Kamila Rezende Dázio de; Barbosa, João Paulo Rodrigues Alves Delfino; Alves, José DonizetiThe spatial variability of the total chlorophyll content and carotenoids content, starch and soluble sugars of coffee canopy were mapped throughout the day. Therefore, evaluations were carried out in a ‘Catuaí Vermelho’ coffee plant with 1.7 meters height. A vertical gradient (from the apex to the base of the plant canopy) and a horizontal gradient (plagiotropic branches) were established to analyze different positions of the canopy. Thus, in the vertical direction, four heights were analyzed in the plant: top, upper, middle and lower regions. In the horizontal gradient, the plagiotropic branches were divided into three parts: basal, median and apical. Collection of leaf samples was performed on the east and west sides of the canopy, at 9 a.m., totaling 24 collection points at each time. Higher content of photosynthetic pigments and concentration of sugars were observed in the western face and in the inner parts of the coffee tree. The content of chloroplast pigments and sugars of an individual coffee leaf diverge considerably from other leaves, which requires caution when scaling estimates at the global canopy level. The analysis of some punctual leaves does not serve to discriminate the overall dynamics of a canopy.Item Estimativa do IAF de cafeeiro a partir do volume de folhas e arquitetura da planta(Editora UFLA, 2012-09) Barbosa, João Paulo Rodrigues Alves Delfino; Martins, Giordane Augusto; Ferreira, Rafael Teixeira; Pennacchi, João Paulo; Souza, Vinícius Fernandes de; Soares, Angela MariaOs métodos de estimativa do índice de área foliar (IAF) utilizados para cafeeiros (Coffea arabica L.) apresentam limitações relacionadas à representação de particularidades da cultura que afetam o IAF no tempo e no espaço. Desenvolveu- se este trabalho objetivando propor um método de estimativa do IAF de forma a reduzir essas limitações. Foram utilizados cafeeiros em fase produtiva, de cultivos da região de Lavras-MG, das variedades Mundo Novo e Catuaí, coletados durante a estação seca e a estação chuvosa de 2010 a 2011. Nessas plantas avaliou-se a altura a partir do nível do solo, comprimento total de ramos plagiotrópicos, o comprimento da região sem folhas na copa e o IAF. Esses dados foram utilizados para estimar o volume de folhas das plantas e, posteriormente, para a obtenção de equações que descrevem o comportamento do IAF em função do volume de folhas. Verificaram-se três ajustes das variações de IAF em função do volume de folhas: comportamento linear, expolinear e sazonal. Os três modelos apresentaram estimativas realistas, quan do aplicados em cafeeiros do município de Três Pontas-MG. Potencialmente, os modelos podem ser aplicados na estimativa do IAF de uma planta isolada ou para parcelas homogêneas. Possuem a vantagem de uma representação mais realista da forma da planta no tempo e no espaço em comparação com métodos semelhantes. Com o método proposto, espera-se atender demandas de modelos de previsão de produtividade de cafeeiros, reduzindo as limitações observadas nos métodos comumente utilizados para a determinação do IAF.Item Trocas gasosas e características estruturais adaptativas de cafeeiros cultivados em diferentes níveis de radiação(Editora UFLA, 2012-09) Baliza, Danielle Pereira; Cunha, Rodrigo Luz da; Castro, Evaristo Mauro de; Barbosa, João Paulo Rodrigues Alves Delfino; Pires, Marinês Ferreira; Gomes, Rodrigo AbreuDiferenças nos níveis de radiação podem causar modificações nas características estruturais e funcionais das folhas, que podem responder diferencialmente por modificações anatômicas, morfológicas e fotossintéticas. Objetivou-se, no presente trabalho, verificar as possíveis modificações na anatomia foliar e características fotossintéticas de cafeeiros em fase de formação, submetidos a diferentes níveis de radiação. Após o plantio dos cafeeiros no campo, esses foram submetidos a cinco níveis de radiação (pleno sol e sob telas plásticas/sombrites de 35, 50, 65 e 90% de sombra). Os cafeeiros foram avaliados quanto às trocas gasosas e anatomia foliar dez meses após a instalação do ensaio em campo. De acordo com os resultados obtidos nesse experimento, verifica-se que a quantidade de radiação incidente influencia a estrutura interna das folhas dos cafeeiros e suas respectivas funções. O nível com 90% de sombra não é recomendado para o cultivo do cafeeiro, pois reduz a taxa fotossintética, apresentando menor espessamento do mesofilo e do parênquima paliçádico. O nível com 35% de sombra é o mais recomendado para cultivo do cafeeiro em ambiente sombreado pois, nesse nível ocorre melhoria da estrutura interna das folhas do cafeeiro, o que pode favorecer características fisiológicas interessantes para otimizar o desenvolvimento dessa cultura.