Coffee Science - v.14, n.3, 2019

URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/12417

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Initial stages of infectious process of Pseudomonas syringae pv. garcae in coffee leaves
(Editora UFLA, 2019-07) Souza, José Otávio Gusmão de; Pozza, Edson Ampélio; Belan, Leônidas Leoni; Freitas, Marcelo Loran de Oliveira; Oliveira, Júlia Marques
Bacterial blight of coffee (Pseudomonas syringae pv. garcae) (PSG) has been causing damage and losses to coffee growing. However, initial stages of the infectious process should be described in order to understand the relationship cycle and to propose efficient management strategies. This study described the initial stages of infectious process of the PSG in coffee leaves over time. The bacterial penetration sites studied were stomata, leaf margins, and wounds. Coffee seedlings received 50μL inoculum suspension at marked points on the abaxial face and leaf margins, and around wounds. By 30 minutes, 1, 3, 6, and 12 hours after inoculation, leaf disks collected at inoculated points were analyzed with scanning electron microscopy. One hour after inoculation, bacterial groups could be seen as result of cell multiplication. Subsequently, the number of grouped bacteria increased proportionally over time. A growing population concentration was found near stomata, wounds, epidermal appendages, and wax layer on leaf margins and leaf tip. From these places bacteria were positioned in their long axis starting from structures, thus created a population gradient and displacement flow toward penetration sites. Initial stages of infectious process occurred in all penetration sites, thus it was not possible to determine a preferred pathway.
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 Donizeti
The 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.
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 Donizeti
The 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.