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

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

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Effects of shade trees spatial distribution and species on photosynthetic rate of coffee trees
(Editora UFLA, 2019-07) Silva Neto, Francisco José da; Bonfanti, Leila; Gazaffi, Rodrigo; Fontanetti, Anastácia
The use of shade trees in coffee fields have been motivated by climatic changes. However, microclimatic conditions in shaded coffee fields differ due to shade tree spatial distribution and species, altering physiological responses of coffee trees. This study aimed to evaluate the effects of shade tree spatial distribution and species on coffee trees photosynthetic rate in two growth seasons, of high (HSD) and low (LSD) sink demand. The experimental design consisted of randomized blocks with three replicates in split-split-plots. Plots were the shade tree species: Anadenanthera falcata, Cassia grandis and Peltophorum dubium. Split plot was formed by five distances between coffee trees and shade tree trunks: coffee trees on planting row of shade trees, distancing one (D1L) and five (D5L) meters from shade trees trunk; coffee trees on inter-rows of shade trees, parallel to D1L and D5L (D1E and D5E); coffee trees distancing 77 meters from shade tree trunks, in a full-sun field (PS). The split-split-plots correspond to coffee tree canopy exposure to the sun: branches facing North or South. Shade trees canopy density and occupation was evaluated with a convex densiometer. Photosynthetic rate (P n )and photosynthetic active radiation (PAR) were measured with an Infrared Gas Analyzer (IRGA) on two time-frames, between 7.00 and 9.00 solar hours and between 11.00 and 13.00. Shade tree canopy density and occupation was not homogenous during the change of seasons and shift due to spatial distribution, which also changes PAR levels. Shade trees reduce PAR to more suitable values for coffee tree exploitation, especially on D1L and D5L. During HSD, shading did not affect P n , which was greater in branches facing North. Yet, in LSD, between 11.00 and 13.00, coffee trees shaded with A. falcata showed greater P n than at PS. Coffee trees shaded with C. grandis at D5L and D1E had greater values of P n than PS.
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.