Revista Engenharia na Agricultura
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Item Uso do calcário e do gesso agrícola em duas épocas de implantação do Coffea arabica L.(Revista Engenharia na Agricultura, 2020-10-30) Costa, Bruna Penha; Duarte Júnior, José Barbosa; Rego, Carlos Augusto Rocha de Moraes; Costa, Antonio Carlos Torres da; Lana, Maria do CarmoO Brasil apresenta predominância de solos ácidos sendo necessário à sua correção para atenuar o efeito da acidez sobre as culturas agrícolas, em especial o café que é sensível ao pH baixo e a quantidade de cálcio no solo. Diante disso, o objetivo deste trabalho foi avaliar o efeito da adição de diferentes doses de calcário e gesso agrícola e seus efeitos nas características agronômicas do cafeeiro em dois experimentos com época distinta de implantação da cultura. O delineamento experimental foi em blocos casualizados, com quatro repetições em esquema fatorial 4 x 4, onde o primeiro fator foi constituído por doses crescentes de calcário e o segundo por doses crescente de gesso. O primeiro experimento foi conduzido no período do inverno - verão e o segundo experimento no período da primavera – outono. As variáveis analisadas foram altura de planta (AP), diâmetro do caule (DC), índice de área foliar (IAF), matéria seca foliar (MSF), matéria seca radicular (MSR) e comprimento radicular (CR). Ao analisar as médias dos experimentos se observou que no experimento I, a AP apresentou valores superiores a do experimento II, com acréscimo de 1,84 cm nessa variável. Para as demais variáveis DC, IAF, MSF e MSR no experimento II alcançaram um incremento superior em relação ao experimento I na ordem de 0,4 mm, 9,08 cm2, 1,54 g, 4,12 g respectivamente. As doses de calcário e gesso agrícola não proporcionaram alterações das variáveis agronômicas em ambas às épocas avaliadas, durante o período de seis meses após transplantio.Item Pyraclostrobin preserves photosynthesis in arabica coffee plants subjected to water deficit(Revista Engenharia na Agricultura, 2020-02-07) Peloso, Anelisa Figueiredo; Tatagiba, Sandro Dan; Amaral, Francisco José Teixeira; Cavatte, Paulo César; Pezzopane, José Eduardo MacedoThe objective of this study was to investigate the effect of pyraclostrobin on the photosynthetic performance of rabica coffee plants subjected or not to a water deficit, using the parameter of gas exchange (net CO2 assimilation, stomatal conductance, transpiration rate, and internal CO2 concentration and nocturnal respiration), chlorophyll fluorescence a parameters (minimum fluorescence, maximum fluorescence, maximum quantum yield of photosystem II, effective quantum yield of PSII, quantum yield of regulated energy dissipation and quantum yield dissipation non-regulated) as well as the concentrations of chloroplast pigments. In the plants maintained without water deficit, pyraclostrobin did not cause any alteration on the parameters of chlorophyll a fluorescence; however, it contributed to an increase in the level of chlorophyll a + b, CO2 assimilation and CO2 influx for the carboxylation sites of the stroma. Decreases in nocturnal respiration in plants treated with pyraclostrobin, submitted or not to water deficit seems to be a common strategy in reducing energy waste in the maintenance metabolism. Under water deficit, pyraclostrobin contributed to increase the photochemical yield, enabling plants to effectively prevent the capture, use and dissipation of light energy.Item Drying kinetics of peeled coffee submitted to different temperatures and relative humidity of the air of drying after partial drying(Revista Engenharia na Agricultura, 2020-12-15) Moreira, Rodrigo Victor; Correa, Jefferson Luiz Gomes; Andrade, Ednilton Tavares de; Rocha, Roney Alves daThe mathematical modelling is fundamental for the understanding of the related processes the drying, that influences the quality of the coffee drink. The objective of this study was to evaluate the influence of different relative humidity of the drying air after partial drying on drying kinetics of peeled coffees. Coffee fruits were harvested in the cherry stage and processed by wet, resulting in the portion of peeled coffee. Eleven treatments of drying were accomplished, being nine results of the combination of three dry bulb temperatures and three dew point temperatures, more two treatments without the control of the dew point temperatures. The control of the relative humidity by the dew point temperature was made after the grains reached the partial drying. Among the studied models, those of Diffusion Approximation and Modified Midilli were the most adequate for describing the drying process of the first and second part of drying respectively. The effective diffusivity coefficient of water in coffee grains ranged from 0.81 x 10-11 to 1.84 x 10-11 m² .s-1 during the first part of the drying and ranged from 1.49 x 10-11 to 3.29 x 10-11 m² .s-1 during the second part of the drying, increasing significantly with the reduction of the dew point temperature and increase of the dry bulb temperature.