A process-based model to simulate sugarcane orange rust severity from weather data in Southern Brazil.

Forecasting the severity of plant diseases is an emerging need for farmers and companies to optimize management actions and to predict crop yields. Process-based models are viable tools for this purpose, thanks to their capability to reproduce pathogen epidemiological processes as a function of the variability of agro-environmental conditions. We formalized the key phases of the life cycle of Puccinia kuenhii (W. Krüger) EJ Butler, the causal agent of orange rust on sugarcane, into a new simulation model, called ARISE (Orange Rust Intensity Index). ARISE is composed of generic models of epidemiological processes modulated by partial components of host resistance and was parameterized according to P. kuenhii hydro-thermal requirements. After calibration and evaluation with field data, ARISE was executed on sugarcane areas in Brazil, India and Australia to assess the pathogen suitability in different environments. ARISE performed well in calibration and evaluation, where it accurately matched observations of orange rust severity. It also reproduced a large spatial and temporal variability in simulated areas, confirming that the pathogen suitability is strictly dependent on warm temperatures and high relative air humidity. Further improvements will entail coupling ARISE with a sugarcane growth model to assess yield losses, while further testing the model with field data, using input weather data at a finer resolution to develop a decision support system for sugarcane growers.

Speed and rotation variations in gathering coffee machine / Variações de velocidades e rotações no recolhimento mecanizado do café

The mechanized harvesting operation of coffee sweep from ground have a great importance, due the value of the coffee that was lost by the harvest process, as well as the breakdown of the cycle of pests that can damage the coffee. To change work settings can influence significantly the capacity of the gathering system. Due, the objective of this study was to evaluate the influence the speed of displacement and rotations of the components of gathering coffee machine in its performance. The experiment was carried out in the municipality of Presidente Olegário-MG on coffee plantations aged 10 to 11 years. The field, presenting an average of 990 kg ha-1 of coffee present in the soil after the machine harvest. The engine rotations of the tractor evaluated were 146.6, 162.3, 178.0, 193.7, and 209.4 rad.s-1 combined with the 1stA and 2ndA gears, resulting in different working speeds. The treatments were distributed in randomized blocks with five replicates. The variables analyzed were the gathering efficiency, cleaning efficiency, coffee losses, and percentage of mineral and vegetal impurities. It was concluded that the gathering efficiency was higher when working with 178.0 rad.s-1 at 1.26 km h-1, resulting in lower coffee losses in the operation, a preponderant factor in the study. On the other hand, the best cleaning efficiency of the machine was found when using 193.7 rad.s-1 and 1.37 km h-1.

A operação de recolhimento mecanizado do café de varreção apresenta grande importância, devido ao valor do café que é perdido pelo processo de colheita, como também pela quebra do ciclo de pragas que podem prejudicar o cafeeiro. A alteração de regulagens de trabalho da recolhedora pode influenciar significantemente na capacidade do sistema de recolhimento. Portanto, objetivou-se neste trabalho avaliar a influência da velocidade de deslocamento e das rotações dos componentes da recolhedora no seu desempenho. O experimento foi realizado no município de Presidente Olegário-MG em lavoura de café com idade de 10 a 11 anos. A área estudada foi caracterizada, apresentando média de 990 kg ha-1 de café presentes no solo para recolhimento. As rotações do motor do trator avaliadas foram de 146.6, 162.3, 178.0, 193.7, e 209.4 rad.s-1 combinadas com as marchas 1ªA e 2ªA, resultando em diferentes velocidades de trabalho. Os tratamentos foram distribuídos em blocos casualizados com cinco repetições. As variáveis analisadas foram a eficiência de recolhimento, eficiência de limpeza, perdas de café e porcentagem de impurezas minerais e vegetais. Concluiu-se que a eficiência de recolhimento foi maior quando se trabalhou com 178.0 rad.s-1 à 1,26 km h-1, originando assim menores perdas de café na operação, fator preponderante no estudo. Por outro lado, a melhor eficiência de limpeza da máquina foi encontrada quando se utilizou 193.7 rad.s-1 e 1,37 km h-1.

Maturation periods for Coffea arabica cultivars and their implications for yield and quality in Brazil.

BACKGROUND: Climatic conditions directly affect the maturation period of coffee plantations, affecting yield and beverage quality. The quality of coffee beverages is highly correlated with the length of fruit maturation, which is strongly influenced by meteorological elements. The objective was to estimate the probable times of graining and maturation of the main coffee varieties in Brazil and to quantify the influences of climate on coffee maturation. We used degree days to estimate flowering/graining periods (green fruit) and flowering/maturation periods (cherry fruit) for all cultivars. We evaluated the influence of climate on the time of maturity using Pearson correlation and nonlinear regression analysis and successfully mapped the influences of these elements. RESULTS: Arabica coffee matured up to 2-3 months earlier in São Paulo, where air temperatures (TAIR ) were higher, than in Minas Gerais, which would allow earlier harvesting and the training of seedlings at the beginning of the rainy season. Catuaí-Amarelo-IAC-62 cultivar needed 205-226 days between the end of flowering and maturation at locations with high TAIR and 375-396 days at locations with low TAIR . CONCLUSION: Water surplus and deficit were generally the most important variables for coffee maturation. Coffee matured faster in regions with high TAIR and evapotranspiration, moderate altitudes and deficits. Acaiá-Cerrado-MG-1474 and Icatu-Precoce-Amarelo-3282 were cultivars with an early cycle. © 2018 Society of Chemical Industry.

Climatic potential for summer and winter wine production.

BACKGROUND: The geoviticultural multicriteria climatic classification (MCC) system provides an efficient guide for assessing the influence of climate on wine varieties. Paraná is one of the three states in southern Brazil that has great potential for the expansion of wine production, mainly due to the conditions that favour two harvests a year. The objective was to apply the geoviticultural MCC system in two production seasons. We used maximum, mean and minimum air temperature and precipitation for 1990-2015 for the state of Paraná. Air temperature and Precipitation were used to calculate the evapotranspiration and water balance. We applied the MCC system to identify potential areas for grapevine production for harvests in both summer and winter and then determined the climatic zones for each geoviticultural climate. RESULTS: Paraná has viticultural climates with conditions favourable for grapevine cultivation for the production of fine wines from summer and winter harvests. The conditions for the winter harvest provided wines with good coloration and high aromatic potential relative to the summer harvest. CONCLUSION: Chardonnay, Merlot, Pinot Blanc and Müller-Thurgau were suitable for regions with lower air temperatures and water deficits. Pinot Blanc and Müller-Thurgau were typical for the southern region of Paraná. © 2017 Society of Chemical Industry.