Luiz Gonsaga de Carvalho

Application of the Köppen classification for climatic zoning in the state of Minas Gerais, Brazil

The knowledge of the climatic conditions of a region is crucial for its agricultural development. It is also extremely important for understanding the fact that certain cultures have to develop under prevailing temperature and humidity conditions and assist in the adoption of a suitable irrigation technique, as well as its management and operationalization. The Köppen system of climate classification is widely used for the identification of homogeneous climate zones as it considers only rainfall and temperature as the meteorological elements for classification. For this study, we used climatic databases of rainfall and temperature in a raster format, with a spatial resolution of 30″ of arc (an approximate area of 0.86 km2 pixel−1), from 1961 to 1990. Through geoprocessing techniques, we obtained a map of climatic classification for the state of Minas Gerais. We found that the state has the following three major climatic groups: A, B and C, which correspond to tropical rainy, dry and warm temperate climates, respectively. The climate classes obtained were Aw, Am, BSh, Cwa and Cwb, with Aw, Cwa and Cwb classes occupying 99.89% of the territorial area of the state. The validation of the results showed a satisfactory agreement, with 93.75% reliability.

Zoneamento climático associado ao potencial produtivo da cultura do café no Estado de Minas Gerais

Os sistemas de informacoes geograficas podem ser considerados instrumentos para mapear e indicar respostas as varias questoes sobre o planejamento urbano e regional, o meio rural e levantamento dos recursos renovaveis. A execucao do zoneamento climatico para a cultura do cafe, utilizando-se sistemas de informacoes geograficas, proporciona resultados mais satisfatorios, visto que os dados inicialmente coletados sao armazenados, facilitando sua manipulacao e analise e exibindo um resultado final de melhor qualidade, quando comparado com outros metodos mais tradicionais. As caracteristicas agroclimaticas das diversas regioes influenciam, diferentemente, a produtividade final da cultura do cafe. Assim, este trabalho teve como objetivo analisar o grau de correspondencia entre o zoneamento climatico para a cultura do cafe e o potencial produtivo da cultura no Estado de Minas Gerais. O zoneamento climatico mostrou-se eficiente na delimitacao das regioes climaticamente homogeneas quanto a capacidade produtiva da cultura do cafe no Estado; Minas Gerais apresenta 37% de seu territorio com condicoes adequadas ao cultivo do cafe, 45% com alguma restricao e 18% sao considerados inaptos; as areas aptas ao cultivo do cafe se concentram no Centro-Sul do Estado.

Modelo de regressão para a previsão de produdividade de cafeeiros no Estado de Minas Gerais

The objective of this work was to set up and test a multiple linear regression model applied to principal components for representative coffee crop yield series for three places in Southern Minas Gerais, based on the model proposed by Stewart et al. (1976), with new variables, represented by agrometeorological elements, besides the soil water depletion for the four quarterly periods in agricultural cycle (July to June). Since the number of observations was lower than the amount number of variables, we resorted to principal component analysis to reduce the dimension of this set of variables. The multiple linear regression analysis was applied to the first three principal components. In agreement with the tests, the model presented relative errors of estimates with high discrepancies and a tendency to overestimate productivity for the three places. However, it was verified that the estimates for the model tended to present behavior similar to observed data.

Coeficiente de cultura (Kc) do cafeeiro (Coffea arabica L.) no período de outono-inverno na região de Lavras - MG

Water balance is very important for evaluating inflow and outflow water in a soil block explored by a crop. This situation allows to estimate parameters associated to crop water schedule such as evapotranspiration and crop coefficient (kc), which are present as physical and biological indicators, especially when associated to the phenologic cycle. Therefore, the objective of this paper was to monitor water and climatic regime from April to Setember/2004 of an adult coffee crop of the cultivar Catuai pruned four years before, and to estimate crop evapotranspiration (ETc) and Kc, applying the water balance method. The results allowed concluding that the coffee crop presented ETc values between 1.23 and 4.39 mm day-1 and Kc from 0.59 to 1.16. Kc showed a relationship with coffee crop phenology; however, it indicated a decrease of the dormancy period and an anticipation of the coffee fruits formation and vegetative development.

Zoneamento bioclimático da região sudeste do Brasil para o conforto térmico animal e humano

The main goal of this study was to evaluate the Southeastern Brazilian climate conditions through temperature-humidity index (THI) and to present a bioclimatic mapping relating to animal and human thermal comfort. The THI values were estimated by air-temperature and relative humidity for a period from 1980 to 2000. Four intervals of THI were used to classify human performance (THI 84: extremely hot) and two intervals to classify animal production (79 84: emergency). The results showed higher risk of thermal discomfort in the period from October to April, comparing to the period between May and September. The worst period was the one between December and March. Although it was observed that THIaverage values among 79 and 83 occurred in less than 3.6% of the time, humans as well as animals could suffer some amount of thermal stress during the hottest period of the day, affecting negatively both animal production and human comfort. THI greater than 84 was not verified on the Southern Brazilian region.

Adaptive neuro-fuzzy inference systems for epidemiological analysis of soybean rust

The objective of this work was to develop and to evaluate adaptive neuro-fuzzy inference systems as methodology to describe the severity of soybean rust (Phakopsora pachyrhizi) monocyclic process in soybean Glycine max (L.) Merr.], under effects of leaf wetness, temperature, and days after fungi inoculation. The experiment was conducted in growth chambers with mean air temperatures of 15, 20, 25 and 30?C and leaf wetness periods of 6, 12, 18 and 24h. The plants were inoculated by spraying a suspension of P.?pachyrhizi inoculum at concentration of 104 uredinosporemL-1. A disease assessment key was adopted for estimate amounts of soybean rust at 0, 6, 9, 12 and 15 days after fungi inoculation. A hybrid neural network training with 3 and 3000 epochs was applied to disease severity data for optimization of fuzzy system parameters used to describe the severity of soybean rust based on leaf wetness, temperature and days after fungi inoculation. Higher accuracy and precision of the neuro-fuzzy systems estimates were obtained after training with 3000 epochs. Nevertheless, training with 3 epochs produced smoother estimates. The neuro-fuzzy systems enabled to describe the severity of soybean rust monocyclic process under effects of leaf wetness, mean air temperature and days after fungi inoculation and was better applied for Conquista cultivar, followed by Savana and Suprema cultivars. Higher soybean rust severity was verified under temperatures among 20?C and 25?C, leaf wetness above 6h, with higher values above 10h, and 15 days after fungi inoculation. Temperatures near 15?C increased the latent period of the disease but not inhibited its development after 10 days of fungi inoculation.

Spatial analysis of the influence of meteorological elements on the reference evapotranspiration in the State of Minas Gerais, Brazil

In general the methodologies most used and recommended to estimate crop water requirements are based on meteorological data. The aim of this study was to evaluate the effect of some meteorological elements on reference evapotrasnpiration (ET0) estimate in Minas Gerais State, Brazil. The values of ET0 were estimated daily by the Penman-Monteith-FAO method, using daily data over a period of 17 years. The influence of each meteorological element on ET0 values was determined by sensitivity tests and interpolated map analysis for each element under study. The results showed that the reference evapotranspiration is very variable in Minas Gerais, with annual average values between 2.51 to 4.59 mm d-1. The sensitivity analysis showed a high variation effect of meteorological elements in ET0 in Minas Gerais, with high sensitivity to vapor pressure deficit, wind speed and radiation. The radiation was the most important meteorological element, with the highest influence in ET0.

Geostatistical improvements of evapotranspiration spatial information using satellite land surface and weather stations data

The objective of the present study was to use the simple cokriging methodology to characterize the spatial variability of Penman–Monteith reference evapotranspiration and Thornthwaite potential evapotranspiration methods based on Moderate Resolution Imaging Spetroradiometer (MODIS) global evapotranspiration products and high-resolution surfaces of WordClim temperature and precipitation data. The climatic element data referred to 39 National Institute of Meteorology climatic stations located in Minas Gerais state, Brazil and surrounding states. The use of geostatistics and simple cokriging technique enabled the characterization of the spatial variability of the evapotranspiration providing uncertainty information on the spatial prediction pattern. Evapotranspiration and precipitation surfaces were implemented for the climatic classification in Minas Gerais. Multivariate geostatistical determined improvements of evapotranspiration spatial information. The regions in the south of Minas Gerais derived from the moisture index estimated with the MODIS evapotranspiration (2000–2010), presented divergence of humid conditions when compared to the moisture index derived from the simple kriged and cokriged evapotranspiration (1961–1990), indicating climate change in this region. There was stronger pattern of crossed covariance between evapotranspiration and precipitation rather than temperature, indicating that trends in precipitation could be one of the main external drivers of the evapotranspiration in Minas Gerais state, Brazil.

Spatial-temporal analysis of water requirements of coffee crop in Minas Gerais State, Brazil

Scientific investigations about crop water requirements are of fundamental importance to the irrigation process. The main objective of this paper is to analyze and to map water requirements of coffee crop in Minas Gerais State, Brazil. Potential evapotranspiration values (ET0) were estimated by the Penman-Monteith-FAO method, using daily data sets available for 42 National Meteorology Institute (INMET) stations for a period of 17 years. The crop coefficient values (kc) considered were extracted from literature. The results were analyzed by means of geostatistical tools. The theoretical semi-variograms were fitted by the Maximum Likelihood method, considering spherical, exponential and Gaussian models. The maps were created using the ordinary kriging method. In a general way, the results have showed that the coffee crop evapotranspiration (ETc) presents high variability in Minas Gerais State. The largest variations, both spatial and temporal, have been observed in the northern part of the State. January and June, respectively, presented the highest and the smallest water requirements of coffee crop. Based on this, we can conclude that due to the coffee crop evapotranspiration (ETc) data distinction in different regions of Minas Gerais, a good estimate of the ETc values for each locality will bring many benefits to the coffee growers regarding irrigation scheduling.

FAO Penman-Monteith equation for reference evapotranspiration from missing data

The determination of the amount of water needed for crops is one of the main parameters for correct irrigation planning. In this context the FAO Penman-Monteith method (FAO-PM) has been recommended as the best for the reference evapotranspiration (ETo) estimates. However it is not always possible to have all the necessary data for its application; in this case, alternative criteria must be used for this estimation. In this study, the objective was to estimate ETo by the FAO-PM method with only the maximum and minimum temperature values, here called Simplified FAO-PM, and compare it to the standard method (FAO-PM) with all input data, for Lavras, Minas Gerais State, Brazil. It was observed that the alternative method has the tendency to overestimate the standard method, however, this approach is feasible to estimate ETo for irrigation scheduling in localities where not all input data required for FAO-PM is available.