Resumo: A cultura da mamona é considerada resistente a deficiências hídricas, no entanto, apresenta considerável incremento de produtividade quando submetida à irrigação. Para o adequado manejo da irrigação um dos critérios passíveis de serem adotados baseia-se na evapotranspiração da cultura (ETc) e para tanto torna-se necessário o conhecimento do valor do coeficiente de cultura (Kc). Com o presente trabalho objetivou-se determinar o Kc da mamoneira em plantio adensado, no período de safrinha, utilizando-se lisímetro de drenagem. Foram utilizados três lisímetros de drenagem, com dimensões de 1,2 m de comprimento, 1,4 m de largura e 1,2 m de profundidade. Nos lisímetros foram plantadas oito mudas de mamoneira da cultivar Al Guarany 2002 com espaçamento de 0,3 m entre plantas e 0,7 m entre linhas. A ETc foi contabilizada no intervalo de 5 a 12 dias, conforme se observou o fim da drenagem. A evapotranspiração de referência (ETo) foi estimada pela equação de Penman-Monteith-FAO. A partir da relação ETc/ETo obteve-se o Kc para os diferentes períodos ao longo do ciclo da cultura. Os valores de ETc encontrados nas fases inicial, de crescimento, intermediária e final foram 1,65; 3,07; 9,14 e 5,85 mm d -1 , respectivamente. Os valores de Kc para as fases mencionadas foram 0,98; 1,41; 2,11 e 1,65, respectivamente. Palavras-chaves: evapotranspiração, lisimetria, Ricinus communis L., safrinhaAbstract: Castor bean culture is considered resistant to water deficit. However, it presents considerable increase in productivity when submitted to irrigation. For the adequate irrigation management, one of the criterion considered is based on the crop evapotranspiration (ETc) and is necessary for finding the crop coefficient (Kc) value. With the present work, we aimed at determining the Kc of the castor bean in dense plantation, during the off-season, using a drainage lysimeter.

ABSTRACT A low availability of water in the soil may alter morphological traits and physiological processes in soybean, limiting its development, mainly at late sowings. This study aimed to evaluate the leaf gas exchanges and dry matter accumulation in soybean cultivars under low water availability at late sowing. An Oxisol with a very clayey texture was employed. A completely randomized design, in a 5 × 3 factorial scheme, with four replications, was used. The treatments were five water tensions (10 kPa, 15 kPa, 25 kPa, 40 kPa and 60 kPa) combined with three soybean cultivars (BRS Favorita, BRSMG 820 and BRSMG 850). The response variables were measured at 55 days after the emergence. The values for stomatal conductance, transpiration, photosynthesis rate, intercellular CO2 concentration and instantaneous carboxylation efficiency were significantly reduced (p < 0.05) with the increase of the water tension in the soil. The gas exchanges in the soybean plants were also reduced with the increase of the water tension in the soil, being the most critical ones observed from 25 kPa. BRSMG 850 showed the best performance for production of root dry matter in this water tension in the soil.

Air temperature significantly affects the processes involving agricultural and human activities. The knowledge of the temperature of a given location is essential for agricultural planning. It also helps to make decisions regarding human activities. However, it is not always possible to determine this variable. It is necessary to make a precise estimate, using methods that are capable of detecting the existing variations. The aim of this study was to develop models of multiple linear regression (MLR), artificial neural network (ANN), and random forest (RF) to estimate the mean (Tmean), maximum (Tmax), and minimum (Tmin) monthly air temperatures as a function of geographic coordinates and altitude for different localities in Minas Gerais state, Brazil, with climatic classification Cwa or Cwb. The average monthly data (Tmean, Tmax, and Tmin), over a period of 30 years, were collected from 20 climatological stations. The MLR was able to estimate the Tmax with accuracy. However, the predictive capacity of estimating Tmean and Tmin was low. The algorithms RF and ANN were used to estimate Tmean, Tmax, and Tmin with high accuracy. The best results were obtained using the RF model.

INFLUÊNCIA DO CANHÃO FINAL NA DISTRIBUIÇÃO DE PRESSÃO E VAZÃO DA LINHA LATERAL DE UM PIVÔ CENTRAL     VICTOR BUONO DA SILVA BAPTISTA1; ALBERTO COLOMBO2; THIAGO HENRIQUE BURGARELLI TEIXEIRA3; PIETROS ANDRÉ BALBINO SANTOS4; ADRIANO VALENTIM DIOTTO5 E LESSANDRO COLL FARIA6   1  Professor Assistente, Departamento de Engenharia, Universidade Federal de Lavras, Campus Universitario, s/n, Caixa Postal 3034, CEP 37200-000, Lavras, MG, Brasil. Email: victor.buonosb@ufla.br 2  Professor Titular, Departamento de Recursos Hídricos e Saneamento, Universidade Federal de Lavras, Campus Universitario, s/n, Caixa Postal 3034, CEP 37200-000, Lavras, MG, Brasil. Email: acolombo@ufla.br 3  Doutorando, Programa de Pós-graduação em Recursos Hídricos, Universidade Federal de Lavras, Campus Universitario, s/n, Caixa Postal 3034, CEP 37200-000, Lavras, MG, Brasil. Email:  teixeira.agricola@gmail.com 4  Doutorando, Programa de Pós-graduação em Recursos Hídricos, Universidade Federal de Lavras, Campus Universitario, s/n, Caixa Postal 3034, CEP 37200-000, Lavras, MG, Brasil. Email: pietros.balbino@gmail.com 5  Professor Adjunto, Departamento de Recursos Hídricos e Saneamento, Universidade Federal de Lavras, Campus Universitario, s/n, Caixa Postal 3034, CEP 37200-000, Lavras, MG, Brasil. Email: adriano.diotto@ufla.br 6  Professor Associado, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Rua Gomes Carneiro, Centro, CEP 96010-610, Pelotas, RS, Brasil. Email: lessandro.faria@ufpel.edu.br     1 RESUMO   O objetivo deste trabalho foi analisar a influência da presença do canhão final, com diferentes vazões, na distribuição de pressão e vazão da linha lateral de um sistema de irrigação do tipo pivô central utilizando o simulador hidráulico EPANET em comparação com um modelo analítico. Foram realizadas simulações de uma linha lateral do pivô central, localizado em Lavras/MG, com a inserção de um canhão final fictício de altas vazões. Houve também a diminuição do diâmetro da linha lateral, visando provocar maior perda de carga. Os resultados obtidos pelo EPANET foram comparados com resultados determinados a partir de um método analítico. Dessa forma, este estudo demonstrou a influência do acréscimo de vazão na distribuição de pressão da linha lateral do pivô central, devido à presença do canhão final. Os resultados também demonstraram a qualidade da simulação hidráulica do EPANET, que apresentou desvio relativo máximo de 1% em relação ao método analítico.   Keywords: simulação hidráulica, distribuição de pressão, EPANET, modelagem.     BAPTISTA, V. B. S.; COLOMBO, A.; TEIXEIRA, T. H. B.; SANTOS, P. A. B.; DIOTTO, A. V.; FARIA, L. C. INFLUENCE OF END GUN IN THE PRESSURE AND FLOW RATE DISTRIBUTION OF A CENTER PIVOT LATERAL LINES     2 ABSTRACT   The aim of this work was to analyze the influence of the presence of the end gun, with different flow rates, on the pressure distribution and lateral line flow of a center pivot irrigation system using the EPANET hydraulic simulator compared to an analytical model. Simulations were performed on center pivot lateral line located in Lavras/MG. In the simulations was inserted an end gun operating under high flow. There was also decrease lateral line diameter aiming to cause greater head loss. The results obtained were compared with the use of EPANET parameters and with an analytical method. Thus, this study showed the influence from flow increase in the pressure distribution of the pivot lateral line, since there was an end gun in the end of the lateral. The results also demonstrated a satisfied estimative of EPANET's hydraulic theory.   Keywords: hydraulic simulation, pressure distribution, EPANET, modeling.

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There is a lack of information on the production of irrigated radish associated with the use of mulching and on the economic viability of these production technologies. The objective of this study was to evaluate the growth, yield, and economic viability of the radish crop under different soil water tensions (SWT) and mulching types. The experiment was conducted in a greenhouse. During the experiment, the following variables were evaluates: growth parameters, yield and economic viability. SWT at 7 kpa in the treatments without mulching and at 12 kPa in the treatments with black plastic and black non-woven resulted in higher growth parameters and yield. The leaf area index and the root diameter were the parameters that had a high and positive correlation with yield. Expenses with variable resources represent on average 75% of the total production cost. Therefore, the investment pays all resources applied in the activity and provides an economic profit. In this context, the higher radish yield with 37.5 t ha-1 provided the highest profitability of the evaluated treatments, thus, for radish production, the recommendation is to use 12 kPa as an indicator of the moment for irrigation, associated with the use of black plastic.

Reference evapotranspiration (ET0) is one important agrometeorological parameter for hydrological studies and agricultural water management. The ET0 calculated by the Penman-Monteith - FAO method requires several input data. However, in the Minas Gerais region, the meteorological data are limited. The aim of this study was to evaluate the performance of Artificial Neural Network (ANN), Random Forest (RF), Support Vector Machine (SVM) and Multiple Linear Regression (MLR) to estimate the monthly mean ET0 with different input data combinations and scenarios. Three scenarios were evaluated: at the state level, where all climatological stations were used (Scenario I - SI) ; and at regional level, where the Minas Gerais state was divided according to the climatic classification of Thornthwaite (Scenario II - SII) and by Köppen (Scenario III - SIII). ANN and RF performed better in ET0 estimating among the models evaluated in the SI, SII and SIII scenarios with the following data combination: i) latitude, longitude, altitude, month, mean, maximum and minimum temperature, and relative humidity; and ii) latitude, longitude, altitude, month, mean temperature, and relative humidity. Also, the SVM and MLR models are recommended for all scenarios in situations with limited climatic data, where only air temperature and relative humidity data are available. Although dividing into scenarios results in less input data for models training, SII and SIII showed a slightly better result in the southern areas of the Minas Gerais state.