ABSTRACT CROPWAT is a model that uses water balance to study the water factor and productivity in production systems. In this sense, this study aimed to calibrate the CROPWAT for modeling rainfed and irrigated soybean production systems. Climate and soil data from a soybean-producing region in the south of Mato Grosso do Sul, Brazil, were used to implementing simulations in nine agricultural years, and crop shortfalls were calculated and compared with reference data. Statistical indices were applied to evaluate the performance of the model in its calibration. For validation, two field trials with 12 cultivars were implemented under irrigation and rainfed and the mean productivity in each water management was compared with the CROPWAT estimate by Student’s t-test. Accuracy (r) was 0.976 (“very strong”), precision (r2) was equivalent to 95.3%, and the indices of agreement (d) and performance (c) were considered excellent (0.95 and 0.93, respectively) in the calibration. Validation demonstrated that the hypothesis that CROPWAT correctly estimated soybean productivity under irrigated and rainfed systems cannot be rejected at 1 or 5% significance levels.

ABSTRACT This study aimed to evaluate the effect of water supply and sowing time on yield and yield components of two corn hybrids grown during offseason in the region of Dourados-MS, Brazil. The experimental design was randomized blocks in sub-divided plots, with four replications. In the main plot, two sowing dates were defined (2013 crop year: February 27 and March 27; and 2014 crop year: March 18 and April 5). In subplots, irrigation management systems were defined (irrigated and rainfed). Hybrids AS 1555 and AS 1590 were grown in the sub-plots. The parameters evaluated were plant height, ear insertion height, stem diameter, ear length and diameter, 100-grain weight, and grain yield. Regardless of irrigation and hybrid used, sowing time significantly affected corn yield, which responded to climate changes throughout crop cycle. Water supply increased corn yield, with the highest value being of 9338 kg ha-1 (156 bags ha-1) and obtained when irrigated AS 1555 hybrid was sown on February 27, 2013.

ABSTRACT Sandy-textured soils are naturally more vulnerable to the erosion process and their exploitation, although possible, is often performed inappropriately, favoring its degradation. In this context, this study aimed to classify the rainfall erosivity in a region of sandy soils to identify critical situations of soil and water loss and also correlate it with rainfall data to assess whether there is temporal dependence of this variable using geostatistical techniques. The potential for alternative and sustainable production systems to be used in regions with sandy soils was also analyzed. Historical data of precipitation in the study region were analyzed to determine the average monthly and annual erosivity indices, which were classified and its temporal dependence was assessed by applying geostatistics. NDVI data from satellite images were used to investigate the soil cover pattern in different production systems. Geostatistics was adequate for the analysis of rainfall erosivity, which showed moderate to strong temporal dependence. It was classified between strong and very strong and was highly dependent on precipitation, with events of higher erosion potential between October and March in the studied region. The vicious circle of degradation of sandy soils, such as those of the Bolsão region of Mato Grosso do Sul, Brazil, can be modified by adopting alternative and sustainable production systems that value the maximization of soil cover. Sandytextured Sandy textured exploitation possible inappropriately context techniques indices geostatistics Sul Brazil

ABSTRACT The area cultivated with sugarcane in Mato Grosso do Sul, Brazil, has increased significantly in recent years, in which to meet the demand of the mills, the use of adapted varieties has proved to be a fundamental strategy, combined with the use of irrigation, especially in periods of water deficit. The study aimed to evaluate the growth and yield of four sugarcane varieties (CTC 4, RB966928, RB975201, and RB92579) in plant cane cultivated with and without irrigation. The experiment was conducted at Embrapa Western Agriculture (Embrapa Agropecuária Oeste) in Dourados, MS, Brazil. A randomized block design arranged in a 2 x 4 factorial scheme with three replications was used. At 90, 150, 210, 270, 330, and 390 days after planting (DAP), stalk height and diameter, leaf area index (LAI), and dry biomass were evaluated. The soil cover percentage (%SC) was determined through aerial images taken with a drone, with evaluations made from planting to the maximum soil cover. Total recoverable sugar (TRS), number of stalks m-1, stalk (STY), and sugar (SGY) yield were evaluated at 390 DAP (harvest). The RB975201 variety has the highest growth in height, stem diameter, and LAI when grown under irrigation or without irrigation, and the CTC 4 variety has the smallest. The irrigated production system increases the growth of stalks, LAI, and degree of soil cover for the sugarcane varieties in plant cane and a greater amount of stems m-1, STY, and SGY, highlighting the varieties RB92579 and RB975201.

RESUMO A área cultivada com cana-de-açúcar em Mato Grosso do Sul, Brasil tem aumentado significativamente nos últimos anos, em que para atender à demanda das usinas o uso de variedades adaptadas tem se mostrado estratégia fundamental, aliado ao uso da irrigação, sobretudo em períodos de déficit hídrico. Objetivou-se avaliar o crescimento e a produção de quatro variedades de cana-deaçúcar (CTC 4, RB966928, RB975201, RB92579), em cana-planta, cultivadas sob irrigação e sequeiro. O experimento foi conduzido na Embrapa Agropecuária Oeste, em Dourados, MS, Brasil em um delineamento em blocos ao acaso, em esquema fatorial 2 x 4, com três repetições. Aos 90, 150, 210, 270, 330 e 390 dias após o plantio (DAP) avaliou-se a altura e o diâmetro de colmos, o índice de área foliar (LAI) e a biomassa seca. O percentual de cobertura do solo (% SC) foi determinado, através de imagens aéreas tomadas com drone, com avaliações feitas desde o plantio até a máxima cobertura do solo. O açúcar total recuperável (TRS), o número de colmos m-1, a produtividade de colmos (TSH) e de açúcar (TUH) foram avaliados aos 390 DAP (colheita). A variedade RB975201 apresenta maior crescimento em altura, diâmetro de colmo e LAI quando cultivada em sequeiro ou irrigação, a variedade CTC4, o menor. O sistema produtivo irrigado proporciona aumento no crescimento de colmos, LAI e grau de cobertura do solo para as variedades de cana-deaçúcar, em cana-planta, assim como maior quantidade de colmos m-1, TSH e TUH, destacando-se as variedades RB92579 e RB975201.

ABSTRACT Plant yield is strongly influenced by the amount of water used by it. In this sense, yield response factor (Ky) allows evaluating the decrease in yield as a function of the evapotranspiration that occurs, which may be an important tool for harvest forecasting. Therefore, this study aimed to determine Ky for winter corn crop grown in the region of Dourados, MS, Brazil. The yield function analysis based on the water factor, which requires actual (Ya) and maximum (Ym) yield data, as well as actual (ETa) and maximum (ETm) evapotranspiration, was used to adjust Ky. Ym was assumed to be 8,820 kg ha−1, while Ya was obtained for each season from the database SIDRA from IBGE. ETm and ETa were estimated by sequential daily water balance, considering four different sowing dates (all in the off-season). In total, seasons from 2001 to 2013 were analyzed. The high Ky value obtained (1.22) for winter corn crop showed its high sensitivity to water deficit. Its yield is strongly influenced by water availability so that for every 1% reduction in evapotranspiration, there is a 1.22% yield reduction.

ABSTRACT Net radiation (Rn) of reference surface is important information that has many applications, but its measurement is rare due to the high cost of the sensor and the complexity involved on the measurement. Therefore, estimate Rn from another variable is desirable, as from solar radiation (Rs); however, standard methods used are complex, making interesting the use of simplified methodologies. Considering these aspects, the present study aimed to set two empirical methods to estimate Rn from Rs for Dourados region, Mato Grosso do Sul, Brazil. One method was based on mathematical modeling (Gauss Method). The other one was a more simplified and practical approach (Practical Method) comprising the determination of fixed monthly conversion factors. It was used daily Rs data of a 12-years database. With these, there were estimated Rn values by the standard method recommended by FAO. Gauss Method was set using Table Curve 2D 5.01 software. Modeling consisted in defining the values of the equation parameters. On Practical Method, we developed monthly coefficients of the ratio Rn/Rs. In order to validate both methods it was measured Rs and Rn during two years using high precision sensors. Both estimating methods showed satisfactory results, with relative mean absolute error values lower than 5.8%.

O uso da irrigação na triticultura tem aumentado significativamente nos últimos anos no Brasil. Neste trabalho, objetivou-se avaliar a influência da irrigação na produtividade, na qualidade tecnológica da farinha e no sistema radicular do trigo. Em experimento de campo no IAPAR, em Londrina, Paraná, a cultivar IPR 118 foi cultivada sob irrigação por aspersão convencional (Tratamento Irrigado) e sem irrigação (Tratamento Sequeiro). A produtividade foi determinada, colhendo-se três amostras de 25 m² por tratamento. Nestas mesmas amostras, procedeu-se à análise da qualidade tecnológica da farinha, sendo avaliada, entre outros parâmetros, a força de glúten (W). A avaliação do sistema radicular foi realizada após a colheita, no perfil de 0 a 45 cm de profundidade do solo, amostrando-se oito plantas em cada tratamento. O método da parede do perfil foi utilizado para determinar o número de raízes (NR) e o método do monólito para determinar a massa seca de raízes (MSR). A irrigação aumentou em três vezes a produtividade do trigo, porém diminuiu o W na farinha. Ainda assim, o valor de W encontrado no Tratamento Irrigado (249 10-4 J) foi suficiente para manter a classificação do trigo como tipo-pão, a mesma para o qual a cultivar IPR 118 é classificada. Os valores medidos de NR e a MSR foram iguais ou maiores no Tratamento Sequeiro.

The use of irrigation has been increased significantly in wheat crops in Brazil. This study aims to evaluate the effect of irrigation on the productivity, on flour technological quality and on the wheat root system. In a field experiment conducted at IAPAR, in Londrina -state of Paraná (PR), Brazil, the IPR 118 cultivar was grown under sprinkler irrigation (Irrigated Treatment) and without irrigation (Non-irrigated Treatment). The productivity was determined by harvesting three samples of 25 m² per treatment. The same samples were used to evaluate the flour technological quality, considering, among other parameters, gluten strength (W). The evaluation of the root system was performed after the harvest, considering a profile of 0 to 45 cm of soil depth, and sampling eight plants per treatment. The profile wall method was used to determine the roots number (RN) and the monolith method to determine the root dry mass (RDM). Irrigation increased wheat productivity in three times, while W was reduced in the flour. Nevertheless, the value of W found in the Irrigated Treatment (249 10-4 J) was sufficient to keep wheat classification as bread type, the same as IPR 118 cultivar is classified. The measured values of RN and RDM were similar or higher for the Non-irrigated Treatment.

A quantificação da evaporação do solo é requerida em estudos de balanço hídrico de culturas e em aplicações que visam a aumentar a eficiência do uso da água pelos cultivos. O objetivo deste trabalho foi testar um modelo de microlisímetro (ML) para medir a evaporação do solo em condições irrigada e não irrigada. Os MLs foram construídos utilizando tubos de PVC rígido, medindo 100 mm de diâmetro interno, 150 mm de profundidade e 2,5 mm de espessura da parede. Quatro MLs foram assentados sobre a superfície de dois lisímetros de pesagem de alta precisão conduzidos com solo nu, previamente instalados no Iapar, em Londrina-PR. Os lisímetros tinham dimensões de 1,4 m de largura, 1,9 m de comprimento e 1,3 m de profundidade, e estavam sendo conduzidos com e sem irrigação. A evaporação medida nos MLs (E ML) foi comparada com a medida nos lisímetros (E L), durante quatro períodos do ano. As diferenças entre E ML e E L foram mínimas para condições de baixa e elevada demanda atmosférica, e também para condições de solo irrigado ou não irrigado, indicado que o modelo de ML testado neste trabalho é adequado para medir a evaporação do solo.

Quantifying soil evaporation is required on studies of soil water balance and applications aiming to improve water use efficiency by crops. The performance of a microlysimeter (ML) to measure soil evaporation under irrigation and non-irrigation was evaluated. The MLs were constructed using PVC tubes, with dimensions of 100 mm inner diameter, 150 mm depth and 2.5 mm wall thickness. Four MLs were uniformly distributed on the soil surface of two weighing lysimeters conducted under bare soil, previously installed at Iapar, in Londrina, PR, Brazil. The lysimeters had 1.4 m width, 1.9 m length and 1.3 m depth and were conducted with and without irrigation. Evaporation measurements by MLs (E ML) were compared with measurements by lysimeters (E L) during four different periods in the year. Differences between E ML and E L were small either for low or high atmospheric demand and also for either irrigated or non-irrigated conditions, which indicates that the ML tested here is suitable for measurement of soil evaporation.

Devido ao recente Programa de Produção de Biocombustíveis do Brasil, o interesse comercial tem crescido em relação à produção de pinhão-manso (Jatropha curcas L.). Informações sobre esta cultura ainda são escassas, o que remete a necessidade de mais pesquisas que possam estabelecer condições de adaptabilidade desta cultura em diferentes condições. Neste contexto, realizou-se um experimento para estudar o crescimento e a qualidade das mudas de pinhão-manso, produzidas em ambiente protegido; as mudas foram monitoradas até o momento de serem transplantadas para o campo. Foi analisada a influência dos tipos e volumes de recipientes, juntamente com diferentes substratos e formas de adubação; o consumo de água também foi analisado durante o experimento. De acordo com os resultados, as melhores taxas de crescimento e qualidade de mudas até a condição de transplantio, foram obtidas com a combinação do substrato comercial, maior tubete e adubo de liberação lenta.

There has been an increasing interest in the commercial production of physic nut (Jatropha curcas L.) due to the recent Brazilian Program of Biofuel Production. Information on this crop is still scarce and more research is necessary to set the grounds of crop adaptability in different local conditions. An experiment was set up on this issue under greenhouse environment. Growth and quality of physic nut seedlings was monitored up to transplanting time. The influence of types and volumes of seedling containers was analysed along with different substrates and fertilization strategies. The water use was also detailed in the trial. Results showed the best achievements of growth rate and seedling quality, at appropriate transplanting time, were reached from the combination of the commercial substrate, largest containers and fertilizers of slow nutrient liberation.