DIVERGENCIA GENÉTICA DE GENOTIPOS DE MAÍZ CULTIVADOS BAJO FERTILIZACIÓN NITROGENADA E INOCULACIÓN CON Azospirillum brasilense

Objetivou-se avaliar e caracterizar o desempenho agronômico de genótipos de milho submetidos a dois fornecimentos de nitrogênio (químico e biológico). O experimento foi conduzido na em segunda safra 2017 e primeira safra 2017/2018, utilizando-se 48 genótipos de milho. Foram adotados dois manejos de fornecimento de nitrogênio em cobertura, sendo eles (1) aplicação de 140 kg ha-1 de nitrogênio mineral em cobertura e (2) inoculação com Azospirillum brasilense (600 mL ha-1 via solo). Os dados foram submetidos a análises exploratórias multivariadas de agrupamento, por método hierárquico, e de componentes principais. Foram identificados quatro grupos, associando as maiores produtividades de grãos com plantas com maior altura e as menores produtividades com período de florescimento curto, plantas com menor altura a com maiores taxas de quebramento e acamamento. Os dois primeiros componentes principais explicaram 70,67% e 66,54% da variabilidade total dos dados para a inoculação com A. brasilense e adubação nitrogenada em cobertura, respectivamente. As análises exploratórias de dados são ferramentas eficientes na caracterização, seleção e agrupamento de genótipos superiores e contrastantes de milho aos manejos de fornecimento de nitrogênio.The aim was to characterize and evaluate the agronomic performance of corn genotypes submitted to two nitrogen supply managements (chemical and biological). The experiment was conducted in the first season (summer season) of the 2017/2018 agricultural year, using 48 corn genotypes. Two managements of nitrogen supply in topdressing were adopted, namely (1) application of 140 kg ha-1 of mineral nitrogen in coverage (urea) and (2) inoculation with Azospirillum brasilense (600 mL ha-1 via soil). The data were submitted to exploratory multivariate analysis of grouping, by hierarchical method, and of main components. Four groups were identified, associating the highest grain yields with plants with higher height and the lowest yields with short flowering period, plants with shorter height and with higher rates of breakage and lodging. The first two main components explained 70.67% and 66.54% of the total variability of the data for inoculation with A. brasilense and nitrogen fertilization in topdressing, respectively. Exploratory data analysis is an efficient tool in the characterization, selection and grouping of superior and contrasting maize genotypes for nitrogen supply management.El objetivo fue caracterizar y evaluar el rendimiento agronómico de los genotipos de maíz sometidos a dos gestiones de suministro de nitrógeno (químico y biológico). El experimento se realizó en la primera cosecha (cosecha de verano) del año agrícola 2017/2018, utilizando 48 genotipos de maíz. Se adoptaron dos gestiones de suministro de nitrógeno en cobertura, a saber (1) la aplicación de 140 kg ha-1 de nitrógeno mineral en cobertura (urea) y (2) la inoculación con Azospirillum brasilense (600 ml ha-1 a través del suelo). Los datos se sometieron a análisis exploratorios multivariados de agrupación, por método jerárquico y de componentes principales. Se identificaron cuatro grupos, que asociaron los rendimientos de grano más altos con plantas con mayor altura y los rendimientos más bajos con un período de floración corto, plantas con altura más corta y con mayores tasas de rotura y alojamiento. Los primeros dos componentes principales explicaron el 70.67% y el 66.54% de la variabilidad total de los datos para la inoculación con A. brasilense y la fertilización nitrogenada en cobertura, respectivamente. El análisis exploratorio de datos es una herramienta eficiente en la caracterización, selección y agrupamiento de genotipos de maíz superiores y contrastantes para el manejo de la oferta de nitrógeno

CRECIMIENTO VEGETATIVO, PRODUCTIVIDAD Y CALIDAD POSTERIOR A LA COSECHA DE CULTIVARES BAJOS DE CAFÉ EN UNA REGIÓN DE BAJA ALTITUD

O objetivo do trabalho foi avaliar o desempenho agronômico e a qualidade pós colheita de 12 cultivares de cafeeiro arábica de porte baixo em região de baixa altitude. O experimento foi conduzido entre os anos de 2008 e 2010, em Jaboticabal, SP, região de altitude média de 575 m. O delineamento utilizado foi o inteiramente casualizado, com 12 tratamentos e 4 repetições. As 12 cultivares de café foram: Catuaí Vermelho IAC 99, Catuaí Vermelho IAC 144, Catuaí Amarelo IAC 62, Catuaí Amarelo IAC 74, Catucaí Amarelo 2 SL, Acauã P 363, Sabiá Tardio, Obatã IAC 1669-20, Tupi IAC 1669-33, Tupi RN, IAC 1669-13, Paraíso MG H419-1 e Rubi MG 1192. Foram analisados os parâmetros de crescimento vegetativo e produtividade durante a fase de formação da lavoura, primeira colheita e avaliações pós-colheita. As cultivares apresentam diferenças no seu crescimento inicial, com as variáveis de crescimento se correlacionando diretamente com a produtividade do cafeeiro, destacando-se a variável diâmetro de copa. As cultivares Sabiá Tardio e Obatã podem ser recomendadas para o cultivo em regiões de baixa altitude, apresentando produtividade acima de 40 sacas por hectare. Além de produtividade satisfatória, a cultivar Catuaí Amarelo IAC62 apresenta as melhores características dos grãos para a obtenção de qualidade de bebida superior, podendo ser recomendada para regiões de baixa altitude.The aim was to evaluate the agronomic performance and postharvest quality of 12 dwarf arabica coffee cultivars in a low altitude region. The experiment was conducted between 2008 and 2010, in Jaboticabal, SP, a region with an average altitude of 550 m. The design used was completely randomized, with 12 treatments and 4 repetitions. The 12 dwarf coffee cultivars were: Catuaí Vermelho IAC 99, Catuaí Vermelho IAC 144, Catuaí Amarelo IAC 62, Catuaí Amarelo IAC 74, Catucaí Amarelo 2 SL, Acauã P 363, Sabiá Tardio, Obatã IAC 1669-20, Tupi IAC 1669-33, Tupi RN, IAC 1669-13, Paraíso MG H419-1 and Rubi MG 1192. Vegetative growth and yield parameters were analyzed during the crop formation phase, first harvest and post-harvest evaluations. The cultivars show differences in their initial growth, with the growth variables directly correlating with the yield of the coffee, especially the crown diameter variable. The cultivars Sabiá Tardio and Obatã can be recommended for cultivation in low altitude regions, with yield above 40 bags per hectare. In addition to satisfactory yield, the cultivar Catuaí Amarelo IAC62 has the best grain characteristics for obtaining superior drink quality, and can be recommended for low altitude regions.El objetivo del trabajo fue evaluar el rendimiento agronómico y la calidad poscosecha de 12 bajos cultivares de café arábica en una región de baja altitud. El experimento se realizó entre 2008 y 2010, en Jaboticabal, SP, una región con una altitud promedio de 550 m. El diseño utilizado fue completamente al azar, con 12 tratamientos y 4 repeticiones. Los 12 cultivares de café fueron: Catuaí Vermelho IAC 99, Catuaí Vermelho IAC 144, Catuaí Amarelo IAC 62, Catuaí Amarelo IAC 74, Catucaí Amarelo 2 SL, Acauã P 363, Sabiá Tardio, Obatã IAC 1669-20, Tupi IAC 1669-33, Tupi RN, IAC 1669-13, Paraíso MG H419-1 y Rubi MG 1192. Se analizaron los parámetros de crecimiento vegetativo y productividad durante la fase de formación del cultivo, la primera cosecha y las evaluaciones posteriores a la cosecha. Los cultivares muestran diferencias en su crecimiento inicial, con las variables de crecimiento directamente correlacionadas con la productividad del cafeto, especialmente la variable de diámetro del dosel. Los cultivares Sabiá Tardio y Obatã pueden recomendarse para el cultivo en regiones de baja altitud, con una productividad superior a 40 sacos por hectárea. Además de una productividad satisfactoria, el cultivar Catuaí Amarelo IAC62 presenta las mejores características de los granos para obtener una calidad de bebida superior, que puede recomendarse para regiones de baja altitud

Portable chlorophyll meter in monitoring and management of nitrogen in common bean cultivars

More sustainable practices involving biological nitrogen fixation (BNF) and the use of portable chlorophyll meter in fertilization management are promising to increase nitrogen (N) use efficiency in the common bean crop. This study aimed to monitor N managements using a portable chlorophyll meter and its effects on agronomic attributes of Carioca-type common bean cultivars with indeterminate and determinate growth habits (‘IPR Campos Gerais’ and ‘IAC Imperador’). The experiment was carried out in a randomized block design (RBD), in a 2 × 9 factorial scheme, with four replicates. The first factor consisted of the cultivars and the second factor of the N management. The data were subjected to analysis of variance by F test and, when necessary, the means were grouped by the Scott-Knott test at 5% probability level. The use of portable chlorophyll meter is a viable alternative for N monitoring and management in common bean, allowing the reduction of top-dressing N application, regardless of the cultivar used. Highlights The use of portable chlorophyll meter is a viable alternative for nitrogen monitoring and management in common bean. Management with chlorophyll meter reduced the need for chemical fertilizer application, saving 105 kg ha-1 of urea. Further studies are needed to better understand this technology under conditions with different genotypes, soils and production systems.More sustainable practices involving biological nitrogen fixation (BNF) and the use of portable chlorophyll meter in fertilization management are promising to increase nitrogen (N) use efficiency in the common bean crop. This study aimed to monitor N managements using a portable chlorophyll meter and its effects on agronomic attributes of Carioca-type common bean cultivars with indeterminate and determinate growth habits (‘IPR Campos Gerais’ and ‘IAC Imperador’). The experiment was carried out in a randomized block design (RBD), in a 2 × 9 factorial scheme, with four replicates. The first factor consisted of the cultivars and the second factor of the N management. The data were subjected to analysis of variance by F test and, when necessary, the means were grouped by the Scott-Knott test at 5% probability level. The use of portable chlorophyll meter is a viable alternative for N monitoring and management in common bean, allowing the reduction of top-dressing N application, regardless of the cultivar used. Highlights The use of portable chlorophyll meter is a viable alternative for nitrogen monitoring and management in common bean. Management with chlorophyll meter reduced the need for chemical fertilizer application, saving 105 kg ha-1 of urea. Further studies are needed to better understand this technology under conditions with different genotypes, soils and production systems

Vegetation indices in the prediction of biomass and grain yield of white oat under irrigation levels

Vegetation indices are widely used to indicate the nutritional status of crops, as well as to estimate their harvest yield. However, their accuracy is influenced by the phenological stage of evaluation and the index used. The present study aimed to evaluate the accuracy of the Normalized Difference Vegetation Index (NDVI) and Inverse Ratio Vegetation Index (IRVI) in the prediction of grain yield and biomass of white oat cultivated under irrigation levels, besides indicating the best phenological stage for evaluation. The irrigation levels consisted of 11 %, 31 %, 60 %, 87 % and 100 % of the maximum evapotranspiration, with four replicates. The mean values ​​for NDVI and IRVI were determined using an active terrestrial sensor, at four phenological stages (4, 8, 10 and 10.5.4). The white oat grain yield and biomass may be estimated with a high precision using the NDVI and IRVI. The NDVI was more accurate than the IRVI. The grain yield estimate was more accurate from the flag leaf sheath appearance stage (10), whereas, for the biomass, the best estimate was for the kernel watery ripe stage (10.5.4)

Ecofisiologia e irrigação do amendoim cultivado na segunda safra

A cultura do amendoim é uma excelente alternativa de cultivo ao produtor, seja na questão agrícola, sendo ótima alternativa para a sucessão e rotação de culturas, seja na financeira, tornando-se boa fonte de renda e lucro aos agricultores. Culturas anuais, como o amendoim, geralmente podem ser semeadas em qualquer época do ano. No entanto, devido a características agrícolas, de clima, custos, mercado e logística muitas delas ficam direcionadas somente a uma determinada época de plantio. A safra de verão, ou primeira safra de amendoim, é responsável por quase a totalidade da área plantada no Brasil anualmente, dessa forma, as pesquisas para o cultivo da cultura são praticamente direcionadas para essa época. No entanto, o cultivo do amendoim fora de época, ou segunda safra, vem ganhando destaque por sua rentabilidade, fato devido tanto aos melhores preços do produto no mercado, quanto para a produção de sementes. Sendo assim, esse trabalho tem como objetivo reunir informações técnicas e características do cultivo de amendoim na segunda safra para diminuição dos riscos de produção. Além disso, dará ênfase na utilização e manejo da irrigação, tecnologia que é praticamente imprescindível para o cultivo da leguminosa na segunda safra.The peanut crop is an excellent alternative for cultivation to farmers, whether in the agricultural field, being a good alternative for the succession and rotation of crops, whether in the financial sector, becoming a good source of income and profit for the farmers. Annual crops, such as peanuts, can usually be sown at any time of the year. However, due to the agricultural characteristics, climate, costs, market and logistics, many of them are directed only at a specific planting season. The summer crop, or first peanut crop, is responsible for almost all of the planted area in Brazil annually, in this way, the searches for the cultivation of crop are practically directed for this time. However, the cultivation of peanuts out of season, or second crop, has been gaining prominence due to its profitability, a fact due to both the best prices of the product on the market and for seed production. Thus, this work aims to gather technical information and characteristics of the cultivation of peanuts in the second season to reduce production risks. In addition, will focus on the use and management of irrigation, technology that is practically indispensable for the cultivation of peanuts in the second season.La cosecha de cacahuete es una excelente alternativa para el cultivo a los agricultores, ya sea en el campo agrícola, siendo una buena alternativa para la sucesión y rotación de cultivos, ya sea en el sector financiero, convirtiéndose en una buena fuente de ingresos y ganancias para los agricultores. Los cultivos anuales, como los cacahuetes, se pueden sembrar en cualquier época del año. Sin embargo, debido a las características agrícolas, el clima, los costos, el mercado y la logística, muchos de ellos están dirigidos sólo en una temporada de siembra específica. La cosecha de verano, o primera cosecha de maní, es responsable de casi toda la superficie plantada en Brasil anualmente, de esta manera, las búsquedas para el cultivo de la cosecha se dirigen prácticamente para este tiempo. Sin embargo, el cultivo de cacahuetes fuera de temporada, o segunda cosecha, ha ido ganando prominencia debido a su rentabilidad, un hecho debido tanto a los mejores precios del producto en el mercado como a la producción de semillas. Por lo tanto, este trabajo tiene como objetivo reunir información técnica y características del cultivo de cacahuetes en la segunda temporada para reducir los riesgos de producción. Además, se centrará en el uso y manejo del riego, tecnología que es prácticamente indispensable para el cultivo de cacahuetes en la segunda temporada

Peanut yield under irrigation levels in off-season cultivation

Water deficit is considered the most critical environmental factor for peanut production in Brazil, as it constitutes one of the major constraints to the expansion of its cultivation in the suitable crop zones of the country. Determining crop water demand is fundamental to increasing yield with lower water consumption. The present study aimed to evaluate the effects of full and deficit irrigation levels (L1 = 8%, L2 = 27%, L3 = 63%, L4 = 94% and L5 = 100% replenishment of crop evapotranspiration) on the development, growth and yield of peanut crop sown in two times, February and March. Treatments were distributed in a split-plot randomized complete block design, with four replicates, using a line-source sprinkler system. Irrigation depths from 65 to 314 mm were applied with the levels L1 to L5 during the first and second cropping cycles. Full irrigation with sowing in March was more advantageous due to yield increase of up to 30% compared to sowing in February, but crop cycle was 25 days longer. Water stress caused by deficit irrigation reduced plant height, seed mass and pod yield, while full irrigation (L5) led to yields from 4,141 to 5,102 kg ha-1 for February and March, approximately three times higher than those obtained with the lowest irrigation level (L1). Highlights Peanut has great importance in the food and industry of several countries. The results of this research apply to regions that require irrigation, which is of about 70% of the areas of the globe with this legume. This paper contributes with information that emphasizes the possibility of cultivation in the drought season, aiming at the expansion of the crop and the production of quality seeds using irrigation.Water deficit is considered the most critical environmental factor for peanut production in Brazil, as it constitutes one of the major constraints to the expansion of its cultivation in the suitable crop zones of the country. Determining crop water demand is fundamental to increasing yield with lower water consumption. The present study aimed to evaluate the effects of full and deficit irrigation levels (L1 = 8%, L2 = 27%, L3 = 63%, L4 = 94% and L5 = 100% replenishment of crop evapotranspiration) on the development, growth and yield of peanut crop sown in two times, February and March. Treatments were distributed in a split-plot randomized complete block design, with four replicates, using a line-source sprinkler system. Irrigation depths from 65 to 314 mm were applied with the levels L1 to L5 during the first and second cropping cycles. Full irrigation with sowing in March was more advantageous due to yield increase of up to 30% compared to sowing in February, but crop cycle was 25 days longer. Water stress caused by deficit irrigation reduced plant height, seed mass and pod yield, while full irrigation (L5) led to yields from 4,141 to 5,102 kg ha-1 for February and March, approximately three times higher than those obtained with the lowest irrigation level (L1). Highlights Peanut has great importance in the food and industry of several countries. The results of this research apply to regions that require irrigation, which is of about 70% of the areas of the globe with this legume. This paper contributes with information that emphasizes the possibility of cultivation in the drought season, aiming at the expansion of the crop and the production of quality seeds using irrigation

What are the impacts of the common bean production system on production and quality attributes of the grains?

The cultivar choice can promote significant impacts on yield and grain quality of common bean within a production system. The aim of this work was to evaluate the effect of common bean cultivars from the Carioca commercial group on grain yield and quality in a production system, as well as to verify the correlation between the variables. The experiment was carried out in Southeastern Brazil in the winter/spring season. A randomized block design with four replications was used. The treatments consisted of 13 common bean cultivars (Pérola, BRSMG Majestoso, BRS Estilo, BRSMG Madrepérola, IPR Campos Gerais, IPR Tangará, IPR Andorinha, IPR 139, IAC Imperador, IAC Formoso, IAC Alvorada, IAC Milênio and TAA Bola Cheia). The cultivar factor promoted differences of up to 34% in yield, 20% in sieve yield greater than or equal to 12 (SY≥12), 16% in grain protein content and 47% in cooking time. Among the cultivars, BRSMG Majestoso had the highest grain yield (3805 kg ha-1). All cultivars provided SY≥12 above 70%, highlighting IPR Andorinha (93%). The cultivar BRSMG Madrepérola stood out for its grains with clear tegument. Grain yield increases as the number of pods per plant and grains per pod increase, negatively correlated with crude protein content and cooking time. These results demonstrate the importance of choosing the correct cultivar in a production system, helping to increase yield and profit for farmers.The choice of a cultivar can significantly affect grain yield and quality of common bean crops in production systems. The objective of this work was to evaluate the effect of common bean cultivars of the carioca commercial group on grain yield and quality in a production system, and assess the correlation between their variables. The experiment was carried out in the Southeast region of Brazil, in the winter-spring crop season. A randomized block design was used, with 13 treatments and four replications per treatment. The treatments were consisted of common bean cultivars (Pérola, BRSMG-Majestoso, BRS-Estilo, BRSMG-Madrepérola, IPR-Campos Gerais, IPR-Tangará, IPR-Andorinha, IPR-139, IAC-Imperador, IAC-Formoso, IAC-Alvorada, IAC-Milênio, and TAA-Bola Cheia). The choice of a cultivar affects production and quality attributes of common bean in production systems, as it can result in increases of up to 34% in grain yield, 20% in grain yield in sieves equal to or higher than 12 (GYS≥12), 16% in grain protein contents, and 47% in cooking time. The cultivar BRSMG-Majestoso presented the highest grain yield (3,805 kg ha-1), and IPR-Andorinha and BRSMG-Madrepérola stood out with GYS≥12 of 93% and grains with clear integument, respectively. Grain yield increases as the number of pods per plant and grains per pod increase, presenting a negative correlation with crude protein contents and cooking time

Uniformity of water application to central pivot and to super 10 sprayer

O aumento da preocupação mundial com o aproveitamento e uso da água e a expansão da agricultura irrigada exigem otimização da eficiência de seu uso, destacando-se a sua uniformidade de aplicação, que influencia a otimização do uso da água pelas plantas. Objetivou-se, com o presente estudo, comparar a uniformidade de aplicação de água de um aspersor, obtido em condições de campo com o catálogo do fabricante, além de avaliar a uniformidade de aplicação de água de um pivô-central com aspersores novos e usados. Em condições de campo, a uniformidade de aplicação de água do aspersor SUPER 10 foi inferior à informada no catálogo do fabricante. Não se recomenda a utilização do aspersor SUPER 10 em espaçamentos iguais ou superiores a 12 x 12 m. Além disso, em culturas com alto valor agregado, como hortaliças, indica-se a utilização desse aspersor no espaçamento de 8 x 8 m. O pivô central apresenta boa uniformidade de aplicação de água, com CUH de 87,4% e CUD de 82,8%, além de aplicar uma lâmina média de 7,39 mm. The increase in global concern with the use and use of water and the expansion of irrigated agriculture require optimization of the efficiency of its use, highlighting its uniformity of application, which influences the optimization of water use by plants. The objective of this study was to compare the uniformity of water application of a sprinkler, obtained in field conditions with the manufacturer's catalog, and to evaluate the uniformity of water application of a central pivot with new and used sprinklers. Under field conditions, the water application uniformity of the SUPER 10 sprinkler was lower than that reported in the manufacturer's catalog. It is not recommended to use the SUPER 10 sprinkler in spacings equal to or greater than 12 x 12 m. In addition, in cultures with high added value, such as vegetables, the use of this sprinkler in the 8 x 8 m spacing is indicated. The central pivot shows good uniformity of water application, with CUH of 87.4% and CUD of 82.8%, besides applying a mean blade of 7.39 mm.El aumento de la preocupación mundial con el aprovechamiento y uso del agua y la expansión de la agricultura irrigada exigen optimización de la eficiencia de su uso, destacándose la uniformidad de aplicación, que influye en la optimización del uso del agua por las plantas. Se objetivó, con el presente estudio, comparar la uniformidad de aplicación de agua de un aspersor, obtenido en condiciones de campo con el catálogo del fabricante, además de evaluar la uniformidad de aplicación de agua de un pivote central con aspersores nuevos y usados. En condiciones de campo, la uniformidad de aplicación de agua del aspersor SUPER 10 fue inferior a la indicada en el catálogo del fabricante. No se recomienda el uso del aspersor SUPER 10 en espaciamientos igual o superiores a 12 x 12 m. Además, en cultivos con alto valor agregado, como hortalizas, se indica la utilización de este aspersor en el espaciado de 8 x 8 m. El pivote central presenta buena uniformidad de aplicación de agua, con CUH de 87,4% y CUD del 82,8%, además de aplicar una lámina media de 7,39 mm

Doses de nitrogênio em cultivares de feijão-comum em sistema plantio direto recém-instalado

The first years of the no-tillage system can promote changes in soil balance that directly impact on managements such as nitrogen fertilization. The aim was to evaluate the agronomic and qualitative performance of common bean cultivars under nitrogen rates in top-dressing in the first year of no-tillage system. The experiment was carried out in the winter season in a randomized block design in a split plot scheme, with four replications. The plots consisted of three common bean cultivars (IAC Alvorada, IAC Milênio and Pérola) and the subplots by four N rates (urea) applied in top-dressing (0, 70, 140 and 210 kg ha-1),. The common bean were sown under no-tillage system after maize crop, which showed a straw production of 7.0 Mg ha-1 of dry matter. The cultivars IAC Alvorada and IAC Milênio were more efficient and responsive than Pérola cultivar. The cultivars IAC Alvorada and IAC Milênio presented, on average, grain yield and sieve yield 12.5 and 15.2% higher than Pérola cultivar, respectively. Nitrogen rates in top-dressing and common bean cultivars promote differences in agronomic performance and quality independently. The grain yield of common bean cultivars showed linear increments with the nitrogen rates in top-dressing in the first year of no-tillage system, indicating a higher N requirement than the rate of 90 kg ha-1 of N recommended for the crop.Os primeiros anos da adoção do sistema plantio direto pode promover alterações no equilíbrio do solo que impactam diretamente em manejos, como a adubação nitrogenada. Objetivou-se avaliar o desempenho agronômico e qualitativo de cultivares de feijão-comum sob doses de nitrogênio em cobertura no primeiro ano de adoção do sistema plantio direto. O experimento foi conduzido na safra de inverno em delineamento de blocos casualizados em esquema de parcelas subdivididas, com quatro repetições. As parcelas foram constituídas de três cultivares de feijão (IAC Alvorada, IAC Milênio e Pérola) e as subparcelas por quatro doses de N (ureia) aplicadas em cobertura (0, 70, 140 e 210 kg ha-1). O feijão foi semeado em sistema plantio direto após a cultura do milho, que apresentou produção de palhada de 7,0 Mg ha-1 de massa seca. As cultivares IAC Alvorada e IAC Milênio foram mais eficientes e responsivas do que a cultivar Pérola. As cultivares IAC Alvorada e IAC Milênio apresentaram, na média, produtividade e rendimento de peneiras 12,5 e 15,2% superior à cultivar Pérola, respectivamente. As doses de nitrogênio em cobertura e as cultivares de feijão-comum promovem diferenças no desempenho agronômico e qualidade de maneira independente. A produtividade das cultivares de feijão apresentam incrementos lineares com as doses de nitrogênio em cobertura no primeiro ano de adoção do sistema plantio direto, indicando maior exigência de N do que a dose ideal de 90 kg ha-1 de N recomendada para a cultura

Comparison of equations for the estimation of head loss in polyethylene tube

La determinación de la pérdida de carga en proyectos de riego no es utilizada por ser un método de baja practicidad. Para ello, existen ecuaciones que estiman esa variable, basándose en características de las tuberías y del proyecto, tales como material del tubo, diámetro y caudal del sistema. De esta forma, se objetivó evaluar la mejor ecuación para la estimación de la pérdida de carga en tubería de polietileno con diámetro interno de 25 mm, comparando los resultados a la pérdida de carga determinada en manómetro de mercurio. El experimento fue realizado en lo laboratorio de irrigación de la FCAV / Unesp, Jaboticabal en junio de 2017. La estimación de la pérdida de carga fue realizada por la ecuación de Hazen-Williams y de Darcy-Weisbach, siendo que para esa última el factor de fricción (f ) fue estimado por los modelos de Swamee y Jain y de Blasius. Las ecuaciones fueron comparadas con los datos determinados en columna de mercurio en 5 caudales, con valores que varían de 1,55 m3 h-1 a 5,15 m3 h-1. La estimación de la pérdida de carga por el método de Swamee y Jain sobreestimó los valores determinados en la columna de mercurio. Hasta el caudal de 5,15 m3  h-1 el método de Hazen-Williams presentó la menor variación y, consecuentemente, la mayor eficiencia de estimación de pérdida de carga en relación a los valores determinados para la tubería de polietileno de diámetro de 25 mm.A determinação da perda de carga em projetos de irrigação não é utilizada por ser um método de baixa praticidade. Para isso, existem equações que estimam essa variável, embasando-se em características das tubulações e do projeto, tais como material do tubo, diâmetro e vazão do sistema. Dessa forma, objetivou-se avaliar a melhor equação para a estimativa da perda de carga em tubulação de polietileno com diâmetro interno de 25 mm, comparando os resultados à perda de carga determinada em manômetro de mercúrio. O experimento foi realizado no laboratório de irrigação da FCAV/Unesp, Jaboticabal em junho de 2017. A estimativa da perda de carga foi realizada pela equação de Hazen-Williams e de Darcy-Weisbach, sendo que para essa última o fator de atrito (f) foi estimado pelos modelos de Swamee & Jain e de Blasius. As equações foram comparadas com os dados determinados em coluna de mercúrio em 5 vazões, com valores variando de 1,55 m3 h-1 a 5,15 m3 h-1. A estimativa da perda de carga pelo método de Swamee & Jain superestimou os valores determinados na coluna de mercúrio. Até a vazão de 5,15 m3 h-1 o método de Hazen-Williams apresentou a menor variação e, consequentemente, a maior eficiência de estimativa de perda de carga em relação aos valores determinados para a tubulação de polietileno com diâmetro de 25 mm. The determination of the head loss in irrigation projects is not used because it is a low practical method. For this, there are equations that estimate this variable, based on characteristics of the pipes material, diameter and system flow. Thus, the objective of this study was to evaluate the best equation for estimating the head loss in polyethylene tubing with internal diameter of 25 mm, comparing the results to the head loss determined in a mercury manometer. The experiment was carried out in the irrigation laboratory of the FCAV/Unesp, Jaboticabal, in June 2017. The estimation of the head loss was performed by the Hazen-Williams and Darcy-Weisbach equation, with the friction factor (f) estimated by Swamee and Jain and Blasius models. The equations were compared with the data determined in column of mercury in five flows, with values ranging from 1.55 m3 h-1 a 5.15 m3 h-1. The estimation of the head loss by Swamee and Jain method overestimated the values determined in the mercury column. Up to the 5.15 m3 h-1 flow the Hazen-Williams method presented the lowest variation and, consequently, the higher efficiency of estimated of head loss in relation to the values determined for polyethylene tubing with a diameter of 25 mm