RESUMO O uso de índices de vegetação apresenta bom potencial para a predição da produtividade de diversas culturas, porém fatores como a época de avaliação, cultivares e fenologia da planta podem influenciar na performance de modelos preditivos. O objetivo do trabalho foi avaliar e comparar a precisão de estimativa da produtividade do feijoeiro, em função do índice de vegetação NDVI, utilizando modelos individuais por cultivar e geral com todas as cultivares. Foram avaliadas as cultivares IAC Imperador e IPR Campos Gerais, de hábitos de crescimento determinado e indeterminado, respectivamente. Foram submetidas a diferentes manejos de fornecimento de nitrogênio, a fim de proporcionar variação da produtividade. Foram realizadas avaliações do NDVI ao longo do ciclo da cultura, em 6 datas, durante estádios vegetativos e reprodutivos. A produtividade de grãos do feijão pode ser estimada com elevada performance em função do índice de vegetação NDVI, obtendo-se R2 de até 78% e erro médio próximo de 350 kg ha-1. Os melhores ajuste de estimativa são obtidas em estádios fenológicos reprodutivos do feijão, especialmente após o florescimento da cultura (R6). Modelos generalistas, compostos por dados de mais de uma cultivar, apresentam precisão semelhante e, em alguns casos, superior aos modelos ajustados para cada cultivar, demonstrando a viabilidade da utilização de um mesmo modelo para vários genótipos.

ABSTRACT The use of vegetation indices has good potential for predicting the productivity of several crops, but factors such as the time of assessment, cultivar, and plant phenology can influence the performance of predictive models. The objective of this study was to evaluate and compare the precision of estimating the common bean grain yield, according to the normalized difference vegetation index (NDVI), using individual models per cultivar and a general model with all cultivars. The cultivars IAC Imperador and IPR Campos Gerais, with determined and indeterminate growth habits, respectively, were evaluated. They were subjected to different nitrogen management methods to provide grain yield variability. NDVI evaluations were conducted throughout the culture cycle on six dates during the vegetative and reproductive stages. The common bean grain yield was estimated with high precision as a function of NDVI, obtaining a precision of up to 78% and an average error close to 350 kg ha-1. The greatest fit of estimation was obtained in the phenological reproductive stages of beans, especially after crop flowering. General models, composed of data from more than one cultivar, had similar precision and, in some cases, superiority to the fitted models for each cultivar, demonstrating the feasibility of using the same model for several genotypes.

ABSTRACT A study was undertaken comparing the water requirements of two common bean ( Phaseolus vulgaris L.) cultivars to generate specific recommendations aimed at optimizing water use. To accomplish this work, the agronomic performance, responsiveness to water and water productivity of these two common bean cultivars of determinate and indeterminate growth habits were identified. The 2-year experiment was carried out during the winter growing season in the southeast of Brazil. Cultivars IAC Imperador, with an early season of determinate growth habit, and IPR Campos Gerais, having a mid-season of indeterminate growth habit, were subjected to five irrigation levels (54, 70, 77, 100, and 132 % of the crop evapotranspiration). Water deficit affected agronomic performance, reducing plant height (by up to 29 %), leaf area index (by up to 40 %), soil cover fraction (by up to 28 %), and grain yield (GY - by up to 31 %), in both cultivars. In contrast, excess water was more detrimental to cultivar IAC Imperador. Cultivar IPR Campos Gerais produced 18 % more than GY, showing superior water productivity and response to irrigation depth than IAC Imperador. Out of all the variables evaluated, the soil cover fraction correlated the most with grain yield in both common bean cultivars during the 2-year study. In other words, cover fraction evaluation in common bean allows for estimating crop production potential, which helps producers and technicians in their decision making regarding management practices. Thus, a cultivar directly affects water use in common bean production, thereby suggesting the need for a or water conservation strategy and sustainability of irrigated common bean production.

ABSTRACT The cultivation of Coffea arabica L. in a low-altitude region is a sustainable alternative for diversifying the income of farmers. On account of the variability of available cultivars, the use of indirect selection through initial vegetative development may be an auxiliary tool for identifying the most suitable genotypes for this environment. This study aimed to identify the dwarf Arabica coffee cultivars with better initial development in a low-altitude region and the morphological traits with greater relevance for the early selection of cultivars with high yield potential. The experiment was installed in the northeast of São Paulo, Brazil. The experimental design used was randomized blocks with four replications. The treatments consisted of 17 dwarf Arabica coffee cultivars. There is variability among dwarf Arabica coffee cultivars for initial vegetative development. The growth and increase in the number of nodes of the plagiotropic branch can be used in early selection to identify cultivars with greater yield potential. The cultivars IAC Obatã 4739, Obatã IAC 1669-20, and Tupi IAC 1669-33 present higher initial vegetative performance in low-altitude environments. The results obtained are useful to breeders and producers for choosing the cultivars best adapted to cultivation in this environment.

ABSTRACT The demand for specialty coffees in the national and international market grows and generates an excellent opportunity for the exploration of new business. The cup quality of coffee is defined by the genetic predisposition of varietal groups, effects of the production environment, crop management, and form of post-harvest processing. Genotypes of Yellow Bourbon have already shown a predisposition to the production of excellent cup quality, but it may differ in sensory attributes and cup quality. The aim of this article was to evaluate the agronomic and qualitative performance of Yellow Bourbon strains from the Active Germplasm Bank of the Agronomic Institute of Campinas, in order to identify the best genotypes for the production of specialty coffees. The experiment was conducted in São Sebastião da Grama, SP, Brazil, at 1,100 meters of altitude in a medium-textured Ultisol. Treatments consisted of 14 strains of Yellow Bourbon, arranged in a randomized block design with three replicates. Field, post-harvest and laboratory evaluations were carried out. The strains IAC J3-1, IAC J9-16 and IAC J19-18-10 stood out in terms of yield values and sensory quality above the average of the studied group. The strains IAC J9-16 and IAC J19-18-10 showed predominance of floral and honey nuances, respectively, indicating that they may have high potential to express these characteristics in the beverage. The results suggested that there are Yellow Bourbon strains suitable for production and with superior cup quality, which highlights the importance of the appropriate choice of genotypes for the production of differentiated specialty coffees.

Abstract Maize has a high nitrogen (N) demand; as a result, more sustainable alternatives are needed to reduce demand for mineral fertilizers. The hypothesis is that the agronomic perfor mance of maize genotypes diverges in their potential when subjected to different supplies of N. This study aimed to evaluate and characterize the agronomic performance of maize geno types submitted to topdressing nitrogen fertilization and inoculation with Azospirillum brasilense and select the best genotypes within each management. An experiment was conducted in the second season of 2017, in Jaboticabal-SP (Brazil), using 48 maize geno types in a randomized block design. Treatments consisted of: 1) application of 140 kg ha-1 nitrogen, using urea as mineral fertilizer; 2) A. brasilense inoculation via soil, at a rate of 600 mL ha-1, as biological fertilization. Grain yield and agronomic traits were evaluated. The data were subjected to analysis of variance (F-Test), means were compared by Scott-Knott test at 5% probability, and multivariate statistical analysis was performed by principal component analysis. The maize genotypes showed contrasting agronomic performance in relation to the nitrogen supplies evaluated. Inoculation with A. brasilense via soil has a significant effect on increasing maize grain yield, making it a viable and more sustainable alternative in the supply of N. The choice of the genotype is an essential factor for the successful use of mineral nitrogen fertilization or A. brasiliense inoculation.

Resumen El maíz tiene una alta demanda de nitrógeno (N), como resultado, se necesitan alter nativas más sostenibles para reducir la demanda de fertilizantes minerales. La hipótesis es que el comportamiento agronómico de los genotipos de maíz diverge en su potencial cuando se someten a diferentes suministrados de N. Este estudio tuvo como objetivo evaluar y caracte rizar el rendimiento agronómico de los genotipos de maíz sometidos a fertilización nitro genada e inoculación con Azospirillum brasilense y seleccionar los mejores genotipos dentro de cada manejo. Se realizó un experimento en la segunda temporada de 2017, en Jabotica bal-SP (Brasil), utilizando 48 genotipos de maíz en un diseño de bloques al azar. Los trata mientos consistieron en: 1) aplicación de 140 kg ha-1 de nitrógeno, utilizando urea como fertilizante mineral; 2) Inoculación de A. brasilense vía suelo, a razón de 600 mL ha-1, como fertilización biológica. Se evaluaron el rendimiento de granos y los rasgos agronómicos. Los datos se sometieron a análisis de varianza (prueba F), y las medias se compararon mediante la prueba de Scott-Knott con una probabilidad del 5%, y el análisis estadístico multivariado se realizó mediante análisis de componentes principales. Los genotipos de maíz mostraron un comportamiento agronómico contrastante en relación con los suministrados de N evaluados. La inoculación con A. brasilense vía suelo tiene un efecto significativo en incrementar el rendi miento de granos de maíz, convirtiéndolo en una alternativa viable y más sustentable en el sumi nistrado de N. La elección del genotipo es un factor esencial para el uso exitoso de la fertilización con nitrógeno mineral o la inoculación con A. brasiliense.

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.

Las prácticas más sostenibles que involucran la fijación biológica de nitrógeno (BNF) y el uso del clorofilómetro portátil en el manejo de fertilizantes son prometedoras para aumentar la eficiencia del uso de nitrógeno (N) en el cultivo de frijol común. El objetivo fue monitorear el manejo de N con el clorofilómetro portátil y sus efectos sobre los atributos agronómicos de los cultivares de frijol carioca de crecimiento indeterminado y determinado ('IPR Campos Gerais' e 'IAC Imperador'). El experimento se implementó en un diseño de bloques al azar (DBC), en un esquema factorial 2 x 9, con cuatro repeticiones. El primer factor consistió en cultivares, y el segundo factor fue el manejo de N. Los datos fueron sometidos a análisis de varianza por la prueba F, y cuando fue necesario los medios se agruparon por la prueba de Scott-Knott con un 5% de probabilidad. El uso clorofilómetro portátil es una alternativa viable para el monitoreo y manejo del N en el frijol común, permitiendo la reducción de la aplicación del nutriente en la cobertura, independientemente del cultivar utilizado.

RESUMO O feijão é a principal fonte de proteína dos países subdesenvolvidos, e o nitrogênio (N) é um dos nutrientes que mais limita a produtividade dessa cultura. Objetivou-se com esse trabalho, sob condição de campo: a) determinar por meio dos índices de eficiência como o N é utilizado por 16 cultivares de feijoeiro comum; and b) classificar estas cultivares em relação à eficiência de uso e responsividade à aplicação de N. O delineamento experimental foi em blocos casualizados em esquema de parcelas subdivididas, com quatro repetições. As parcelas foram constituídas por 16 cultivares de feijoeiro comum de grão comercial tipo carioca. As subparcelas foram compostas por duas doses de N: 20 e 120 kg ha-1 aplicadas em cobertura. As avaliações foram número de vagens por planta e grãos por vagem, massa de cem grãos, massa seca da parte aérea no florescimento pleno, massa seca de palha e de grãos na maturidade fisiológica e produtividade de grãos. Com base na matéria seca e no teor de nutrientes, os acúmulos de N foram calculados na parte aérea e nos grãos. As eficiências agronômicas, fisiológicas, agro-fisiológicas, recuperação e uso de N foram calculadas. A cultivar BRSMG Uai destaca-se pelas eficiências agronômica, fisiológica, de recuperação e de utilização. Os genótipos BRSMG Uai, BRS FC402, IPR Campos Gerais, IPR Maracanã e TAA Bola Cheia são eficientes e responsivos a aplicação de N em cobertura.

ABSTRACT Common beans are the main source of protein in underdeveloped countries, and nitrogen (N) is one of the nutrients the most limits the productivity of this crop. This study, under field conditions, aimed to: a) determinate through efficiency indices how N is used by 16 cultivars of common beans; and b) classify these cultivars regarding use efficiency and responsivity to N application. The experimental design was in randomized blocks in split-plot scheme, with four replicates. Main plots consisted of 16 cultivars of common beans commercially classified as ‘Carioca type’. Subplots comprised two rates of N: 20 and 120 kg ha-1 applied as top-dressing. The evaluations were number of pods per plant and grains per pod, hundred-grain weight, shoots dry matter at full flowering, straw and grains dry matter at physiological maturity and grain yield. Based on the dry matter and its nutrient contents, the N accumulations were calculated in shoots and grains. The agronomic, physiological, agro-physiological, recovery and use efficiencies of N were calculated. Cultivar BRSMG Uai stands out by agronomic, physiological, recovery and use efficiencies of N. Genotypes BRSMG Uai, BRS FC402, IPR Campos Gerais, IPR Maracanã and TAA Bola Cheia are efficient and responsive to top-dressing N application.