Investigación Agraria

Las re-evoluciones de la agricultura

Soil water balance and soybean productivity cultivated under different water deficit levels in South Brazil

RESUMO O balanço hídrico do solo tem sido objeto de estudo por vários anos, devido ao detalhamento das informações geradas e que auxiliam no entendimento da disponibilidade de água no solo às plantas, no desenvolvimento das culturas agrícolas e, consequentemente, na produtividade das mesmas. O principal objetivo desse trabalho foi avaliar a dinâmica do balanço hídrico para a cultura da soja [Glycine max (L) Merrill.) submetida a diferentes níveis de déficit hídrico e seu impacto na produtividade da cultura. O experimento foi conduzido no interior de uma cobertura móvel (Rainout shelter), onde foram testados quatro tratamentos com diferentes níveis de déficit hídrico: T1 (Sem déficit hídrico), T2 (Déficit hídrico leve), T3 (Déficit hídrico moderado) e T4 (Déficit hídrico severo). Utilizou-se o delineamento experimental inteiramente casualizado, com três repetições. As variáveis do balanço hídrico como evapotranspiração da cultura (ETc), irrigação, precipitação, escoamento, e variação da água disponível no solo (ΔASW) foram monitoradas diariamente. Os resultados demostram uma influência dos diferentes níveis de irrigação deficitária e as condições meteorológicas sobre os componentes do balanço hídrico, o ciclo da cultura, características morfológicas e componentes de rendimento. Observou-se redução no rendimento de grãos com o aumento do déficit hídrico, do tratamento sem déficit para o déficit severo, de 42 a 11,5%, respectivamente, para o ano 1 e 2.

ABSTRACT The water balance of soil has been studied for several years, due to the detailed information generated and that help in understanding the availability of water in soil to the plants, in the development of agricultural crops and, consequently, in their productivity. The main objective of this work was to evaluate the dynamics of the water balance for the soybean crop [Glycine max (L.) Merrill.] submitted to different levels of water deficit and its impact on crop productivity. The experiment was conducted inside a mobile cover (Rainout shelter) in the period 2014/2015 and 2016, where four treatments with different levels of water deficit were tested: T1 (no water deficit), T2 (light water deficit), T3 moderate water deficit) and T4 (severe water deficit). The experimental design was completely randomized, with three replicates. Water balance variables such as crop evapotranspiration (ETc), irrigation, precipitation, runoff and soil water variation (ΔASW) were monitored daily. The results show an influence of the different levels of deficit irrigation and the meteorological conditions on the components of the water balance, the crop cycle, morphological characteristics and, yield components. A grains yield reduction was observed with the increase in soil water deficit, for treatments without deficit to severe deficit, from 42 to 11,5%, respectively, for year 1 and year 2, respectively.

Compactación del suelo y su efecto en el crecimiento vegetativo de soja, maíz y guandú

RESUMEN El crecimiento radicular y el rendimiento de un cultivo son afectados por la compactación del suelo. El objetivo de este trabajo fue evaluar el desarrollo de los cultivos de soja (Glycine max (L.) Merr.), maíz (Zea mays L.) y guandú (Cajanus cajan (L.) Millsp.) en suelo arcilloso con diferentes densidades en Katueté, Canindeyú. El diseño experimental fue completamente al azar con un arreglo factorial de tratamientos (3 x 4). Los factores fueron cultivos (soja, maíz y guandú) y densidades de suelo (0,9; 1,19; 1,39 y 1,59 g cm-3), con 4 repeticiones. Las unidades experimentales consistieron en tubos de PVC con 20 cm de diámetro y 48,5 cm de altura, divididos en tres secciones: A (0-10 cm), B (10-13,5 cm), donde fue simulada la compactación del suelo y C (13,5-48,5 cm), respectivamente. Se realizó análisis de varianza y comparación de medias con la prueba de Tukey al 5%. Se determinó altura de planta a los 30, 60 y 75 días, diámetro de planta, peso de materia verde y seca, área de raíces y peso seco de raíces. El maíz presentó diferencia significativa en la altura de planta a los 75 días con la mayor densidad de suelo. En lo que se refiere a área y peso seco de raíces estos fueron superiores en el maíz en las camadas A y B. La densidad del suelo afectó negativamente al peso seco de raíces en la sección B siendo mayor con densidad de suelo de 1,19 g cm-3 (5,37 g maceta-1) y menor con densidad 1,59 g cm-3 (4,79 g maceta-1). En la sección C la densidad del suelo no afectó la materia seca de raíces de soja y guandú, pero disminuyó en el maíz. Suelos con camadas compactadas afectan mayormente al desarrollo radicular del maíz, comparado a la soja y guandú.

ABSTRACT Soil compaction affects root growth and crop yield. The objective of this work was to evaluate the development of soybean (Glycine max (L.) Merr.), corn (Zea mays L.) and pigeon pea (Cajanus cajan (L.) Millsp) crops in different soil densities. The experimental design was completely randomized, with treatments arranged in a 3 x 4 factorial scheme, with three crops (soybean, corn and pigeon pea) and four soil densities (0.9; 1, 19, 1.39 and 1.59 g cm-3), with 4 replications. The experimental units consisted of PVC tubes with 20 cm diameter and 48.5 cm height, divided into sections: A (0-10 cm), B (10-13.5 cm), where the compaction was simulated and C (13.5-48.5 cm), respectively. ANAVA was used at 5% probability and where there was significance, Tukey test performed mean comparison. Plant height was determined at 30, 60 and 75 days, plant diameter, weight of green and dry matter, root area and root dry weight. Corn showed the highest values in the evaluated parameters of the aerial part. There was a significant difference between the soil compaction levels in plant height at 75 days with the highest soil density. In terms of area and dry weight of roots, they were higher in maize in sections A and B. Soil density negatively affected the dry weight of roots in section B, being higher with soil density of 1.19 g cm-3 (5.37 g pot-1) and smaller with density 1.59 g cm-3 (4.79 g pot-1). In section C soil density did not affect dry matter of soybean roots and pigeon pea, but decreased in corn. Soil compaction mainly affects the root development of corn, compared to soybean and pigeon pea.

Leaf fertilization in nutritional supplementation of micropropagated pineapple cultivars

RESUMO Embora já se disponha de cultivares de abacaxizeiro resistentes à fusariose, a produção brasileira é baseada na cultivar Pérola, susceptível à fusariose. Estudos com essas cultivares resistentes devem priorizar o atendimento das exigências nutricionais, para que elas expressem seu potencial produtivo e se tornem opções viáveis para os produtores. Objetivou-se estudar os efeitos de composições de adubo foliar no crescimento e produção de cinco cultivares de abacaxizeiro micropropagadas. O estudo foi iniciado em casa de vegetação e aos 210 dias após o transplantio, as mudas foram transferidas para o campo. O delineamento experimental foi em blocos casualizados, em parcelas subdivididas com três fatores e quatro repetições. A combinação das cinco cultivares de abacaxizeiro (BRS Ajubá, IAC Fantástico, BRS Imperial, Pérola e BRS Vitória) e três composições de adubo foliar (NK, NPK e NPK + micronutrientes) foram aleatorizadas nas parcelas e seis épocas de avaliação, nas subparcelas. Atributos agronômicos foram analisados nas épocas de avaliação. Os resultados obtidos foram submetidos à análise de variância pelo teste F. Foi empregado o teste de Scott-Knott para as comparações entre cultivares e adubação, e de regressão para as épocas, empregando-se o programa SISVAR. Independente da adubação, a cv. IAC Fantástico se destacou na maioria dos caracteres avaliados, sendo superior a cv. Pérola, considerada padrão. A fórmula NK mostra ser a melhor opção para utilização como adubo foliar na cultura do abacaxizeiro. A cultivar IAC Fantástico apresenta boas características vegetativas e produtivas, tendo potencial para ser uma opção viável para cultivo no estado de Roraima.

ABSTRACT Although there are already available pineapple cultivars resistant to fusariosis, Brazilian production is based on the cultivar Pérola, susceptible to fusariosis. Studies with these resistant cultivars should prioritize the fulfillment of nutritional requirements, so that they express their productive potential and become viable options for producers. The objective of this study was to study the effects of foliar fertilizer compositions on the growth and yield of five micropropagated pineapple cultivars. The study was started in a greenhouse and at 210 days after transplanting, the seedlings were transferred to field conditions. The experimental design was in randomized blocks, in subdivided plots with three factors and four replications. The combination of the five pineapple cultivars (BRS Ajubá, IAC Fantástico, BRS Imperial, Pérola and BRS Vitória) and three leaf fertilizer compositions (NK, NPK and NPK + micronutrients) were randomized in plots and six evaluation periods consisted of subplots. Agronomic attributes were analyzed at the time of evaluation. The results obtained were subjected to analysis of variance by the F test. The Scott-Knott test was used for comparisons between cultivars and fertilization, and regression for the seasons, using the SISVAR program. Regardless of fertilization, cv. IAC Fantástico stood out in the majority of the evaluated characters, being superior to cv. Pérola, considered standard. The NK formula shows to be the best option for use as leaf fertilizer in the pineapple crop. The cultivar IAC Fantástico has good vegetative and productive characteristics, having the potential to be a viable option for cultivation in the state of Roraima.

Comparación de las concepciones de extensión rural de extensionistas de Argentina, Guatemala y Paraguay

RESUMEN Se estudiaron de manera comparativa los enfoques de extensión rural de extensionistas de Argentina, Guatemala y Paraguay a partir de la utilización de una escala tipo Likert que evalúa el grado de acuerdo o desacuerdo con dos modelos diferentes de extensión rural, uno difusionista y otro horizontal centrado en el diálogo entre técnicos y productores. Los cuestionarios se tomaron a extensionistas que trabajan en el sector público en los tres países. Para el análisis se utilizó el software SPSS. Los resultados muestran un fuerte acuerdo con un enfoque horizontal y dialógico en las tres muestras. En contraste, existen diferencias significativas en el grado de acuerdo con las premisas de una extensión rural orientada a la transferencia de tecnologías. Esto es importante ya que las teorías actuales sobre el funcionamiento de sistemas de innovación destacan la necesidad de establecer un diálogo horizontal entre los diferentes actores. Los resultados sugieren que las mujeres y los extensionistas de mayor edad y experiencia acuerdan menos con las propuestas difusionistas de transferencia tecnológica, lo que invita a pensar en los factores que pueden reducir la orientación difusionista de los técnicos.

ABSTRACT The rural extension approaches of extension workers from Argentina, Guatemala and Paraguay were compared using a Likert type scale, which assesses the degree of agreement or disagreement with two different models of rural extension, one characterized by diffusionism, and other by horizontality and dialogue between technicians and farmers. Research participants work as rural extension agents in the public sector in the three countries. SPSS software was used to analyze the data. Results show that extensionists strongly agree with a horizontal, dialogical extension approach. In contrast, there are significant differences with regards to the degree of agreement with a rural extension aimed at technology transfer. This is important, because current theories on the functioning of innovation systems highlight the need for establishing a horizontal dialogue between different actors. The results suggest that women and older and experienced extensionists support the transfer of technology approach to a lesser degree, which invites to think about the factors that could reduce the technicians’ diffusionist orientation.

Influence of season and number of landslides on initial development of Tectona grandis l. F. in silvopastoral system

RESUMO O presente estudo foi desenvolvido como o objetivo de avaliar o número e a época de desrama e sua influência sobre o desenvolvimento em altura, diâmetro e a qualidade do fuste de um povoamento de Teca, no sistema silvipastoril, localizado no município de Alta Floresta, região Norte do Estado do Mato Grosso.O delineamento experimental utilizado foi em blocos casualizados, com quatro tratamentos (T1: desrama três vezes ao ano nos meses de agosto, novembro e fevereiro, T2: desrama somente em fevereiro, T3: desrama somente em agosto e T4: desrama somente em novembro) e cinco repetições com oito árvores por parcela totalizando 160 árvores. A desrama foi aplicada aos 12, 24 e 36 meses de idade. Avaliou-se o DAP (1,30 m), altura total, incremento corrente anual em altura e diâmetro e a qualidade do fuste. A aplicação do tratamento T2 (desrama realizada no mês de fevereiro) proporcionou efeito positivo no desenvolvimento inicial de povoamento de Tectona grandis l. F. no sistema silvipastoril na região de Alta Floresta, estado de Mato Grosso.

ABSTRACT This study was developed to evaluate the number and timing of pruning and its influence on the development in height, diameter and the quality of the stem of a Teak settlement, in the silvipastoral system, located in the municipality of Alta Floresta, northern region of the State of Mato Grosso. The experimental design used was in randomized blocks, with four treatments (T1: pruning three times a year in August, November and February, T2: pruning only in February, T3: pruning only in August and T4: pruning only in November) and five repetitions with eight trees per plot totaling 160 trees. The pruning was applied at 12, 24 and 36 months of age. The DAP (1.30 m), total height, annual current increment in height and diameter and the quality of the stem were evaluated. The application of T2 treatment (pruning performed in February) provided positive effect on the initial development of Tectona grandis l. F. stands in the silvipastoral system in the Alta Floresta region, state of Mato Grosso.

Caracterización fisicoquímica de la pulpa y almendra de Acrocomia aculeata

RESUMEN La fruta de Acrocomia aculeata, localmente conocida como coco o “mbokaja” en idioma guaraní es una especie nativa abundante del suelo paraguayo, cuya almendra y pulpa contienen cantidades importantes de proteínas, fibras, carbohidratos, lípidos, vitaminas y minerales, con un alto potencial para su consumo tanto en forma natural o para su utilización en la producción de alimentos. Este trabajo tuvo como objetivo evaluar aspectos fisicoquímicos y compuestos nutricionales de los frutos. Se evaluaron las distintas fracciones de la fruta y se determinó la porción comestible, utilizando métodos gravimétricos. Se determinó además el contenido de lípidos totales por el método de extracción con solvente (Soxhlet), la proteína fue determinada por el método de Kjeldahl, el contenido total de carbohidratos se determinó por espectrofotometría con el método de la antrona, el residuo mineral por calcinación en mufla, el contenido de fibra se calculó por diferencia y finalmente el perfil lipídico y minerales por métodos instrumentales. La pulpa y almendra representaron el 43,9% y 10,13% del peso total de la fruta respectivamente. Los componentes principales presentes en la pulpa y la almendra respectivamente son lípidos (24,1% y 57,1%), fibra (28,2% y 19,7%) y proteínas (14,0% y 16,4%). Los resultados obtenidos en la evaluación de las características físicas y químicas del coco nativo, se destacaron los contenidos de compuestos nutritivos del coco, sobre todo la proteína en la almendra y el alto contenido de ácido oleico en la pulpa, datos que resultan prometedores para su aprovechamiento en la industria alimenticia.

ABSTRACT The fruit of Acrocomiaaculeata, locally known as “coco” or “mbokaja” in Guaraní language is a native species abundant in Paraguayan soil, whose kernel and pulp contain important amounts of proteins, fibers, carbohydrates, lipids, vitamins and minerals, with a high potential for consumption both in natural form or for its use in food production. This study aimed to evaluate physicochemical aspects and nutritional compounds of the fruits. The different fractions of the fruit were evaluated and the edible portion was determined using gravimetric methods. The solvent extraction method (Soxhlet) determined the total lipid content, the Kjeldahl method determined the protein, the anthrone method (spectrophotometry) determined the total carbohydrate content. The mineral residue was determined by calcination in muffle. The fiber content was calculated by difference. Finally, lipid profiled and minerals by instrumental methods.. The pulp and kernel represent 43.9% and 10.13% of the total weight of the fruit respectively. The main components present in the pulp and kernel are lipids (24.1 and 57.1%), fiber (28.2% and 19.7%) and proteins (14.0% and 16.4%) respectively. The results obtained in the evaluation of the physical and chemical characteristics of the native coconut, the contents of nutritious compounds of the coconut were highlighted, mainly the protein in the almond and the high content of oleic acid in the pulp, which are promising for its use in the food industry.

Evaluación de aislados de Trichoderma spp. nativos del Paraguay para el control de Colletotrichum spp. causante de la antracnosis en frutilla

RESUMEN Uno de los agentes de control biológico más estudiados y efectivos en varios fitopatosistemas, es el hongo Trichoderma spp.; sin embargo, en Paraguay no existen productos comerciales a base de aislados nativos. El objetivo del trabajo fue seleccionar aislados de Trichoderma nativos del Paraguay como biocontroladores de Colletotrichum spp. causante de la antracnosis en frutilla, midiendo la velocidad de crecimiento, sobreposición micelial y la capacidad de inhibición de crecimiento in vitro. Se verificaron diferencias significativas entre los aislados de Trichoderma spp. para la inhibición de crecimiento de Colletotrichum spp. registrándose valores de 50,00 hasta 74,44%, siendo el aislado TFC14-06 el que ejerció mayor inhibición. Para evaluar el efecto sobre la producción de frutilla, se realizaron aplicaciones semanales de la mezcla de la suspensión de esporas de Trichoderma spp. TKC14-03, TFC14-06 y TFLE-08 en las parcelas experimentales de frutilla variedad Dover del CIHB/IPTA. Durante evaluaciones de campo bajo condiciones de infección natural, no se observaron diferencias significativas entre los tratamientos testigo y tratados con la suspensión de esporas de Trichoderma. En conclusión, los aislados nativos TFC14-04, TFC14-05, y TFC14-06 presentan potencial antagónico ante Colletotrichum spp. en base a su capacidad de inhibición de crecimiento del patógeno in vitro. Sin embargo, bajo condiciones de infección natural del patógeno no se observó el efecto de la aplicación de la suspensión de esporas de Trichoderma sobre la producción de frutilla. Futuros trabajos de selección deberán evaluar aislados nativos de Trichoderma bajo condiciones ambientales controladas que aseguren una alta presión de la enfermedad.

ABSTRACT One of the most studied and effective biological control agents in several phytopatosystems is the fungus Trichoderma spp.. However, in Paraguay there are no commercial products based on native isolates. The objective of this work was to select Trichoderma isolates native to Paraguay as biocontrol agents of Colletotrichum spp. causal agent of the anthracnose in strawberries. It was measured the average speed of growth, degree of mycelial overlap and capacity of inhibition of growth in vitro of the plant pathogen Colletotrichum spp. using the dual culture technique. Significant differences were observed between isolates of Trichoderma spp. for the inhibition of growth of Colletotrichum spp. with values of 50.00 to 74.44%, being the native isolate TFC14-06 the one that exerted the greatest inhibition. To evaluate the effect on strawberry production, weekly applications of spore suspension mix of Trichoderma spp. TKC14-03, TFC14-06 and TFLE-08 were carried out in the experimental plots of strawberry cv. Dover in the CIHB/IPTA. During field evaluations under conditions of natural infection, no significant differences were observed between control treatments and treated with Trichoderma spore suspension. In conclusion, the native isolates TFC14-04, TFC14-05, and TFC14-06 have antagonistic potential against Colletotrichum spp. based on their ability to inhibit pathogen growth in vitro. However, the effect of the application of the spore suspension of Trichoderma isolates on strawberry production under conditions of natural infection was not observed. Therefore, future screening experiments of native Trichoderma isolates should evaluate their effect under controlled environmental conditions that ensure high disease pressure.