Investigación Agraria

Tratamento de sementes de pimentão com ácido salicílico- efeitos no potencial fisiológico de sementes e produção de mudas

RESUMO A qualidade da semente é um fator primordial no sucesso de cultivos. O tratamento de sementes pode contribuir para uniformizar parâmetros de qualidade de um lote de sementes, e por consequência da produção de mudas. Desta forma, o objetivo dessa pesquisa foi avaliar o efeito do tratamento de sementes de diferentes cultivares de pimentão, com doses de ácido salicílico, no potencial fisiológico de sementes e na produção de mudas. Os experimentos foram realizados em duas etapas: em laboratório para avaliação do potencial fisiológico, e em estufa agrícola, para avaliação do efeito dos tratamentos na produção de mudas. Foram utilizadas sementes de pimentão das cultivares All Big e Ikeda. O tratamento de sementes foi realizado com ácido salicílico nas doses de: 0, 0,1, 0,2, e 0,4 (mM). Após o tratamento as sementes foram submetidas a: teste de germinação, e crescimento de plântulas em condições normais e em meio salino (em laboratório). Na segunda etapa as sementes foram utilizadas na produção de mudas de pimentão em estufa agrícola, e avaliou-se: emergência de plantas, altura de plantas, número de folhas, comprimento de raízes, massa seca de plantas, durante 35 dias. Foi possível concluir-se que, nas condições em que foi realizada essa pesquisa não foram observados efeitos de incremento no potencial fisiológico de sementes de pimentão, cultivares All Big e Ikeda, em função do tratamento de sementes com doses entre 0 a 0,4mM de AS; assim como não se observou efeitos positivos de estimulo de crescimento de mudas. Ainda, observou-se redução em alguns parâmetros, tanto em laboratório, quanto em casa de vegetação, com o aumento das doses, especialmente para a cultivar Ikeda, que de maneira geral teve um efeito inibitório com o aumento das doses de AS.

ABSTRACT Seed quality is a key factor for crops success. Seed treatment can contribute to standardizing seed quality parameters, and consequently seedling production. Thus, the objective of this research was to evaluate the effect of seed treatment of different sweet pepper cultivars, with doses of salicylic acid, on the physiological potential of seeds and seedling production. The experiments were carried out in two stages: in the laboratory to evaluate the physiological potential, and in an agricultural greenhouse, to evaluate the effect of treatments on seedling production. Bell pepper seeds of cultivars All Big and Ikeda were used. Seed treatment was performed with salicylic acid at doses of 0, 0.1, 0.2, and 0.4 (mM). After the treatment, the seeds were submitted to germination test, and seedling growth under normal conditions and in a saline medium (in the laboratory). In the second stage, the seeds were used in the production of sweet pepper seedlings in an agricultural greenhouse, and the following were evaluated: plant emergence, plant height, number of leaves, root length, and dry mass of plants during 35 days. It was possible to conclude that under the conditions in which this research was carried out, no effects were observed to increase the physiological potential of sweet pepper seeds, cultivars All Big and Ikeda, as a function of seed treatment with doses between 0 and 0.4 mM of SA; as well as no positive effects of stimulating the growth of seedlings were observed. Furthermore, a reduction was observed in some parameters, both in the laboratory and in the greenhouse, with increasing doses, especially for the Ikeda cultivar, which generally had an inhibitory effect with increasing AS doses.

Doses de dejetos líquidos de suínos e seu efeito na germinação de sementes de soja, trigo e milho

RESUMO A produção de suínos confinados gera efluentes que quando aplicados no solo servem como fonte de fertilizante e quando aplicados sem tratamento adequado alteram a qualidade ambiental. Estes dejetos contêm elementos potenciais contaminantes cuja aplicação excessiva gera acúmulo de materiais e podem ocasionar efeitos tóxicos para as plantas, como na germinação de sementes. Neste estudo objetivou-se analisar o efeito de doses de dejetos líquidos de suínos (DLS) sobre a germinação de três culturas de grãos de interesse agrícola. Os ensaios foram realizados em condições de laboratório com sementes de soja, trigo e milho, que foram dispostas em placas de Petri, na quantidade de dez sementes por placa. Foram aplicadas doses tratamentos de DLS, caracterizado quimicamente, correspondentes a 0, 1,4 e 2,1 xDP (vezes a Dose Padrão) m³ ha-1 com três repetições. As placas foram colocadas na BOD em temperatura 24 0C. Os dados obtidos foram analisados pelo teste de Tukey (5%). Aos sete dias do início do ensaio foi determinada a porcentagem de germinação. O DLS possui em sua composição alguns elementos potenciais contaminantes, como o cobre, o zinco e o amônio, os quais podem ocasionar prejuízos na germinação de diversas culturas, sobretudo com exposição direta das sementes nas placas de Petri. As sementes de soja e trigo sofreram efeito negativo da aplicação de DLS apresentando redução na taxa de germinação com o uso de 1,4 e 2,1 xDP m³ ha-1. A aplicação do equivalente a 1,4 e 2,1 xDP m³ ha-1 de DLS não afetaram significativamente a germinação de sementes de milho.

ABSTRACT Pig production generates effluents that, when applied to the soil, serve as a source of fertilizer and, when applied without adequate treatment, alter the environmental quality. These wastes contain potential contaminating elements whose excessive application generates an accumulation of materials and can cause toxic effects for plants, such as seed germination. This study aimed to analyze the effect of doses of pig slurry (SP) on seed germination of three grain crops of agricultural interest. The assays were carried out under laboratory conditions with soybean, wheat, and corn seeds placed in Petri dishes, with ten seeds per dish. SP doses/treatments, chemically characterized, corresponding to 0, 1,4, and 2,1 tSD (times the Standard Dose) m³ ha-1 were applied with three replicates. The plates were placed in the BOD at temperature 24°C. The data obtained were analyzed using the Tukey test (5%). Seven days from the beginning of the trial, the percentage of germination was determined. SP has in its composition some potential contaminating elements, such as copper, zinc, and ammonium, which can cause damage to the germination of several cultures, especially with direct exposure of the seeds in Petri dishes. Soybean and wheat seeds were significantly affected by the application of SP, showing a reduction in the germination rate with the use of 100 and 150 m³ ha-1. The application of the equivalent of 1,4, and 2,1 tSD m³ ha-1 of SP did not significantly affect the germination of maize seeds.

Availability of Zinc in soils of the Eastern region of Paraguay

RESUMEN El Zinc (Zn) es un nutriente esencial para las plantas, existe limitada información de su disponibilidad en los suelos de Paraguay. El objetivo de la investigación consistió en evaluar y clasificar la disponibilidad de Zn en suelos de la región Oriental del Paraguay. Para ello fue generada una base de datos con los resultados de análisis de suelo de los laboratorios de la FCA-UNA, CIHB-IPTA y FUCAI-UCA. Se clasificó la concentración de Zn disponible de los suelos en nivel “alto” (>1,2 mg kg-1); “medio” (0,5 - 1,2 mg kg-1) y “bajo” (<0,5 mg kg-1), generándose un mapa de disponibilidad de Zn a nivel distrital. Se evaluó la disponibilidad de Zn a nivel distrital, departamental, así como, con parámetros de estadística descriptiva. Considerando la media de los niveles de Zn a nivel de distrito, de los 234 distritos que conforman la región Oriental del Paraguay, en el 74% de los distritos (174 distritos) presentaron nivel “alto”, 6% nivel “medio” (15 distritos) y el 3% nivel “bajo” de Zn (6 distritos). Considerando el número total de muestras de suelo analizadas (11.395 muestras), el 79% (9.038 muestras) presentaron niveles “alto” de Zn, el 12% (1.316 muestras) presentaron niveles “medio” de Zn, y solo el 9% (1.041 muestras) presentaron niveles “bajo” de Zn. La media nacional considerando las 11.395 muestras de suelo fue de 6,5 mg kg-1 de Zn, por lo tanto, en 79% de los suelos analizados de la región Oriental hay niveles de Zn superior al nivel crítico de Zn para las actividades agrícolas, de forrajes y forestales de producción.

ABSTRACT Zinc (Zn) is an essential nutrient for plants, and there is limited information on its availability in Paraguayan soils. The objective of the research was to evaluate and classify the availability of Zn in soils of the Eastern region of Paraguay. For this, a database was generated with the results of soil analyses from the FCA-UNA, CIHB-IPTA and FUCAI-UCA laboratories. The concentration of available Zn in soils was classified as "high" (>1.2 mg kg-1); “medium” (0.5 - 1.2 mg kg-1) and “low” (<0.5 mg kg-1), generating a Zn availability map at the district level. The availability of Zn was evaluated at the district and departmental levels, as well as with descriptive statistics parameters. Considering the average Zn levels at the district level, of the 234 districts that make up the Eastern region of Paraguay, 74% of the districts (174 districts) presented a "high" level, 6% a "medium" level (15 districts) and 3% “low” level of Zn (6 districts). Considering the total number of soil samples analyzed (11,395 samples), 79% (9,038 samples) presented "high" levels of Zn, 12% (1,316 samples) presented "medium" levels of Zn, and only 9% (1,041 samples) presented “low” levels of Zn. The national average, considering the 11,395 soil samples, was 6.5 mg kg-1 of Zn, therefore, in 79% of the soils analyzed in the Eastern region there are Zn levels above the critical level of Zn for agricultural activities, forage and forestry production.

Soybean production (Glycine max, L) as a function of different doses of simple superphosphate: yield parameters and damage caused by stink bugs

RESUMEN El fósforo (P) es unos de los elementos fundamentales para el desarrollo de la soja. Un suministro inadecuado en la planta podría limitar considerablemente el rendimiento. En el campo experimental de la Facultad de Ciencias Agrarias, Filial Pedro Juan Caballero de la Universidad Nacional de Asunción, situado en el Distrito de Cerro Corá, sobre un Alfisol, se instaló un experimento con el objetivo de evaluar los efectos de la aplicación de diferentes dosis de superfosfato simple en el rendimiento productivo de la soja y los danos. Se encontraron diferencias significativas entre el testigo y los tratamientos fertilizados en cuanto a los parámetros de rendimiento, existiendo un aumento del rendimiento de granos de acuerdo al aumento de la dosis de fósforo aplicado, ajustándose a una ecuación lineal. La producción media de granos en kg ha-1 fueron de 3.837,50, 4.148,61, 4.290,28, y 4.455,56 kg ha-1 para dosis de 30, 60, 90, y 120 kg ha-1 de P2O5 respectivamente, siendo la media obtenida en el testigo igual a 3.527,78 kg ha-1. Se encontraron diferencias significativas entre el testigo y los tratamientos fertilizados en cuanto a la variable de porcentaje de vainas atacadas por chinches y vainas sanas. Se ha verificado plantas sanas, sin ataque o puncturas en mayores dosis de P2O5.

ABSTRACT Phosphorus (P) is one of the fundamental elements for the development of soybean. An inadequate supply in the plant could seriously limit production. In the experimental field of the Faculty of Agrarian Sciences, Pedro Juan Caballero Branch of the National University of Asunción, located in the Cerro Corá District, on an Alfisol, an experiment was installed to evaluate the effects of the application of different simple superphosphate dose in soybean yield and damages. Significant differences were found between the control and the fertilized treatments in terms of yield parameters, with an increase in grain yield according to the increase in the applied phosphorus dose, adjusting to a linear equation. The average production of grains in kg ha-1 was 3,837.50, 4,148.61, 4,290.28, and 4,455.56 kg ha-1 for doses of 30, 60, 90, and 120 kg ha-1 of P2O5 respectively, being the mean obtained in the control equal to 3,527.78 kg ha-1. Significant differences were found between the control and the fertilized treatments in terms of the percentage variable of pods attacked by bedbugs and healthy pods. Healthy plants have been verified, without attack or punctures in higher doses of P2O5.

Agroecology practices to increase productivity on Cuba agricultural farms

RESUMEN La agricultura moderna transita hacia la transformación de la producción agropecuaria con sistemas más sostenibles y se nutre de experiencias de la agricultura orgánica y tradicional, así como de buenas prácticas agronómicas. En este escenario, el desarrollo agropecuario sostenible y la seguridad alimentaria son una prioridad estratégica para Cuba hacia el desarrollo económico y social. El presente trabajo tuvo como objetivo, evaluar el efecto de la aplicación de prácticas agroecológicas para el incremento de la productividad de tres fincas en transición agroecológica del Municipio Jaruco en la provincia de Mayabeque, Cuba. Se abarcó el período de 2020 (línea base) a 2022. Se aplicaron entrevistas a los agricultores para recopilar información acerca de las innovaciones implementadas para mejorar los resultados productivos, y se utilizó el método de observación participante para constatar la efectividad de estas prácticas sobre el incremento de los rendimientos agrícolas de los cultivos evaluados. Los resultados muestran que la utilización de buenas prácticas agrícolas como el uso de bioproductos para la nutrición de las plantas, la diversificación varietal, el uso de abonos orgánicos y de controladores biológicos, permite el incremento del rendimiento agrícola de diferentes cultivos de interés económico para Cuba. Entre ellos se destacan aumentos de rendimiento de 30-60% en boniato, 20-50% en frijol y de 40-50% en maíz, con respecto a los rendimientos obtenidos en el año 2020, tributando de esta manera a la soberanía y seguridad alimentaria local.

ABSTRACT Modern agriculture is moving towards more sustainable systems and is nourished by the experiences of organic and traditional agriculture, as well as good agronomic practices. In this scenario, sustainable agricultural development and food security are a strategic priority for Cuba towards economic and social development. The objective of this work was to evaluate the effect of the application of agroecology practices in increasing the productivity of three farms in agroecology transition in the Jaruco municipality in the Mayabeque province, Cuba. The period from 2020 (baseline) to 2022 was covered. Interviews were applied to farmers to collect information about the innovations implemented to improve production results and the participant observation method was used to verify the effectiveness of the innovation on the increase of the agricultural yields of the evaluated crops. The results show that the use of good agricultural practices such as the use and management of bioproducts for plant nutrition, varietal diversification, the use of organic fertilizers, and biological controls, allowed the increase in the agricultural yield of different crops of economic interest for Cuba. Among them are increases in crop yields of 30-60% in sweet potato, 20-50% in beans, and 40-50% in corn, with respect to the yields obtained in the year 2020, thus paying tribute to local food security and sovereignty.

Effect of pre-emergent herbicides applied by drip irrigation in the transplanted onion crop

RESUMEN La herbigación tiene como ventajas la reducción de la deriva, menor exposición del operador al producto y la disminución de los costos asociados al manejo de arvenses. Este trabajo se realizó en el Departamento Caaguazú, Paraguay, entre marzo y octubre de 2018, con el objetivo de evaluar la eficacia de diferentes dosis de herbicidas preemergentes, aplicados mediante riego por goteo, en el cultivo de cebolla trasplantada. Se empleó un diseño experimental de bloques completos al azar con arreglo en parcelas divididas (5>5), donde la parcela principal estuvo constituida por los herbicidas y las subparcelas por las dosis: Flumioxazin (0, 15, 25, 35 y 45 g i.a. ha-1), Oxyfluorfen (0, 240, 312, 384 y 456 g i.a. ha-1), Pendimethalin (0, 800, 1.000, 1.200 y 1.400 g i.a. ha-1), Trifluralin (0, 576, 768, 960 y 1.152 g i.a. ha-1) y S-metolachlor (0, 480, 960, 1.440 y 1.920 g i.a. ha-1), con cuatro repeticiones. Las arvenses con mayor importancia relativa fueron: Digitaria horizontalis, Richardia brasiliensis, Galinsoga parviflora, Bidens pilosa, Amaranthus spinosus y Portulaca oleracea. Los herbicidas utilizados fueron eficaces sobre las especies sensibles y no causaron síntomas de fitotoxicidad sobre el cultivo de cebolla hasta los 21 días después de la aplicación. Las dosis empleadas de oxyfluorfen, pendimethalin, trifluralin y s-metolachlor no afectaron el rendimiento de bulbos del cultivo de cebolla trasplantada.

ABSTRACT Herbigation has several advantages, such as the reduction of drift, the operator's exposure to the product, and the reduction of costs associated with weed management. This work was carried out in the Department of Caaguazú, Paraguay, during the period from March to October 2018, to evaluate the efficacy of different doses of pre-emergent herbicides applied via irrigation water in the transplanted onion crop. The experimental design used was the randomized complete blocks with arrangement in divided plots (5>5), where the main plot consisted of the herbicides (Flumioxazin, Oxyfluorfen, Pendimethalin, Trifluralin and S-metolachlor) and the subplots of the doses of Flumioxazin (0, 15, 25, 35 and 45 g a.i. ha-1), Oxyfluorfen (0, 240, 312, 384 and 456 g a.i. ha-1); Pendimethalin (0, 800, 1,000, 1,200 and 1,400 g a.i. ha-1); Trifluralin (0, 576, 768, 960 and 1,152 g a.i. ha-1) and S-metolachlor (0, 480, 960, 1,440 and 1,920 g a.i.ha-1) with four repetitions. The weeds with the highest relative importance were: Digitaria horizontalis, Richardia brasiliensis, Galinsoga parviflora, Bidens pilosa, Amaranthus spinosus and Portulaca oleracea. Herbicides in the studied doses applied through irrigation water were effective on sensitive species and did not cause symptoms of phytotoxicity on onion crops until 21 DAA. The evaluated doses of Oxyfluorfen, Pendimethalin, Trifluralin and S-metolachlor did not affect the bulb yield in the transplanted onion crop.

First report of Pseudimatidium pici (Staines, 2009), Coleoptera: Chrysomelidae: Cassidinae in ornamental palms from Paraguay

RESUMEN El Paraguay reporta varias especies de coleópteros de la Subfamilia Cassidinae que tienen como hospederos a plantas de diferentes familias, como así también palmáceas de uso industrial como ornamental. Las palmeras ornamentales ocupan un lugar relevante en varios ámbitos paisajísticos, siendo del género Phoenix una de las más importantes desde el punto de vista estético como económico. En los primeros meses del año 2022, fueron observados daños en hojas nuevas de palmeras de la especie Phoenix roebelenii, presentando un raspado del mesófilo, adquiriendo las hojas franjas de color marrón ceniciento, con la consecuente pérdida del valor estético. La inspección de dichas plantas registró la presencia de un pequeño coleóptero de cuerpo achatado, color marrón oscuro, que fue identificado como Pseudimatidium pici, Familia Chrysomelidae, Subfamilia Cassidinae.

ABSTRACT Paraguay reports several species of Coleoptera of the Cassidinae Subfamily that have plants from different families as hosts, as well as palm trees for industrial use as ornamentals. Ornamental palms occupy an important place in several landscape areas, being those of the genus Phoenix one of the most important from the aesthetic and economic point of view. In the first months of the year 2022, damage was observed in new palm leaves of the species Phoenix roebelenii, presenting a scratching of the mesophyll, the leaves acquiring ashen-brown stripes, with the consequent loss of aesthetic value. The inspection of these plants recorded the presence of a small beetle with a flattened dark brown body, which was identified as Pseudimatidium pici, Family Chrysomelidae, Subfamily Cassidinae.

The dilemma between own or rented machinery: the case of a modal farm in Northern Alto Paraná-Paraguay

RESUMEN En Paraguay son escasos los estudios económicos y financieros, de acceso público, relacionados a maquinarias agrícolas, así como a su impacto en los resultados de una finca. Existe lo que se puede caracterizar como un vacío documental. Por ello ante consultas, de parte de agricultores u otros cualesquiera, tales como ¿es rentable tener máquinas propias?, o ¿a partir de que superficie es rentable tener máquinas propias?, no se tienen respuestas documentadas cuyas metodologías puedan ser replicadas. Ante esta situación, este trabajo se propuso contribuir a reducir el vacío documental en el tema. Su objetivo general fue determinar el efecto de la compra de maquinaria agrícola (sembradora, pulverizadora y cosechadora) en la rentabilidad de una finca agrícola. A fin de alcanzar el objetivo indicado se recurrió a un estudio de caso. Se realizó un análisis económico de una finca modal de la Región norte de Alto Paraná con los siguientes indicadores: margen bruto, resultado operativo, ingreso neto, ingreso al capital, rentabilidad, y utilidad líquida. Se construyeron tres escenarios para el análisis: (i) línea de base, (ii) las maquinarias brindan servicios en la finca modal a precio de costo y los excedentes se venden a precios de mercado a terceros, y (iii) todos los servicios (finca modal y terceros) se venden a precios que incluye un margen de beneficio. Se concluyó que la prestación de los servicios con máquinas propias incrementa la rentabilidad de la finca por encima de la línea base.

ABSTRACT In Paraguay, there are few economic and financial studies, of public access, related to agricultural machinery as well as its impact on the results of a farm, which can be characterized as a documentary gap. For this reason, queries, from farmers or any other, such as: is it profitable to have your own machines? or, from what area is it profitable to have your own machines? There are no documented answers whose methodologies can be replicated. Faced with this situation, this work proposed to contribute to reducing the documentary gap on the subject. Its general objective was to determine the effect of the purchase of agricultural machinery (seeder, sprayer, and harvester) on the profitability of an agricultural farm. In order to achieve the indicated objective, a case study was used. An economic analysis of a modal farm in the northern region of Alto Paraná was carried out with the following indicators: gross margin, operating result, net income, capital income, profitability, and liquid profit. Three scenarios were built for the analysis: (i) baseline, (ii) the machinery provides services in the modal farm at cost price and the surplus was sold at market prices to third parties, and (iii) all services (finca modal and third parties) were sold at prices that include a profit margin. It was concluded that the provision of services with its own machines increases the profitability of the farm above the baseline.