Investigación Agraria

Zinc fertilization in wheat, corn and sesame in soils of different textures

RESUMEN El zinc (Zn) es un nutriente esencial para las plantas, sin embargo, aún existen escasos estudios de fertilización relacionados a este nutriente en Paraguay. El objetivo de este experimento fue evaluar el efecto de la aplicación de Zn sobre los cultivos de trigo, maíz y sésamo en dos suelos de diferentes texturas. La investigación fue realizada en ambiente controlado, en macetas con 5 kg de suelo, entre febrero de 2017 a enero de 2018. El diseño experimental utilizado fue completamente al azar con arreglo bifactorial, con 5 repeticiones. Los factores evaluados fueron: Factor 1, texturas de suelo (franco arenosa y arcillosa) y dosis de Zn (0, 10, 20, 40 y 80 mg kg-1 de Zn) aplicados antes de la siembra del trigo y maíz, evaluando el efecto residual del Zn en el sésamo. Se determinó el nivel de Zn en el suelo y en el tejido, la altura de planta y el peso de materia seca. La textura del suelo no influyó en el contenido de Zn en el suelo y en el tejido foliar de las plantas. El contenido de zinc en el suelo y la concentración de Zn en el tejido aumentaron en forma lineal a mayor dosis de Zn aplicada. La altura de planta fue afectada por la textura del suelo en los tres cultivos y la producción de materia seca en las gramíneas. El Zn aumentó la altura de planta de trigo y maíz, no así la del sésamo. La materia seca y la altura de planta del trigo y maíz aumentaron en el suelo arenoso, no así en el sésamo. El maíz y el trigo presentaron efecto significativo en parámetros de crecimiento en función a las dosis de Zn aplicadas en el suelo arenoso. La producción de materia seca sufrió interacción entre suelo y dosis de Zn en el trigo y maíz. La aplicación de Zn permite el aumento de los niveles de este en el suelo y en el tejido de las plantas, pero no siempre en la producción de materia seca.

ABSTRACT Zinc (Zn) is an essential nutrient for plants, however, there are still few studies related to this nutrient in Paraguay. The aim of this experiment was to evaluate the effect of the application of Zn on wheat, corn and sesame crops in two soils of different textures. The experiment was carried out in a greenhouse, in pots with 5 kg of soil, between February 2017 and January 2018. The experimental design used was completely randomized with a bifactorial arrangement, with 5 repetitions. The factors evaluated were: Factor 1, soil textures (sandy and clay loam) and Zn doses (0, 10, 20, 40 and 80 mg kg-1 of Zn) applied before sowing wheat and corn, evaluating the residual effect of Zn in sesame. The Zn level in the soil and in the tissue, the plant height and the dry matter weight were determined. The soil texture did not influence the Zn content in the soil and in the leaf tissue of the plants. The zinc content in the soil and the Zn concentration in the tissue increased linearly with the higher dose of Zn applied. Plant height was affected by soil texture in the three crops and dry matter production in grasses. Zn increased the plant height of wheat and corn, but not that of sesame. Dry matter and plant height of wheat and corn increased in sandy soil, not so in sesame. Corn and wheat showed a significant effect on growth parameters depending on the Zn doses applied to the sandy soil. Dry matter production suffered interaction between soil and Zn doses in wheat and corn. The application of Zn allows the increase of its levels in the soil and plant tissue, but not always in the production of dry matter.

Determination of the spatial behavior of anthracnose in avocado cultivation using spatial statistics

RESUMEN La antracnosis es una enfermedad fúngica presente en el cultivo de aguacate de manera recurrente, generando pérdidas económicas importantes para el sector productivo del Estado de México. Para focalizar las medidas de control, resulta importante conocer la distribución espacial y la dinámica que siguen las enfermedades como la antracnosis a través de métodos geoestadísticos. Por tal motivo, el objetivo de este estudio fue determinar el comportamiento espacial de la antracnosis en el cultivo de aguacate Hass en Coatepec Harinas y Tenancingo, dos municipios productores del Estado de México. Se muestrearon cuatro hectáreas, estableciendo 40 cuadrantes en cada una, y en cada una de ellos, 10 árboles de aguacate cultivar Hass de 10 años fueron georreferenciados con un DGPS y utilizados para medir la incidencia de síntomas de antracnosis en 12 frutos. Los datos fueron analizados con el software Variowin 2.2 y los mapas generados con el programa Surfer 16. Los mapas elaborados muestran centros de agregación, y los semivariogramas sugieren una distribución ajustada en su mayoría a modelos de tipo gaussiano y exponencial; con rangos que fluctúan entre los 12 y los 56 metros, indicando asociación entre los datos; el mayor porcentaje de superficie infectada fue de 99% para el primer muestreo de abril, mientras para el primer muestreo de noviembre, el mayor porcentaje fue de 98% en ambos municipios. El índice de distancia para la regularidad Ia corroboró la existencia de focos de agregación en todos los muestreos, al igual que los valores obtenidos del índice de agrupamiento Ja.

ABSTRACT Anthracnose is a fungal disease that is present in avocado crops on a recurring basis, generating significant economic losses for the productive sector of the State of Mexico. To focus control measures, it is important to know the spatial distribution and dynamics that diseases such as anthracnose follow through geostatistical methods. For this reason, the objective of this study was to determine the spatial behavior of anthracnose in the Hass avocado crop in Coatepec Harinas and Tenancingo, two producing municipalities in the State of Mexico. Four hectares were sampled, establishing 40 quadrants in each one, and in each one of them, 10 10-year-old Hass avocado trees were georeferenced with a DGPS and used to measure the incidence of anthracnose symptoms in 12 fruits. The data were analyzed with the Variowin 2.2 software and the maps generated with the Surfer 16 program. The maps produced show aggregation centers, and the semivariograms suggest a distribution fitted mostly to Gaussian and exponential models; with ranges fluctuate between 12 and 56 meters, indicating an association between the data; the highest percentage of infected surface was 99% for the first sampling in April, while for the first sampling in November, the highest percentage was 98% in both municipalities. The distance index for the regularity Ia corroborated the existence of aggregation foci in all samplings, as well as the values obtained from the clustering index Ja.

Geometric recovery by humidification of densified wood of eight Mexican species

RESUMEN El densificado de la madera mejora sus propiedades higroscópicas; no obstante, si la madera densificada se expone a la humedad, tiende a recuperar su forma original. El objetivo de este trabajo fue determinar las recuperaciones geométricas de la madera densificada y determinar las higroexpansiones radiales de la madera sólida de ocho especies mexicanas: Cupressus lindleyi, Cedrela odorata, Swietenia macrophylla, Tabebuia donnell-smithii, Fraxinus uhdei, Fagus mexicana, Dalbergia palo-escrito y Guazuma ulmifolia. Para eso, se aplicó un tratamiento de densificado a madera de estas especies y posteriormente fueron humidificadas para observar sus higroexpansiones. Los valores promedio de la recuperación geométrica y de la higroexpansión radial de las maderas C. lindleyi, C. odorata, T. donnell-smithii, F. uhdei, F. mexicana, y G. ulmifolia aumentan a medida que sus densidades se incrementan (αR = 0,0095 ρCH - 2,66; R2 = 0,79). Caso diferente son las maderas S. macrophylla y D. palo-escrito, para las cuales la recuperación geométrica y la higroexpansión radial son menores comparativamente a las otras especies. Se concluye que los valores promedio de la recuperación geométrica y de la higroexpansión radial de las maderas C. lindleyi, C. odorata, T. donnell-smithii, F. uhdei, F. mexicana, y G. ulmifolia aumentan a medida que sus densidades se incrementan. En cambio, para S. macrophylla y D. palo-escrito, la recuperación geométrica y la higroexpansión radial son menores comparativamente a las otras especies. Asimismo, para las ocho especies estudiadas la recuperación geométrica de la madera densificada es mayor que la higroexpansión radial de la madera sin densificar.

ABSTRACT The densification of the wood improves its hygroscopic properties; however, if the densified wood is exposed to moisture, it tends to regain its original shape. The research, with a comparative approach, aimed to determine the geometric recoveries of densified wood and to determine the radial hygroexpansions of solid wood of eight Mexican species: Cupressus lindleyi, Cedrela odorata, Swietenia macrophylla, Tabebuia donnell-smithii, Fraxinus uhdei, Fagus mexicana, Dalbergia palo-escrito and Guazuma ulmifolia. For this, a densification treatment was applied to wood of these species and later they were humidified to observe their hygroexpansions. The mean values of geometric recovery and radial hygroexpansion of the woods C. lindleyi, C. odorata, T. donnell-smithii, F. uhdei, F. mexicana, and G. ulmifolia increase as their densities increase (αR = 0,0095 ρCH - 2,66; R2 = 0,79). Different cases are the woods S. macrophylla and D. palo-escrito, for which the geometric recovery and radial hygroexpansion are comparatively lower than the other species. It is concluded that the average values of the geometric recovery and of the radial hygroexpansion of the woods C. lindleyi, C. odorata, T. donnell-smithii, F. uhdei, F. mexicana, and G. ulmifolia increase as their densities increase. On the other hand, for S. macrophylla and D. palo-escrito, geometric recovery and radial hygroexpansion are comparatively lower than the other species. Likewise, for the eight species studied, the geometric recovery of the densified wood is greater than the radial hygroexpansion of the non-densified wood. In the opposite sense, the coefficient of variation of the geometric recovery of densified wood is lower than that of non-densified wood. The values are different for each species, but their magnitudes are positioned close to the statistical trends obtained by other researchers.

Electrical conductivity test on flex seeds

RESUMO Para determinar a qualidade fisiológica de lotes de sementes o teste de condutividade elétrica tem se mostrado eficiente devido sua rapidez e facilidade na execução. Objetivou-se com o presente trabalho avaliar o teste de condutividade elétrica, considerando, lotes, número de sementes e volumes de água, buscando estabelecer a metodologia mais adequada para a estratificação de lotes. O trabalho foi conduzido no Laboratório de Análise de Sementes do Departamento de Ciências Agrárias da Universidade Estadual de Montes Claros (DCA/UNIMONTES), Janaúba, MG, utilizando-se quatro lotes de sementes de linhaça da safra 2017. Inicialmente, determinou-se, o teor de água, germinação, primeira contagem de germinação, emergência de plântulas, índice de velocidade de emergência, comprimento, massa fresca e seca de plântulas. O teste de condutividade elétrica foi realizado com 25 e 50 sementes embebidas em 25, 50 e 75 mL de água deionizada nas temperaturas de 25 e 30 °C, com leituras 24 horas de embebição. O teste de condutividade elétrica conduzido com quatro repetições de 25 sementes puras embebidas em 75 mL de água deionizada, na temperatura de 30 ºC, permitiu a separação dos lotes, mostrando-se promissor na avaliação da qualidade das sementes de linhaça.

ABSTRACT In order to determine the physiological quality of seed lots the electrical conductivity test has shown to be efficient due to its speed and ease of execution. The objective of this study was to evaluate the electrical conductivity test, considering water volumes, number of seeds and conditioning temperatures, in order to establish the methodology more suitable for batch stratification. Four batches of flax seed of the golden group were used. Initially, water content, germination, first germination count, seedling emergence and emergence speed index were determined. The electrical conductivity test was performed with the following variations: 25 and 50 seeds soaked in 25, 50 and 75 mL of distilled water at temperatures of 25 and 30 ° C, with readings 24 hours of imbibition. The most suitable condition for the electrical conductivity test of flax seeds is the soaking of 25 seeds in 75 mL of water at 30ºC.

Comparison of the initial development of four species in forest restoration plots with three different soil preparation systems in the department of Caazapa, Paraguay

RESUMEN Como resultado del avance de la frontera agropecuaria, la ecorregión Alto Paraná ha perdido más del 90% de su superficie original, dejando en la actualidad solo remanentes aislados de este ecosistema. Por lo tanto, los esfuerzos de restauración de esta ecorregión y su éxito son clave para la conservación de la biodiversidad que alberga. En este contexto, el objetivo de este trabajo fue conocer el desarrollo inicial de Campomanesia xanthocarpa, Cordia americana, Cordia trichotoma y Melia azedarach bajo tres sistemas de preparación del terreno en un proyecto de restauración: i) perforación manual, ii) quema controlada + perforación manual y iii) preparación convencional de la tierra; en cuatro parcelas de la finca Golondrina, Caazapá. Los datos recolectados fueron (a) diámetro a la altura del cuello (DAC), (b) altura y (c) número de ramas. Para el análisis de los datos se realizaron ANOVA y la prueba de Tukey-Kramer. Cordia americana fue la especie con mejor desarrollo en las tres variables estudiadas en los tres sistemas de preparación del suelo, mientras que Campomanesia xanthocarpa tuvo el menor desarrollo entre las cuatro especies estudiadas. Cordia trichotoma fue la segunda especie de mejor desarrollo seguida de Melia azedarach, que se vio afectada por las heladas.

ABSTRACT As a result of the advance of the agro-livestock frontier, the Alto Paraná ecoregion has lost more than 90% of its original surface, currently leaving only isolated remnants of this ecosystem. Thus, this ecoregion’s restoration efforts and their success are key to the conservation of the biodiversity that it harbors. In this context, the objective of this work was to know the initial development of Campomanesia xanthocarpa, Cordia americana, Cordia trichotoma and Melia azedarach under three land preparation systems in a restoration project: i) manual drilling, ii) controlled burning + manual drilling and iii) conventional land preparation; in four plots in the Golondrina farm, Caazapá. The data collected were (a) diameter at neck height (DNH), (b) height, and (c) number of branches. For data analysis, ANOVA and the Tukey-Kramer test were performed. Cordia americana was the species with the best development in the three variables studied in the three soil preparation systems, while Campomanesia xanthocarpa had the lowest development among the four species studied. Cordia trichotoma was the second best-developing species followed by Melia azedarach, which was affected by frost.

Soil tillage systems and their effects on soybean crop development

RESUMO Sistemas de preparo do solo podem influenciar o desenvolvimento das culturas. Com o objetivo de avaliar os efeitos de equipamentos de preparo na física do solo e desenvolvimento da soja, foram avaliados cinco sistemas de preparo do solo (arado de aivecas, arado de discos, grade aradora intermediária, escarificador e enxada rotativa) e seu efeito nos agregados de um Latossolo Vermelho Amarelo distrófico. Foi utilizado o delineamento inteiramente casualizado com quatro repetições. Os sistemas de preparo do solo influenciaram na altura média das plantas na cultura da soja. O preparo do solo com os arados de discos e aivecas ocasionam maior tamanho de plantas em comparação ao escarificador. Os sistemas de preparo periódico do solo não influenciam no desenvolvimento e a produtividade da cultura da soja.

ABSTRACT Soil tillage systems can influence crop development. In order to evaluate the effects of tillage equipment on soil physics and soybean development, five soil tillage systems were evaluated (mouldboard plow, disc plow, intermediate harrow, scarifier and rotary hoe) and their effect on aggregates of a dystrophic Red Yellow Latosol. A completely randomized design with four replications was used. The tillage systems influenced the average height of the plants in the soybean crop. Soil preparation with disc plows and moldboards cause larger plant sizes compared to the scarifier. Periodic soil tillage systems do not influence the development and productivity of the soybean crop.

Economic valuations composition, structure and floristic diversity in a semi-deciduous mesoxerophytic forest of Schinopsis balansae Engl., Ecoregion Humid Chaco, Paraguay

RESUMEN En el año 2006 iniciaron esfuerzos de valoración económica de los servicios ecosistémicos que brindan los bosques en Paraguay, esta información es de mucha utilidad para la implementación de políticas públicas. Esta investigación buscó estimar valores económicos de bienes de uso directo e indirecto de un bosque mesoxerofítico semicaducifolio de Schinopsis balansae Engl., Ecorregión Chaco Húmedo, Paraguay, detallando su composición, estructura y diversidad florística, analizando dos Parcelas Permanentes de Monitoreo de la Biodiversidad de 1 ha cada una. En ambas se registraron 1.388 individuos con DAP ≥ 10 cm, pertenecientes a 54 especies, 1 morfoespecie, 48 géneros y 25 familias botánicas. Phyllostylon rhamnoides (J. Poiss.) Taub. fue la especie con mayor Índice de Valor de Importancia (39,20 %). El sitio 02 es el de mayor diversidad. Para valorar su uso directo, luego de un censo a 303 industrias forestales, fueron clasificadas 13 especies con valor de mercado para el uso industrial. El valor económico de bienes de uso directo, con un plan de uso de la tierra, para el sitio 01 fue 256,81 US$ ha-1 y para el sitio 02, 1.562 US$ ha-1. Considerando la opción de manejo forestal el valor para sitio 02 fue 124,52 US$ ha-1, mientras que en sitio 01 ninguna especie comercializable alcanzó los diámetros mínimos establecidos. El valor económico del servicio ecosistémico por reserva de carbono para el sitio 01 ascendió a 129,47 US$ ha-1 y para el sitio 02, 150,81 US$ ha-1. Estos valores ayudarían a mejorar las estrategias de valoración de bosques en la región.

ABSTRACT In 2006, efforts were launched towards the economic valuation of ecosystemic services provided by forests in Paraguay, this information is very useful for the implementation of public policies. This research sought to estimate the economic value of direct and indirect use of a semi-deciduous mesoxerophytic Schinopsis balansae Engl. Forest, Ecoregion Humid Chaco, Paraguay; detailing its composition, structure and floristic diversity by analyzing two Permanent Biodiversity Monitoring Plots of 1 ha each. In both, 1388 individuals were recorded with BHD ≥ 10 cm, belonging to 54 species, 1 morphospecies, 48 genera and 25 botanic families. Phyllostylon rhamnoides (J. Poiss.) Taub. was the species with higher Importance Value Index (39,20%). According to the Diversity Indexes, site 02 was the most diverse. To valuate the direct use of these sites, according to a census to 303 forestry industries, 13 species were selected as species with a market value for industrial use. The economic value of direct use goods for site 01 was 256,81 US$ ha-1 and for site 02 it was 1.562 US$ ha-1. Considering the forest management option, the value for site 02 was 124,52 US$/ha, while no commercial species in site 01 reached the established minimum felling diameter. The economic value of ecosystemic services of carbon reservoir for site 01 amounted to 129,47 US$ and for site 02 150,81 US$. These tangible values could help improve the regional forest valuation strategies.

Effects of the use of α-amylase and lipase enzymes on the productive performance of recently weaned piglets

RESUMEN Durante el destete los lechones presentan baja capacidad digestiva por la limitada secreción de las enzimas encargadas de digerir alimentos afectando el desempeño productivo de los mismos, con lo que resulta necesario suplementar con enzimas de manera exógena. Para esto, 12 lechones machos enteros mestizos de razas no definidas recién destetados fueron empleados con el objetivo de evaluar los efectos de la utilización de enzimas α-amilasa y lipasa sobre el desempeño productivo. Se utilizó el diseño experimental de bloques aleatorizados, con tres tratamientos (T1: testigo, T2: α-amilasa y T3: Lipasa) y cuatro repeticiones. Los datos fueron sometidos a ANAVA y las medias comparadas por el test de Duncan (p<0,05). Fue verificado que los lechones suplementados con α-amilasa y Lipasa presentaron mayores ganancias de peso (GPV y GDP) durante el ensayo, al igual que para la GPV total y la GDP promedio y en el CDA se destacaron en el segundo y tercer periodo (30 y 45 días) y en el CDA promedio; mientras que en la CA solo se destacaron en los dos periodos iniciales (15 y 30 días) y en la CA promedio, mientras que en la evaluación realizada a los 45 días, los tratamientos presentaron comportamientos similares para esta variable. Se concluye que es eficaz la adición de enzimas α-amilasa y lipasa en la alimentación de lechones destetados pues mejoran el consumo de alimento, la conversión alimentar y consecuentemente la ganancia de peso y se recomienda suministrar hasta los 30 días post destete.

ABSTRACT During weaning, piglets have low digestive capacity due to the limited secretion of the enzymes responsible for digesting feed, affecting their productive performance, making it necessary to supplement with enzymes exogenously. For this, twelve non-castrated recently weaned and undefined breeds’ male piglets were used with the objective of evaluating the effects on productive performance of the use of α-amylase and lipase enzymes. The experimental design of randomized blocks was used, with three treatments (T1: control, T2: α-amylase and T3: Lipase) and four repetitions. The data were submitted to ANAVA and the means were compared by Duncan's test (p <0.05). It was verified that the piglets supplemented with α-amylase and Lipase presented greater weight gains (LWG and DWG) during the trial, as well as for the total LWG and the average DWG and in the DFI they stood out in the second and third period (30 and 45 days) and in the average DFI; while in the FC they only stood out in the two initial periods (15 and days) and in the average FC, while in the evaluation carried out at 45 days, the treatments presented similar behaviors for this variable. It is concluded that the addition of α-amylase and lipase enzymes in the feeding of weaned piglets is effective as they improve feed consumption, feed conversion and consequently weight gain and it is recommended to supply up to 30 days post-weaning.

Evolution of the milk production chain in two municipalities in southern Brazil

RESUMO O leite é uma das fontes de alimentação mais ricas em nutrientes e vitaminas para os seres humanos, principalmente devido ao seu teor de cálcio e proteínas de alta qualidade. Devido à importância deste alimento, a cadeia produtiva do leite é um dos segmentos que tem gerado enormes impactos socioeconômicos no cenário nacional, a qual sofreu inúmeras transformações nas últimas décadas. Dessa forma, o objetivo deste trabalho foi estudar os principais fatores responsáveis pela evolução da cadeia produtiva do leite nos municípios de Três Passos e Tiradentes do Sul, RS, Brasil. Para tal, foi realizada uma pesquisa a campo, onde foi aplicado um questionário semiestruturado, dirigido a 20 produtores que desenvolvem atividades na área de produção de leite nestes municípios. Constatou-se que a adoção de inovações tecnológicas foi o ponto fundamental para que a atividade leiteira passasse por mudanças expressivas nos últimos anos, tanto na quantidade quanto na qualidade do leite produzido, sendo o fator responsável pelo aprimoramento e potencialização do setor. Portanto, a modernização e a implantação de inovações tecnológicas são fatores fundamentais para as mudanças positivas ocorridas no setor leiteiro.

ABSTRACT Milk is one of the richest food sources of nutrients and vitamins for humans, mainly due to its calcium content and high quality proteins. Due to the importance of this food, the milk production chain is one of the segments that has generated huge socioeconomic impacts on the national scene, which has undergone countless transformations in the last decades. Thus, the objective of this work was to study the main factors responsible for the evolution of the milk production chain in the municipalities of Três Passos and Tiradentes do Sul, RS, Brazil. To this end, a field survey was carried out, where a semi-structured questionnaire was applied, addressed to 20 producers that develop activities in the area of milk production in these municipalities. It was found that the adoption of technological innovations was the fundamental point for the dairy activity to undergo expressive changes in recent years, both in the quantity and in the quality of the milk produced, being the factor responsible for the improvement and enhancement of the sector. Therefore, the modernization and implementation of technological innovations are fundamental factors for the positive changes that have occurred in the dairy sector.