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Chilean Journal of Agricultural & Animal Sciences
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  This is an Open Access Journal Open Access journal
ISSN (Print) 0719-3882 - ISSN (Online) 0719-3890
Published by SciELO Homepage  [688 journals]
           (Persea americana Mill.) IN PERU

    • Abstract: RESUMEN Perú posee condiciones favorables para la producción orgánica de palto (Persea americana Mill.), lo que ha permitido una importante expansión del cultivo en la última década. Sin embargo, los factores que afectan el rendimiento de palto en sistemas orgánicos han sido poco discutidos. Los objetivos de este estudio fueron describir el contexto físico en el cual se desarrollan los sistemas de producción de palto orgánico y determinar factores técnicos que influyen en su rendimiento en Perú. El estudio se realizó en cuatro distritos de la provincia de Huaura y un distrito de la provincia de Barranca, región Lima, Perú. La descripción del entorno físico se realizó utilizando información secundaria previamente publicada. Se encuestó a productores con certificación orgánica o en transición, proveedores de tres empresas exportadoras. Los registros de cada predio fueron revisados para recolectar información sobre el proceso productivo. La información de cosecha, calidad de exportación y certificación, fue proporcionada por las empresas exportadoras. Predios que usan sistema de riego localizado tuvieron mayores rendimientos que predios que usan riego por gravedad. Los factores que tuvieron alto grado de correlación positiva con el rendimiento fueron las dosis aplicadas de N orgánico, fósforo y potasio (kg ha-1), el número de jornales, y el número de aplicaciones foliares. Es necesario mejorar significativamente el manejo técnico del cultivo, para incrementar el rendimiento y calidad de fruto.ABSTRACT Peru has favorable conditions for organic avocado (Persea americana Mill.) production, which has allowed a significant expansion of its cultivation in the last decade. However, factors affecting avocado yield in organic systems have been little discussed. The objectives of this study were to describe the physical environment in which organic avocado production systems are developed and to determine the technical factors that influence yield in Perú. The study was carried out in four districts of the province of Huaura, and one district of the province of Barranca, Lima Department, Perú. The physical environment was described using published secondary-source information. Producers with organic certification or in transition, suppliers of three exporting companies were surveyed. Records of each farm were reviewed to collect information on the production process. Harvest information, export quality and certification were provided by the exporting companies. Farms that use a localized irrigation system had higher yields than those that use gravity irrigation. The factors that had a high degree of positive correlation with yield were applied doses of organic N, phosphorus and potassium (kg ha-1), number of daily wages, and number of applications. There is a need for a significant improvement in the technical management of the crop to increase yield and fruit quality.

    • Abstract: ABSTRACT Avocado crop (Persea americana Mill.) is of great commercial importance due to its high profitability. However, it is being affected by various diseases and pests that affect yield and reduce fruit quality. The aim of this research was to develop methodologies for the evaluation of avocado plantations using different non-destructive technologies for rapid phenotyping and early detection of the incidence of diseases or damage due to stress in the stem. A plot of 0.7 ha. was evaluated, with a total of 44 individuals using Field-Map technology (dasometric and morphological characterization), RGB-multispectral images from Remotely Piloted Aircraft System (RPAS) (rapid phenotyping), while 15 individuals were evaluated using tomography (assessment of the internal state of the stem). The results with tomography indicated that there is a tree with wood rot of 14% with a lower acoustic speed with respect to the other trees evaluated. A high correlation was observed between the dasometric variables (r-Pearson from 0.63 to 0.98) estimated with Field-Map [crown base height, crown projection (m2) and total height] and with RPAS (height, perimeter and area). The vegetation indices do not have a direct correlation with the dasometric variables; five of the indices have a high contribution to variability except for the Normalized Difference Red Edge (NDRE). It can be concluded that the technologies used in this study would help to perform evaluations with a greater number of reliable and precise data with respect to the information obtained in a traditional way, while they can be replicated in commercial plots or research studies of different perennial crops, generating useful information for management decisions and crop evaluation.

    • Abstract: ABSTRACT The Diagnosis and Recommendation Integrated System (DRIS) is a tool to evaluate the nutritional status and obtain fertilizer recommendations of several crops. Unlike other methods, DRIS works directly with farmer’s information, focusing on understanding the nutritional balance of the crop. However, the selection of indexes is long and time-consuming. The objective of this work was to develop an algorithm to estimate reference and DRIS indexes for crops in order to facilitate the use of the DRIS methodology. The construction of the algorithm included four stages, (1) theoretical bases, (2) conceptual model design, (3) algorithm implementation, and (4) validation. For a database of crop yield and foliar analyses, the developed algorithm is divided into two subsets (high and low yield), estimating nutrient ratios and variability. For leaf sample diagnosis, the algorithm compares nutritional balance with highy-ield population, generating DRIS indexes numerically and graphically. A nutrient is imbalanced if its DRIS index in the graph is outside the whiskers. The efficiency and operability of the algorithm was tested with foliar analyses of fifty plantain crops distributed in two subregions of the Antioquia Department, Colombia. The developed procedure allowed determining quantitative and graphical information of the nutrient balance in foliar samples.

    • Abstract: ABSTRACT Mutation induction is used to improve existing or generate new varieties. The objective of this study was to evaluate the effect of gamma radiation doses under successive generations of cultivation on seed quality of two soybean lines (VX04-6828 and VX04-5692). Different gamma-ray doses (60Co) were evaluated (0; 50; 150 and 250 Gray) in the M0 (first sowing) generation, and analyzed for water content, germination, vigor, abnormal seedlings, dead seeds, and hilum color. Then, sowing (M0) was carried out to obtain plants and seeds of the first production cycle (M1 generation), and then those of the subsequent cycle (M2 generation). The same analyses of M0 were performed for M2 and M3 generations, with the addition of germination rate and emergence speed index in the field. The data were submitted to analysis of variance in a factorial arrangement. The generations were compared using Tukey’s test, while doses were evaluated by regression analysis. Seeds of the two soybean lines showed significant interaction for the different generations and gamma-ray doses in all the variables analyzed, except for water content. The application of gamma rays in soybean seeds showed effects on successive generations of cultivation, with better physiological quality up to the dose of 150 Gy (Gray) and greater sensitivity to gamma radiation for the VX04-5692 line.

    • Abstract: ABSTRACT Cowpea bean (Vigna unguiculata L. Walp) is a nutrient-rich crop that can be produced in dry periods. As an alternative to synthetic chemical fertilization (SCF) in this species, the effects of a biostimulant (bovine manure vermicompost leachate, BMVL) on growth and yield variables were studied. The research was carried out at the Las Maravillas site, Rocafuerte canton, province of Manabí, Ecuador. Foliar application of four dilutions of BMVL (1:10, 1:20, 1:30 and 1:40 v/v) were made at 10, 20, 30 and 40 days after sowing. Two control treatments, one with SCF (NPK 15-15-15), and the other without fertilization or biostimulant (absolute control) were included. Biostimulation with BMVL significantly increased plant length with respect to both controls. Grain weight and estimated yield had higher values in the plants that received biostimulants compared to the absolute control. However, values were lower than those in the control with SCF, which may indicate that the use of biostimulants cannot fully replace the contribution of nutrients by SCF. The estimated yields in the dilutions of BMVL 1:10, 1:30 and 1:40 v/v, which reached values between 89 and 94% of those obtained with SCF, show that BMVL can be used as an alternative to SCF to achieve reasonable production levels at low economic and environmental cost in the cultivation of cowpea bean.

    • Abstract: RESUMEN La fertilización foliar es una estrategia que permite complementar la nutrición de los cultivos cuando algún factor del suelo limita la absorción de nutrientes por la raíz. El objetivo del estudio fue evaluar la efectividad de momentos y fuentes de aplicación foliar de Ca, B y Zn en el rendimiento y rentabilidad del cacao nacional. Los tratamientos consistieron en tres fuentes foliares de Ca, B y Zn (sales, quelatos y aminoquelatos) y tres tiempos de aplicación foliar (06:00 - 08:00, 11:00 - 13:00 y 16:00 - 18:00 horas). Además, se incluyó un tratamiento control que solo recibió fertilización edáfica. Se registró el rendimiento de grano (kg ha-1) y beneficio económico neto de la fertilización foliar (USD ha-1). Los datos fueron analizados a través del ANOVA y la prueba de Tukey (α = 0,05). El rendimiento de grano fue influenciado significativamente (p < 0,05) por las fuentes foliares y los tiempos de aplicación foliar. Los aminoquelatos permitieron alcanzar el mayor rendimiento de grano, con un incremento de 198, 289 y 440 kg, con relación a los tratamientos con quelatos, sales y control, respectivamente. Las aplicaciones foliares en la mañana y tarde, mostraron mayor rendimiento de grano con relación a la aplicación del medio día, e incrementaron el rendimiento en un 20,46 y 20,06% con relación al tratamiento control. El mayor beneficio económico neto de la fertilización foliar se produjo con los aminoquelatos aplicados en horas de la mañana y tarde, con 442 y 418 USD ha-1, respectivamente. La aplicación foliar de aminoquelatos de Ca, B y Zn es una estrategia efectiva para incrementar rendimiento y rentabilidad del cacao nacional.ABSTRACT Foliar fertilization is a strategy that allows complemented crop nutrition when soil factors limit the absorption of nutrients by the roots. The aim of the research was to evaluate the effectiveness of foliar application times and sources of Ca, B, and Zn in the yield and profitability of national cocoa. The treatments consisted of three foliar sources of Ca, B, and Zn (salts, chelates, and aminochelates) and three foliar application times (06:00 - 08:00, 11:00 - 13:00 and 16:00 - 18:00 hours). In addition, a control treatment that only received edaphic fertilization was included. Data were analyzed through ANOVA and Tukey's test (α = 0.05). Grain yield (kg ha-1) and net economic benefit of foliar fertilization (USD ha-1) were recorded. Grain yield was significantly (p < 0.05) influenced by foliar sources and foliar application times. The aminochelates allowed reaching the highest grain yield, with an increase of 198, 289, and 440 kg, in relation to the treatments with chelates, salts, and control, respectively. Foliar applications in the morning and afternoon showed higher grain yield in relation to the noon application, and increased yield by 20.46 and 20.06% in relation to the control treatment. The greatest net economic benefit of foliar fertilization occurred with aminochelates applied in the morning and afternoon, with 442 and 418 USD ha-1, respectively. The foliar application of aminochelates of Ca, B, and Zn is an effective strategy to increase yield and profitability of Ecuador’s national cocoa.
  • EARLY INFECTIONS BY Botrytis cinerea AND Alternaria spp. AND THEIR

    • Abstract: RESUMEN Las podredumbres en postcosecha por heridas en frutos han sido ampliamente estudiadas, pero existe escasa información sobre aquellas producidas por infecciones latentes. Botrytis cinerea y Alternaria alternata producen infecciones en etapas tempranas del desarrollo de pera cv. “d’Anjou”, ocasionando importantes pérdidas en el Alto Valle de Río Negro, Argentina. Los objetivos de la investigación incluyeron la evaluación de la susceptibilidad de los órganos florales/frutos a infecciones producidas por la inoculación artificial (ILA) de B. cinerea y A. alternata, la evaluación de la ocurrencia natural de infecciones fúngicas latentes (ILN) durante el desarrollo y crecimiento del fruto, y el estudio de la relación entre infecciones latentes tempranas (por B. cinerea y A. alternata) y la incidencia de pudriciones y mohos en el cáliz y pedúnculo del fruto, y las características fisiológicas del fruto durante la conservación frigorífica. El estudio se realizó en un monte comercial de pera cv. “d’Anjou” en las temporadas 2018/19 y 2019/20. Se evaluó la ocurrencia de ILN por ambos patógenos en plena flor (PF), caída de pétalos (CP), 30 días de plena flor (DPF), 60 DPF y 120 DPF (pre-cosecha), y la susceptibilidad de los diferentes órganos desde PF a 60 DPF. La frecuencia de ILN y ILA se determinó por disección y aislamiento in vitro. Las condiciones de la fruta, incidencia de mohos y podredumbres, e ILN se estudiaron hasta 120 días de conservación y 7 días en anaquel. A pesar de la variabilidad entre temporadas, se presentaron infecciones por los hongos estudiados en PF y CP, siendo severas en cáliz y pedúnculo 60 y 120 DPF. En postcosecha, las ILN fueron altas. Sin embargo, las podredumbres calicinales por B. cinerea no superaron el 2,5% en la temporada con precipitaciones y alta HR durante la primavera. Además, hubo 0,5% de podredumbres por Alternaria en fruta y un incremento significativo del moho en pedúnculo desde los 90 días de conservación. En este momento, se observó una reducción significativa del contenido relativo de agua y la firmeza de los frutos.ABSTRACT Postharvest rot of fruit due to injury has been extensively studied, but there is scarce information about rot caused by latent infections. Botrytis cinerea and Alternaria spp. produce infections at early stages of fruit development of pear cv. ’d'Anjou’, causing significant losses in the Alto Valle de Río Negro, Argentina. Research objectives have included evaluation of the susceptibility of floral organs/fruits to infections produced by the artificial inoculation (ALI) of B. cinerea and A. alternata, evaluation of the occurrence of natural latent fungal infections (NLI) during fruit development and growth, and study of the relationship between early latent infections by B. cinerea and A. alternata on the incidence of rot and mold in the fruit calyx and stem, and the physiological characteristics of the fruit during cold storage. The study was conducted in a commercial ‘d'Anjou’ pear orchard during the 2018/19 and 2019/20 seasons. The occurrence of NLI was determined at full blossom (FB), petal fall (PF), 30 days after full blossom (DFB), 60 DFB and 120 DFB (pre-harvest), while susceptibility of the different organs was evaluated from FB to 60 DFB. Frequency of NLI and ALI was determined by dissection and in vitro isolation. The postharvest physiological conditions of the fruit, incidence of NLI, and incidence of mold and rot were studied up to 120 days of cold storage and after 7 days of shelf life. Despite the variability between seasons, fungal infections occurred at FB and PF, being severe in the calix and stem at 60 and 120 DFB. NLI had a high incidence at postharvest. However, calix-end rot by B. cinerea did not exceed 2.5% in the season with precipitations and high RH during spring. In addition, Alternaria rot reached 0.5%, while stem mold increased significantly after 90 days of cold storage. At this moment, fruit significantly reduced its relative water content and firmness.

    • Abstract: ABSTRACT Manure compost is a type of organic fertilizer derived from animal feces. Even though compost has a slow-release nature, it can be a good alternative to chemical fertilizers. The addition of Trichoderma sp. as a decomposer microorganism can accelerate nutrient availability. The objective of this study was to determine the effect of the combined application of different types of manure compost and doses of Trichoderma sp. on the growth performance, yield as well as stem rot disease incidence of shallot (Allium cepa L. var. aggregatum). The study was carried out using a split-plot design (P<0.05) with the types of manure compost as the main plot with five levels (no compost, cattle manure, chicken manure, goat manure, and petrogenic compost), and different doses of Trichoderma as subplots with three levels (no Trichoderma, 200 kg ha-1, and 400 kg ha-1). In general, the combined application of manure compost and Trichoderma significantly increased growth performance and yield of shallot compared to no compost (B0) and Trichoderma (T0). However, no differences were observed between manure compost and the addition of Trichoderma. Growth performance of shallots grown in soil amended with cattle manure compost was better compared to the other treatments. The use of 5 t ha-1 cattle manure compost combined with 400 kg ha-1 Trichoderma increased yield by 10.02 t ha-1 and reduced stem rot diseases incidence by 0.67%.
           (Bougainvillea spectabilis) HEDGES AS A WINDBREAK

    • Abstract: RESUMEN El objetivo de este trabajo fue determinar experimentalmente los parámetros aerodinámicos de setos de Bugambilia a emplear como cortina rompevientos para su caracterización como medios porosos en los programas comerciales de dinámica de fluido computacional. Esta investigación pertenece a un proyecto aprobado por el Programa Nacional de Energía de Cuba. Muestras de setos de Bugambilia con densidad aparente del follaje de 7,19 kg m-3 fueron sometidas a la acción de corrientes de aire en un túnel aerodinámico construido en el Centro de Mecanización Agropecuaria (CEMA) de la Universidad Agraria de La Habana. El diseño experimental contempló tres niveles de profundidad de la cortina (1; 1,5 y 2 m) y cuatro niveles del flujo volumétrico del aire (entre 5,2 y 7,5 m3 s-1). Se encontraron diferencias estadísticamente significativas entre los tres niveles de profundidad en términos de porosidad aerodinámica de la cortina ( ε 𝑎𝑑 ), con valores promedio 𝜀 𝑎𝑑 de 0,77±0,05; 0,70±0,07 y 0,64±0,08; 𝑘 𝑝 resistencia al paso del fluido por la cortina ( 𝑘 𝑝 ), con valores promedio de 6,39; 9,96 y 12,69 s-1; y coeficiente de arrastre, con valores de 0,35; 0,55 y 0,89 para 1; 1,5 y 2 m de profundidad, respectivamente. Se obtuvo modelos estadísticos lineales para la predicción de la diferencia de presión ( ∆𝑃 𝑡 ) en función del flujo volumétrico, con coeficientes de determinación de 0,68; 0,77 y 0,78 para los tres niveles de profundidad de la cortina estudiados.ABSTRACT The objective of this study was to determine experimentally the aerodynamic parameters of Bugambilia hedges to be used as a windbreak for their characterization as porous media in commercial programs of computational fluid dynamics. This research is part of a project approved by the National Energy Program of Cuba. Samples of Bugambilia hedges with apparent foliage density of 7.19 kg m-3 were subjected to the action of air currents in an aerodynamic tunnel built in the Center for Agricultural Mechanization (CEMA) of the Agrarian University of Havana. The experimental design included three depth levels of the windbreak (1, 1.5 and 2 m) and four levels of the volumetric air flow (between 5.2 and 7.5 m3 s-1). Statistically significant differences were found between the three depth levels in terms of aerodynamic porosity of the windbreak ( 𝜀 𝑎𝑑 ), with average values of 0.77 ± 0.05, 0.70 ± 0.07 and 0.64 ± 0.08; resistance of the windbreak ( 𝑘 𝑝 ) to fluid flow, with average values of 6.39, 9.96 and 12.69 s-1; and drag coefficient, with values of 0.35, 0.55 and 0.89 for depths of 1, 1.5 and 2 m, respectively. Linear statistical models were obtained for the prediction of the pressure difference ( ∆𝑃 𝑡 ) in function of volume flow, with coefficients of determination of 0.68, 0.77 and 0.78 for the three depth levels of the windbreak studied.
           (Medicago sativa L.): BIOMASS PRODUCTION AND PERSISTENCE

    • Abstract: ABSTRACT The intensification of dairy production systems has resulted in a higher generation of waste. The aim of this study was to evaluate the impact of different doses of farm dairy effluent (FDE) applied to the soil on aerial biomass production, persistence and chemical composition of alfalfa pastures, in Santa Fe province, Argentina. The study was conducted in four randomized complete blocks with four treatments (FDE doses): 0 m3 ha-1 (T0: without FDE), 82 m3 ha-1 (T1: low rate), 151 m3 ha-1 (T2: medium rate) and 282 m3 ha-1 (T3: high rate). The soil application of FDE increased the total aerial biomass produced (ABP) but reduced the persistence of plants. Total nitrogen (Nt) of alfalfa was significantly higher, but phosphorus (P) concentrations did not vary after the application of FDE to the soil . Ca and Mg concentrations in plants were lower in T3 compared to T0, which can be explained by the imbalance produced in the soil after FDE was applied, presenting high levels of Na, K and NH4-N but low levels of Ca and Mg. Soil application of FDE on alfalfa pastures must be carefully planned in terms of composition and amount to be applied in order to increase biomass production, prevent the decrease in persistence, and control changes in the mineral composition of plants.

    • Abstract: ABSTRACT The aims of this study were to evaluate the effect of genetic and non-genetic factors on the growth of Socorro Island Merino lambs and to model their growth curve using nonlinear mathematical models. The weight of 41 Socorro Island Merino lambs was recorded at birth and at 45, 90, 135, 180, 225, 270, 315 and 365 days of life from May 2019 to September 2021. The effects on growth of sex, genotype, year of birth, and parity of the dam were analyzed. Four non-linear models (Brody, Logistic, Gompertz and von Bertalanffy) were fitted for determining the best model to describe growth curve. Birth weight and pre-weaning growth rate were not affected (P > 0.05) by any of the factors studied, while weaning weight was only significantly affected (P < 0.05) by sex. Year of birth significantly affected (P < 0.05) post-weaning growth rate and weight of the lamb from 270 days, while sex significantly affected (P < 0.05) weight at 315 days. The Gompertz and Brody models were the best fitted to describe growth curves of lambs. Purebred males showed a larger response to increasing levels of energy-protein supplementation, while they had greater mature weight and lower maturation rate compared to females and crossbred males. In conclusion, knowledge of growth and factors influencing growth pattern can help implement appropriate management strategies and make decisions aimed at the conservation of Socorro Island Merino lambs.
           WOOD TREE SPECIES, ULCUMANO (Retrophyllum rospigliosii, PODOCARPACEAE)

    • Abstract: ABSTRACT Ulcumano, which is native to South America, is an important conifer in Peru. Molecular studies are scarce, limiting modern breeding and appropriate conservation activities. Currently, molecular markers are widely employed to explore genetic structure and diversity parameters of plant species in a fast and precise manner. The objective of this study was to analyze the genetic diversity and population structure of ulcumano in Peru by using DNA-based molecular markers. Nine Randomly Amplified Polymorphic DNA (RAPD) markers were used, while 95 individuals of ulcumano were sampled from three departments of Peru. A total of 265 DNA fragments were manually scored, but 247 of them were kept after removing the non-polymorphic markers. Genetic distances were calculated using R software based on Provesti´s coefficient. A dendrogram was obtained using the UPGMA clustering algorithm, showing no clear clustering. The principal coordinate analysis agreed with two population structure analyses, demonstrating that ulcumano is contained within two clusters, (i) Junín + Pasco, and (ii) Cajamarca, while very few individuals are intermixed. Genetic diversity parameters were estimated considering the two groups (populations) identified by STRUCTURE software. Nei's genetic diversity estimate varied between 0.22 and 0.28, while Shannon index ranged from 3.43 to 4.16. Population divergence (Fst) between the two clusters revealed low genetic differentiation (0.064). AMOVA analysis revealed that 87.31 and 12.69% of the total genetic variation were found within populations and between individuals, respectively. To the best of our knowledge, this is the first molecular study in ulcumano in Peru, and provides valuable information for the genetic improvement and sustainable management of this conifer in the country.
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