Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Las frecuencias de defoliación y la edad de la pradera son variables estratégicas en el manejo del cultivo de la alfalfa para incrementar la biomasa producida. El objetivo del presente trabajo fue determinar el efecto de tres frecuencias de corte en el ciclo primavera-verano sobre la producción de materia seca, tasa de crecimiento y componentes del rendimiento de praderas de alfalfa de uno, dos y tres años de establecimiento. Se utilizó un diseño en bloques al azar con arreglo factorial 3 x 3 (frecuencias de corte y edad de la pradera). La mayor producción promedio de materia seca (7,528 Kg MS ha-1) y tasa de crecimiento (257 Kg MS ha-1día) se registró en praderas de un año de establecimiento (P<0.01). De otra forma, la frecuencia de corte a cuatro semanas (6,844 Kg MS ha-1) superó en 29 y 16 %, respectivamente a las frecuencias de tres y cinco semanas en la producción de materia seca. La producción de hoja y tallo en la pradera de un año de establecida superó en 45 % a la de tres años y la altura en 32 %; mientras que en la frecuencia de corte cada cuatro semanas los valores de hoja y tallo fueron 21 y 49 % superiores a tres semanas de corte y la altura en 33 %. Las variables evaluadas y su interacción determinan los componentes de rendimiento estimados en praderas de alfalfa variedad Oaxaca Criolla.

El objetivo fue determinar la productividad, costos de producción y costo-beneficio de dos esquemas de alimentación (EA) para cerdas lactantes: 1) alimentación convencional (EAC) y, 2) alimentación convencional más nopal (EAN). Se evaluaron 116 partos de cerdas hibridas: 58 partos de cerdas sometidas al EAC (n=17 cerdas) y 58 partos de cerdas bajo el EAN (n=17 cerdas). Se evaluó: glucosa sanguínea (GS), consumo de alimento diario (CAd-1), pérdida de peso corporal (PPC), intervalo destete-estro (IDE), porcentaje de servicios repetidos (PSR), días no productivos (DNP) y tamaño de camada subsiguiente (TC). El análisis estadístico se realizó mediante modelos de efectos fijos (MIXED SAS®) y la evaluación económica bajo la metodología del análisis costo-beneficio. Las cerdas sometidas al EAN presentaron mejor (P<0.05) comportamiento en las variables evaluadas: menores niveles de GS preprandial (55.5 ± 2.31 mg dL-1), mayor CAd-1 (5.3 ± 0.17 kg d-1); menor: PPC (6.0 %), IDE (144 h), PSR (12.4 %) y DNP (36.0 días) y mayor TC (11.2 lechones). Ello en comparación con el EAC:  GS preprandial, 70.0 ± 2.31 mg dL-1; CAd-1, 4.7 ± 0.17 kg d-1; PPC, 11.7 %; PSR, 17.1 %; DNP, 50.0 días y TC, 9.8 lechones. El costo de producción lechón-1 destetado en el EAN fue de $ 539.02 MXN vs $ 590.81 MXN para el EAC. La ganancia fue de $ 216.68 y $ 168.88 MXN lechón-1 vendido para EAN y EAC, respectivamente. El EAN reduce la GS e incrementa el CAd-1 de las cerdas lactantes, lo que reduce la PPC en dicha fase y genera mayor productividad de las cerdas y mayor eficiencia económica.

This study assesses the in vitro fungitoxic effect of the red bell pepper (Capsicum annuum L.) on mycelial growth of Colletotrichum gloeosporioides. The experiment had a completly randomized design in a 2 x 10 factorial scheme, with two types of extracts (ethanolic and hydroethanolic) applied in ten concentrations (0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 3.0, 4.0, and 5.0). Each extract was added to PDA (Potato Dextrose Agar) medium and poured in Petri dishes. The dishes were inoculated with 1 cm diameter disc containing fungal mycelia and incubated for seven days at 27±2°C. To verify the difference among treatments, we estimated the percentage of mycelial growth inhibition (PGI) and index of mycelial growth speed (IMGS). All concentrations of both extracts inhibited the mycelial growth of C. gloeosporioides when compared to the negative control. The complete inhibition was obtained when the ethanolic extract was used in the highest concentration (5.0%) and surpassed 50% of inhibition with 2% concentration, being superior to the hydroethanolic extract that in maximum concentration inhibited only 27.5% of fungus growth. Thus, under in vitro conditions, the ethanolic extract of red bell pepper at showed to be promising in the control of C. gloeosporioides. The concentration of 5.0% promoted the greatest inhibitory effect.

The pressure on natural resources for agriculture and livestock activities has caused changes and losses of ecosystem services essential to the well-being of populations. The aim of this study was to evaluate the influence of deforestation on climate change in areas of agriculture and livestock exploitation in the city of Currais-PI. A space time analysis of land use and land cover in the municipality was carried out over a 32-year time series (1986 to 2018), correlating with meteorological variables. To perform the space time analysis Landsat 5 and Landsat 8 satellite images were used, acquired free of charge from the National Institute for Space Research (INPE), between june and october. Meteorological data (mean maximum temperature, relative humidity and total precipitation) were obtained from the website of the National Institute of Meteorology (INMET). During the study period there was a decrease of 15.90% of the native vegetation and simultaneously changes in the microclimate, with a 2,06 °C increase in temperature and a 25% decrease in relative humidity. The progressive pressure on native vegetation for land use and land cover caused quick changes in the natural landscape and microclimate of the region.

Ver-o-Peso Complex is located in the city of Belém, Pará, and is considered the largest free market in Latin America. The Fish Iron Market is part of this complex, and is where fish is marketed, filleting is processed, and other types of cuts occur, which generate waste. The aim of this study was to conduct a survey on the generation and disposal of fish waste generated in the Fish Iron Market of Ver-o-Peso Complex. Data were collected in 2015 and 2018, and information on fish waste was obtained by applying forms with market vendors. Additionally, fish waste was sorted and weighed, and divided in type 1 (skin), type 2 (carcass), and type 3 (others), the latter encompassing other types of waste. In 2018, 1,845.65 kg of fish waste was generated in one single day, and fish carcass was the most recurring waste category. The other categories were low and were not found in the intestines, as fish is usually eviscerated while still on board the vessel. Most merchants produce 50 kg or more of waste per box daily, and most of this waste is disposed in landfills. The majority of merchants who produced the waste from which the sample was collected were familiar with the use of fish waste in the production of fertilizers, animal feed, and human food. The most frequent waste item in the Fish Iron Market of Ver-o-Peso Complex is carcass, and the quantification of this waste reaches a total value higher than one ton per day.

This study reveals the vulnerability of the Ecuadorian banana industry to diseases caused by leaf spotting of Sigatoka, which affects the productivity of banana plantations. The pathogen was described and information was collected from several scientific articles and studies in banana producer’s countries, as a result of the theoretical review evidence of reduced production, increased doses and applications of fungicides. Generating a greater environmental impact as a result of the phytosanitary control mechanisms that in turn increase production costs becoming an unsustainable production system.

The search for plant bioinsecticides has intensified, since natural insecticides are not persistent and degrade faster than synthetic ones without leaving residues in food or in the environment. The objective of this work was to evaluate the repellent action of essential oils and vegetables in black aphid (Aphis craccivora Koch) on Fava bean (Phaseolus lunatus L.) cultivars. To perform the experiment, leaf discs were immersed for 30 seconds in a solution of 0.05% of each treatment and the control in distilled water. The leaf discs were then placed two-by-two (treated and control) into petri dishes with open-top lids in the center covered with "voil" fabric containing 1% agar-water solution, joined by a strip of paper . In the paper rectangle were placed adult adults of A. craccivora. The essential oils testede were rosemary (Rosmarinus officinalis), copaíba (Copaifera langsdorfii), mint (Mentha L.) and citronella (Cymbopogon winterianus) and three vegetable oils, pequi (Caryocar brasiliense), sunflower (Helianthus annuus) and castor bean (Ricinus communis). The collected data were recorded in the period of 48h. The number of females attracted and nymphs produced were analyzed by non-parametric test x2 (chi-square). The essential oil of C. winterianus had higher repellency and lower production of nymphs, whereas R. communis oil had no significant repellency effect, increasing the production of nymphs and the essential oils R. officinalis, C. Langsdorfii and Mentha L. and the vegetable oils C. brasiliense and H. annuus, showed a significant effect on the reduction of nymphs.

Cassava stands out in the brazilian economy because it is grown in several regions, due to tolerance to diverse soil and climate conditions. To be conducted effectively a property must be prepared cost estimates for decision-making, especially in the Southeast region of Goiás, where the cultivation of species is performed empirically. Therefore, the objective of this work was to survey the production costs and to determine the economic viability of the implantation of the cassava crop through economic indicators. For this purpose, the economic viability study was carried out using the following indicators: Gross Revenue (RB), Internal Rate of Return (IRR), Net Present Value (NPV), Cost Benefit Index (IBC) and Payback updated. Sensitivity analysis was carried out in order to design scenarios that could contextualize a real situation. The feasibility analysis was carried out with a rate of 6.6% pa, in a 5-year horizon, RB = R $ 10,350.00, IRR = 45%, NPV = R $ 49,268.45, IBC = 1.37 and Payback updated = second year. In the sensitivity analysis it was shown that the oscillation between +10% and -10% did not make the project unfeasible, ensuring the return of the capital invested in the project, except when these are carried out simultaneously, rendering the results unfeasible. According to the conditions of the study concluded that the project is economically viable and the cultivation of cassava stands out as a good alternative in the practice of economic diversification in the production of the rural property.

The cowpea is one of the main crops of importance for the Northeast region, being cultivated in areas of the Caatinga, considering that it is necessary to study the interaction between agricultural crops and forest species in this biome. Therefore, the present study aimed to evaluate a possible allelopathic influence of dried leaves in the decomposition process of Libidibia ferrea Mart. on the development of caupi bean seedlings, cv. Canapu. The leaves of the forest species were collected in the morning and dried at 40 ºC for 24 hours in the greenhouse, then were manually fragmented and added to sand forming the substrate, the following proportions of dry leaves and sand were adopted: 1:0 (control); 1:1/2; 1:1 and 1:2 (v:v). The substrates were decomposed for 15, 30, 45 and 60 days, the control treatment without decomposition, so subsequently the seeds of cowpea were sown. The seedling height and root length, dry mass of the aerial part of the root system and total normal seedlings were evaluated. The entirely randomized 4x5 factor scheme was used (sand proportions: dry leaves x periods of decomposition). The period of 30 days of decomposition causes a reduction in the length of the aerial part, in the dry mass of the aerial part, in the root system and in the total of the seedlings, the increase in the proportions of dry ironwood leaves affects the dry mass of the aerial part and total of the seedlings. Therefore, the cultivation of caupi beans, cv. Canapu, and ironwood in an agroforestry system is not feasible.