• Energy Research
• CA close
• Spanish; Castilian close
• University of Toronto close

Two Chilean isolates of Metarhizium anisopliae (Metschnikoff) Sorokin (QU-M363 and QU-M221b) were exposed to increasing doses of ultraviolet light (UV) under laboratory conditions. Conidia suspended in aqueous solution were spread on Petri dishes containing agar-agar and were placed under a UV lamp ( λ = 254 nm). Without sunscreen, exposure of conidia to UV-C light reduced germination after 40 s from 80-95% to 5-2%, for QU-M221b and QU-M363, respectively. Using the solar screen Blankophor P167® â at 1% w/v, conidia germination decreased after 40 s from 68-82% to 50-33% for QU-M221b and QU-M363, respectively. Results indicate that the sunscreen Blankophor P167 is a potential adjuvant to be used in biopesticides based on M. anisopliae .

Conservationist tillage systems have advantages over conventional systems because they allow the protection of natural resources. However, it is important to validate these advantages to encourage the adoption of this type of technology by farmers. The objective of this study was to determine if the type of tillage affects moisture content in the soil profile. To this end, the effect of three tillage systems on water availability in an Ultisol soil was compared. The treatments were: no tillage and burning residues (CL+Q); no tillage without burning residues (CL-Q); and traditional tillage (TRAD). The results showed that between end of tilling - beginning of internode elongation and heading, the mean value of the moisture index for CL-Q was 1.023, significantly higher than 1.001 and 0.998 corresponding to CL+Q and TRAD, while between heading and harvest the index for CL-Q was 0.963, statistically higher than 0.941 and 0.938 corresponding to CL+Q and TRAD. This effect was due to water content differences in the soil profile above 40 cm. Considering the three periods of plant development together, the mean value of the moisture index for CL-Q was 1.015, statistically higher than 0.996 and 0.990 from CL+Q and TRAD. This study confirmed that in terms of soil moisture retention in the profile of an Ultisol soil, it is recommendable to use zero tillage without burning the residues.

A study was conducted in Colima, México, with the objective to carry out a forage, energy and protein balance of a traditional dual purpose livestock production system based on corn stubble ( Zea mays ) and star grass ( Cynodon plectostachyus ) during the dry season. This balance was carried out taking into consideration dry matter, energy, and protein requirements, production, availability and utilization, as well as their imports to the production system. The production system was energetically sustainable, providing 99% of the cattle requirements. Dry matter and protein production were insufficient, providing only 80 and 68% of the requirements, respectively. The producer was able to solve this deficit by importing local available feedstuff, such as ground corncob with molasses and sugarcane tops ( Saccharum officinarum ). It was apparent the need to introduce new technology and methods to improve this production system. ; Con el objetivo de realizar un balance forrajero, energético y proteico durante la época seca de un sistema de producción tradicional de doble propósito sustentado en la utilización de rastrojo de maíz ( Zea mays ) y pasto estrella ( Cynodon plectostachyus ) se realizó un balance forrajero, energético y proteico en Colima, México. Se evaluó mediante un estudio dinámico la producción, disponibilidad y utilización de la materia seca, la energía y la proteína dentro del sistema, así como su introducción al sistema pare determinar su sostenibilidad considerando las necesidades nutricionales del ganado. Los resultados mostraron que el sistema es energéticamente sostenible produciendo 99% de la energía requerida. La producción de materia seca y proteína fueron deficitarias produciéndose únicamente 80 y 68% de los requerimientos, respectivamente. El productor fue capaz de complementar la falta de estos elementos mediante la introducción de alimentos producidos en la región como la punta de caña ( Saccharum officinarum ) y el olote de maíz enmelazado, detectándose además la oportunidad de mejorar estos sistemas productivos mediante la implementación de nuevas prácticas de manejo, así como la introducción de nuevas tecnologías.

A Basic Unit of Cooperative Production (BUCP) of Granma Province, Republic of Cuba was selected to carry out research from 2004 to 2007 and its projection for 2008. From 13 farms of the BUCP, two units were selected and unified, comprising 335 ha, in which a methodology of quantitative and qualitative steps for a husbandry, agriculture and forest diversification processes to encourage the process of local economic development. The changes produced between the diagnosis and the results obtained at present, as well as the perspectives were compared. It was obtained a favorable transformation in the pasture land, as well as in the agroforestry and forage crops, besides a considerable increase of biodiversity and cattle-agriculture integration. With the introduction of the applied technologies, positive results in productive and reproductive indicators were achieved that offer guarantees for the repeatability of the model. ; Fue seleccionada una Unidad Básica de Producción Cooperativa (UBPC) de la provincia de Granma de la República de Cuba, la cual fue investigada desde 2004 al 2007 y su proyección para el 2008. De las 13 unidades de la UBPC se seleccionaron y unieron dos unidades con una superficie total de 335 ha, en las cuales se aplicó una metodología de cambios escalonados cuantitativos y cualitativos para un proceso de diversificación pecuaria, agrícola y forestal y potenciar un proceso de desarrollo económico local. Se compararon los cambios producidos entre el diagnóstico y los resultados obtenidos actuales y perspectivos. Se logró una transformación favorable en la superficie destinada a pastoreo, cultivos forrajeros y agroforestales, así como un aumento de la biodiversidad y la integración de la ganadería–agricultura. Con la introducción de las tecnologías aplicadas se lograron resultados positivos en los indicadores productivos y reproductivos que ofrecen garantías para la repetibilidad del modelo.

Nitrogen fertilization is the most costly production factor in wheat cropping systems on Ultisols, one of the most eroded soil types in Southern Chile. The utilization efficiency of N-fertilizer was assessed in a wheat cultivar ( Triticum aestivum L.) growing under three soil tillage systems: Traditional, burning of crop residues/soil plow down (TRAD); no-till/burning (CL+Q), and no-till/no burning (CL-Q). The method used measurements of grain yield, total N uptake by plants and their components: N derived from fertilizer (Nddf) and N derived from soil (Ndds). Physiological N use efficiency, was evaluated for total plant N (EFNt = grain yield/Nddf +Ndds) and for N-fertilizer in plants (EFNf = grain yields/N-fertilizer). 15 N-labelled urea, 10 % atom excess (a.e.) was added to the microplots at the rate of 150 kg N ha -1 . The fertilizer was applied three times: 10% at planting, 45% at tilling and 45% at jointing stage. There were no significant seasonal differences for wheat grain yield among tillage treatments with yield of 6.7 to 7.5 t ha -1 on 1997/1998 and 4.6 to 5.4 t ha -1 on 1998/99 season. The treatments CL+Q in 1997/1998 and TRAD in 1998/1999 had the highest total N uptake. The CL-Q treatment showed lowest N-fertilizer uptake by plants for each season, while keeping similar grain yields as the other two tillage systems. This led to higher physiological nitrogen use efficiency on grain production per unit of N-fertilizer absorbed by plants.

Nursery is a stage most important in the productive process of fruit crops. A trial was conducted for analyzed the effect of two types of pack and two substrates on vegetative growth of papaya seedlings. The experiment was made from June to August 2006. The experimental design was randomized completely, four treatments and three replicates. T1 plastic bags (730 ml) and lime loam soil, T2 plastic bags and peat moss, T3 plastic trays of two hundred cavities (20 ml per cavity) and lime loam soil and T4 plastic trays and peat moss. The variables studied were: seedling height, stem diameter, number of leaves photo synthetically active and dry biomass of roots and stem plus leaves of seedlings. Statistical analysis was variance analysis and test Tukey 5 %. Medium values of seedlings height varied from 5.10 to 21.29 cm, stem diameter 3.23 to 6.87 mm, number of leaves 4 to 7, dry biomass stem plus leaves 0.01 to 0.69 g and dry biomass roots 0.01 to 0.48 g. T2 was the highest in all studied variables. Results showed that plastic bags and lime loam soil were more adequate for propagation of papaya seedlings at nursery ; El establecimiento y manejo de la planta en el vivero es una de las etapas más importantes del proceso productivo de los cultivos frutícolas. El objetivo del trabajo fue analizar el efecto de dos tipos de envase y dos sustratos, sobre el desarrollo vegetativo de plántulas de lechosa. La investigación se efectuó de junio a agosto de 2006. El diseño experimental utilizado fue completamente al azar, se usaron dos tipos de envase y dos sustratos, que generaron cuatro tratamientos (T1: Bolsas de polietileno negro (730 ml) y turba de musgo; T2: Bolsas de polietileno negro y suelo franco limoso; T3: Bandejas de plástico negro de 200 cavidades (20 ml por cavidad) y turba de musgo y T4: Bandejas de plástico negro y suelo franco limoso), se emplearon tres repeticiones por tratamiento. Las variables estudiadas fueron: altura de plántula, diámetro de tallo, número de hojas fotosintéticamente activas y biomasa seca de las partes aérea y radical de las plántulas. Los datos se analizaron mediante varianza y comparación de medias Tukey 5 %. La altura de plántula varió de 5,10 a 21,29 cm, diámetro de tallo de 3,23 a 6,87 mm, número de hojas de 4 a 7, masa seca aérea de 0,01 a 0,69 gramos y masa seca radical de 0,01 a 0,48 gramos. El T2 fue superior a los demás tratamientos en todas las variables evaluadas. Con base en los resultados se recomienda el uso de bolsas plásticas y suelo franco limoso, para la propagación de plántulas de lechosa en vivero.

Using the main components (ACP) and automatic classification (ACA) analysis, the variations of the fodder potential of twenty species in Trujillo state, Venezuela, according to the propagation method (stake and botanical seed) were studied. The production of edible biomass, the relative acceptability by goats and the chemical composition were evaluated. Independently of the propagation form, a high variability for the first three components were detected (64.3-72.8%). The fibre neuter detergent, ash, and phenolic fraction showed the biggest fluctuations among the species. The edible biomass production, proteic and terpenoids levels and preferences showed low inter-specific variations. The species with better integral results were Morus alba , Chlorophora tinctoria , Cordia alba , Pentaclethra macroloba, Hibiscus rosa-sinensis , Wedelia aff. caracasana , Gliricidia sepium , and Guazuma ulmifolia . However, by the fodder potential index, Pithecellobium pedicellare and Bauhinia cumanensis were identified as promissory. Trichantera gigantea , Tithonia diversifolia , Capparis odoratissima , Moringa oleifera , and Leucaena leucocephala exhibited an intermediate potential. However, the biomass of Acacia spp., Azadirachta indica , Bulnesia arborea , Cassia alata , and Samanea saman presented little use feasibility as forage. The production of edible biomass and the acceptability constituted the most relevant variables to estimate the fodder potential. In the evaluated species the goat acceptability related with the fibre (P<0.05) and terpenoids (P<0.01) levels. No relationship among acceptability and phenolic compounds level were observed. ; Mediante el análisis de componentes principales (ACP) y de clasificación automática, se estudiaron las variaciones del potencial forrajero de veinte especies en el estado Trujillo, Venezuela, en función del método de propagación (semilla botánica y estaca) y la época del año. Se evaluó la producción de biomasa comestible, la aceptabilidad relativa con cabras y la composición química. Independiente de la forma de propagación, el ACP detectó una alta variabilidad para los primeros tres componentes (64,3-72,8%). Las variables que presentaron las mayores fluctuaciones entre las especies fueron los contenidos de fibra detergente neutra, cenizas y fracción fenólica. La producción de biomasa comestible, el contenido proteico y de terpenos; así como la preferencia exhibieron menos variaciones inter-específicas. Los ramones con mejores resultados integrales fueron Morus alba , Chlorophora tinctoria , Cordia alba , Gliricidia sepium , Pentaclethra macroloba , Hibiscus rosa-sinensis , Wedelia aff. caracasana y Guazuma ulmifolia . No obstante, mediante el índice de potencial forrajero, también se identificaron como promisorias a Pithecellobium pedicellare y Bauhinia cumanensis . Trichantera gigantea , Tithonia diversifolia , Capparis odoratissima , Moringa oleifera , Leucaena leucocephala exhibieron un potencial intermedio. Sin embargo, la biomasa de Acacia spp., Azadirachta indica , Bulnesia arborea , Cassia alata y Samanea saman presentaron poca factibilidad de uso como forraje. La producción de material comestible y la aceptabilidad constituyeron las variables de mayor relevancia para la estimación del potencial forrajero integral. En las especies evaluadas la aceptabilidad de las cabras se encontró relacionada negativamente con los niveles de fibra (P<0,05) y terpenoides (P<0,01), y no con los compuestos fenólicos.

To study the growth of four asparagus (Asparagus officinalis L.) cultivars during the first year after seeding, a pot experiment was established in Ñuble province (36°34' S lat, 72°06' W long, Chile). The cultivars evaluated were Atlas, UC157F1, JWC1 and UC157F2. A high positive correlation between accumulation of biomass and time (days after seeding) and also with temperature was found. The lineal model biomass vs. time had a high correlation (r = 0.96), because of which it might not be necessary to include climatological data to estimate growth at this crop stage. Including the photosynthetic active radiation did not improve the thermal lineal model. For foliage and crowns, lineal growth models (relative growth rates) were found, that corresponded to the slope of the line, that only differed between cv. Atlas and UC157F2. Nevertheless, this did not translate into differences for the majority of vegetative parameters evaluated. The cv. UC157F1 only differed in dry weight from the foliage of JWC1 and in the number of shoots from Atlas.At the root level, there were no differences between cultivars, except in soluble solids (UC1571 less than JWC1). The new cultivars, Atlas and JWC1, showed a similar final crown quality to the traditional UC157 hybrids, expressed as fresh weight, bud number and root number.

The secondary tillage with the use of the disk harrows is the one that is carried out generally in Venezuela, due to the inadequate friability conditions, the opportune time of the operation, purchase price relatively cheaper, easy use and maintenance, the weed control is easy and quicker, and the application of lime. It is the certain farm tool in the agricultural fields of the whole Country. The specific objectives are the disk harrows evaluation with the purpose of appreciating some economic parameters that cooperate their use process in decision taking: (a) The total costs including the timeliness factor (0,0002 day-1), (b) energy costs, (c) evaluation of the optimum economic width by maxim and minimum and (d) Comparisons with lease prices. In the methodology it was used the costs analysis and the regression analysis, to the cost items. Among the obtained results: The total costs of 14561,20 (USD/year), the optimum economic width of harrowing similar to 0,153*AR0,515 (m), the cost for disk harrowing pass turned out to be of 20 USD/ha if it is leased, and of 33,71 USD/ha if the team tractor-harrow were acquired. It is concluded: (a) The disk harrows caused high production costs to the proprietary and it was better the use of an external service for field less than 1311,85 ha/year and (b) it would be demanded an unit tractor-harrow by each 432 ha/year, this was overalls due to that the harrows used in the Venezuelan field are very small. ; La labranza secundaria con el uso de las rastras de discos es la que generalmente se realiza en Venezuela, debido a las condiciones inadecuadas de friabilidad, el tiempo oportuno de la operación, precio de adquisición relativamente más barato, fácil uso y mantenimiento, el control fácil y más rápido de malezas y la aplicación de cal. Es el apero más común en los campos agrícolas de todo el país. Los objetivos específicos son la evaluación de las rastras de discos con el propósito de apreciar algunos parámetros económicos que coadyuven su proceso de uso en la toma de decisiones: (a) Los costos totales incluyendo el coeficiente operacional agrícola (0,0002 día-1), (b) costos energéticos, (c) evaluación del ancho de corte económico óptimo por máxima y mínimo y (d) Comparaciones con los precios de alquiler. En la metodología se utilizó el análisis de costos y el análisis de regresión aplicado a los ítems de costo. Entre los resultados obtenidos se tienen: Los costos totales de 14561,20 (USD/año), el ancho económico óptimo de la labor igual a 0,153*AR0,515 (m), el costo por pase para las rastras de discos resultó ser de 20 USD/ha si se alquila, y de 33,71 USD/ha si se adquiere el equipo tractor-rastra. Se concluye: (a) Las rastras de discos ocasionan altos costos de producción al productor propietario y mejor se recomendaría el uso de un servicio externo para áreas menores de 1311,85 ha/año y (b) Se exigirían una unidad tractor rastra por cada 432 ha/año debido a que las rastras utilizadas en el campo venezolano son muy pequeñas.

With the objective to know the biomass production of Bambusa vulgaris in the Granma province, there were evaluated plots located in three locations: Cauto Cristo, Río Cauto, and Manzanillo, on fluvisol, vertisol, and sialitic soils, respectively. Green and ripen culms, and ripen culm branches biomass were measured, obtained a general mean of 31.7 kg/culms for green, 25.4 kg/culms for ripen, and 8.1 kg for branches with ripen culms. General means for different plantation lots were 9.65, 7.75, and 2.4 t/ha for green culms, ripen culms, and branches, respectively, that varied in function of the population and the quality of the site, with which, it is contributed to the protection of the soils reducing soil erosion. ; Con la finalidad de conocer el rendimiento de biomasa de la especie Bambusa vulgaris en la provincia de Granma, se evaluaron parcelas ubicadas en tres localidades: Cauto Cristo, Río Cauto y Manzanillo, sobre suelos fluvisol, vertisol y pardo sialítico, respectivamente. Se midió la biomasa de culmos verdes y maduros, así como el peso de las ramas maduras, con lo que se obtuvo una media general de 31,7 kg/culmo verde, 25,40 kg/culmo maduros y 8,06 kg de ramas de culmos maduros. Los rendimientos medio para diferentes marcos de plantación fueron 9,65 7,75 y 2,4 t/ha para culmos verdes, culmos maduros y ramas, respectivamente, que variaron en función de las densidades de población y la calidad de sitio, con lo cual se contribuye a la protección de los suelos al disminuir la erosión en estas áreas.