Nitrogen fertilization of wheat for forage and grain production in the south west of Buenos Aires province (Argentina)

Cuando del cultivo de trigo (Triticum aestivum) se obtiene forraje y grano, i.e. cultivo doble propósito (DP), la disponibilidad de nitrógeno puede ser un aspecto clave para la expansión de esta alternativa. Se comparó la respuesta al N en trigo DP fertilizado en abril (DPF), en agosto (DPG), en ambas fechas (DPFG) y en el cultivo para grano (TC) en un experimento factorial con las dosis de N: 0, 40, 80, 120, y 160 kg ha-1, aplicado como urea al voleo. Se determinó el rendimiento de forraje y de grano y el contenido de N en cada producto. El rendimiento de forraje se incrementó en promedio en 10,3 kg MS kg-1 de N aplicado, hasta la dosis de 120 kg ha-1. El rendimiento de grano fue menor en los DP, pero tuvo una mayor respuesta a N, incrementándose en 8,3, 7,3, 4,7, y 4,7 kg kg-1 de N aplicado para DPG, DPFG, DPF y TC respectivamente. La eficiencia agronómica de la respuesta a N en el rendimiento de grano fue superior en los manejos de DP y estos resultados muestran una mayor conveniencia de la fertilización nitrogenada en estos que en TC.When forage and grain are obtained from a wheat crop, (Triticum aestivum), i.e. a dual purpose crop (DP), the availability of N can be a key factor for the expansion of this alternative system. The response to nitrogen fertilization of a DP crop fertilized in April (DPF), in August (DPG), in both dates (DPFG) and in wheat grown only for grain (TC) was compared in a factorial experiment with the N levels 0, 40, 80, 120, and 160 N kg ha-1, applied as broadcast urea. Forage and grain yield and N content of each product were determined. Forage yield increased, on average, 10.3 kg dry matter per kg of applied N, up to the 120 kg ha-1 level. Grain yield was lower in DP than TC but had a higher response to N, increasing on average 8.3, 7.3, 4.7, and 4.7 Kg per kg applied N, for DPG, DPFG, DPF and TC respectively. The agronomic efficiency of the response to N in grain yield was higher in DP than in TC and these results show that N fertilization in DP is more convenient than in TC.Fil: Arzadun, M.. Chacra Experimental Coronel Suárez; ArgentinaFil: Laborde, H.. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Arroquy, Jose Ignacio. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero; Argentin

Forage Quality of Mixtures of \u3ci\u3eBromus wildenowii\u3c/i\u3e and \u3ci\u3eB. parodii\u3c/i\u3e Influenced by Nitrogen Fertilization or Alfalfa Interseeding

Under good soil fertility conditions, Bromus wildenowii Kunth and Bromus parodii Covas et Itria are two high producing forage grasses. The objective of this study was to evaluate the effect of nitrogen fertilization or the association with alfalfa (Medicago sativa L) on yield and forage quality of mixtures of both grasses during the establishment year. Nitrogen fertilizer (300 kg ha-1) was broadcasted in three 100 kg N dosis. Nitrogen fertilization or alfalfa intercropping did not increase dry matter yield. Tiller density and crude protein content of grass forage were increased by nitrogen application. Intercropped alfalfa increased N content of grasses mixture. In vitro dry matter disappearance, neutral detergent fiber and lignin content were not affected by treatments

Leaf Growth and Anatomy During Winter Droughting of Tetrachne Dregei Plants

The purpose of this work was to study the leaf growth and anatomy of Tetrachne dregei plants when they were subjected to a winter drought period. Plants were grown in semicontrolled conditions under two soil moisture regimes: irrigated and non-irrigated. Anatomical characterization was made using optical and scanning electron microscopy. No differences were found in stomatal index, stomatal length and epidermal cell size, between irrigated and non-irrigated plants. The adaxial epidermis of water stressed plants was more pubescent. Leaf abaxial epidermis of non-irrigated plants showed more intercostal plates of crystallized epicuticular wax than that of the irrigated ones. Leaf tissue distribution was not affected by the different moisture regimes. The effect of water deficit was neither detected on plant height, nor on leaf width and length. Except for the enhanced adaxial pubescence and abaxial wax crystal content, no other xeroplastic changes were noticed

Una opinión sobre el estado actual y las perspectivas de la ganadería bovina en el sudoeste bonaerense

La presente exposición no tiene un carácter estrictamente técnico sino que trata de presentar las opiniones condensadas de varios actores que han tenido desempeño profesional en producción animal en distintas zonas que componen el sudoeste bonaerense (SOB). Con las entrevistas mantenidas con todos ellos se resumió una opinión sobre la evolución que tuvo la ganadería luego de los aportes en conocimientos en sanidad., genética y nutrición animal difundidos en los últimos de 30-40 años. Asimismo se evaluaron perspectivas hacia el futuro de la actividad en la región.Academia Nacional de Agronomía y Veterinari

Yield and Forage Quality in Alfalfa-Weeping Lovegrass Mixtures

Little is known about the relative performance of weeping lovegrass in mixtures with alfalfa. Our objective was to compare the productivity and forage quality of monocultures and binary mixtures of the species. Mixtures always gave higher yields than any of the monocultures and the highest was obtained in the mixture with the largest proportion of alfalfa. In the second year weeping lovegrass N concentration in the mixtures were higher than in monoculture. Weeping lovegrass did not affect the alfalfa N concentration. There was not differences in the NDF, for between these species

El Rol del Ítem “Impacta Social” en los Formularios de Presentación y Evaluación de Proyectos

Las tesis de este trabajo plantean que la universidad debe recuperar su identidad y sus objetivos para estar a la altura de los acontecimientos sociales de su tiempo en todos los tiempos, así como también, que está en condiciones de proponer múltiples soluciones a los múltiples problemas que tiene el país, por poseer los recursos humanos necesarios. Se concibe la actividad científica como una tarea cultural realizada por mujeres y hombres, cuyos objetos de estudio están dentro de esa misma cultura y que toda investigación científica tiene un impacto sobre la sociedad. Esto último lleva a otro supuesto en que se basa esta investigación y es aquel que se relaciona con la concepción respecto de que la ciencia es pura o simplemente no es ciencia. En el marco de lo anteriormente señalado los objetivos planteados en el presente trabajo se centraron en: 1) determinar el status del impacto social de las investigaciones científicas en la Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata y 2) proponer alternativas y/o modificaciones que apunten a la toma de conciencia respecto del compromiso social de la investigación científica. La metodología utilizada consistió en: 1. a) Análisis de los Formularios de Presentación de Proyectos de Investigación (F. P. P. I.), identificando aquellos items en donde se requiera información acerca del “impacto social” de la investigación planteada. 1. b) Análisis de los Formularios de Evaluación (F. E.) identificando el valor asignado al ítem “impacto social”. Los resultados obtenidos evidenciaron un escaso valor asignado al ítem “impacto social” en los F. P. P. I. y nulo en los F. E., esto es: la Universidad no exige en la presentación de proyectos que los responsables de los mismos se expidan convenientemente acerca de las áreas socio-económicas de posible aplicación de los resultados de las investigaciones. Además, esta especificación no es obligatoria. Semejantes consideraciones se pueden observar respecto de las instancias de evaluación. Finalmente, se proponen alternativas que involucran a los diferentes actores: alumnos, investigadores y autoridades (facultad y universidad)

Sympathetic Responses to Central Hypovolemia: New Insights from Microneurographic Recordings

Hemorrhage remains a major cause of mortality following traumatic injury in both military and civilian settings. Lower body negative pressure (LBNP) has been used as an experimental model to study the compensatory phase of hemorrhage in conscious humans, as it elicits central hypovolemia like that induced by hemorrhage. One physiological compensatory mechanism that changes during the course of central hypovolemia induced by both LBNP and hemorrhage is a baroreflex-mediated increase in muscle sympathetic nerve activity (MSNA), as assessed with microneurography. The purpose of this review is to describe recent results obtained using microneurography in our laboratory as well as those of others that have revealed new insights into mechanisms underlying compensatory increases in MSNA during progressive reductions in central blood volume and how MSNA is altered at the point of hemodynamic decompensation. We will also review recent work that has compared direct MSNA recordings with non-invasive surrogates of MSNA to determine the appropriateness of using such surrogates in assessing the clinical status of hemorrhaging patients

Stakeholder-designed scenarios for global food security assessments

To guide policymaking, decision makers require a good understanding of the long-term drivers of food security and their interactions. Scenario analysis is widely considered as the appropriate tool to assess ‘wicked problems’, such as ensuring global food security, that are characterized by a high level of complexity and uncertainty. This paper describes the development process, storylines and drivers of four new global scenarios that are specifically designed to explore global food security up to the year 2050. To ensure the relevance, credibility and legitimacy of the scenarios, they have been developed using a participatory process, involving a diverse group of stakeholders. The scenarios consist of storylines and a scenario database that presents projections for key drivers, which can be used as an input into global simulation models

Growth, blood metabolites and hormones in calves fed diets with different amounts of energy and protein during the pre- or post-weaning periods

We investigated the effects of diets differing in energy and protein concentrations given during pre- and post-weaning on hormone and metabolite levels in association to parameters of growth. Sixteen Aberdeen Angus calves four-day-old were allocated in individual pens during 105 days in a randomized complete design. Animals consumed ad libitum various diets differing in proportion of energy and protein (A: 80% of concentrate, 20% alfalfa hay; B: 60% concentrate, 40% of alfalfa hay; C: 40% concentrate, 60% alfalfa hay, and D: 20% concentrate, 80% alfalfa hay). Also, calves consumed milk substitute up to 60-day-old day. Serum growth hormone and cortisol levels were not altered with diet changes (P > 0.05) neither during the pre- nor the post-weaning periods. Plasma insulin concentration average daily intake, glucose and thyroid hormone levels, and concentrations of ammonia nitrogen and propionic acid were greater (P < 0.01) for diets having higher than lower energy and protein levels during the post-weaning but not during the pre-weaning period. These results suggest inclusion of higher amounts of concentrate in the diet of weaned calves.Fil: Fernández, H. T.. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Busso, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Laborde, Hugo Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Torrea, M. B.. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Fernández, L. M.. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: López, G. H.. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Delucchi, F.. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: García, B. N.. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentin