Trayectoria académica orientada al desarrollo productivo

Fil: Golluscio, Rodolfo. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaLa Facultad de Agronomía fue fundada en 1904 como Instituto Superior de Agronomía y Veterinaria\ndependiente del Ministerio del Interior de la Nación, y cinco años después transferida a la UBA. La\nsingularidad de la trayectoria de las facultades de Agronomía y Veterinaria es que, tempranamente, se\ntuvo conciencia de aspectos clave de la vida académica moderna: la imposibilidad de separar la\nciencia y la construcción de conocimiento del impacto social y humano de sus resultados. Por eso,\nsegún sus autoridades , se sigue intentando que sus profesores sean científicos con una fuerte\nvocación humanista

Nota de presentación

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Effect of the Phosphorus-Solubilizing Bacterium Enterobacter Ludwigii on Barley Growth Promotion

Phosphorus (P) is essential for plant growth and development but is often a limiting nutrient in soils. Thus, Pi acquisition from the soil by plant roots is a subject of considerable interest in agriculture. One ecological alternative is the use of P-solubilizing bacteria, which make P available to plants through different mechanisms. Thus, the aim of the present study was to investigate the role of the P-solubilizing bacterium Enterobacter ludwigii in the growth promotion and P content of Hordeum vulgare (barley) under field conditions. Plants were inoculated with E. ludwigii and then its growth promotion effects were compared with those of the reference strain Azospirillum brasilense. The effect of bacterial inoculation showed a beneficial effect on the dry weight, P assimilation and barley yield, especially in E. ludwigii-inoculated plants.  The plant P content at 60 DAS was 38% to 56% higher in E. ludwigii -inoculated plants with respect to non-inoculated plants. The application of bacteria without fertilizer led to the same biological yield (3,795 kg/ha) and increase in one thousand seed weight as the maximum dose of chemical fertilizer applied, while the application of bacteria along with the intermediate fertilizer dose led to a significant increase in grain size (83% of plump grains larger than 2.75 mm wide, whereas 76% of the grains of the control plants reached that size). Endophyte populations of the inoculated bacteria were observed in plants growing under field conditions. The results demonstrated that the inoculation of with E. ludwigii is a promising option to increase P levels in plants and could be a technique for application in agricultural industry

Effect of the phosphorus-solubilizing bacterium Enterobacter ludwigii on barley growth promotion.

Phosphorus (P) is essential for plant growth and development but is often a limiting nutrient in soils. Thus, Pi acquisition from the soil by plant roots is a subject of considerable interest in agriculture. One ecological alternative is the use of P-solubilizing bacteria, which make P available to plants through different mechanisms. Thus, the aim of the present study was to investigate the role of the P-solubilizing bacterium Enterobacter ludwigii in the growth promotion and P content of Hordeum vulgare (barley) under field conditions. Plants were inoculated with E. ludwigii and then its growth promotion effects were compared with those of the reference strain Azospirillum brasilense. The effect of bacterial inoculation showed a beneficial effect on the dry weight, P assimilation and barley yield, especially in E. ludwigii-inoculated plants. The plant P content at 60 DAS was 38% to 56% higher in E. ludwigii -inoculated plants with respect to non-inoculated plants. The application of bacteria without fertilizer led to the same biological yield (3,795 kg/ha) and increase in one thousand seed weight as the maximum dose of chemical fertilizer applied, while the application of bacteria along with the intermediate fertilizer dose led to a significant increase in grain size (83% of plump grains larger than 2.75 mm wide, whereas 76% of the grains of the control plants reached that size). Endophyte populations of the inoculated bacteria were observed in plants growing under field conditions. The results demonstrated that the inoculation of with E. ludwigii is a promising option to increase P levels in plants and could be a technique for application in agricultural industry.Fil: Zaballa, José Ignacio. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Golluscio, Rodolfo. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ribaudo, Claudia Mónica. Universidad de Buenos Aires. Facultad de Agronomía; Argentin

Weed effects on the establishment and nutritive value of pastures with different annual/perennial ratio

Livestock intensification is increasing weed invasion in pastures. We performed an experiment near Buenos Aires, Argentina, to evaluate the impact of weeds on temperate cultivated pastures. We sowed 1,700 viable seeds m–2 in 24, 1.5‐m2 plots. Each plot had seven sowed lines, three of legumes (red clover, Trifolium pratense L.; 50% of seeds) alternating with four of grasses arranged in two sowing designs differing in the annual/perennial ratio: 70% prairie grass (Bromus willdenowii Kunth, Bw, annual species) + 30% of orchardgrass (Dactylis glomerata L., Dg, perennial species) (>Bw), or 30% of Bw + 70% of Dg (>Dg). In the inter‐lines of each plot, we sowed the weed brown mustard (Brassica juncea L.) at four growing densities. At 123 d after sowing, we harvested aerial biomass of weeds and forage species (legume biomass was almost negligible at this date). We quantified aboveground net primary production (ANPP) of weeds and grasses (separated into blades, sheaths, and blades + sheaths), tiller density (indicating potential persistence), blade crude protein (CP), and neutral detergent fiber (NDF) concentrations of grasses.We made regressions to analyze the direct effect of weed biomass on each grass species, their indirect effects on the proportion of each species in the pasture, and their net effects on both species taken together. Weeds had negative direct and net effects. However, they did not have any indirect effect on species proportion. Pastures with lower annual/perennial ratio were more productive and potentially more persistent. Weeds also directly increased blade CP of the annual species.IPAF Región PampeanaFil: Lavarello Herbin, Agustina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Investigación y Desarrollo Tecnológico para la Agricultura Familiar Región Pampeana; ArgentinaFil: Golluscio, Rodolfo A. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Forrajicultura; ArgentinaFil: Rodríguez, Adriana Mabel. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Forrajicultura; Argentin

Controls of forage selective defoliation by sheep in arid rangelands

Selective grazing by domestic livestock is a major control of plant community structure and dynamics in drylands. However, grazing impact predictions supporting management decisions are frequently based on average biomass consumption, neglecting selectivity. We evaluated the relative importance of grazing pressure, total and each species density, and plant dead biomass proportion as drivers of selective defoliation by sheep in three dominant native grass species in Patagonian steppes. Species were Poa ligularis, Festuca pallescens, and Pappostipa speciosa, which a priori present different preference degree by sheep. The relevance of these drivers for differently preferred species has not been simultaneously studied. We recorded the defoliation frequency and degree of the three species (dependent variables) throughout 112 field surveys. Besides, we recorded grazing management and vegetation structure descriptors (independent variables). Poa ligularis was highly defoliated (90% of plants), and grazing pressure was the leading driver (asymptotic exponential relationship). For F. pallescens, almost 70% of plants were defoliated, and defoliation non-linearly increased as grazing pressure rose and linearly decreased as both its dead biomass proportion and P. ligularis density increased. For P. speciosa, defoliation was low (20% of plants) and linearly decreased as both its dead biomass proportion and the density of the other two species increased. Grazing pressure played a negligible role in this species. These patterns confirmed that P. ligularis, F. pallescens, and P. speciosa, respectively, present high, intermediate, and low preference degree by sheep. In conclusion, our findings suggest that (1) selective defoliation can be satisfactorily predicted as function of grazing pressure, species densities, and plant dead biomass proportion; (2) grazing pressure becomes a more relevant driver as species preference rises and its effect on defoliation is markedly non-linear; (3) the dead biomass proportion and the abundance of highly preferred species are the leading factors determining less preferred species defoliation; and (4) grazing pressure management by itself is not enough to reduce the high defoliation of preferred species and increase the defoliation of non-preferred species. This knowledge is critical for developing effective management practices to control forage species defoliation in rangelands worldwide where species with different preference by herbivores coexist.Fil: Oñatibia, Gastón Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Golluscio, Rodolfo. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Texeira González, Marcos Alexis. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Paruelo, José. Instituto Nacional de Investigacion Agropecuaria; Uruguay. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Glyphosate sprayed on the pre-existing vegetation reduces seedling emergence and growth of forage species

Seeding pastures or forage crops by no-tillage methods usually involves the spray of glyphosate to suppress the existing vegetation. While  many studies found detrimentaleffects of glyphosate on seed germination and seedling growth of the subsequent crop, others found negligible effects. This study aimed to evaluate the effect of glyphosate spraying on germination, seedling emergence and seedling growth of four forage species: Trifolium repens, Lotus tenuis, Festuca arundinacea and Paspalum dilatatum. The experiment was carried out spraying glyphosate on the pre-existing vegetation and on bare soil 1, 30, 60 and 90 days before sowing, and a control  treatmentsprayed with water. Glyphosate sprayed on pre-existing vegetation 1 to 60 days before seeding reduced emergence, while sprayed 1 to 30 or 1 to 60 days before seeding reduced seedlings belowground biomass and root length of all species and aboveground biomass of legumes respect to sprayed 90 days before seeding, sprayed on bare soil, and control treatment. This herbicide would remain active in the soil environment for at least 60 days after spraying when it was previously absorbed by plants, causing a severe damage to seedlings emergence and growth. Highlights: Glyphosate sprayed on pre-existing vegetation 1 to 60 days before seeding reduced seedling emergence of Trifolium repens, Lotus tenuis, Festuca arundinacea and Paspalum dilatatum. Glyphosate sprayed on pre-existing vegetation 1-30 or 1-60 days before seeding reduced seedlings belowground biomass and root length of all species and aboveground biomass of legumes Gyphosate sprayed 90 days before seeding or sprayed on bare soil did not affect seggling emergence and growth. Gyphosate would remain active in the soil environment for at least 60 days after spraying when it was previously absorbed by plants.Seeding pastures or forage crops by no-tillage methods usually involves the spray of glyphosate to suppress the existing vegetation. While  many studies found detrimentaleffects of glyphosate on seed germination and seedling growth of the subsequent crop, others found negligible effects. This study aimed to evaluate the effect of glyphosate spraying on germination, seedling emergence and seedling growth of four forage species: Trifolium repens, Lotus tenuis, Festuca arundinacea and Paspalum dilatatum. The experiment was carried out spraying glyphosate on the pre-existing vegetation and on bare soil 1, 30, 60 and 90 days before sowing, and a control  treatmentsprayed with water. Glyphosate sprayed on pre-existing vegetation 1 to 60 days before seeding reduced emergence, while sprayed 1 to 30 or 1 to 60 days before seeding reduced seedlings belowground biomass and root length of all species and aboveground biomass of legumes respect to sprayed 90 days before seeding, sprayed on bare soil, and control treatment. This herbicide would remain active in the soil environment for at least 60 days after spraying when it was previously absorbed by plants, causing a severe damage to seedlings emergence and growth. Highlights: Glyphosate sprayed on pre-existing vegetation 1 to 60 days before seeding reduced seedling emergence of Trifolium repens, Lotus tenuis, Festuca arundinacea and Paspalum dilatatum. Glyphosate sprayed on pre-existing vegetation 1-30 or 1-60 days before seeding reduced seedlings belowground biomass and root length of all species and aboveground biomass of legumes Gyphosate sprayed 90 days before seeding or sprayed on bare soil did not affect seggling emergence and growth. Gyphosate would remain active in the soil environment for at least 60 days after spraying when it was previously absorbed by plants

Pastizal pampeano: “del mar de pasto” descripto por Darwin a la actualidad : Lectura del tiempo en un espacio

El pastizal pampeano, como todo pastizal, tiene una estructura (representada por el número de especies, la cobertura de esas especies y cuanto queda de suelo desnudo) y un funcionamiento (dado por la productividad y el ciclado de nutrientes) que lo define. Esto da un aspecto definido del pastizal Pampeano, que es como se lo aprecia en la actualidad. ¿Pero siempre fue así?Facultad de Ciencias Agrarias y Forestale

Pastizal pampeano: “del mar de pasto” descripto por Darwin a la actualidad : Lectura del tiempo en un espacio

El pastizal pampeano, como todo pastizal, tiene una estructura (representada por el número de especies, la cobertura de esas especies y cuanto queda de suelo desnudo) y un funcionamiento (dado por la productividad y el ciclado de nutrientes) que lo define. Esto da un aspecto definido del pastizal Pampeano, que es como se lo aprecia en la actualidad. ¿Pero siempre fue así?Facultad de Ciencias Agrarias y Forestale

Pastizal pampeano: “del mar de pasto” descripto por Darwin a la actualidad : Lectura del tiempo en un espacio

El pastizal pampeano, como todo pastizal, tiene una estructura (representada por el número de especies, la cobertura de esas especies y cuanto queda de suelo desnudo) y un funcionamiento (dado por la productividad y el ciclado de nutrientes) que lo define. Esto da un aspecto definido del pastizal Pampeano, que es como se lo aprecia en la actualidad. ¿Pero siempre fue así?Facultad de Ciencias Agrarias y Forestale