1000 resultados para Pre-producción
Resumo:
In the present study, a 2-year N rate response experiment was conducted in different fields to monitor NO3-N soil profiles, N accumulation by the crop and final crop performance, in order to assess if soil NO3-N at pre-sidedressing (Pre-Sidedress Soil Nitrate Test, PSNT) is a reliable indicator for soil N availability for corn in the irrigated area served by canal d’Urgell (Lleida, Spain), and if the test can be used to separate responsive fields from non-responsive fields to sidedress N fertilizer applications. Preliminary soil N availability (N sidedress fertilizer rate + PSNT) critical levels to identify fields that need supplementary N fertilizer applications were established at ca. 300 and 210 kg NO3-N·ha–1, for PSNTrooting–zone and PSNT0–30 cm, respectively (for a yield goal of 14 t grain·ha–1).
Resumo:
The effect of environmental conditions immediately before anthesis on potential grain weight was investigated in wheat at the experimental field of the Faculty of Agronomy (University of Buenos Aires, Argentina) during 1995 and 1996. Plants of two cultivars of wheat were grown in two environments (two contrasting sowing dates) to provide different background temperature conditions. In these environments, transparent boxes were installed covering the spikes in order to increase spike temperature for a short period (c. 6 days) immediately before anthesis, i.e. between ear emergence and anthesis. In both environments, transparent boxes increased mean temperatures by at least 3n8 mC. These increases were almost entirely due to the changes in maximum temperatures because minimum temperatures were little affected. Final grain weight was significantly reduced by higher temperature during the ear emergence–anthesis period. It is possible that this reduction could be mediated by the effect of the heat treatment on carpel weight at anthesis because a curvilinear association between final grain weight and carpel weight at anthesis was found. This curvilinear association may also indicate a threshold carpel weight for maximizing grain weight.
Resumo:
En este trabajo se repasan algunas de las principales conceptualizaciones que los "estudios campesinos" han elaborado sobre el mundo rural y se señalan las limitaciones del propio concepto del papel y las expectativas que la agricultura familiar tiene dentro del capitalismo avanzado. Se hace hincapié en los factores causales de su pervivencia y de las estrategias adaptativas desarrolladas por las unidades de producción domésticas.
Resumo:
Los rankings de productividad científica resultan cada vez más relevantes, tanto a nivel individual como institucional. Garantizar que se basan en información confiable y exhaustiva es, por tanto, importante. Este estudio indica que la posición de los individuos en esa clase de ranking puede cambiar sustancialmente cuando se consideran diversos indicadores bibliométricos internacionalmente reconocidos. Se usa, como ilustración, el caso de los diez profesores del área de ‘Personalidad, Evaluación y Tratamiento Psicológico’ consignados en el reciente análisis de Olivas-Ávila y Musi-Lechuga (Psicothema 2010. Vol. 22, nº 4, pp. 909-916).
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1894.
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1896.
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1897.
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1898.
