Fluxos de CO2, calor sensível e calor latente na cultura de caupi (Vigna unguiculata L.)

• Autor(a) principal: Neves, Leonardo de Oliveira
• Data de Publicação: 2006
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5248
• topic: Micrometeorologia; Ciclo de carbono; Bioenérgetica; Caupi; Micrometeorology; Carbon cycle; Bioenergetics; Cowpea; CNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::METEOROLOGIA::MICROMETEOROLOGIA

Measurements of carbon dioxide, latent heat and sensible heat fluxes were made during the cycle of the cowpea crop, in Tracuateua-PA, during the months of the august and September of 2002. The objectives of the present work were: 1 To quantify the magnitudes of the carbon dioxide, latent heat and sensible heat fluxes, during the development cycle of the cowpea crop; 2 - To analyze the energy balance and the net radiation partition in their components of latent heat and sensible heat fluxes; 3 To evaluate the water use efficiency for a cowpea crop. The fluxes of carbon dioxide and energy were measured using the eddy covariance method. These informations were supported with measurements of net radiation, global solar radiation, precipitation, air temperature, relative humidity and wind speed and direction, using an automatic weather. The hourly mean value of the carbon dioxide, sensible heat and latent heat fluxes in the studied period were -2.34 µmol.m-2.s-1, 206 W.m-2 and 76 W.m-2, respectively. The daily mean value of the sensible heat and latent heat fluxes in the studied period were 7.7 MJ.m-2d-1 e 2.7 MJ.m-2d-1, respectively. The partition of the net radiation in sensible heat flux showed a mean value of 0.58, while a partition of the net radiation in latent heat flux showed a mean value of 0.21 during all the experimental period. The partition of the energy balance components expressed by the Bowen ratio, varied between 1.52 to 4.88, with a mean value of 2.82. The mean values of the respiration rate was of 1.9 µmol.m-2.s-1. The water use efficiency, defined by the ratio between the carbon dioxide and latent fluxes, presented a mean daily value of 1.35 µmolCO2.mmolH2O-1 during the experimental period. The sensible heat fluxes were higher than the latent heat fluxes during the cycle of the cowpea crop. The predominant conditions of water deficiency during the cycle of the crop resulted in low values in the carbon dioxide and latent heat fluxes, affecting the water use efficiency of the cowpea crop.