GRANGEIRO, R. S. B.; http://lattes.cnpq.br/9058136899259998; GRANGEIRO, Raimundo de Sá Barreto.
Résumé:
A field experiment was carried out at the experimental farm of the Brazilian Company of
Agricultural and animal Research - Embrapa Algodao, in Barbalha-CE, (07°18'39 "S;
39°23'39 "W; 415,7 m) from of August to December of 2003.The main objective of the
study was to evaluate the evapotranspiration and the energy balance components of an
irrigated cotton crop cultivar BRS 200, under the soil and climate conditions of the cariri
region. Inside the experimental, area a sir installing sensors to measure
micrometeorological tower was mounted in the experimental area, the components the
energy balance over the crop canopy. All sensors were ones were connected to an
automatic system (Datalogger 2IX do Campbell Sci), programmed for readings at every 5
seconds and to extract averages at a 20 minutes interval. The growth variavles: leaf area,
leaf area index and plant height were measured weekly. These variavles reached maximum
values of: 1,965.7 cm2, 2.2 cm2/cm2 and 75.1 cm, respectively. The crop phenological
cycle was divided into four phase, with a water consumption of 5.0 mm/day, 5.0 mm/day,
6.2 mm/day and 6.0 mm/day, in the phases I , II, III and IV, respectively. The total water
required by the crop was 582.2 mm. The energy balance components were observed to be
similar for net radiation, latent heat flux, soil heat flux and sensible heat flux, before,
during and after irrigation. During the irrigation, all energy balance components were
reduced. The behaviour of the energy balance components for days with and without
cloudiness on each phenological phases were also analysed. It was observed that the
maximum values occurred around mid-day and that the net radiation was higher than the
other components However, in the end of the crop cycle, the values of Rn and LE were
close to each other.