Métodos de estimativa da evapotranspiração da cultura da cana-de-açúcar em condições de sequeiro.

Abstract

The main objective of this study was to find an efficient method in determining the evapotranspiration of cane sugar with little requirement for environmental measurements. Field experiments were conducted in Grass Farm II (UNIAGRO), located in the city of Grass - PB, from October 2009 to August 2010. The data for determining evapotranspiration were obtained in upland portion of the data and to determine the reference evapotranspiration were obtained in PCD (Data Collection Platform) INPE. The survey results allow us to conclude that the method of Priestley-Taylor showed values very close to those of the reference evapotranspiration throughout the crop cycle. Moreover, the method of Priestley-Taylor with the adjusted coefficient showed the best performance in the evapotranspiration of cane sugar when compared with measurements obtained by the method of soil water balance. The results also indicate that the coefficient of Priestley-Taylor method of energy balance is most appropriate for determination of crop evapotranspiration of sugar cane cultivation in the conditions of the coastal plains of the state of Paraíba. Moreover, the coefficient  Priestley-Taylor varies considerably depending on the growth stage of the crop. The values of α for the cultivation of cane sugar were significantly higher than those adopted by Priestley-Taylor, with median values of 1.5, 1.6 and 1.5, respectively, by the methods of energy balance, crop coefficient and soil water balance.