Evapotranspiração e coeficientes de cultivos simples e dual da cana-de açúcar cultivada em condições tropicais.

Abstract

The field experiment was carried out in Distillery Miriri S/A, located in Paraiba State, during the productive cycle of sugar cane crop irrigated by central pivot irrigation (sprinkler), variety RB 92 579, in the period from October 10, 2009 to September 10, 2010. The objective of this study was to determine the evapotranspiration and single and dual crop coefficients for sugar cane grown in tropical environments. The single and dual coefficients were obtained following FAOnomenclature. The crop evapotranspiration was obtained based on soil water balance and reference evapotranspiration by Penman-Monteith method (FAO/56), using the data of air temperature, relative humidity, wind speed and solar radiation from Data Collection Platform, next to the experimental site. Soil water moisture was monitored by TDR probes (Frequency Domain Reflectometry), Model PR2/6, Delta-T. The error analysis was based on mean bias difference (MBD) and the normalized root mean square difference (NRMSD), using both measured and estimated data of crop evapotranspiration. The results showed that the crop coefficients values proposed by the FAO for sugar cane are not suitable for tropical regions as well as dual crop coefficient approach can provide accurate estimates of water requirements for sugar cane growth in tropical environment.