Avaliação de métodos de determinação da evapotranspiração, no interior de casa de vegetação, em Lavras-MG

Abstract

The plant inside the greenhouse is in an atmosphere different from the outside. It was aimed, in the present work, to estimate the potential evapotranspiration (ETp) inside and outside the greenhouse, by utilizing the method of Penman-Monteith, considered a pattern, as well as to evaluate the performance of the four methods of estimation of ETp proposed by FAO, besides the method of Makkink and of the modified Atmometer SOILCONTROL, in the region of Lavras-MG. The experiment was accomplished in the Federal University of Lavras, during the period of february to may of the year of 1999. An automatic broadcasting station, tank Class A and three modified atmometers, in a greenhouse of 350 m2, cultivated with pepper was set up. The data were collected daily and analyzed statistically. On the oásis ofthe results, a reduction of about 26% of the values of global solar radiation was verified inside the greenhouse. The values of potential evapotranspiration obtained inside the greenhouse, inferior to those found in the open sky, for ali the methods studied except for the method of Blaney-Criddle. The methods of modified Penman and Makkink presented an excellent performance in the estimation of ETp, as compared with the method ofPenman-Monteith. Even so, the methods of Blaney-Criddle and of the modified Atmometer SOILCONTROL did not estimate ETp accurately inside the greenhouse.