Functioning evaluation of the thermal validation sensor in the estimation of water consumption by pupunheira (Bactris gasipaes Kunth.) plants

• Grant number: 10/01116-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2010
• End date: September 30, 2011
• Field of knowledge: Agronomical Sciences - Agronomy - Agricultural Meteorology
• Principal Investigator: Marcos Vinícius Folegatti
• Grantee: Larissa Liane Heidorn
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The Thermal Dissipation method was elaborated due to difficulty in measuring transpiration in vegetal large port species. It works with the insertion of two sensors in the same axial line of a tree trunk. An electrical power is supplied to the upper sensor, so that it is warmed to a constant value. The variation of the temperature between the two sensors is registered by a data acquisition system. The heat connective transport made by the sap reduces the temperature in the upper region, so that the temperature difference lowers as the sap flux rises. This is the most used method nowadays, because of its operational easiness. There are, however, many sources of errors, which are still studied by many authors. In this research, Granier sensors will be constructed, installed in pupunheiras, a type of palm tree used as an alternative to Jussara pal cabbage, and connected to a Campbell Sci datalogger program to collect data. The values of temperature difference will be used to create a Granier flux meter calibration equation and to determine pupunheira transpiration. Sensors effectiveness will be evaluated by comparative studies with meteorological variables, in order to identify possible errors sources. The experiment makes it possible to learn how to program Campbell Sci dataloggers and to manage the construction of Granier sensors and the technique used to estimate sap flux, and, with that, plant transpiration. (AU)