Determinação da linha base para avaliação do CWSI da cultura do café (Coffea arabica L.) por termometria a infravermelho.

Abstract

With the objective to determine the line base not stressed for coffee crop under clean sky condition for evaluation the water stress index (CWSI), an experiment was carried out in area of the Agriculture Department at Federal University of Lavras, Minas Gerais State, Brazil. Adult plants were evaluated with spacing 2.0 x 1.0 and 3.0 x 1.0 m under irrigation regime monitored by sensors of water tension installed in field, tends as irrigation criterion when the water tension in the soil reached 20 kPa. Through a portable infrared thermometer, was made readings of crop temperatures(Tc) and diference dT between air temperature (Ta) and the own culture in three daily hours, at 12:00 o'clock, 13:00 and 14:00h, and meteorological data was collected in an automatic station installed in the area, for determination the deficit pressure vapor of water (DPV). The simple linear regression of dT in function of DPV with spacing 2.0 x 1.0 m generated the adjusted equation for the line base not stressed with intercept equal to 3.9905 and the angular coefficient equal to -1.2044, with adjustment of the equation (r² = 0.7236) indicating that there was good correlation between dT and DPV. For the spacing 3.0 x 1.0 m the correlation between dT and DPV don’t showed satisftory with r2 = 0,0298.