Transpiração em plantas de laranja e manga utilizando sonda de dissipação térmica e balanço de calor

Abstract

This paper had as objective to evaluate the heat dissipation and heat balance methods in the estimate of transpiration in young trees of orange and mango. The experiments had been lead at EMBRAPA - Mandioca e Fruticultura Tropical, Cruz das Almas - BA (12º48`S; 39°06`W; 225 m). The work was developed with mango and orange trees planted in vases that placed on weighting platforms had functioned as lysimeters. The heat dissipation method was applied in mango trees in such a way in vase how much in field conditions. Heat dissipation probes had confectioned with 1 2 and 3 cm of length. The sapwood area was determined in stem of diverse diameter of the application of pigment. To minimize the effect of the natural thermal gradients different thermal shield in the plants in vase had been tested. The correction of the thermal gradients natural gifts in stem revealed essential for the adequate estimate of the sap flow (FS) for the heat dissipation method in mango. The probes must be installed below of not conducting an external layer (C) that varies with the diameter of stem (D) for relation C=0,0625D. The stem sapwood area (AS) can be esteem by D for equation AS=0.667D2-0.006D. Modifying the empirical parameters of the general equation of Granier (FS=0.00017k1.231AS) the average error in relation to the lisimétricas measures was of -1.4% with high precision. The estimates of sap flow for the heat balance method if gave later in 2 young sleeve plants and in 3 plants of orange. The heat balance method esteem the daily transpiration of necessary form in daily intervals underestimating in average 4.6% daily transpiration in orange plants and overestimating in average 0.3% in mango plants.