TRANSPIRATION OF SPECIES TYPICAL OF CERRADO AS MEASURED BY BALANCE TRANSPIROMETER AND BY POROMETER

Abstract

Ecophysiological criteria need to be known in order to adopt effective forest management models, since through them relationships are established between environmental factors and metabolic responses of species. Transpiration is influenced by several factors, including the relevant species. This study aims to relate measurements of transpiration using a ‘Balance State Transpirometer’ (Transpirometer) and a ‘Steady State Porometer’ (Porometer) for the following forest species: Yellow Ipe (Tabebuia serratifolia Nichols), Jatoba (Hymenaea stigonocarpa Mart. Ex Hayne), Balsamo (Myroxilom balsamum Harms.), Eucalyptus camaldulensis Dehn. and E. citriodora Hook. The experiment was set up in the greenhouse of the Federal University of Goiás and consisted of five treatments with four replicates in a completely randomized design, over a period of three months. Results revealed that transpiration values provided by the Transpirometer were higher than those provided by the Porometer for the eucalyptuses, in all days. As for jatoba and ipe, the transpiration measured by the Transpirometer was lower than that measured by the Porometer in at least one day. And as for balsamo, the value measured was similar in both devices on JD 292. These differences are justified by the fact that the Porometer records leaf transpiration instantly while the Transpirometer quantifies transpiration by the entire plant and therefore is a cumulative measure. The species being studied had different response: the eucalyptuses transpire more than the native trees, namely twelve times more than balsamo, seven times more than ipe and six times as much as jatoba.