African Mahogany transpiration with Granier method and water table lysimeter

Transpiração de Mogno Africano com método de Granier e com lisímetro de lençol freático constante

ABSTRACT

The thermal dissipation probe (Granier method) is useful in the water deficit monitoring and irrigation management of African Mahogany, but its model needs proper adjustment. This paper aimed to adjust and validate the Granier sap flux model to estimate African Mahogany transpiration, measure transpiration using lysimeter and relate it to atmospheric water demand. Weather conditions, transpiration and sap flux were monitored in three units of 2.5-year-old African Mahogany trees in constant water table lysimeter, in Goiânia, GO. Sapwood area (SA), leaf area (LA), transpiration measured by lysimeter (T_LYS) and estimated by sap flux (T_SF) were evaluated. The SA comprised 55.24% of the trunk’s transversal section. The LA varied from 11.95 to 10.66 m². T_LYS and T_SF varied from 2.94 to 29.31 and from 0.94 to 15.45 L d^-1, respectively. The original model underestimated transpiration by 44.4%, being the adjusted equation F = 268.25 . k^1.231. SA was significant (F < 0.05). Due the root confinement, the transpiration showed low correlation, but positive, with the atmospheric water demand.

Key words:
Khaya ivorensis; sap flux; transpiration; lysimeter; sapwood