THERMAL MEASUREMENT OF SAP FLOW AND HYDRIC BEHAVIOR OF TREES .2. SAP FLOW EVOLUTION AND HYDRIC BEHAVIOR OF IRRIGATED AND NONIRRIGATED TREES UNDER TRICKLE IRRIGATION

A thermal method for measuring sap flow in apple tree trunks and roots has been applied for characterising relative behavior of non-irrigated trees and trees irrigated by trickle irrigation (fig 1). The hourly and daily transpiration rate was estimated (figs 2, 3 and 7; table I) and the soil water uptake of the different components of the root systems was determined (figs 5 and 6). In the trunks, the study of flow kinetics allowed characterization of hydric stress in trees and therefore the irrigation requirements of the orchard; and in the roots (fig 4), determination and estimation of the spatial and temporal heterogeneity of root sink function for soil-water.