Sap flow in peach trees during water stress and recovery in two environmental conditions

Data on sap flow rate during cycles of water stress and recovery, recorded on peach trees in two different locations in Italy and Portugal, are reported. Pre-dawn leaf water potential and the diurnal leaf temperature trends are also reported. Tree water requirements and consumption were strongly influenced by soil characteristics and root distribution. In the Italian orchard, planted in deep soil with medium clay content, a decrease in sap flow rate and daily cumulative sap flow did not occur until 20-30 days after the beginning of drought. cycle; in contrast, the Portuguese orchard, planted in a sandy soil and having a shallow root system, showed stress symptoms as early as 1-2 days after withholding irrigation. Recovery from stress was less influenced by soil and climatic conditions; sap flow per m(2) leaf area increased strongly on the day after rewatering and showed further progressive increase during the subsequent days, independently of the location considered. However, sap flow recovery never reached control tree values in the Italian location while pre-dawn water potential recovered completely one week after rewatering.