Amazingly, in contrast with other crops and in stark contrast to their tree crop counterparts in the Southwest, little is known regarding the response of pecan trees to their environment in the Southeast. Surprisingly, few studies have been carried out regarding the response of pecan trees to factors influencing their response to variable such as vapor pressure deficit, water availability and other environmental variables. This paper reports on tree sap flow properties in a micro-irrigated pecan orchard near Hawkinsville, GA in 2022 and 2023. Results presented describe the diurnal trend in the sap flow behavior. The paper also reports how the timing of the peak in sap flow density in relation to solar radiation, vapor pressure deficit and temperature. It also reports on the intraseasonal variability and changes in sap flow density throughout the growing season. The daily patterns of sap flow through the day along with their accompanying hysteresis loops and implications for water management are discussed. The hysteretic strength for the sub-diurnal sap flow density against the vapor pressure deficit for the Southeastern pecan is quantified using a hysteresis index. Tree transpiration for these southern pecan trees is also discussed. This new data regarding sap flow properties in pecan trees shed useful insight on how trees respond to environmental conditions in a micro-irrigated orchard in the Southeast.
