SAP FLOW RESPONSES TO ELEVATED TEMPERATURE AND FRUIT LOAD IN YOUNG OLIVE TREES

MARIA CECILIA ROUSSEAUX; ANDREA MISERERE; GUADAUPE MANCHO; PABLO MASEDA; MARIA MAGDALENA BRIZUELA; PETER STOUGHTON SEARLES

Sevilla

Congreso; Olive Bioteq'18: 6th International Conference on the Olive Tree and Olive Products; 2018

Consejo Superior de Investigaciones Científicas (CSIC)

Global warming is resulting in temperature increases in South America where temperatures are already considered to be high for many crop species, and greater increases are expected by the end of the century. In perennial crops, there is little understanding as to how water use and other aspects of crop functioning will be affected. Thus, our objectives were to: i) evaluate the response of olive tree sap flow and xylem anatomy to elevated temperature; and ii) determine whether fruit load may affect temperature responses. Two temperature levels were applied in the summer and fall using open top chambers: a control near airtemperature and a treatment 4°C above the control. Whole tree sap flow was measured under these treatment conditions using an energy balance methodology in well-watered,three year-old olive trees (cv. Arbequina). The number, diameter, and area of xylem elements was also assessed in shoots formed under the two treatments. Sap flow increased under the elevated temperature treatment, and it was also greater at a given temperature in trees growing under elevated temperature compared to the control trees. This apparent acclimation to elevated temperature may be a function of the greater xylem area observed at elevated temperature. Similar trees were evaluated at ambient temperature with a range of fruit loads. With increasing fruit load, sap flow and stomatal conductance increased linearly up to a threshold above which they remained constant. Thus, other crop factors such as fruit load will likely affect the physiological responses to elevated temperature.