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

ROUSSEAUX, M. CECILIA; MISERERE, ANDREA; MANCHÓ, GUADALUPE; MASEDA, PABLO; BRIZUELA, M. M.; SEARLES, PETER S.

Sevilla

Congreso; Olivebioteq. 6th International Conference on olive tree and olive products; 2018

Global warming is resulting in temperature increases in South America where temperatures are already consideredto 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, ourobjectives were to: i) evaluate the response of olive tree sap flow and xylem anatomy to elevated temperature; andii) determine whether fruit load may affect temperature responses. Two temperature levels were applied in thesummer and fall using open top chambers: a control near air temperature and a treatment 4°C above the control.Whole tree sap flow was measured under these treatment conditions using an energy balance methodology in wellwatered,three year-old olive trees (cv. Arbequina). The number, diameter, and area of xylem elements was alsoassessed 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 controltrees. This apparent acclimation to elevated temperature may be a function of the greater xylem area observed atelevated temperature. Similar trees were evaluated at ambient temperature with a range of fruit loads. Withincreasing fruit load, sap flow and stomatal conductance increased linearly up to a threshold above which theyremained constant. Thus, other crop factors such as fruit load will likely affect the physiological responses toelevated temperature.