Response of photosynthetic gas exchange and leaf characteristics to elevated temperature in young olive trees

ANDREA MISERERE; ROUSSEAUX, M CECILIA; PLOSCHUK, EDMUNDO L; MAGDALENA BRIZUELA; CURCIO, MATÍAS H; ZABALETA NIEVAS ROMINA BELÉN; PETER SEARLES

Conferencia; 6th International Conference on the Olive Tree and Olive Products; 2018

Leaf photosynthetic rate and water loss are both affected by temperature via stomatal opening, and global warming could affect these coupled processes in olive trees. Additionally, leaf characteristics including stomatal density can vary according to the environment in which they developed.Thus, our objectives were to: i) evaluate the response of leaf photosyntheticgas exchange as well as tree sap flow to elevated temperature in two olive cultivars; and ii) determine the density of stomata and trichomes in leaves acclimated to two temperature regimes.  Two temperature levels were applied in the summer and fall of two consecutive growing seasons in open top chambers: a control (T0) near air temperature and atreatment 4°C above the control (T+). Two to three year-old olive trees (cvs.´Arbequina´ and ´Coratina´) were grown in pots and well-watered throughout the experiment. The leaf photosynthetic gas exchange was measured monthly, and treesap flow was measured twice during the second growing season. Stomatal and tricome density were determined for leaves developed during the experiment. Photosyntheticrate showed no significant response to elevated temperature, but increases in leaf transpiration, stomatal conductance, and sap flow were consistently observed inboth cultivars under elevated temperature. Thus, water use efficiency was significantly reduced in the heated trees.Leaves of T+ showed some minor changes in stomatal density and tricome density. However, the differences were not consistent between growing seasons. The results suggest that elevated temperature with global warming may increase cropwater consumption in well-irrigated orchards.