Water deficit and acclimation to low temperatures improve supercooling in leaves of Olea europaea cultivars

ARIAS NADIA SOLEDAD; BUCCI SANDRA JANET; SCHOLZ FABIAN; GOLDSTEIN GUILLERMO

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Simposio; VIII International Olive Symposium; 2016

Low temperatures and drought are recognized asenvironmental factors that affect growth, productivity and distribution of manycrops. During summer Olea europaea L.(olive) exhibits osmotic and elastic adjustments and stomatal control which improvesdrought tolerance and during winter olive tissues do not tolerate intracellularice formation and present supercooling as the main mechanism to resist lowtemperatures. The aim of this work was to evaluate leaf morfo-physiologicalresponses of Olea europaea in termsof their resistance to low temperatures to different water treatments. Wedetermined leaf water relations traits, ice nucleation temperature (INT) and thetemperature at which 50% of ions release of the plasmatic membrane occurs (LT50)during late summer and winter in 5 olive cultivars growing in pots in ArgentinePatagonia. The INT and LT50 varied seasonally in all cultivars andwater treatments. The INT in winter was between 5.83 and 2.37°C lower than inlate summer and, LT50 ranged between -6.51°C and -10.83°C in latesummer and -10.13 to -13.5 ° C in winter. There was a significant treatmenteffect in the INT and LT50 during late summer. LT50 wasnegatively correlated with osmotically active solutes content, cell wall elasticityand apoplastic water fraction across cultivars, treatments and seasons. On theother hand, cultivars that during late summer had lower water potentials werethose with lower INT´s. The maintenance of water in an unfrozen state undercold temperature was the consequence of the acclimation process from summer towinter which involved changes in water relations traits. The findings suggestthan water deficit applying during cold acclimating conditions improves thesupercooling capacity in olive trees, which may be considered as a tool toextend the crop to higher latitudes.