Different population tolerance to drought stress in a common garden experiment: the case of Nothofagus pumilio

CAROLINA SOLIANI; MARÍA VERÓNICA ARANA; MARÍA MARTA AZPILICUETA; GUILLERMINA DALLA SALDA; MARÍA GABRIELA MATTERA; PAULA MARCHELLI

Bariloche

Conferencia; Topwood Conference - Adapting forest ecosystems and wood products to biotic and abiotic stress; 2019

EU Marie-Curie project Topwwod; LIA Forestia INRA-INTA

Tolerance to stressing factors canbe studied through the characterization of populations holding adaptedgenotypes, coming from different environmental origins. Accordingly, the ecophysiologicalresponse of Nothofagus pumilio to drought tolerance was evaluated onpopulations representing a pluviometric gradient, in a common garden trial. Wehypothesized that the population response has a genetic base determined by theselection pressure of its own native site. Therefore, we predict that the xericpopulations will be less vulnerable to cavitation, i.e. the individuals fromdryer origins will have minor loss of hydraulic conductivity under simulatedconditions of water deficit. A split-plot experimental design with replicates(three blocks) was used, being the watering treatment the main factor (with twolevels: regular irrigation, no irrigation) and the provenance of material thesplit factor (humid, intermediate and xeric origin). First, each population wascharacterized through the measurement of morphological traits and by performingcurves of cavitation vulnerability. In addition, stomatic conductivity andvolumetric water content of the pots were measured twice a week. At differentmoments along the experiment, daily curves of water potential (pre-dawn andminimum) and volume-pressure were performed. Differences in physiologicalresponse were detected at population level. A significantly higher cavitationvulnerability (less negative P50) and narrower safety margin (lowest waterpotential) were detected in the humid provenance. During early stages, the identification of differential adaptive capacity to water stress in native populations may be the key for domestication programs successful.