Differences among Nothofagus pumilio populations in tolerance to drought in a common garden experiment

SOLIANI, C.; MATTERA, M. G.; AZPILICUETA, M.M.; ARANA, V.; MARCHELLI, P.; DALLA-SALDA, G.

Bariloche

Conferencia; International Conference TOPWOOD + LIA FORESTIA; 2019

Tolerance to stressing factors can be studied through the characterization of populations holding adapted genotypes, coming from different environmental origins. Accordingly, the ecophysiological response of Nothofagus pumilio to drought tolerance was evaluated on populations representing a pluviometric gradient, in a common garden trial. We hypothesized that the population response has a genetic base determined by the selection pressure of its own native site. Therefore, we predict that the xeric populations will be less vulnerable to cavitation, i.e. the individuals from dryer origins will have minor loss of hydraulic conductivity under simulated conditions of water deficit. A split-plot experimental design with replicates (three blocks) was used, being the watering treatment the main factor (with two levels: regular irrigation, no irrigation) and the provenance of material the split factor (humid, intermediate and xeric origin). First, each population was characterized through the measurement of morphological traits and by performing curves of cavitation vulnerability. In addition, stomatic conductivity and volumetric water content of the pots were measured twice a week. At different moments along the experiment, daily curves of water potential (pre-dawn and minimum) and volume-pressure were run.Differences in physiological response were detected at population level. A significantly higher cavitation vulnerability (less negative P50) and narrower safety margin (lowest water potential) 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.