One of the biggest global challenges in plant science´s is to determine how plants can increase stress tolerance (ST) without penalizing productivity. I hypothesise that exists a trade-off at leaf level between the maximal photosynthetic capacity (Amax) and ST and it can be explained by foliar structure and antioxidant traits that affect in an opposite manner the Amax and ST. Polyploid systems can help to elucidate the trade-off. Thereby, I would like to perform a primary and secondary metabolism flux enrichment experiment, together with physiological measurements in co-habiting populations of both ploidy levels in Adventdalen (Longyearbyen). Diploids and tetraploids are here already established by the project owner Dr. Eidesen. I will employ an ecological gradient to associate their ecophysiological performance with the molecular mechanisms driving it. I plan to measure 7 individuals per ploidy level and in 3 sites, each selected site is separated each other by 3.3 km. This design will let us to avoid a possible "site effect" and obtain more robust results. Both photosynthetical characterization and flux assay would be developed in parallel to ensure that individual´s status is the same for both techniques. Leaf anatomy samples will be ketp in the fixer solution, and samples for metabolic flux analysis will be stored in a dry-shipper with liquid N2 or at -80ºC at UNIS. After the field campaign, I plan 3 months to process and data extraction of these samples.