Growth, morphology and gas exchange responses of two-year-old Quercus castaneifolia seedlings to flooding stress

Tolerance to flooding is crucial when thinking in promissory species for restoration of ecosystems prone to suffer soil water excess. In this study, we tested the flooding tolerance of two-years-old seedlings of Chestnut-leaved oak (Quercus castaneifolia C.A.Mey.) to determine whether it can be recommended for use in wetland restoration programs. Seedlings of Q. castaneifolia were subjected to three treatments: (1) control (C), (2) flooding for 60 days followed by a 42-day recovery period (F+R) and (3) continuous flooding for 102 days (F). Physiological performance, plant morphological changes and biomass accumulation were assessed. Results showed that, although net photosynthetic rates, stomatal conductance and transpiration decreased with prolonged flooding, when flood waters were removed, plants were able to recover their physiological activity (49-80% compared to controls). By contrast, when plants were continually flooded, their physiological activity decreased as well as the leaves experienced precocious senescence and wilting. Biomass responses paralleled physiological responses: leaf and root biomass were 42-49% higher under F+R treatment than under continuous flooding, and all plants under the F+R survived. Therefore, Q. castaneifolia appears as a promising species to be further studied when thinking re-vegetation of riverine areas and other temporarily flooded wetlands.