Inter- and intra-specific variability in physiological traits and post-anoxia recovery of photosynthetic efficiency in grasses under oxygen deprivation.

Low oxygen conditions occur in grass sites due to high and frequent precipitation, poor soil quality, and over-irrigation followed by slow drainage. Three warm-season and one cool-season grasses were analyzed at metabolic level during a time-course experiment performed in a controlled anoxic environment. Prolonged oxygen depletion proved detrimental by leading to premature death to all the species, with the exception of seashore paspalum. Moreover, the anoxia tolerance observed in these grasses has been associated with slow use of carbohydrates, rather than with their relative abundance, which was more important than their antioxidant capacity. Further physiological characterization of eight seashore paspalum genotypes to anoxia was also performed, by examining the variation in photosystem II (PSII) efficiency and gas exchange during post-anoxia recovery. Multivariate analysis highlighted the presence of three main clusters of seashore paspalum genotypes, characterized by different ability to restore the PSII photochemistry during recovery after one day of anoxia. Taken together, our data demonstrate that the analysis of post-anoxia recovery of fluorescence and gas exchange parameters can represent a fast and reliable indicator for selecting species and cultivars more able to acclimate their photosynthetic apparatus.