Embolism resistance and dehydration tolerance in a perennial grass

More intense droughts under climate change threaten species resilience. Hydraulic strategies determine drought survival in woody species but are hardly explored in herbaceous species. Volaire et al. investigated the intraspecific variability of hydraulic and morphological traits as indicators of dehydration tolerance in a perennial grass, cocksfoot (Dactylis glomerata), which has a large biogeographical distribution in Europe.

The authors grew twelve populations of cocksfoot originating from Mediterranean, Temperate and Northern European areas in a controlled environment in pots. They measured dehydration tolerance, leaf and stem anatomical traits and xylem pressure associated with 88 or 50 % loss of xylem conductance (P₈₈, P₅₀). They found embolism resistance correlated with the precipitations of the origin sites of the populations, dehydration tolerance, leaf mechanical resistance and the thickness of metaxylem vessel walls in stems.

Compared with woody species, the large intraspecific variability in dehydration tolerance and embolism resistance within cocksfoot has consequences for its sensitivity to climate change. To better understand adaptive strategies of herbaceous species to increasing drought and frost requires further exploration of the role of hydraulic and mechanical traits using a larger inter- and intraspecific range of species.