Embolism and mechanical resistances play a key role in dehydration tolerance of a perennial grass Dactylis glomerata L.

Volaire, F.; Lens, F.P.; Cochard, H.; Xu, H.; Doria, L.C.; Bristiel, P.; Balachowski, J.; Rowe, N.; Violle, C.; Picon-Cochard, C.

doi:doi:10.1093/aob/mcy073

More intense droughts under climate change threaten species resilience. Hydraulicstrategies determine drought survival in woody plants but have been hardly studied in herbaceous species. Weexplored the intraspecific variability of hydraulic and morphological traits as indicators of dehydration tolerancein a perennial grass, cocksfoot (Dactylis glomerata), which has a large biogeographical distribution in Europe. Twelve populations of cocksfoot originating from Mediterranean, Temperate and Northern Europeanareas were grown in a controlled environment in pots. Dehydration tolerance, leaf and stem anatomical traits andxylem pressure associated with 88 or 50 % loss of xylem conductance (P₈₈, P₅₀) were measured. Across the 12 populations of cocksfoot, P₅₀ ranged from –3.06 to – 6.36 MPa, while P₈₈ranged from –5.06 to –11.6 MPa. This large intraspecific variability of embolism thresholds corresponded withthe biogeographical...Show moreMore intense droughts under climate change threaten species resilience. Hydraulicstrategies determine drought survival in woody plants but have been hardly studied in herbaceous species. Weexplored the intraspecific variability of hydraulic and morphological traits as indicators of dehydration tolerancein a perennial grass, cocksfoot (Dactylis glomerata), which has a large biogeographical distribution in Europe. Twelve populations of cocksfoot originating from Mediterranean, Temperate and Northern Europeanareas were grown in a controlled environment in pots. Dehydration tolerance, leaf and stem anatomical traits andxylem pressure associated with 88 or 50 % loss of xylem conductance (P₈₈, P₅₀) were measured. Across the 12 populations of cocksfoot, P₅₀ ranged from –3.06 to – 6.36 MPa, while P₈₈ranged from –5.06 to –11.6 MPa. This large intraspecific variability of embolism thresholds corresponded withthe biogeographical distribution and some key traits of the populations. In particular, P₈₈ was correlated withdehydration tolerance (r = –0.79). The dehydration-sensitive Temperate populations exhibited the highest P₈₈(–6.1 MPa). The most dehydration-tolerant Mediterranean populations had the greatest leaf dry matter content andleaf fracture toughness, and the lowest P₈₈ (–10.4 MPa). The Northern populations displayed intermediate traitvalues, potentially attributable to frost resistance. The thickness of metaxylem vessel walls in stems was highlycorrelated with P₅₀ (r = –0.92), but no trade-off with stem lignification was observed. The relevance of the linkagebetween hydraulic and stomatal traits is discussed for drought survival in perennial grasses. Compared with woody species, the large intraspecific variability in dehydration tolerance andembolism resistance within cocksfoot has consequences for its sensitivity to climate change. To better understandadaptive strategies of herbaceous species to increasing drought and frost requires further exploration of the role ofhydraulic and mechanical traits using a larger inter- and intraspecific range of species.Show less

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Embolism and mechanical resistances play a key role in dehydration tolerance of a perennial grass Dactylis glomerata L.