Does the turgor loss point characterize drought response in dryland plants?
The water potential at turgor loss point (Ψtlp) has been suggested as a key functional trait for determining plant drought tolerance, because of its close relationship with stomatal closure. Ψtlpmay indicate drought tolerance as plants, which maintain gas exchange at lower midday water potentials as soil water availability declines also have lower Ψtlp. We evaluated 17 species from seasonally dry habitats, representing a range of life-forms, under well-watered and drought conditions, to determine how Ψtlprelates to stomatal sensitivity (pre-dawn water potential at stomatal closure: Ψgs0) and drought strategy (degree of isohydry or anisohydry; ΔΨMDbetween well-watered conditions and stomatal closure). Although Ψgs0was related to Ψtlp, Ψgs0was better related to drought strategy (ΔΨMD). Drought avoiders (isohydric) closed stomata at water potentials higher than their Ψtlp; whereas, drought tolerant (anisohydric) species maintained stomatal conductance at lower water potentials than their Ψtlpand were more dehydration tolerant. There was no significant relationship between Ψtlpand ΔΨMD. While Ψtlphas been related to biome water availability, we found that Ψtlpdid not relate strongly to stomatal closure or drought strategy, for either drought avoiders or tolerators. We therefore suggest caution in using Ψtlpto predict vulnerability to drought.
School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3121, Australia.
Claire
http://orcid.org/0000-0002-5822-7529
C
Farrell
School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3121, Australia.
Christopher
C
Szota
School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3121, Australia.
Stefan K
SK
Arndt
D055864:Droughts; D017753:Ecosystem; D018515:Plant Leaves / Q000502:physiology*; D054046:Plant Stomata / Q000502:physiology; D010944:Plants / Q000378:metabolism*; D011312:Pressure; D013045:Species Specificity; D014867:Water / Q000502:physiology
D014867:Water
P-V curve; TLP; isohydry; water relations