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Rapid determination of comparative drought tolerance traits: using an osmometer to predict turgor loss point
Author(s) -
Bartlett Megan K.,
Scoffoni Christine,
Ardy Rico,
Zhang Ya,
Sun Shanwen,
Cao Kunfang,
Sack Lawren
Publication year - 2012
Publication title -
methods in ecology and evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.425
H-Index - 105
ISSN - 2041-210X
DOI - 10.1111/j.2041-210x.2012.00230.x
Subject(s) - osmometer , turgor pressure , osmotic pressure , apoplast , transpiration , chemistry , freezing point , horticulture , botany , thermodynamics , chromatography , biology , photosynthesis , cell wall , physics
Summary 1. Across plant species, drought tolerance and distributions with respect to water availability are strongly correlated with two physiological traits, the leaf water potential at wilting, that is, turgor loss point (π tlp ), and the cell solute potential at full hydration, that is, osmotic potential (π o ). We present methods to determine these parameters 30 times more rapidly than the standard pressure–volume (p–v) curve approach, making feasible community‐scale studies of plant drought tolerance. 2. We optimized existing methods for measurements of π o using vapour‐pressure osmometry of freeze‐thawed leaf discs from 30 species growing in two precipitation regimes, and developed the first regression relationships to accurately estimate pressure–volume curve values of both π o and π tlp from osmometer values . 3. The π o determined with the osmometer (π osm ) was an excellent predictor of the π o determined from the p–v curve (π pv, r 2 = 0·80). Although the correlation of π osm and π pv enabled prediction, the relationship departed from the 1 : 1 line. The discrepancy between the methods could be quantitatively accounted for by known sources of error in osmometer measurements, that is, dilution by the apoplastic water, and solute dissolution from destroyed cell walls. An even stronger prediction of π pv could be made using π osm, leaf density (ρ), and their interaction ( r 2 = 0·85, all P < 2 × 10 −10 ). 4. The π osm could also be used to predict π tlp ( r 2 = 0·86). Indeed, π osm was a better predictor of π tlp than leaf mass per unit area (LMA; r 2 = 0·54), leaf thickness (T; r 2 = 0·12), ρ ( r 2 = 0·63), and leaf dry matter content (LDMC; r 2 = 0·60), which have been previously proposed as drought tolerance indicators. Models combining π osm with LMA, T, ρ, or LDMC or other p–v curve parameters (i.e. elasticity and apoplastic fraction) did not significantly improve prediction of π tlp . 5. This osmometer method enables accurate measurements of drought tolerance traits across a wide range of leaf types and for plants with diverse habitat preferences, with a fraction of effort of previous methods. We expect it to have wide application for predicting species responses to climate variability and for assessing ecological and evolutionary variation in drought tolerance in natural populations and agricultural cultivars.