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Minimum hydraulic safety leads to maximum water-use efficiency in a forage grass
journal contribution
posted on 2023-05-17, 07:09 authored by Holloway-Phillips, M, Timothy BrodribbTimothy BrodribbUnderstanding how water-use regulation relates to biomass accumulation is imperative for improving crop production in water-limited environments. Here, we examine how the vulnerability of xylem to water stress-induced cavitation and the coordination between water transport capacity and assimilation (A) influences diurnal water-use efficiency (WUE) and dry-matter production in Lolium perenne L. – a commercial forage grass. Plants were exposed to a range of water stresses, causing up to 90% leaf death, by withholding water and then rewatering to observe the recovery process. Leaf hydraulic conductance (Kleaf) declined to 50% of maximum at a leaf water potential (yleaf) of -1 MPa, whereas complete stomatal closure occurred well after this point, at -2.35 MPa, providing no protection against hydraulic dysfunction. Instantaneous A remained maximal until >70% of hydraulic conductivity had been lost. Poststress rewatering showed that 95% loss of Kleaf could be incurred before the recovery of gas exchange exceeded 1 d, with a rapid transition to leaf death after this point. Plants exposed to sustained soil water deficits through restricted nightly watering regimes did not suffer cumulative losses in Kleaf; instead, yleaf and gas exchange recovered diurnally. The effect was improved WUE during the day and optimal yleaf during the night for the maintenance of growth.
History
Publication title
Plant, Cell and EnvironmentVolume
34Pagination
302-313ISSN
0140-7791Department/School
School of Natural SciencesPublisher
Blackwell Publishing LtdPlace of publication
9600 Garsington Rd, Oxford, England, Oxon, Ox4 2DgRights statement
Copyright © 2010 The definitive published version is available online at: http://onlinelibrary.wiley.com/Repository Status
- Restricted