Skip to Main Content
Diurnal and seasonal variation in root xylem embolism in neotropical savanna woody species: impact on stomatal control of plant water status.Author(s): J-C. Domec; F.G. Scholz; S.J. Bucci; F.C. Meinzer; G. Goldstein; R. Villalobos-Vega
Source: Plant, Cell and Environment. 29: 26-35
Publication Series: Scientific Journal (JRNL)
PDF: Download Publication (1.2 MB)
DescriptionVulnerability to water-stress-induced embolism and variation in the degree of native embolism were measured in lateral roots of four co-occuring neotropical savanna tree species. Root embolism varied diurnally and seasonally. Late in the dry season, loss of root xylem conductivity reached 80% in the afternoon when root water potential (ψroot) was about -2.6 MPa, and recovered to 25-40% loss of conductivity in the morning when ψroot, was about -1.0 MPa. Daily variation in ψroot decreased, and root xylem vulnerability and capacitance increased with rooting depth. However, all species experienced seasonal minimum ψroot close to complete hydraulic failure independent of their rooting depth or resistance to embolism. Predawn ψroot was lower than ψsoil when ψsoil was relatively high (>-0.7 MPa) but became less negative than ψsoil later in the dry season, consistent with a transition from a disequilibrium between plant and soil ψ induced by nocturnal transpiration to one induced by hydraulic redistribution of water from deeper soil layers. Shallow longitudinal root incisions external to the xylem prevented reversal of embolism overnight, suggesting that root mechanical integrity was necessary for recovery, consistent with the hypothesis that if embolism is a function of tension, refilling may be a functioii of internal pressure imbalances. All species shared a common relationship in which maximum daily stomatal conductance declined linearly with increasing afternoon loss of root conductivity over the course of the dry season. Daily embolism and refilling in roots is a common occurrence and thus may be an inherent component of a hydraulic signaling mechanism enabling stomata to maintain the integrity of the hydraulic pipeline in long-lived structures such as stems.
- Visit PNW's Publication Request Page to request a hard copy of this publication.
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationDomec, J-C.; Scholz, F.G.; Bucci, S.J.; Meinzer, F.C.; Goldstein, G.; Villalobos-Vega, R. 2006. Diurnal and seasonal variation in root xylem embolism in neotropical savanna woody species: impact on stomatal control of plant water status. Plant, Cell and Environment. 29: 26-35
Keywordscavitation, capacitance, hydraulic conductivity, water relations, xylem vulnerability
- Divergence in strategies for coping with winter embolism among co-occurring temperate tree species: the role of positive xylem pressure, wood type and tree stature
- Coordination of leaf and stem water transport properties in tropical forest trees
- Xylem hydraulic safety margins in woody plants: coordination of stomatal control of xylem tension with hydraulic capacitance
XML: View XML