Low apoplastic water potential in trees

dehydration stress on living cells and embolism in xylem

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

Low apoplastic water potentials can affect trees by decreasing the hydraulic conductivity of xylem due to embolism and by causing dehydration stress in living cells. Low apoplastic water potentials regularly occur in trees during summer and winter. These can either be caused by loss of water due to transpiration or by freezing due to the chemical properties of ice. In this thesis the effects of low apoplastic water potential on trees were studied by causing low water potentials with three different methods: desiccation, freezing and by adjusting the osmotic concentration of xylem sap. Tree responses in this thesis were measured with stem diameter changes, leaf gas exchange, tree temperature and xylem water potential. Living parenchyma cells are thought to have negligible effect on xylem diameter changes but this thesis shows that the role of parenchyma can, in fact, be much more significant. Evidence for the major role of parenchyma cells in the diameter changes of frozen xylem also supported the theory of extracellular freezing. Furthermore, mesophyll cells were shown to react to freezing with a rapid depression of photosynthesis. It was also studied how a pressure increase in the xylem conduits, resulting from low water potentials, affects tree water relations during embolism formation and ice propagation. A gas burst was detected emerging from the tree stem during freezing. A decrease in the amount of gases in the xylem conduit can benefit trees in avoiding winter embolism. It was also experimentally confirmed that the formation of embolism in trees can temporarily even help relieve water stress due to the so called ´capacitive effect´. Low apoplastic water potential affects both the xylem and living cells in trees, and the interconnectedness of these responses are also shown in this thesis.
Original languageEnglish
Awarding Institution
  • University of Helsinki
Supervisors/Advisors
  • Hölttä, Teemu, Supervisor
  • Juurola, Eija, Supervisor
Award date21 Apr 2017
Place of PublicationHelsinki
Publisher
Print ISBNs978-951-651-561-1
Electronic ISBNs978-951-651-560-4
DOIs
Publication statusPublished - 2017
MoE publication typeG5 Doctoral dissertation (article)

Fields of Science

  • 4112 Forestry
  • vesipotentiaali
  • kuivuminen
  • jäätyminen
  • embolismi
  • fotosynteesi
  • läpimitanmuutos
  • puu

Cite this

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title = "Low apoplastic water potential in trees: dehydration stress on living cells and embolism in xylem",
abstract = "Low apoplastic water potentials can affect trees by decreasing the hydraulic conductivity of xylem due to embolism and by causing dehydration stress in living cells. Low apoplastic water potentials regularly occur in trees during summer and winter. These can either be caused by loss of water due to transpiration or by freezing due to the chemical properties of ice. In this thesis the effects of low apoplastic water potential on trees were studied by causing low water potentials with three different methods: desiccation, freezing and by adjusting the osmotic concentration of xylem sap. Tree responses in this thesis were measured with stem diameter changes, leaf gas exchange, tree temperature and xylem water potential. Living parenchyma cells are thought to have negligible effect on xylem diameter changes but this thesis shows that the role of parenchyma can, in fact, be much more significant. Evidence for the major role of parenchyma cells in the diameter changes of frozen xylem also supported the theory of extracellular freezing. Furthermore, mesophyll cells were shown to react to freezing with a rapid depression of photosynthesis. It was also studied how a pressure increase in the xylem conduits, resulting from low water potentials, affects tree water relations during embolism formation and ice propagation. A gas burst was detected emerging from the tree stem during freezing. A decrease in the amount of gases in the xylem conduit can benefit trees in avoiding winter embolism. It was also experimentally confirmed that the formation of embolism in trees can temporarily even help relieve water stress due to the so called ´capacitive effect´. Low apoplastic water potential affects both the xylem and living cells in trees, and the interconnectedness of these responses are also shown in this thesis.",
keywords = "4112 Forestry, vesipotentiaali, kuivuminen, j{\"a}{\"a}tyminen, embolismi, fotosynteesi, l{\"a}pimitanmuutos, puu",
author = "Lauri Lindfors",
year = "2017",
doi = "10.14214/df.235",
language = "English",
isbn = "978-951-651-561-1",
series = "Dissertationes forestales",
publisher = "Finnish Society of Forest Science",
number = "235",
address = "Finland",
school = "University of Helsinki",

}

Low apoplastic water potential in trees : dehydration stress on living cells and embolism in xylem. / Lindfors, Lauri .

Helsinki : Finnish Society of Forest Science, 2017. 38 p.

Research output: ThesisDoctoral ThesisCollection of Articles

TY - THES

T1 - Low apoplastic water potential in trees

T2 - dehydration stress on living cells and embolism in xylem

AU - Lindfors, Lauri

PY - 2017

Y1 - 2017

N2 - Low apoplastic water potentials can affect trees by decreasing the hydraulic conductivity of xylem due to embolism and by causing dehydration stress in living cells. Low apoplastic water potentials regularly occur in trees during summer and winter. These can either be caused by loss of water due to transpiration or by freezing due to the chemical properties of ice. In this thesis the effects of low apoplastic water potential on trees were studied by causing low water potentials with three different methods: desiccation, freezing and by adjusting the osmotic concentration of xylem sap. Tree responses in this thesis were measured with stem diameter changes, leaf gas exchange, tree temperature and xylem water potential. Living parenchyma cells are thought to have negligible effect on xylem diameter changes but this thesis shows that the role of parenchyma can, in fact, be much more significant. Evidence for the major role of parenchyma cells in the diameter changes of frozen xylem also supported the theory of extracellular freezing. Furthermore, mesophyll cells were shown to react to freezing with a rapid depression of photosynthesis. It was also studied how a pressure increase in the xylem conduits, resulting from low water potentials, affects tree water relations during embolism formation and ice propagation. A gas burst was detected emerging from the tree stem during freezing. A decrease in the amount of gases in the xylem conduit can benefit trees in avoiding winter embolism. It was also experimentally confirmed that the formation of embolism in trees can temporarily even help relieve water stress due to the so called ´capacitive effect´. Low apoplastic water potential affects both the xylem and living cells in trees, and the interconnectedness of these responses are also shown in this thesis.

AB - Low apoplastic water potentials can affect trees by decreasing the hydraulic conductivity of xylem due to embolism and by causing dehydration stress in living cells. Low apoplastic water potentials regularly occur in trees during summer and winter. These can either be caused by loss of water due to transpiration or by freezing due to the chemical properties of ice. In this thesis the effects of low apoplastic water potential on trees were studied by causing low water potentials with three different methods: desiccation, freezing and by adjusting the osmotic concentration of xylem sap. Tree responses in this thesis were measured with stem diameter changes, leaf gas exchange, tree temperature and xylem water potential. Living parenchyma cells are thought to have negligible effect on xylem diameter changes but this thesis shows that the role of parenchyma can, in fact, be much more significant. Evidence for the major role of parenchyma cells in the diameter changes of frozen xylem also supported the theory of extracellular freezing. Furthermore, mesophyll cells were shown to react to freezing with a rapid depression of photosynthesis. It was also studied how a pressure increase in the xylem conduits, resulting from low water potentials, affects tree water relations during embolism formation and ice propagation. A gas burst was detected emerging from the tree stem during freezing. A decrease in the amount of gases in the xylem conduit can benefit trees in avoiding winter embolism. It was also experimentally confirmed that the formation of embolism in trees can temporarily even help relieve water stress due to the so called ´capacitive effect´. Low apoplastic water potential affects both the xylem and living cells in trees, and the interconnectedness of these responses are also shown in this thesis.

KW - 4112 Forestry

KW - vesipotentiaali

KW - kuivuminen

KW - jäätyminen

KW - embolismi

KW - fotosynteesi

KW - läpimitanmuutos

KW - puu

U2 - 10.14214/df.235

DO - 10.14214/df.235

M3 - Doctoral Thesis

SN - 978-951-651-561-1

T3 - Dissertationes forestales

PB - Finnish Society of Forest Science

CY - Helsinki

ER -

Lindfors L. Low apoplastic water potential in trees: dehydration stress on living cells and embolism in xylem. Helsinki: Finnish Society of Forest Science, 2017. 38 p. (Dissertationes forestales; 235). https://doi.org/10.14214/df.235