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Organic acids in root exudates and soil solutions. Importance to calcicole and calcifuge behaviour of plants.

Ström, Lena LU (1998)
Abstract (Swedish)
Popular Abstract in Swedish

Många växtarter kan inte kolonisera kalkjordar och det är stora skillnader i artsammansättningen mellan kalkjordar och närliggande surare jordar. Detta beteende kallas ofta för kalkskyende och tycks orsakas av en oförmåga hos dessa växtarter att lösa och ta upp fosfat och järn ur kalkjordar. Kalkjordar innehåller mycket låga halter av järn och fosfat löst i marklösningen och lättillgängligt för upptag av växtrötter. I min avhandling visar jag att kalkgynnade arter, som normalt växer på kalkjordar, utsöndrar vissa organiska syror i mycket större mängder än kalkskyende arter. De syror som främst utsöndras av kalkgynnade arter är dikarboxylsyran oxalat och trikarboxylsyran citrat. I försök där... (More)
Popular Abstract in Swedish

Många växtarter kan inte kolonisera kalkjordar och det är stora skillnader i artsammansättningen mellan kalkjordar och närliggande surare jordar. Detta beteende kallas ofta för kalkskyende och tycks orsakas av en oförmåga hos dessa växtarter att lösa och ta upp fosfat och järn ur kalkjordar. Kalkjordar innehåller mycket låga halter av järn och fosfat löst i marklösningen och lättillgängligt för upptag av växtrötter. I min avhandling visar jag att kalkgynnade arter, som normalt växer på kalkjordar, utsöndrar vissa organiska syror i mycket större mängder än kalkskyende arter. De syror som främst utsöndras av kalkgynnade arter är dikarboxylsyran oxalat och trikarboxylsyran citrat. I försök där kalkjord extraherats med dessa två syror har de visat sig lösa järn och fosfat mycket bra. En av mekanismerna bakom kalkgynnat beteende hos växter kan alltså vara att dessa arter utsöndrar substanser från sina rötter som gör det möjligt för dem att lösa järn och fosfat ur kalkjorden och själva göra dessa bristämnen tillgängliga för upptag, en förmåga som saknas hos kalkskyende arter. (Less)
Abstract
Many vascular plant species are unable to colonise calcareous sites, the floristic composition of adjacent limestone and acid silicate soils differing markedly. The inability of these 'calcifuge' species to establish themselves and grow on limestone soil appears to mainly be related to their low capacity for solubilising and absorbing phosphate and/or iron from such soils. Differences between calcifuge and calcicole species (the latter normally growing on calcareous soil) in their root exudation of low-molecular organic acids (LOAs) can lead to their ability to solubilise mineral nutrients from the soil differing. In the studies presented in this thesis I examined exudation by many calcicole and calcifuge species. Exudation was studied for... (More)
Many vascular plant species are unable to colonise calcareous sites, the floristic composition of adjacent limestone and acid silicate soils differing markedly. The inability of these 'calcifuge' species to establish themselves and grow on limestone soil appears to mainly be related to their low capacity for solubilising and absorbing phosphate and/or iron from such soils. Differences between calcifuge and calcicole species (the latter normally growing on calcareous soil) in their root exudation of low-molecular organic acids (LOAs) can lead to their ability to solubilise mineral nutrients from the soil differing. In the studies presented in this thesis I examined exudation by many calcicole and calcifuge species. Exudation was studied for plants grown hydroponically, for germinating seeds and seedlings and for plants grown in a pH intermediate soil. I found that calcicole species generally have a higher, often much higher, exudation rate of dicarboxylic oxalate and tricarboxylic citrate than calcifuge species do. These two LOAs were also shown to have a strong solubilising effect on soil phosphate and iron, both in calcareous and silicate soil. I also studied the calcifuge behaviour of Rumex acetosella in greater detail. R. acetosella was found to be a highly phosphate-limited species, its growth being closely correlated to the amount of easily exchangeable phosphate in the soil. This species, which contain large amounts of oxalate in its leaves, appears in any case to lack the ability to increase the exudation rate of LOAs in response to phosphate limitation. In my thesis I propose that high exudation rates of dicarboxylic and tricarboxylic organic acids is one of the mechanisms explaining calcifuge behaviour in plants. I also propose that high root exudation rates of LOAs from plants can be an adaptation to nutrient limiting conditions in soils. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof Lee, John A, Department of Animal and Plant Science, University of Sheffield, UK.
organization
publishing date
type
Thesis
publication status
published
subject
keywords
nutrient-solubilisation, iron, phosphate, nutrient-limitations, citrate, oxalate, organic acids, root exudation, acidifuge, Calcicole, calcifuge, adaptations., Plant ecology, Växtekologi
pages
108 pages
publisher
Department of Ecology, Lund University
defense location
Blå Hallen, Ecology Building, Sölvegatan 37
defense date
1998-11-13 10:00
external identifiers
  • other:ISRN: SE-LUNBDS/NBBE-98/1050/+108
ISBN
ISBN 91-7105-106-6
language
English
LU publication?
yes
id
b6a34c8c-20dc-464e-805c-4f8090bc2dee (old id 39037)
date added to LUP
2007-08-01 09:16:13
date last changed
2016-09-19 08:45:12
@phdthesis{b6a34c8c-20dc-464e-805c-4f8090bc2dee,
  abstract     = {Many vascular plant species are unable to colonise calcareous sites, the floristic composition of adjacent limestone and acid silicate soils differing markedly. The inability of these 'calcifuge' species to establish themselves and grow on limestone soil appears to mainly be related to their low capacity for solubilising and absorbing phosphate and/or iron from such soils. Differences between calcifuge and calcicole species (the latter normally growing on calcareous soil) in their root exudation of low-molecular organic acids (LOAs) can lead to their ability to solubilise mineral nutrients from the soil differing. In the studies presented in this thesis I examined exudation by many calcicole and calcifuge species. Exudation was studied for plants grown hydroponically, for germinating seeds and seedlings and for plants grown in a pH intermediate soil. I found that calcicole species generally have a higher, often much higher, exudation rate of dicarboxylic oxalate and tricarboxylic citrate than calcifuge species do. These two LOAs were also shown to have a strong solubilising effect on soil phosphate and iron, both in calcareous and silicate soil. I also studied the calcifuge behaviour of Rumex acetosella in greater detail. R. acetosella was found to be a highly phosphate-limited species, its growth being closely correlated to the amount of easily exchangeable phosphate in the soil. This species, which contain large amounts of oxalate in its leaves, appears in any case to lack the ability to increase the exudation rate of LOAs in response to phosphate limitation. In my thesis I propose that high exudation rates of dicarboxylic and tricarboxylic organic acids is one of the mechanisms explaining calcifuge behaviour in plants. I also propose that high root exudation rates of LOAs from plants can be an adaptation to nutrient limiting conditions in soils.},
  author       = {Ström, Lena},
  isbn         = {ISBN 91-7105-106-6},
  keyword      = {nutrient-solubilisation,iron,phosphate,nutrient-limitations,citrate,oxalate,organic acids,root exudation,acidifuge,Calcicole,calcifuge,adaptations.,Plant ecology,Växtekologi},
  language     = {eng},
  pages        = {108},
  publisher    = {Department of Ecology, Lund University},
  school       = {Lund University},
  title        = {Organic acids in root exudates and soil solutions. Importance to calcicole and calcifuge behaviour of plants.},
  year         = {1998},
}