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Root exudation, organic acids, and element distribution in roots of Norway spruce seedlings treated with aluminum in hydroponics
Author(s) -
Heim Alexander,
Brunner Ivano,
Frey Beat,
Frossard Emmanuel,
Luster Jörg
Publication year - 2001
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/1522-2624(200110)164:5<519::aid-jpln519>3.0.co;2-y
Subject(s) - chemistry , oxalate , picea abies , phosphate , organic acid , dry weight , hydroponics , horticulture , botany , root system , biology , biochemistry , organic chemistry
Seedlings of Norway spruce ( Picea abies [L.] Karst.), which had been grown under sterile conditions for three months, were treated for one week in a hydroculture system with either 500 μM AlCl 3 or 750 μM CaCl 2 solutions at pH 4. Organic acids were determined in hot‐water extracts of ground root tissue. Oxalate (3.3—6.6 μmol (g root dry weight) —1 ) was most abundant. Malate, citrate, formate, acetate, and lactate concentrations ranged between 1—2 μmol (g root dry weight) —1 . Organic substances and phosphate found in the treatment solutions at the end of the experimental period were considered to be root exudates. Total root exudation within a 2‐day period ranged from 20—40 μmol C (g root weight) —1 . In root exudates, organic acids, and total carbohydrates, total amino acids, and total phenolic substances were quantified. Citrate and malate, although present in hot‐water extracts of root tissue, were not detected in root exudates. Phosphate was released from Ca‐treated plants. In Al treatments, there was indication of Al phosphate precipitation at the root surface. Oxalate and phenolics present in the exudates of Norway spruce seedlings are ligands that can form stable complexes with Al. However, concentrations of these substances in the treatment solutions were at micromolar levels. Their importance for the protection of the sensitive root apex under natural conditions is discussed.