Altered aluminum inhibition of soybean root elongation in the presence of magnesium

Variations in genotype rankings among screenings for A1 tolerance in hydroponics may be related to differences in the composition of the solutions. In the present study, we investigated the involvement of Mg ions in modifying Al rhizotoxicity in soybeans. Root elongation was strongly inhibited by Al...

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Bibliographic Details
Published in:Plant and soil 2001-03, Vol.230 (2), p.223-230
Main Authors: Silva, Ivo R., Smyth, T. Jot, Israel, Daniel W., Rufty, Thomas W.
Format: Article
Language:English
Subjects:
Acid soils
Adaptation to environment and cultivation conditions
Agronomy. Soil science and plant productions
Aluminum
Biological and medical sciences
Calcium
Fundamental and applied biological sciences. Psychology
Genetics and breeding of economic plants
Genotypes
Magnesium
Nutrient solutions
Plants
Root growth
Soil toxicity
Soybeans
Varietal selection. Specialized plant breeding, plant breeding aims
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Summary:Variations in genotype rankings among screenings for A1 tolerance in hydroponics may be related to differences in the composition of the solutions. In the present study, we investigated the involvement of Mg ions in modifying Al rhizotoxicity in soybeans. Root elongation was strongly inhibited by Al in a simple, 800 µM CaSO₄ solution, but elongation increased noticeably when the solutions also contained Mg. Amelioration of Al rhizotoxicity was not associated with an increase in ionic strength of treatment solutions because Al³⁺ activities were kept constant. Concentration series experiments indicated that the Mg effect occurred in the µM range, while Ca amelioration of Al toxicity occurred at mM concentrations. The positive effect of Mg on root elongation was greatest for Al-sensitive genotypes and minimized genotypic differences for Al-tolerance. The Mg protection against Al rhizotoxicity apparently does not occur with all species, because it was not observed in Atlas and Scout 66 wheat varieties. The ability of Mg to ameliorate Al toxicity in soybean at µM levels suggests the involvement of distinct physiological factors.
ISSN:0032-079X
1573-5036
DOI:10.1023/A:1010384516517