Evaluating the contribution of magnesium deficiency in the aluminium toxicity syndrome in twelve sorghum genotypes

• Published in: Plant and soil 1993-02, Vol.149 (2), p.255-261
• Main Authors: TAN, KEZHENG, KELTJENS, WILLEM G., FINDENEGG, GÜNTER R.
• Format: Article
• Language: English
• Subjects: Acid soils; Agronomy. Soil science and plant productions; aluminio; aluminium; Aluminum; Biological and medical sciences; carence minerale; deficiencia de minerales; Fundamental and applied biological sciences. Psychology; genotipos; genotype; Genotypes; magnesio; magnesium; mineral deficiencies; Nutrient solutions; Physiological diseases. Varia; Phytopathology. Animal pests. Plant and forest protection; Plant growth; Plant roots; Plants; Sectie Bodemkwaliteit; Soil toxicity; Sorghum; sorghum bicolor; Sub-department of Soil Quality; toxicidad; toxicite; toxicity
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/BF00016616

The contribution of Mg deficiency to Al stress in twelve different sorghum (Sorghum bicolor (L.) Moench) genotypes was investigated in nutrient solution culture under conditions of low Mg supply (between 50 and 1000 µM) at two pH values. At pH 4.2, 30 µM Al strongly inhibited Mg uptake. When dry matter yield was plotted as a function of the plant Mg concentration, similar response curves were obtained in the absence and the presence of Al with three genotypes. With many other genotypes dry matter yields of the control (without Al treatment) and Al-stressed plants were remarkably different at similar internal Mg concentrations, suggesting that growth had been suppressed not by Mg deficiency but by another factor, i.e. Al-induced root damage. At pH 4.8, 30 µM Al hardly induced root damage but reduced Mg uptake and Al-induced Mg deficiency could almost completely account for the growth reaction of all genotypes. Therefore, at this pH the efficiency of uptake or use of Mg in different genotypes was the basis of their respective susceptibility to Al toxicity. When specific root length surpassed a certain critical range below 80-100 m per g dry root, growth control by Al-induced Mg deficiency was nearly abolished. The pH and Al concentration where this range was reached depended on the Al sensitivity of the genotypes.