Relationship of iron-manganese toxicity disorder in marigold to manganese and magnesium nutrition

• Published in: Journal of plant nutrition 2012, Vol.35 (1), p.142-164
• Main Authors: El-Jaoual Eaton, Touria, Cox, Douglas A, Barker, Allen V
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; bronze-speckle disorder; chlorosis; dry matter accumulation; Economic plant physiology; Fundamental and applied biological sciences. Psychology; greenhouses; leaves; magnesium; magnesium deficiency; manganese; manganese toxicity; Metabolism; Metabolism. Physicochemical requirements; nutrient deficiencies; Nutrition; Nutrition. Photosynthesis. Respiration. Metabolism; Plant physiology and development; shoots; Tagetes erecta; toxicity
• ISSN: 1532-4087; 0190-4167; 1532-4087
• DOI: 10.1080/01904167.2012.631674

The iron-manganese (Fe-Mn) disorder in marigold (Tagetes erecta L.) is related to high Mn and low magnesium (Mg) in leaves. Three solution-culture experiments with marigold were conducted in a greenhouse. One investigated Mn and the disorder. Based on dry matter production, 4.5 mg Mn/L was the toxicity concentration and gave 880 mg Mn g⁻¹ dry weight in new leaves and 1200 in old leaves. Manganese above 4.5 mg L⁻¹ produced bronzed speckles on leaves. A second experiment investigated Mg and the disorder. Based on dry matter production, 10 mg Mg L⁻¹ was the deficiency concentration and gave 1.5% Mg in the shoots. Symptoms of Mg deficiency did not resemble those of the disorder. A third experiment investigated Mn and Mg. Leaf chlorosis appeared at 2.5 mg Mn L⁻¹ with the lowest supply of Mg. These experiments suggest that Mn supply is related to the disorder but increasing Mg does not alleviate the problem.