Seedling responses of four Australian tree species to toxic concentrations of manganese in solution culture

• Published in: Plant and soil 2004, Vol.258 (1-2), p.341-350
• Main Authors: Reichman, S.M, Menzies, N.W, Asher, C.J, Mulligan, D.R
• Format: Article
• Language: English
• Subjects: Acacia; Acacia holosericea; Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; contaminants; Deficiencies. Phytotoxicity of elements. Salinity; dose response; dry matter accumulation; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Eucalyptus; Eucalyptus camaldulensis; Eucalyptus crebra; Fauna; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Leaves; lesions (plant); Manganese; Melaleuca; Melaleuca leucadendra; metal tolerance; Metals; Non agrochemicals pollutants; Nutrient solutions; Phytopathology. Animal pests. Plant and forest protection; Plant growth; plant response; Plant roots; Plant species; Plants; Pollution effects and side effects of agrochemicals on crop plants and forest trees. Other anthropogenic factors; Pollution effects. Side effects of agrochemicals; Seedlings; Seeds; Soil and water pollution; soil pollution; Soil science; Soil toxicity; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Toxicity; Trees
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/B:PLSO.0000016564.14512.eb

Little is known about the responses of Australian plants to excess metal, including Mn. It is important to remedy this lack of information so that knowledgeable decisions can be made about managing Mn contaminated sites where inhabited by Australian vegetation. Acacia holosericea, Melaleuca leucadendra, Eucalyptus crebra and Eucalyptus camaldulensis were grown in dilute solution culture for 10 weeks. The seedlings (42 days old) were exposed to six Mn treatments viz., 1, 8, 32, 128, 512 and 2048 μM. The order of tolerance to toxic concentrations of Mn was A. holosericea ≌ E. crebra < M. leucadendra < E. camaldulensis, the critical external concentrations being approximately 5.1, 5.0, 21 and 330 µM, respectively. The critical tissue Mn concentrations for the youngest fully expanded leaf and total shoots were, respectively, 265 and 215 µg g⁻¹ DM for A. holosericea, 445 and 495 µg g⁻¹ DM for M. leucadendra, 495 and 710 µg g⁻¹ DM for E. crebra and 7230 and 6510 µg g⁻¹ DM for E. camaldulensis. The high tolerance of E. camaldulensis (as opposed to the sensitivity of E. crebra) to excess Mn raises concern about fauna feeding on the plant and is consistent with hypotheses suggesting the Eucalyptus subgenus Symphomyrtus is particularly tolerant of stress, including excess Mn. The results from this paper provide the first comprehensive combination of growth responses, critical external concentrations, critical tissue concentrations and plant toxicity symptoms for three important Australian genera, viz., Eucalyptus, Acacia and Melaleuca, for use in the management of Mn toxic sites.