Toxic effects of low concentrations of Cu on nodulation of cowpea ( Vigna unguiculata)

• Published in: Environmental pollution (1987) 2007, Vol.145 (1), p.309-315
• Main Authors: Kopittke, Peter M., Dart, Peter J., Menzies, Neal W.
• Format: Article
• Language: English
• Subjects: cation exchange resins; chemical concentration; Copper; Copper - analysis; Copper - toxicity; cowpeas; cultivars; Culture Media; dose response; Fabaceae - chemistry; Fabaceae - drug effects; Fabaceae - microbiology; Legumes; Nodulation; phytotoxicity; Phytotoxicity symptoms; plant growth; plant response; Plant Roots - drug effects; Plant Roots - growth & development; Plant Roots - microbiology; Plant Shoots - chemistry; Plant Shoots - drug effects; Plant Shoots - growth & development; Rhizobium; Rhizobium - growth & development; root growth; Root hairs; Root Nodules, Plant - drug effects; Root Nodules, Plant - growth & development; shoots; Soil Pollutants - analysis; Soil Pollutants - toxicity; soil pollution; Solutions - chemistry; viability; Vigna unguiculata
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2006.03.007

Although Cu is phytotoxic at Cu 2+ activities as low as 1–2 μM, the effect of Cu 2+ on the nodulation of legumes has received little attention. The effect of Cu 2+ on nodulation of cowpea ( Vigna unguiculata (L.) Walp. cv. Caloona) was examined in a dilute solution culture system utilising a cation exchange resin to buffer solution Cu 2+. The nodulation process was more sensitive to increasing Cu 2+ activities than both shoot and root growth; whilst a Cu 2+ activity of 1.0 μM corresponded to a 10% reduction in the relative yield of the shoots and roots, a Cu 2+ activity of 0.2 μM corresponded to a 10% reduction in nodulation. This reduction in nodulation with increasing Cu 2+ activity was associated with an inhibition of root hair formation in treatments containing ≥0.77 μM Cu 2+, rather than to a reduction in the size of the Rhizobium population. The nodulation process was more sensitive to increasing Cu 2+ activities than either shoot or root growth.