Toxic effects of Ni super(2+) on growth of cowpea (Vigna unguiculata)

• Published in: Plant and soil 2007-03, Vol.292 (1-2), p.283-289
• Main Authors: Kopittke, Peter Martin, Asher, Colin J, Menzies, Neal W
• Format: Article
• Language: English
• Subjects: Chlorosis; Vigna unguiculata
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-007-9226-4

Despite the importance of Ni-polluted soils throughout the world, comparatively little is known about the activity of Ni super(2+) required to reduce plant growth and the effects that Ni super(2+) toxicity has on the plant. Cowpea (Vigna unguiculata (L.) Walp. cv Caloona) was grown in dilute nutrient solutions to investigate the effect of Ni super(2+) activity on shoot and root growth. A Ni super(2+) activity of 1.4 mu M was found to cause a 10% reduction in the relative fresh mass of the root and shoots. The primary site of Ni super(2+) toxicity was the shoots, with the younger leaves displaying an interveinal chlorosis (possibly a Ni-induced Fe deficiency) at Ni super(2+) activities greater than or equal to 1.7 mu M. Lateral root formation was inhibited in the two highest Ni super(2+) treatments (3.3 and 5.1 mu M), and the roots growing at the highest Ni super(2+) activity were short and stubby and brown in color. However, no other symptoms of toxicity were observed on the roots at lower Ni super(2+) activities.