White clover nodulation index in heavy metal contaminated soils- a potential bioindicator.
The morphological effects of heavy metal stress on the nodulation ability of Rhizobium spp. and growth of white clover (Trifolium repens L.) were studied in the laboratory under controlled conditions. Fourteen topsoils were collected from an area with elevated metal concentrations (Cd, Zn, and Pb). White clover was cultivated using a specialized "rhizotron" method to observe the development of root and nodule characteristics. Results show effects of increasing heavy metal concentrations on nodulation development, especially the nodulation index (i.e., the number of nodules per gram of the total fresh biomass). A significant decrease in nodulation index was observed at about 2.64 mg Cd kg(-1), 300 mg Zn kg(-1), and 130 mg Pb kg(-1) in these soils. The sensitivity of the nodulation index in relation to other morphological characteristics is discussed further. It is proposed that the nodulation index of white clover is a suitable bioindicator of increased heavy metal concentrations in soil.
Manier
Nicolas
N
Institut Lillois d'Ingénierie de la Santé (ILIS), EA 2690, 42, rue Ambroise Paré, 59120 Loos, France. nmanier@gmail.com
Deram
Annabelle
A
Broos
Kris
K
Denayer
Franck-Olivier
FO
Van Haluwyn
Chantal
C
D004784:Environmental Monitoring / Q000379:methods*; D019216:Metals, Heavy / Q000494:pharmacology*; D055170:Plant Root Nodulation / Q000187:drug effects*; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000494:pharmacology*; D029921:Trifolium / Q000187:drug effects* / Q000254:growth & development
D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants