Microbial activity related to N cycling in the rhizosphere of maize stressed by heavy metals.
J Environ Sci (China)
; 17(3): 448-51, 2005.
Article
em En
| MEDLINE
| ID: mdl-16083122
ABSTRACT
A greenhouse experiment was carried out to compare differences in potential activities of ammonification, nitrification and denitrification in rhizosphere and bulk soil in a heavy-metal-stressed system. Exchangeable fractions of Cd, Cu and Cr were all higher in the rhizosphere of maize than in bulk soil. Results showed that the mineralization of N in soil was stimulated by low concentration of Cd. Addition of Cd at low levels stimulated the ammonifying and nitrifying activity in soil, while inhibitory influences were shown at high levels. Nitrifying bacteria was proved to be the most sensitive one, whilst the effect on denitrifying bacteria was very limited. Comparing Cd, Cu and Cr(VI) at 20 mg/kg soil, Cd was the most effective inhibitor of ammonification and denitrification, while Cr(VI) had the strongest inhibitory influence on nitrifying activity. Root exudates played important roles on the different exchangeable metal fractions and bacterial activities between rhizosphere and non-rhizosphere. Nitrate was the main form of mineral N in soil, as well as the main form of N absorbed by plants, but the formation and relative absorption of ammonium were promoted in response to high Cd exposure.
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Base de dados:
MEDLINE
Assunto principal:
Microbiologia do Solo
/
Poluentes do Solo
/
Bactérias
/
Raízes de Plantas
/
Metais Pesados
/
Zea mays
/
Nitrogênio
País/Região como assunto:
Asia
Idioma:
En
Revista:
J Environ Sci (China)
Assunto da revista:
SAUDE AMBIENTAL
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
China