Copper availability and bioavailability are controlled by rhizosphere pH in rape grown in an acidic Cu-contaminated soil.
We evaluated how root-induced changes in rhizosphere pH varied and interacted with Cu availability and bioavailability in an acidic soil. Rape was grown on a Cu-contaminated acidic soil, which had been limed at 10 rates. Soil Cu bioavailability was not influenced by liming. However, liming significantly decreased CaCl(2)-extracted Cu for pH between 3.7 and 5.1. Little effect was found for pH above 5.1. For soil pH < 4.4, CaCl(2)-Cu contents were smaller in rhizosphere than uncropped soil. Rhizosphere alkalisation occurred at pH < 4.8, while acidification occurred at greater pH. This explained the changes of CaCl(2)-Cu in the rhizosphere at low pH and the absence of pH dependency of Cu bioavailability to rape. In addition, apoplastic Cu in roots increased with increasing soil pH, most probably as a result of increased dissociation and affinity of cell wall compounds for Cu.
Chaignon
Valérie
V
INRA, UMR 1222 Eco&Sols Ecologie Fonctionnelle & Biogéochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier, France.
Quesnoit
Marie
M
Hinsinger
Philippe
P
D000143:Acids / Q000032:analysis; D001682:Biological Availability; D029688:Brassica napus / Q000254:growth & development / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D058441:Rhizosphere; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000378:metabolism*
D000143:Acids; D012987:Soil; D012989:Soil Pollutants; D003300:Copper