تغییر در قابلیت استفاده و اجزاء مس در ریزوسفر گندم ((Triticum aestivum L. در تعدادی از خاکهای آهکی

Abstract

Rhizosphere is a small zone and has quite different chemical, physical and biological properties from bulk soil. This research was conducted to investigate the availability and fractionation of copper in the wheat rhizosphere and bulk soils by using rhizobox at greenhouse conditions. Three seeds of wheat were plant in the rhizobox. After 8 weeks, plants were harvested and rhizosphere and bulk soils were separated. Total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) and available Cu (by using 7 chemical procedures) and Cu-fractions were determined in the rhizosphere and bulk soils. The results indicated that TOC, DOC and MBC in the rhizosphere were increased significantly (p<0.01). Cu extracted using several chemical extractants in the rhizosphere were significantly (p<0.05) lower than in the bulk soils. In the rhizosphere soils exchangeable Cu, Cu associated with carbonates and Cu associated with manganese-iron oxides were decreased and Cu associated with organic matter and residual Cu were increased. Moreover, results indicated that correlation between Cu associated with iron-manganese oxides and residual fraction with extracted Cu using DTPA-TEA, AB-DTPA and Mehlich 3 with were significant (p<0.05) in the rhizosphere and bulk soils. Correlation between concentration index and extracted Cu using AB-DTPA and Mehlich 3 were significantly (p<0.05) in the rhizosphere and bulk soils. In addition, correlation between uptake index and extracted Cu using 0.01 M CaCl2 was significantly (p<0.05) in the rhizosphere and bulk soils. The result showed that significant correlation (p<0.05) between concentration and uptake indices and Cu associated with iron-manganese and residual fractions in the wheat rhizosphere and bulk soils were found. Result revealed that coefficients in the rhizosphere soils were higher than in the bulk soils.