Detection of Elemental Concentration Change in the Root Environment: I-Contact Micro-Autoradiography

Contact micro-autoradiographic technique involved contact exposure with irradiated (⁴⁵Ca and ³²P) thin sections prepared from impregnated soil blocks, and subsequent development and fixing of the film. Relative efficiencies of the detection of elemental concentration changes of Ca and P in the vicinity of root were tested using x-ray film, industrex fine grain film and Kodak stripping film. The stripping film was found to be the most suitable. Thus, using this film, gradient in the concentration of Ca in the vicinity of the root was detected in case of French bean receiving choline phosphate treatment. When soil received calcium nitrate, Ca was shown to have accumulated on the soil-root interface. No depletion zone of P was detected as such with either of the fertilizer treatments. However, in case of choline phosphate treatment P was found to have migrated to the endodermal layer. General association of P with organic debris of either root or microbial origin and sesquioxidic materials was also apparent.