Investigation of the Role of Organic Acids on the Phosphorus and Zinc Uptake by Corn in Calcareous Soils by Using 32P and 65Zn Radioisotopes

To investigate the effect of oxalic and citric organic acids on the uptake of Phosphorus and Zinc by corn (Zea mays L.), an experiment was conducted by the use of radioactive potassium phosphate and zinc sulfate fertilizers in microcosm and greenhouse condition. For tracing and translocation of these elements to aerial parts of the corn, 32P and 65Zn were produced in Tehran Research Reactor (TRR). After season of plant growth and administration of treatments in microcosm (4 weeks), plants were harvested, digested, extracted and activity of the 32P and 65Zn in the samples was measured by a Liquid Scintillation Counter (LSC) and a HPGe Gamma Spectrometry System (GSS), respectively. The results revealed that organic acids had significant effects on the P releasing from the soil and its uptake by the plant but had no effect on the Zn uptake. The highest uptake of 32P and 65Zn in the aerial parts of corn was observed in oxalic acid of 10mM concentration and blank (water), respectively. Furthermore, it seems that organic acid concentrations of more than 10mM is necessary for extracting elements from soil and following uptake by plants.