Evaluation of Zinc Use Efficiency Using 65Zn Radiotracer Technique in an Alfisol of Turmeric Crop (Curcuma longa Var.)
A glasshouse experiment was carried out to investigate the influence of Zinc (Zn) enriched organics and Zn solubilizing bacteria on use efficiency of Zn by turmeric crop and its availability and distribution among various fractions of Zn in the soil using 65Zn isotope. The profound effect of zinc solubilizing bacteria (ZSB) on the increase of dry matter yield of turmeric was found to be 14.0, 14.3 and 18.1 per cent for ZnSO4, Zn enriched FYM and Zn enriched coirpith along with ZSB respectively than consecutive treatments without the organism. In the pot experiment involving 65Zn isotope, the specific activity, per cent Zn derived from fertilizer Zn and uptake of Zn from applied fertilizer and zinc use efficiency were increased intensely with the zinc enrichment treatments than the direct Zn soil application. The zinc use efficiency increased with the Zn treatments, where Zn enriched coirpith performed best(3.48 % in whole plant) than remaining treatments and ZnSO4 alone (0.99 % in whole plant). The organic and exchangeable fractions of Zn revealed the superior nature of Zn fortified with coirpith treatment which surpassed the remaining treatments with its highest specific activity followed by the treatments that received Zn or Fe or Zn + Fe fortified coirpith/FYM than the per se application of ZnSO4 or FeSO4. The per cent distribution of applied Zn fertilizer into the different forms in the soil based on specific activity of Zn to total fraction was in the order of Organic bound Zn > Exchangeable Zn > Manganese oxide bound Zn > Amorphous iron oxide bound Zn > Crystalline iron oxide bound Zn. The tune of increase seen for the per se effect of Zn solubilizing bacteria was markedly higher for organic Zn fraction for the addition of Zn fortified FYM as well as coirpith followed by exchangeable Zn and DTPA Zn.
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