SULFUR AND ZINC RELATIONSHIP ON UPTAKE AND UTILIZATION OF ZINC IN SOYBEAN

Investigations to study the effect of different sources and levels of zinc with sulfur were carried out. Sulfur was applied at 0, 40, 80, and 120 ppm as K2SO4, and zinc was applied at 0, 5, and 10 ppm as ZnCl2, Zn-EDTA, and Zn-Rayplex. Sulfur application at lower levels increased zinc concentration and at higher levels decreased it in leaves, pod husks, and grains of soybean. But application of 5 and 10 ppm zinc significantly increased the concentration of zinc in all plant parts. Zinc-EDTA gave more than twofold higher concentrations in all plant parts at both the sampling stages. Total zinc uptake was highest with the application of 80 ppm sulfur and 10 ppm zinc at 45 days and maturity. The sulfur and zinc interactions on total zinc uptake at 110 days revealed that 80 ppm sulfur + 10 ppm zinc and 80 ppm sulfur + Zn-EDTA gave significantly higher uptakes of zinc over other treatments. The sources of zinc with respect to its concentration and uptake were found in the order: Zn-EDTA > Zn-Rayplex > ZnCl2. The concentrations of zinc in leaves at 45 and 110 days gave significant positive correlations with grain yield and with the uptake of zinc at 110 days.