Effect of sources and levels of zinc on nutrient content and uptake by rice (Oryza sativa L.)

The present study evaluated the influence of different zinc sources and application levels on nutrient uptake in rice. Zinc was supplied as ZnSO₄, Zn-fulvate, Zn-humate and Zn-chelate in combination with the recommended dose of fertilizers (RDF). Among the treatments, RDF supplemented with ZnSO₄ at 2.5 ppm resulted in the highest uptake of nitrogen, phosphorus, potassium and zinc (45.89, 5.37, 43.94 mg pot⁻¹ and 479.38 µg pot⁻¹, respectively), followed by Zn-fulvate at the same level (41.70, 4.62, 38.67 mg pot⁻¹ and 380.32 µg pot⁻¹). In contrast, the lowest nutrient uptake was observed under RDF alone. Zinc application at 2.5 ppm significantly enhanced N, P, K and Zn uptake compared to the control, whereas increasing the level to 5.0 ppm resulted in only marginal improvement. The effectiveness of zinc sources in improving rice nutrition followed the order: ZnSO₄ > Zn-fulvate > Zn-humate > Zn-chelate. These results highlight the superiority of soluble zinc sources, particularly ZnSO₄ and Zn-fulvate, in enhancing nutrient uptake in rice grown on zinc-deficient soils.