Biogeoaccumulation of zinc in hybrid rice (Oryza sativa L.) in an Inceptisol amended with soil zinc application and its bioavailability to human being

Abstract

Soil Zn amended is an efficient agronomical Zn biofortification approach in rice. However, it is still need to know if higher rate of Zn over recommended dose can influence other essential nutrient uptake, high accumulation of Zn in soils and health risk for human consumption. This study was conducted by taking ten treatments (T1: control, T2: RDF, T3: RDF + 1.25 mg kg-1, T4: RDF + 2.5 mg kg-1, T5: RDF + 3.75 mg kg-1, T6: RDF + 5 mg kg-1, T7: RDF + 6.25 mg kg-1, T8: RDF + 7.5 mg kg-1, T9: RDF + 8.75 mg kg-1, T10: RDF + 10 mg kg-1) on hybrid rice in Zn (1.20 mg kg-1) enriched soil. The findings have shown that 6.25 mg kg-1 Zn application significantly increased crop growth and grain concentrations of N, K, Zn, Cu and Fe by 71.4, 125, 78.9, 28.5 and 2.4%, respectively. Nutrient harvest index was significantly affected by ranged between 29.1–36.4%. Application of Zn at 6.25 mg kg-1 (T7) recorded the highest Zn concentration in grain (28.2 mg kg-1) and bioavailability of the fortified Zn (2.05 mg Zn day-1). The lowest phytatic acid concentration in grain was recorded in T8 (RDF + Zn at 7.5 mg kg-1) and after that a significant increase was observed. Transfer coefficient was inversely behaving with Zn application and ranged between 6.03–18.0 grain. The average daily intake of Zn was ranged between 0.075–0.118 mg-1 kg-1 day. Across different treatments the Zn build-up factor, geo-accumulation index and soil enrichment factor was ranged between 0.98–4.90, -0.61–1.70 and 0.24–1.82, respectively in post-harvest soil. In conclusion, agronomic biofortification of Zn through soil applications at 6.25 mg Zn kg-1 was a sustainable way to improving growth and grain Zn, N, K, Cu and Fe uptake of hybrid rice to meet human recruitment.

Keywords

• nutrient harvest index
• rice
• zinc
• zinc balance sheet
• zn build-up factor