Yield, zinc efficiencies and biofortification of wheat with zinc sulfate application in soil and foliar nanozinc fertilisation

Context Agronomic biofortification of wheat (Triticum aestivum L.) with zinc (Zn) is an effective approach to increase grain Zn concentration and productivity and alleviate Zn malnutrition in humans. Foliar Zn application is an alternative strategy to endorse soil Zn deficiency with better grain Zn partitioning. Aims This study aimed to better understand dose management of soil and foliar Zn application in wheat for biofortification. Methods The objectives was to evaluate the effect of foliar applied nano Zn doses (0, 0.75, 1.5, 3 and 6 kg/ha (zinc oxide, ZnO) 50% at tillering and 50% at grain filling in combination) with soil Zn application (0 and 8 kg/ha, as zinc sulfate) on growth, nutrition, Zn use efficiencies, intake and yield biofortification of wheat in 2019 and 2020 under Brazilian savanna. Key results Combined foliar and soil Zn application increased shoot and grains Zn concentration and accumulation with greater dry matter (9.8 and 10.6%) and grain yield (9.8 and 11%) of wheat as compared to control in 2019 and 2020 respectively. Zinc use efficiency (ZnUE), Zn utilisation efficiency and applied Zn recovery improved with soil Zn application and 2.5 kg/ha foliar nano Zn, but decreased with further increase in foliar Zn application. Zn sulfate stood out for increasing crop productivity while foliar spray with nano Zn for better grains biofortification of wheat. Conclusions Soil Zn application along with 3 kg/ha of foliar nano Zn increased plant and grains Zn concentration and accumulation, dry matter, grain yield, Zn partitioning index and Zn intake in wheat in tropical conditions of Brazil. Implications The combined application of soil and foliar Zn in harsh tropical savannah condition could better improve Zn nutrition, crop growth, and productivity with better Zn biofortification and intake of wheat.