Enrichment of Sunflower Seeds and Harvest Residues with Zn and Se Through Agronomic Biofortification

This research was focused on the effectiveness of sunflower biofortification with Zn and Se towards enriched seeds, but also a side effect on the enrichment of crop residues, which can have a residual fertilizing effect. A two-year study of sunflower biofortification was conducted with foliar application of 10, 20, and 30 g/ha Se as Na-selenate or 3 and 6 kg/ha Zn as Zn sulphate in a randomized complete block design with three replications. Biofortification did not significantly affect either the seeds or the above-ground yields, but it increased the Se and Zn concentrations in seeds and vegetative mass. The Se in seeds increased 14-44 times, whereby 7.3 g/ha Se would be sufficient to achieve 300 µg/kg Se in seed. The Zn in the seed increased up to 72 mg/kg. The efficiency of biofortification in terms of Se accumulation in seeds was 15.4 – 19.3%, and Zn only 1.73 - 3.15%, which means that significant amounts of Se and Zn remain in crop residues whose incorporation into the soil has a residual effect of Zn and Se fertilization for subsequent crops.