Studying differences in soil and foliar uptake and seed deposition of zinc in HarvestPlus-biofortified wheat genotypes grown in greenhouse conditions

More than two billion people around the globe are suffering from malnutrition syndrome specially Zn deficiency. Women and children in developing countries are affected the most and the main reason is reliance on cereal based food to meet daily energy requirement. Wheat being the primary staple food in South Asia (Northern India and Pakistan) is important part of almost every meal and in every house. More than 26% of the population living in region consuming wheat as staple food is diagnosed as Zn deficient. Wheat, like other cereals (maize and rice) are inherently low in micronutrients, therefore, cereal-based foods do not provide enough Zn to meet the individual’s daily Zn requirement. Agriculture strategies offer a practical and cost-effective solution to the problem by increasing the Zn concentration in staple food like cereal crops through breeding (genetic biofortification) or fertilization (agronomic biofortification) or combining both approaches. Agronomic biofortification provides an instant solution to the problem by applying Zn fertilizer to the soil and/or to plant as a foliar spray. As an international group, HarvestPlus program along with collaboration of public and private partners has taken initiatives to develop the biofortified high Zn wheat cultivars along with desired agronomic traits. Current study aimed to evaluate the performance of the high Zn biofortified wheat genotypes developed through long-term breeding activities under the HarvestPlus program in Pakistan and India. Ten advanced breeding lines and two mega varieties as check were tested under four fertilizer treatments i) Deficient Soil Zn (or control) ii) Foliar Zn application iii) Soil Zn application iv) both soil and foliar Zn. The results indicate that biofortified lines have higher capacity to absorb and accumulate Zn in grain from soil and foliar Zn fertilizer as compared to check cultivars. A positive correlation was observed in grain yield and grain Zn concentration of biofortified lines. As an average of all biofortified genotypes, 18 % increase in yield and 3.5 folds increase in grain Zn concentration were recorded with the application of both soil and foliar fertilizers. Highest grain yield and grain Zn concentration was observed in an Indian biofortified genotype with both Soil + Foliar Zn application. In south Asian countries like India and Pakistan where soils are calcareous and Zn deficient, the strategy of growing genetically biofortified wheat cultivars with an added application of Zn in soil and foliar form is the best approach to improve yield and grain Zn accumulation. Under such a scenario, the targets for biofortification will be rapidly achieved by combining agronomic and genetic strategies and hence to overcome the malnutrition problem.