Potato Biofortification with Zinc: Comparison between Soil Application and Foliar Spray

Aims: Two field experiments, one for Zinc (Zn) application in soil and another for Zn application as foliar spray were conducted during November 2019 to February 2020 at the Horticulture Farm, Bangladesh Agricultural University (BAU), Mymensingh, Bangladesh to investigate the proof-of-concept that Bangladesh Agricultural Research Institute (BARI) released potato varieties (Solanum tuberosum L.) can be agronomically biofortified with zinc (Zn) fertilizers. Both the experiments were repeated next year during November 2020 to February 2021 at the same field to validate the results. Study Design: The experiments were set up in a two-way factorial randomized complete block design with three replications. There were three blocks representing the three replications. Texturally, the soil is silty-loam and falls under Sonatala series. Methodology: Both the experiments included six potato cultivars. Soil Zn application trial had four treatment combinations with three replications resulting 72-unit plots; on the other hand, the foliar Zn application trial had eight different treatments having three replications resulting 144-unit plots each of which was 3.6 m2 (1.5 m x 2.4 m) in size in both trials. Results: Tuber Zn concentrations increased 56-116% over control (no Zn applied) due to added Zn in soil @ 8 kg ha-1and 170-284% tuber Zn concentrations increased over control due to Zn application as foliar spray @ 8 kg ha-1(4 kg ha-1applied at 45 and 4 kg ha-1at 60 DAP) under study. Foliar applied Zn is phloem mobile and can be transferred to developing tubers. In a crop like potato, foliar application of Zn has been found to be superior in increasing tuber Zn concentration as compared to soil. The effectiveness of foliar Zn spray on increasing tuber Zn concentration varies significantly with the time of application. Conclusion: Higher tuber Zn enrichment has been achieved when Zn was applied as a later growth stage of potato plant. Some potato varieties have a genetically higher ability to uptake and accumulate more Zn from soil and plant parts as a result of foliar Zn spray which would serve as breeding materials for biofortification of Zn in potatoes without compromising crop yield. The results confirmed that compared to soil Zn application, foliar Zn application is more effective in Zn biofortification.