Agronomic and economic response of bread wheat to foliar zinc application
Reza Keshavarz Afshar, Chengci Chen, Shuang Zhou, Fatemeh Etemadi, Huaqin He, Zhaowei Li
Abstract
Abstract Zinc (Zn) deficiency is a common micronutrient deficiency in human population, especially in regions where grain cereals are the primary supply of daily calorie intake. Zinc also performs an important role in plant growth and Zn deficiency can limit crop yield and quality. A 3‐yr field study was conducted to determine response of wheat cultivars to foliar application of Zn. Zinc sulfate was sprayed on plant canopy at a rate of 1.12 kg Zn ha −1 once (at heading) or twice (at heading and flowering). One application of Zn at heading increased grain Zn concentration by a range of 5.8 to 9.5 mg kg −1 corresponding to a 17–47% increase over the unfertilized control in various years. With the application of Zn at both heading and flowering, grain Zn concentration reached 44.3 and 52.4 mg kg −1 (in Years 2 and 3), implying an increase of 35–93% compared to the untreated control. The second application of Zn at flowering was necessary to produce grains with Zn concentration above the target level of 40 mg kg −1 to have a nutritional effect. Zinc application also marginally increased grain yield. This yield increase, however, was not adequate to offset additional production costs associated with Zn fertilization. The economic analysis revealed that the net return from the first and second Zn application was −1 and +13 USD ha −1 , respectively. Therefore, it is unlikely that farmers will be motivated to adopt this system unless a price incentive or government payments are provided for farmers for producing Zn‐biofortified grains.