Efficacy of zinc application methods for concentration and estimated bioavailability of zinc in grains of rice grown on a calcareous soil

© 2015, University of Agriculture. All right reserved. Zinc biofort ification of cereal grains is suggested for controlling widespread human Zn deficiency in developing countries. In present field trail, various Zn treatments [control, priming of seeds in 0.5% (w/v) Zn solution (seed priming), dipping of roots in 0.5% (w/v) Zn solution (root dipping), application of 20 kg Zn ha −1 (soil application), sprays of 0.25% (w/v) Zn each at tillering and heading stages (foliar application) and combination of soil + foliar Zn applications] were applied as ZnSO4·7H2 O to rice grown under submerged conditions on a Zn deficient calcareous soil. Treat ments significantly (P≤0.05) increased grain and straw yield; however, seed priming and root dipping increased paddy yield only by ≤5%. Increased grain weight also significantly increased grain phytate content. Whole grain Zn concentration increased from 22 (at control) to 29 mg kg −1 (at soil + foliar application).Zinc applications methods, especially soil + foliar applicat ion, decreased grain [phytate]:[Zn] rat io and increased estimated human Zn bioavailability in grains based on trivariate model of Zn absorption. Conclusively, soil + foliar Zn application is suitable for opti mum paddy yield and agronomic Zn biofortification of rice grains. However, a limited increase in grain Zn concentration (7 mg kg −1) by Zn application suggested exploitation of molecular and genetic approaches in Zn biofortification programs.