Abstract
Zinc biofortification 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
ZnSO4·7H2O to rice grown under submerged conditions on a Zn deficient calcareous soil. Treatments 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 application, decreased grain
[phytate]:[Zn] ratio and increased estimated human Zn bioavailability in grains based on trivariate model of Zn absorption.
Conclusively, soil + foliar Zn application is suitable for optimum 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.
