Improving zinc and iron density and estimated human bioavailability in rice grain through fertilization

Micronutrient deficiency in human nutrition is widening in the developing world especially where cereals are the major calorie intake source. A study was conducted comprising pot and field experiments on rice. Rice pot experiment was conducted using differing levels of Zn and Fe (2.5, 5.0, 7.5 mg kg −1 soil) fertilization. Maximum grain yield was with Zn + Fe@5 + 2.5 mg kg −1 (39%) over control. Highest significant increase in grain Zn and Fe density was attained with Zn and Fe@7.5 mg kg −1 . Best performing treatments in pots were applied in the field experiment. It included different levels of zinc and iron alone (10, 15 kg ha −1 ) and in combinations (10 + 5, 5 + 10 kg ha −1 ) and a control (without Zn and Fe). Maximum grain yield was found with Zn + Fe@10 + 5 kg ha −1 soil, 30% increase over control. Zinc and Fe contents were at maximum (37.9 and 34.2 µg g −1 ) with Zn@15 kg ha −1 and Fe@5 + 10 kg ha −1 , respectively. Estimated human bioavailability of Zn augmented by 64% over control with Zn@15 kg ha −1 . Iron bioavailability improved as [phytate]:[Fe] decreased significantly. Conclusively, zinc and iron fertilization along with recommended macronutrients is suitable for improving Zn and Fe density and human bioavailability in rice grain.