Improving Human Zinc Nutrition through a Combination of Crop Management and Plant Breeding for Rice.

Increasing the biovavailable Zn content of the edible part of rice grains is one strategy for improving the micronutrient nutrition of humans who consume rice-based diets. A combined approach using plant breeding techniques with appropriate Zn fertilizer and water management resulted in an increase of the Zn content of brown rice from 20 to 30 mg/kg, which met the intermediate target set for improving immune system function in children. Because rice is usually grown under floodwater, and flooding changes Zn availability in soil, it was necessary to screen the rice genetic resources for high Zn content under strategic soil environmental conditions. Optimal Zn fertilizer management strategies were determined that were designed to ensure that the advanced breeding lines would meet their genetic potential under varied environmental conditions. The water management of the plant breeding trials during the grain-filling stage of plant growth was critical for making accurate comparisons between genotypes.