Scarcity of water is causing a shift from flooded (anaerobic) to aerobic conditions for rice production in North China, where many soils are zinc (Zn) deficient because of high pH and high carbonate content. Aerobic rice varieties are newly bred by crossing lowland with upland varieties and are grown as a dry field crop in irrigated but nonflooded and nonpuddled soils. The introduction of aerobic rice on low Zn soils places the problem of Zn deficiency in rice in a new perspective. The aim of our work is to understand the mechanisms of Zn mobilization in aerobic rice. This happens by using as a tool the genotypic variation in tolerance to Zn deficiency among aerobic rice. Genotypes of plants vary widely in tolerance to Zn deficiency. A mechanistic explanation, however, is still lacking.