Xiaopeng Gao : "Bioavailability of Zinc to Aerobic Rice"

Zinc deficiency is estimated to affect more than two billion people and 30% of the world’s agricultural soils, mainly in developing countries. It causes malfunctioning of the immune system in humans and yield reduction in crop growth. This thesis investigated options to increase zinc (Zn) uptake by rice. It thereby contributes to increased Zn grain levels and mitigation of the human Zn deficiency problem.

The study was done in the Chinese context, where water scarcity has induced a shift from lowland rice with flooded fields towards the water-saving system of aerobic rice. It was shown that this shift further increases the Zn deficiency problem. Zinc fertilizers do increase yield, but they do not increase grain Zn levels. The best solution seems to choose rice genotypes that grow well on Zn deficient soils and have higher grain Zn levels. The thesis has shown that some rice genotypes are able to increase Zn uptake chemically changing the soil around their roots. Also, the use of mycorhizal fungi may help, but the combination of efficient genotypes with mycorrhizas seems impossible.