The international collection of yam (Dioscorea spp.) is maintained in the field bank of GRC. A part of this collection held in trust is duplicated and stored in the in vitro bank. Yam tubers in the field bank side of conservation are done either as plants in the open field or as harvested tubers in the cold store and yam barn. For proper storage, water content of the tubers is allowed to drop at the yam barn where the tubers are first stored. They are later stored in the cold room and this prevents loss due to rot and weevils to a high extent.The wild relatives of GRC yam collection are non-tuber bearing and they are kept as perennial plants in a nursery section in the field bank. In total there are over 5000 accessions of yam in GRC field bank collection. Some of the accessions are maintained in outstations for safe duplication and phenotypic data is collected from them.
Yam species of economic value and considered deserving of conservation in GRC include
D.alata, D. rotundata, D. cayenensis, D. bulbifera, D. esculenta, and D. dumetorum. Wild relatives conserved include D.praehensilis, D. manganotiana, and D. bulkiliana. The regeneratin of yam accessions in the fieldbank is an annual process and s with cassava, the selection of good field comes first in the process.