Field banks for cassava and wild Manihot species

Contributors to this page: IITA, Nigeria (Dominique Dumet), Bioversity International/ILRI, Ethiopia (Alexandra Jorge); INIA, Peru (Llerme Rios); independent consultant (Clair Hershey).

When are field banks used

Cassava and wild Manihot species collections have been traditionally maintained in field conditions. Many cassava collections are still kept under field conditions, despite having the highest risk of losses. However, the advantages of keeping cassava germplam in the field are the relative technical simplicity and to have vegetative material available for immediate use in breeding work, evaluation or dissemination within the country.

How to establish a field bank

Theoretically, a perennial collection of cassava could be maintained for many years without regeneration. However, maintenance problems often increase after a year or two, making replanting at more frequent intervals necessary. Common problems include lodging from excessive growth and the build-up of pests and diseases. Adaptation problems typically occur when the edapho-climatic characteristics of the genebank location are very different from the collection site, where the variety is presumably adapted well enough to be selected and propagated year after year by the growers. These adaptation problems are most likely to occur if the country where the accessions have been collected is geographically and climatically diverse.

Manihot glaziovii in CIAT’s genebank (photo: H. Ceballos)

The wild Manihot species comprise a wide range of plant types, from recumbent vines to medium-sized trees of 20 or more meters in height. Hence, there is no generalization that applies across the species for field conservation practices, nor are there published guidelines. There are four institutions world-wide with extensive experience in field genebank management of the wild Manihot species and these institutions should be consulted for advice with specific species: CIAT (Colombia), IITA (Nigeria), CENARGEN/EMBRAPA (Brazil) and the University of Brasilia (Dr Nagib Nassar).

References and further reading

Fukuda WMG. 1996. Banco de germoplasma de mandioca: manejo, conservação e caracterização. Cruz das Almas, BA: EMBRAPA-CNPMF. 103 p. (EMBRAPA-CNPMF, Documento, 68).

Hershey C. 2008. A global conservation strategy for cassava (Manihot esculenta) and wild Manihot species. Summary of stakeholder deliberations and recommendations prepared for the Global Crop Diversity Trust. Available from: Date accessed: 7 Oct. 2010.

IITA Genebank Manual Series, Cassava field bank operations at the International Institute of Tropical Agriculture (IITA). International Institute of Tropical Agriculture, Ibadan, Nigeria.

Mohd SS, Rao VR, editors. 2001. Establishment and Management of Field Genebank, a Training Manual. IPGRI-APO, Serdang. 121 p. Available here.

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The Genebanks

The 11 CGIAR genebanks currently conserve 730,000 of cereals and grain legumes, forage crops, tree species, root and tuber crops, bananas and crop wild relatives.