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Characterization of maize

Contributors to this page: CIMMYT, Mexico (Suketoshi Taba, Bonnie J. Furman), with inputs also received from IITA, Nigeria (Dominique Dumet), EMBRAPA (maize and sorghum genebank), Brazil (Flavia Teixeira), USDA (ARS/NC7, ISU), USA (Mark Millard).

Contents:
Cultural practices
Descriptors
Information

Planting and cultural practices for characterization

A genebank is often constrained by local environments that may be differ from ‘best practice’ defined environments.

Environment

Soil type

Maize needs a large amount of macronutrients: nitrogen, potassium, and phosphorus. Maize often suffers of iron and zinc micronutrient deficiency.

For example, CIMMYT Tlatizapan station has black vertisols that often limit iron availability for maize growth due to the alkaline conditions of the soil. Some inbred lines and landrace accessions present a retarded growth and even fail to flower due to these conditions.

Rainfall

Season

Planting seasons may have a substantial effect on maize growth patterns. Even in the same locality, a winter season has slower plant growth and more days to flower than a summer season. Rain fall and temperature regimes significantly influence maize growth pattern. In addition, data on leaf diseases, ear quality, ear rots and plant lodging can be affected by wind, edaphic and biotic environmental factors in the different growing seasons.

Plot size

Sampling area/border area

Plant density

Replications

Standard check cultivars

Frequency of standard check cultivars

Time of day for data collection

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Descriptors

Showing maize diversity inside the USDA genebank at Ames, USA (photo: M.Mackay)

Morphological descriptors for characterization

Pictures for characterization

Sufficient detail should be captured in images to taxonomically identify the plant and demonstrate the traits that show variation.

Herbarium samples for characterization

Molecular descriptors for characterization

Cytological characterization

Nutritional traits for characterization

Others

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Recording information during characterization

Below is an example of a maize descriptor used in the CIMMYT maize bank regeneration/characterization field book descriptors:

References and further reading

Bioversity International, CIMMYT. 2009. Key access and utilization descriptors for maize genetic resources. Bioversity International, Rome, Italy; International Maize and Wheat Improvement Center, Mexico. Available here.

IBPGR and CIMMYT. 1991. Descriptors for Maize. International Maize and Wheat Improvement Center, Mexico City; International Board for Plant Genetic Resources, Rome. Available here.

Taba S, Diaz J, Franco J, Crossa J. 1998. Evaluation of Caribbean maize accessions to develop a core subset. Crop Science. 38:1378-1386.

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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.

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