DEFINITIONS AND USE OF THE DESCRIPTORS
Bioversity uses the following definitions in genetic resources documentation:
Passport descriptors: These provide the basic information used for the general management
of the accession (including registration at the genebank and other identification information)
and describe parameters that should be observed when the accession is originally
collected.
Management descriptors: These provide the basis for the management of accessions in the
genebank and assist with their multiplication and regeneration.
Environment and site descriptors: These describe the environmental and site-specific
parameters that are important when characterization and evaluation trials are held. They
can be important for the interpretation of the results of those trials. Site descriptors for
germplasm collecting are also included here.
Characterization descriptors: These enable an easy and quick discrimination between
phenotypes. They are generally highly heritable, can be easily seen by the eye and are
equally expressed in all environments. In addition, these may include a limited number of
additional traits thought desirable by a consensus of users of the particular crop.
Evaluation descriptors: The expression of many of the descriptors in this category will
depend on the environment; consequently, special experimental designs and techniques
are needed to assess them. Their assessment may also require complex biochemical or
molecular characterization methods. These types of descriptors include characters such
as yield, agronomic performance, stress susceptibilities and biochemical and cytological
traits. They are generally the most interesting traits in crop improvement.
Characterization will normally be the responsibility of genebank curators, while evaluation
will typically be carried out elsewhere (possibly by a multidisciplinary team of scientists). The
evaluation data should be fed back to the genebank, which will maintain a data file.
Highly discriminating descriptors are highlighted in the text.
The following internationally accepted norms for the scoring, coding and recording of descriptor
states should be followed:
(a) the Système International d’Unités (SI) is used;
(b) the units to be applied are given in square brackets following the descriptor name;
(c) standard colour charts, e.g. Royal Horticultural Society Colour Chart, Methuen Handbook