BIOVERSITY TECHNICAL BULLETIN NO. 13
Developing crop
descriptor lists
Bioversity Technical Bulletins are published by Bioversity International with the intention
of putting forward deinitive recommendations for techniques in genetic resources. They are
speciically aimed at National Programmes.
Previous titles in this series:
A protocol to determine seed storage behaviour
T.D. Hong and R.H. Ellis
IPGRI Technical Bulletin No. 1, 1996.
Molecular tools in plant genetic resources conservation:
a guide to the technologies
A. Karp, S. Kresovich, K.V. Bhat, W.G. Ayad and T. Hodgkin
IPGRI Technical Bulletin No. 2, 1997.
Core collections of plant genetic resources
Th.J.L. van Hintum, A.H.D. Brown, C. Spillane and T. Hodgkin
IPGRI Technical Bulletin No. 3, 2000.
Design and analysis of evaluation trials of genetic resources collections
Statistical Services Centre and University of Reading
IPGRI Technical Bulletin No. 4, 2001.
Accession management: combining or splitting accessions
as a tool to improve germplasm management efficiency
N.R. Sackville Hamilton, J.M.M. Engels, Th.J.L. van Hintum, B. Koo and M. Smale
IPGRI Technical Bulletin No. 5, 2002.
Forest tree seed health
J.R. Sutherland, M. Diekmann and P. Berjak
IPGRI Technical Bulletin No. 6, 2002.
In vitro collecting techniques for germplasm conservation
V.C. Pence, J.A. Sandoval, V.M. Villalobos A. and F. Engelmann
IPGRI Technical Bulletin No. 7, 2002.
Análisis Estadístico de datos de caracterización morfológica
T.L. Franco y R. Hidalgo
IPGRI Technical Bulletin No. 8, 2002.
A methodological model for ecogeographic surveys of crops
L. Guarino, N. Maxted and E.A. Chiwona
IPGRI Technical Bulletin No. 9, 2005.
Molecular markers for genebank management
D. Spooner, R. van Treuren and M.C. de Vicente
IPGRI Technical Bulletin No. 10, 2005.
In situ conservation of wild plant species
a critical global review of good practices
V.H. Heywood and M.E. Dulloo
Bioversity Technical Bulletin No. 11, 2006
Crop genetic diversity to reduce pests and diseases
on-farm. Participatory diagnosis protocols. Version 1.
D.I. Jarvis and D.M. Campilan
Bioversity Technical Bulletin No. 12, 2007
Copies can be obtained in PDF format from Bioversity’s Web site
(www.bioversityinternational.org) or in printed format by sending a request
to bioversity-publications@cgiar.org.
Developing crop
descriptor lists
Guidelines for developers
Bioversity International is an independent international scientific organization
that seeks to improve the well-being of present and future generations of people
by enhancing conservation and the deployment of agricultural biodiversity
on farms and in forests. It is one of 15 centres supported by the Consultative
Group on International Agricultural Research (CGIAR), an association of public
and private members who support efforts to mobilize cutting-edge science to
reduce hunger and poverty, improve human nutrition and health, and protect the
environment. Bioversity has its headquarters in Maccarese, near Rome, Italy, with
offices in more than 20 other countries worldwide. The Institute operates through
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The geographical designations employed and the presentation of material
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the part of Bioversity or the CGIAR concerning the legal status of any country,
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and do not necessarily reflect the views of these organizations.
Mention of a proprietary name does not constitute endorsement of the product
and is given only for information.
Citation
Bioversity International. 2007. Guidelines for the development of crop descriptor
lists. Bioversity Technical Bulletin Series. Bioversity International, Rome, Italy.
xii+72p.
ISBN: 978-92-9043-792-1
Bioversity encourages the use of material from this publication for educational
or other non-commercial purposes without prior permission from the copyright
holder. Acknowledgement of Bioversity’s material is required. This publication
is available to download in portable document format from URL: <http://www.
bioversityinternational.org>.
Bioversity International
Via dei Tre Denari, 472/a
00057 Maccarese
Rome, Italy
© Bioversity International, 2007
Developing crop descriptor lists
iii
Contents
Acknowledgements
Foreword
Published Descriptor lists
v
vii
ix
BACKGROUND
1
A brief history of descriptors
Bioversity’s role
Impact of descriptors
1
3
3
INTRODUCTION
5
1. The Concept of descriptor lists
1.1 Descriptor deinitions
1.2 Descriptor elements
1.2.1 Descriptor names
1.2.2 Descriptor states
1.2.3 Descriptor methods
5
5
6
6
7
9
2. Descriptors and derived standards
2.1 Crop-speciic descriptors
2.2 Multi-crop passport descriptors (MCPD)
2.3 Descriptors for genetic marker technologies
11
12
12
12
3. Crop-specific descriptors
3.1 Crop descriptor categories
3.1.1 Passport category
3.1.2 Management category
3.1.3 Environment and site category
3.1.4 Characterization category
3.1.5 Evaluation category
13
13
14
15
15
16
17
4. Similarities to and differences from other technical
guidelines
4.1 Union Internationale pour la Protection des Obtentions
Végétales
4.2 Council for Mutual Economic Aid
4.3 United States Department of Agriculture Genetic
Resources Information Network (USDA-GRIN)
18
19
19
20
GATHERING AND ANALYSING DATA
21
5. Types of data
5.1 Qualitative data
5.2 Quantitative data
21
21
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
6. Types of Scales
6.1 Scales for qualitative characteristics
6.1.1 Qualitative descriptors using nominal scale
6.1.2 Qualitative descriptors using ordinal scale
6.1.3 Qualitative descriptors using a binary scale
6.2 Scales for quantitative characteristics
6.2.1 Quantitative descriptors using a continuous scale
6.2.2 Quantitative descriptors using a discrete scale
26
27
28
29
30
30
30
31
7. Resolution, complexity and costs
7.1 Level of precision required
7.2 Complexity of the measurement or observation
7.3 Cost per measurement
33
33
34
34
8. Methods for collecting data
35
9. Experimental design
35
10. Scoring, coding and recording of descriptors
10.1 Recording heterogeneous data
36
38
11. Numeric versus alphanumeric coding schemes
41
MAKING DESCRIPTORS WORK
43
12. The development process
43
13. A few basic rules
43
14. Step-by-step checklist for defining descriptors
44
LOOKING FORWARD
47
BIBLIOGRAPHY AND FURTHER REFERENCES
49
Appendix I – Contributors, Coordinators and Reviewers
51
Appendix II – Standard reference sources
A2.1 References and standards used in developing
crop descriptor lists
A2.2 Base units – Système International d’Unités (SI)
53
53
54
Appendix III – FAO/IPGRI Multi-Crop Passport Descriptors
55
Appendix IV – List of standard descriptors for site
environment
59
Appendix V – Example Collecting form
70
Developing crop descriptor lists
Acknowledgements
Bioversity International wishes to express its sincere thanks to
the numerous scientists and researchers around the world who
contributed directly or indirectly to the development of the Guidelines
for the development of Crop Descriptor Lists.
Ms Adriana Alercia coordinated and managed the production
of this document and provided technical and scientiic advice. Ms
Audrey Chaunac provided assistance during the production process.
Ms Patrizia Tazza prepared the cover and layout.
Special thanks are due to Dr Ramanatha Rao and Bioversity
scientists for their comprehensive technical and scientiic advice
given during the development process for this publication.
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
Developing crop descriptor lists
Foreword
The world faces a continual need to increase crop productivity, and
to develop new varieties more adapted to changing environmental
and biological challenges or to meet the evolving needs of local
communities. To meet these needs and challenges, farmers and
breeders not only must have access to a wide range of plant genetic
resources but also must have access to the essential information
about those plant genetic resources that will allow effective use to
be made of them. These guidelines have been developed to assist
genebank curators, breeders, plant scientists, national programmes,
networks and users of genetic resources working with speciic crops
and gene pools to develop their own descriptor lists in order to
characterize their material and make information available to others
in a systematic and unambiguous form.
In order to increase international exchange of material, a minimum
element of uniformity is critical in data collection, recording, storage
and retrieval. Developing standards for documentation and for
exchanging information is essential for ensuring that the vast
amount of data on crop species and varieties is available to countries
to improve their capacity to store, manage and share information
about biodiversity. The development of descriptor lists will assist in
the systematic and objective recording and exchange of information
such as passport, characterization and evaluation data, which in
turn will increase utilization of germplasm so that people can make
better use of biodiversity.
Descriptors have been developed by Bioversity International
and its predecessors, the International Board for Plant Genetic
Resources (IBPGR) and the International Plant Genetic Resources
Institute (IPGRI), for almost 100 crops in collaboration with scientists
and international research organizations. However, there is a high
demand for new descriptor lists to be developed for many species
and new crops, including neglected crops, crops of regional or local
importance, and forest species.
The guidelines presented here have been produced based on
experience gained from a wide range of crop studies and collaboration
with many scientists, national programmes and crop networks.
Various drafts of this Guide were circulated at different times to a
number of Bioversity scientists and this publication is the consolidated
result of those consultations (see Appendix I — Contributors). The
development process was coordinated by Adriana Alercia, with
scientiic guidance from Dr Ramanatha Rao.
These guidelines provide background information, set objectives
and give insights into the structure, elements and methodology
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
used by Bioversity to develop descriptor lists. They also provide a
step-by-step checklist for deining characterization and evaluation
descriptors, which can serve as a quick reference guide when
developing new descriptor lists.
Bioversity is thankful for the scientiic advice and suggestions
contributed by many scientists during the development of these
guidelines.
Developing crop descriptor lists
ix
Published Descriptor Lists
Allium (E, S)
2000
Almond (revised)* (E)
1985
Apple* (E)
1982
Apricot* (E)
1984
Avocado (E, S)
1995
Bambara groundnut (E, F) 2000
Banana (E, S, F)
1996
Barley (E)
1994
Beta (E)
1991
Black pepper (E, S)
1995
Brassica and Raphanus (E) 1990
Brassica campestris L. (E) 1987
Buckwheat (E)
1994
Capsicum* (E, S)
1995
Cardamom (E)
1994
Carrot (E, S, F)
1999
Cashew* (E)
1986
Chenopodium pallidicaule (S) 2005
Cherry* (E)
1985
Chickpea (E)
1993
Citrus (E,F,S)
1999
Coconut (E)
1992
Coffee (E, S, F)
1996
Cotton (Revised)* (E)
1985
Cowpea* (E)
1983
Cultivated potato* (E)
1977
Echinochloa Millet* (E)
1983
Eggplant (E, F)
1990
Faba bean* (E)
1985
Fig (E)
2003
Finger millet* (E)
1985
Forage grass* (E)
1985
Forage legumes* (E)
1984
Grapevine (E, S, F)
1997
Groundnut (E, S, F)
1992
Jackfruit (E)
2000
Kodo millet* (E)
1983
Lathyrus spp. (E)
2000
Lentil* (E)
1985
Lima bean* (E)
1982
Litchi
2002
Lupin* (E, S)
1981
Maize (E, S, F, P)
Mango (Revised) (E)
Mangosteen (E)
Medicago (Annual)* (E, F)
Melon (E)
Mung bean* (E)
Oat* (E)
Oca* (S)
Oil palm (E)
Palmier dattier (F)
Panicum miliaceum
and P. sumatrense (E)
Papaya (E)
Peach* (E)
Pear* (E)
Pearl millet (E, F)
Pepino (E)
Phaseolus acutifolius (E)
Phaseolus coccineus* (E)
Phaseolus lunatus (P)
Phaseolus vulgaris* (E, P)
Pigeonpea (E)
Pineapple (E)
Pistacia (excluding
P. vera) (E)
Pistachio (E, F, A, R)
Plum* (E)
Potato varieties* (E)
Quinua* (S)
Rambutan (E)
Rice* (E)
Rocket (E,I)
Rye and Triticale* (E)
Saflower* (E)
Sesame* (E)
Setaria italica
and S. pumila (E)
Shea tree (E)
Sorghum (E, F)
Soyabean* (E, C)
Strawberry (E)
Sunlower* (E)
1991
2006
2003
1991
2003
1980
1985
2001
1989
2005
1985
1988
1985
1983
1993
2004
1985
1983
2001
1982
1993
1991
1998
1997
1985
1985
1981
2003
2006
1999
1985
1983
2004
1985
2006
1993
1984
1986
1985
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
Sweet potato (E, S, F)
Taro (E, F, S)
Tea (E, S, F)
Tomato (E, S, F)
Tropical fruit* (E)
Ulluco (S)
Vigna aconitifolia
and V. trilobata (E)
Vigna mungo and
V. radiata (Rev.)* (E)
1991
1999
1997
1996
1980
2003
Walnut (E)
Wheat (Revised)* (E)
Wheat and Aegilops* (E)
White Clover (E)
Winged Bean* (E)
Xanthosoma* (E)
Yam (E, S, F)
1994
1985
1978
1992
1979
1989
1997
1985
1985
Bioversity International’s publications are available free of charge
to the libraries of genebanks, university departments, research
institutions, etc., in the developing world. E, F, S, C, P, I, R and A
indicate English, French, Spanish, Chinese, Portuguese, Italian,
Russian and Arabic respectively. Titles marked with an asterisk are
out of print, but are available as Adobe Acrobat portable document
format (PDF) on request (send email to: bioversity-publications@
cgiar.org). Organizations in the developed world and individuals
requiring personal copies can order copies of Bioversity’s publications
from EarthPrint.com (www.earthprint.com).
Developing crop descriptor lists
Background
One of the main reasons for the under-utilization of germplasm,
according to curators, breeders and other users of plant genetic
resources, is the lack of adequate passport, characterization and
evaluation data: people cannot use genetic resources that lack
essential information. In addition, such information is necessary for
proper management of the resources in the genebanks by genebank
managers. Therefore, the accurate documentation of information
about the origin, characterization and performance of germplasm is
essential for effective conservation and use. To this end, Bioversity
has been promoting the documentation of plant genetic resources
and data exchange by providing collection curators with uniform
guidelines to document their information through the production
of ‘descriptor lists’ to describe effectively diversity, which allowed
better communication between scientists and institutions, resulting
in increased use of conserved genetic resources.
Exchange of data and information between national programmes
for plant genetic resources can help to increase these programmes’
eficiency by minimizing unnecessary duplication of activities and
facilitating priority setting for germplasm collecting, regeneration
of accessions and other activities.
In order to exchange data, it is necessary to have compatible
documentation systems. This can only be achieved through common
standards for information exchange. Descriptor lists provide such
well-established standards. Even though different programmes or
institutions use different documentation systems (i.e. hardware and
software) or languages, if they use a common descriptor system the
exchange of information is facilitated.
The crop descriptor lists have an internationally accepted format
and have been developed by and are shared among scientists
worldwide. The utilization of a ‘universal language’ in well deined
and thoroughly-tested descriptor lists for characterizing germplasm
simpliies data recording, updating, modiication, retrieval, exchange
and analysis. Germplasm conservers and users adopting the same
descriptors at different locations are able easily to exchange and
interpret each other’s data.
A brief history of descriptors
Descriptor lists have been an important element of Bioversity’s
germplasm documentation activities almost since the establishment
of IBPGR in the 1970s and the production of the irst descriptor list
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
in 1977, although the concept, process and format have evolved
substantially over the years.
• Minimum descriptors. The original aim of descriptor lists was
to provide a minimum number of characteristics to describe a
particular crop (e.g. Soyabean). One problem with these initial
descriptor lists was that several useful additional descriptors
lacked the appropriate internationally accepted deinitions and
descriptor states needed for consistent recording and to be able
to communicate with other institutions. This lack of compatibility
in documentation systems for describing plant genetic resources
seriously hampered data exchange between collections.
• Comprehensive lists of descriptors. The idea of minimum lists was
revisited in 1990, and a new approach was developed. Comprehensive
lists of descriptors were produced including all descriptors for
characterization and evaluation (e.g. Descriptors for Sweet Potato/
Descripteurs pour la Patate Douce/Descriptores de la Batata,
developed in collaboration with AVRDC and CIP in 1991). The
comprehensive descriptor lists also included a number of standard
detailed sections (e.g. site environment and management) that were
common across different crop descriptor lists and that provided users
with options to choose from. This improved compatibility between
documentation systems and the ease of information exchange.
• Highly discriminating descriptors for international
harmonization. It was recognized that each curator utilized
only those descriptors that were useful for the maintenance and
management of their collection. Consequently, the descriptor lists
were further revised in 1994 in order to provide users with more
comprehensive lists but at the same time containing a minimum
set of highly discriminating descriptors, which were lagged in the
text with asterisks (*) (e.g. in Descriptors for Barley (Hordeum
vulgare L.) [1994]).
The asterisked descriptors are those that have potential to
discriminate between accessions and are important for the
international harmonization of plant genetic resources data
documentation. These highly discriminating descriptors also
provide basic indicators of diversity within a collection. Curators
and others involved in characterization and evaluation of germplasm
can complement them with additional descriptors from descriptor
lists, depending on the speciic objectives of the collection.
Nowadays, descriptor lists tend to be comprehensive, providing
an internationally recognized reference for most, if not all, known
descriptors for a particular crop or gene pool. This does not mean that
every curator need use all the descriptors listed, but can instead select
those considered relevant to the collection. For example, a fruit tree
Developing crop descriptor lists
collection maintained for the purpose of representing a broad diversity
of ornamental forms would probably emphasize a set of descriptors
different from those used for a collection representing diversity in general.
Likewise, for temperate and tropical species, different descriptors and
descriptor states might be used to describe environmental conditions at
the site of collection, regeneration or evaluation.
Bioversity’s role
A major reason for the success of the descriptors developed by
Bioversity and its partners is that they are well researched and are
the result of extensive collaboration among scientists worldwide.
Bioversity’s role is to act as international facilitator and coordinator,
ensuring that the full extent of global knowledge and expertise is
relected in the crop descriptors, that a standard format is maintained
in the face of potentially conlicting opinions, and that the inal results
have the broad support and consensus of the majority of experts.
When dealing with mandate crops of the Consultative Group on
International Agricultural Research (CGIAR), Bioversity seeks the
scientiic advice of the relevant CGIAR centre and collaborates with
it in the production of the descriptors. This is crucial for descriptor
development since these centres have the expertise needed to
elaborate a high quality product as they conserve and work with
large and diverse collections of speciic crops.
Bioversity has taken the lead in the documentation of plant
genetic resources. The international status of the descriptor lists, as
well established guidelines for documentation, is illustrated by its
collaboration with international and national organizations, such
as The International Union for the Protection of New Varieties of
Plants (UPOV), Organisation internationale de la vigne et vin (OIV),
The World Vegetable Centre (AVRDC), CGIAR Centres, Instituto
Nacional de Investigación Agropecuaria (INIA), French Agricultural
Research Centre for International Development (CIRAD), Institut
national de la recherche agronomique (INRA), and a number of
universities and research organizations. Some indications of the
impact of descriptors that have been drawn in collaboration with
these sources are discussed below.
Impact of descriptors
An indication of the impact of descriptors can be seen in the
recommendations made during the Second Technical Meeting of Focal
Points for Documentation in East European Genebanks (Radzikow,
Poland, 1995):
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
The Meeting concluded that standardization of evaluation
and characterization descriptors is not desirable on a multi
crop basis. The crop-speciic descriptor lists, compiled in
consultation with relevant crop experts worldwide, provide the
crop-speciic standards (van Hintum et al. 1995).
This was also conirmed during the preparatory process for
the International Conference and Programme for Plant Genetic
Resources (ICPPGR) organized at Leipzig, Germany in 1996. The
country reports provided a further useful indication of the extensive
use of these descriptors; their use is also cited by many countries in
the State of the World Report on Genetic Resources (FAO 1996):
To derive an indication of the use of descriptor lists, 152
country reports were analysed in IPGRI HQ for the Leipzig
Conference. The results showed that descriptor lists have a high
degree of penetration and use at the international level. Of the
countries surveyed, 102 are undertaking characterization or
evaluation and speciied which descriptors they are using. Of
these countries, 93 (or 91%) use IPGRI descriptor lists alone
or in combination with other lists.
In 1999, the CG Secretariat published a ‘Synthesis of indings
concerning CG Case Studies on the Adoption of Technological
Innovations’ (Laliberté et al., 1999). The impact study was related
to the adoption of the crop descriptors developed for three different
crops. Some key conclusions could be drawn from the results of
this case study:
• IPGRI (now Bioversity International) descriptors are well known
international standards for the detailed description of crop
speciic resources and are used by the majority of germplasm
collection managers.
• Users consider the descriptors to be very useful for a range
of applications, such as characterization, standardization of
information, the establishment of databases, documentation of
accessions, creation of core collections, and data exchange.
Of the 143 germplasm collection managers responding to the
above survey regarding the use of descriptors, 80% used descriptors
in general and 69% used Bioversity International (ex-IPGRI)
descriptors, while the remaining 11% used their own descriptors
or those developed by UPOV and COMECON.
Developing crop descriptor lists
Introduction
One of the aims of developing international standards such as
descriptor lists is to make the most of biodiversity by describing crops
and species in a lingua franca and increasing access to this diversity
by the users of plant genetic resources, who in turn will beneit from
their economic and social values.
The crop descriptors more recently published include an
‘Introduction to the crop’ section, which aims to promote a speciic
crop to an audience not very familiar with it. Such a section in the
descriptors is particularly useful because it highlights different
values of crops, from nutrition to income generation, which might
not be apparent to user communities. It is also important because
it suggests a method of characterization and evaluation that can
be used to demonstrate potentials and beneits, as in the case of
Descriptors for Rocket. Another example is the list of Descriptors for
Date Palm, which lists the full spectrum of beneit opportunities (e.g.
use of dates to make vinegar or jams), which are not necessarily well
known among scientists and other users.
1. The concept of descriptor lists
When a species name is identiied and listed along with its accession
number, when different shapes of a fruit are described, when the
length of the leaf is measured or the number of accessions in the
collection of a crop species are recorded, observations are being made
on the speciic attributes of a particular plant, and each characteristic
is called a ‘descriptor’.
Descriptor lists include key attributes, characteristics or traits
of a crop, and set out the method used to measure and document
them, along with the relevant registration data.
Descriptor lists therefore aim to include information and data that
are relevant for different types of genebank operations for a speciic
crop or gene pool, from initial registration, through characterization,
evaluation and management, to their eventual use.
1.1 Descriptor definitions
Within the plant genetic resources community, a descriptor is deined
as an attribute, characteristic or measurable trait that is observed in
an accession of a genebank. It is used to facilitate data classiication,
storage, retrieval, exchange and use.
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
Example #01
Accession number
Flower colour
Plant height
A descriptor list is a set of individual descriptors used for the
description of germplasm of a particular crop or species (e.g. list
of Descriptors for Pistachio).
1.2 Descriptor elements
Each descriptor consists of a descriptor name, a descriptor state, and a
descriptor method explaining how the descriptor should be measured
and recorded. A descriptor state could be a quality, measurable
attribute or code.
Example #02
Stem pubescence
(descriptor name)
Observed at the stem base
(descriptor method)
3
Sparse
(descriptor state)
5
Intermediate
(descriptor state)
7
Dense
(descriptor state)
In Example 02, ‘stem pubescence’ is the descriptor name;
‘observed at the stem base’ is the descriptor method, and ‘sparse;
intermediate; dense’ are the descriptor states, with corresponding
numbering codes (3, 5, 7) assigned to descriptor states for ease of
documentation.
1.2.1 Descriptor names
The descriptor should have a full name that is descriptive, unambiguous
and as compact as possible.
Descriptor names are frequently composed of an object or item,
and a characteristic or attribute name.
Example #03
Accession number
Species name
Leaf colour
Flowering habit
Soil fertility
Developing crop descriptor lists
When choosing a descriptor name, it is essential to verify that the
technical terms are correct and that they are generally accepted and
understood by other users. The use of a glossary of botanical terms
is recommended (see Bibliography and further reference sources
listed in Appendix II).
1.2.2 Descriptor states
For a number of qualitative and quantitative descriptors, a descriptor
state is a clearly deinable state of expression to deine a characteristic
and harmonize descriptions. It represents the variation in the
observations or measurements made on a particular descriptor. Each
descriptor is allocated a corresponding numeric code for ease of data
recording and exchange.
Example #04
Leaf shape
1
Cordate
(descriptor state)
2
Oblong
(descriptor state)
3
Ovate
(descriptor state)
Reference materials can be used to help deine the various states of
expression of traits, and recommended resources include drawings,
check cultivars, colour charts, phenological scales, illustrations, and
lists of possible values or codes (if applicable). Examples of such
reference material are given in the following sections.
1.2.2.1 Drawings
Since collections of the plant genetic resources of a crop could be sited
anywhere, and large in number, a collection may not have access to
a standard reference (see Section 1.2.2.2), so simple line drawing or
pictures of stem branching, for example, are easier to refer to and
will help users to selecting states of expression of a trait, avoiding
confusion with environmental effects.
Figure captions should be brief, but complete, and should contain
the name of the relevant descriptor. If a igure is taken from or based
on another source, a full bibliographic reference to the source should
be included in an appendix of the descriptor list.
Example #05
Stem branching
1
Opposite
2
Alternate
3
Ternate
4
Mixed
See Figure 1 (overleaf)
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1
2
3
4
Figure 1. Stem branching
1.2.2.2 Reference standards and parameters
When a descriptor state is open to interpretation or dificult to
explain, reference standards or speciic parameters can be used to
clarify it.
Reference standards provide an objective baseline against which
measurements and comparisons can be made. They provide the
means to make observations more consistent and comparable.
Often, a common cultivar is used as a standard and the standard
reference is then used as a check. Check cultivars and standard
references also provide useful corollary information to gauge the
performance of the accessions being tested. Check cultivars should
be widely available and known.
Example #06
Blade shape of mature leaf
Standard reference
1
Cordate
Vitis cordifolia
2
Wedge-shaped
Vitis riparia
3
Pentagonal
cv. Chasselas blanc
4
Circular
cv. Clairette
5
Reniform
cv. Rupestris du Lot
1.2.2.3 Colour charts
A fruit colour descriptor that describes different shades of a colour
would beneit greatly from the use of a colour chart or reference
standard, if available. Without a reference for comparison, descriptor
states such as ‘light green’, ‘green’ and ‘dark green’ can not be scored
consistently and objectively.
Developing crop descriptor lists
9
Example #07
Fruit colour
RHS colour code (RHS, 1986)
1
Light green
145A
2
Green
146A
3
Dark green
147A
1.2.2.4 Parameters
It is strongly recommended to use actual measurements (cm, g, mm)
for making good use of quantitative data (i.e. continuous variation)
for genetic diversity analysis. Actual measured values can also give
us statistical data to assess variation within an accession. Character
states as listed below should be used only when measuring is very
dificult.
For instance, a fruit length descriptor should specify relevant
ranges of measurements to avoid misinterpretation by different
users. Without these ranges, descriptor states cannot be scored
consistently or objectively.
Example #08
(WRONG)
(RIGHT)
Fruit length
Fruit length
1
Very short
1
Very short
2
Very short to short
2
Very short to short
(>2 – 4 cm)
(<2 cm)
3
Short
3
Short
(>4 – 6 cm)
4
Short to intermediate
4
Short to intermediate
(>6 – 8 cm)
5
Intermediate
5
Intermediate
(>8 – 10 cm)
6
Intermediate to long
6
Intermediate to long
(>10 – 12 cm)
7
Long
7
Long
(>12 – 14 cm)
8
Long to very long
8
Long to very long
(>14 – 16 cm)
9
Very long
9
Very long
(>16 cm)
1.2.3 Descriptor methods
A descriptor method describes in detail how and under what
conditions a descriptor is measured or scored. The description
method facilitates accurate interpretation of results and provides a
protocol to be universally and consistently applied.
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Example #09
Plant height [cm]
Recorded at maturity, measured from ground level to the top of spike, excluding awns.
Average of 5 randomly selected plants
It is important to use technically correct terminology in
descriptions. If possible, record any bibliographical references
consulted and list them in an appendix to the descriptor list. This
will allow others to verify the terminology and methodology.
References commonly used in the development of descriptors are
listed in Appendix II.
Descriptor method elements comprise:
• an Object;
• a Condition; and
• a Sampling procedure.
These are considered more fully below.
Object
This deines the exact part(s) of the plant to be observed or measured.
A measurement of plant height that does not specify exactly between
which points the measurement should be taken is incorrect, because
different people may use different measuring points. In the case of
quantitative descriptors, a unit of measurement should be deined. It
is recommended to use only the Système International d’Unités (SI)
(See Appendix II) and to include the units to be applied in square
brackets following the descriptor name.
Example #10
Leaf lamina length [mm]
Recorded at the widest point. Average of 10 fully developed leaves taken from three
different adult trees. Use apical lealet in the case of compound leaf.
Condition
This deines the conditions under which the observation is made,
such as duration, plant growth stage, phenological condition,
temperature, humidity, ‘priming’ (pre-observation treatments),
and speciications of particular equipment if required. In the above
example (Example 10), ‘fully developed’ is the condition.
Sampling
The number of samples on which the observation is based should
be given, thus providing an indication of data accuracy within the
Developing crop descriptor lists
11
method. The type of method used for sample selection (random,
stratified, etc.) should also be indicated. When variation of a
characteristic within the accession is prevalent, it is essential to
describe how the samples are to be selected and how many samples
are needed.
2. Descriptors and derived standards
Exchange of information requires compatibility of documentation
systems. Documentation systems can be fully compatible even if
different hardware or software is used, but this implies consensus
regarding standards for exchange of information, and consistency in
the implementation of those standards.
Bioversity has developed three types of standard (see
Figure 2):
• Crop descriptors,
• Multi-crop passport descriptors (MCPD) (FAO/IPGRI), and
• Descriptors for genetic marker technologies.
CROP DESCRIPTORS
Categories
Passport
(Accession, collecting,
ethnobotanical data)
Multi-Crop Passport Descriptors
(MCPD)
(FAO/IPGRI)
Management
Site and Environment
Characterization
Evaluation
Figure 2. Descriptors and derived standards.
Genetic Marker Technologies
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2.1 Crop-specific descriptors
The descriptors lists are targeted at curators, breeders, scientists and
others managing crop genetic resource collections. It is an important
tool in standardizing documentation systems, providing as it does
an international format and a universally understood ‘language’ for
plant genetic resources data (see Section 3).
2.2 Multi-crop passport descriptors (MCPD)
With the integration of collections at the national level into multicrop
collections, it became evident that common descriptors needed to
be more consistent across crops. As a result, Bioversity and FAO,
with substantial contributions from European countries through
the European Cooperative Programme for Crop Genetic Resources
Network (ECPGR Network) and CG Centres through the Systemwide Information Network for Genetic Resources (SINGER
system), developed a subset of passport descriptors: the FAO/
IPGRI List of Multi-crop Passport Descriptors (MCPD) (Alercia et
al. 2001).
The MCPD list is a reference tool that provides international
standards to facilitate germplasm passport information exchange
across crops. These descriptors are compatible with the Bioversity
crop descriptor lists, with the descriptors used for the FAO World
Information and Early Warning System (WIEWS) on plant genetic
resources, with CG Centres and with European countries through
the EURISCO Catalogue. In 2005, the MCPD list was fully adopted
in the Passport Module for the development of the GERMINATE
database (which integrates genotypic and phenotypic information
for plant genetic resources collections) in the Generation Challenge
Programme, and many other initiatives. The MCPD list has had a
very positive effect on the establishment of central crop databases,
especially in Europe.
2.3 Descriptors for genetic marker technologies
This list of descriptors deines a minimum set of data needed to
describe accessions using biochemical and molecular markers, and
deines community standards for documenting information about
genetic markers. The document, which was originally based on
some of the descriptors listed in the traditional evaluation category
of the crop descriptors, is targeted at researchers using genetic
marker technologies, to facilitate the generation and exchange of
standardized genetic marker data. It also provides descriptions of
content and coding schemes that can assist in computerized data
exchange.
Developing crop descriptor lists
3. Crop-specific descriptors
The crop descriptor lists provide the plant genetic resources
community with internationally recognized guidelines for the
standardized description of accessions of different crops. As noted
earlier, this series of descriptor lists has had a major impact in the
global plant genetic resources community and in the management
of plant genetic resources.
The purpose of this standardization is to manage genetic
resources, enhance the exchange of information, and increase the
eficiency of communication among germplasm scientists and users
of plant genetic resources. An additional purpose is to facilitate
the use of germplasm resources by the plant genetic resources
community.
3.1 Crop descriptor categories
To facilitate the maintenance, retrieval and updating of information
on accessions, it is advisable to organize descriptors into practical
sets. Bioversity has classiied them into ive main categories, and
encourages the collection of data for all ive types of categories.
These categories are:
• Passport
• Management
• Environment and site
• Characterization
• Evaluation
Data from the irst four categories should be available for every
accession. The number of descriptors selected in each of the categories
will depend on the crop or species and its character. Descriptors
listed under Evaluation allow for a more extensive description of an
accession, but generally require replicated trials over time.
It is recommended that information be produced by closely
following the descriptor list with regard to ordering and numbering
of descriptors, using the descriptors speciied, and using the
recommended descriptor states.
In general, passport, environment and site categories are similar
for all crops. Recent Bioversity descriptor lists and the MCPD list
can be used as reference sources. For the deinition of Management
descriptors, descriptor lists of crops with similar maintenance
regimes can be consulted. However, Characterization and Evaluation
descriptors are very crop speciic, and must be deined speciically
for every new crop. A checklist that can be used in the development
of such descriptors can be found in ‘Making descriptors work’
(Sections 12 to 14, pp. 43–44).
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3.1.1 Passport category
Passport data provide the basic information used for the general
management of an accession (including registration at the genebank
and other identiication information), and describe parameters to be
observed when the accession is originally collected. They constitute
a crucial element in the registration process when the sample is
registered in the genebank as an accession.
Passport category is usually divided into two sections:
• accession descriptors; and
• collecting descriptors.
Accession descriptors are identiication data related to the
registration of the sample at the genebank. These descriptors are
fundamental to the documentation system since descriptors such
as accession number, genus and species can be related to different
accession-speciic data.
Example #11
Accession number
Genus
Species
Donor number
A large part of the passport descriptors category for each sample
is recorded during germplasm collecting. These data describe in
detail the environment from which the germplasm originates.
Ethnobotanical descriptors, such us ethnic group, local vernacular
name, plant uses and parts of the plant used, form an increasing
proportion of these descriptors.
Example #12
Collecting institute
Country where collected
Collecting date
Collecting site
In order to help users during data collection in the ield,
Bioversity has developed a collecting form (see Appendix V for
an example of a collecting form for Allium spp.), which is usually
included as an appendix to the crop descriptor lists.
It is important that passport data are as complete as possible
from the beginning, since it is often dificult or even impossible to
ill in gaps at a later stage. Passport descriptors are to a large extent
Developing crop descriptor lists
15
applicable to all crops and species. To facilitate international access
and exchange of information, it is strongly recommended that the
MCPD list be used as a reference (Alercia et al. 2001). The full MCPD
list can be found in Appendix III.
3.1.2 Management category
Management descriptors provide the basis for the day to day
management of accessions in a genebank and assist with their
multiplication and regeneration. The genebank curator must ensure
that these descriptors are recorded during multiplication, storage,
maintenance or regeneration of each accession. Management
descriptors vary according to crops or gene pools. However, collections
with similar management regimes that are kept as seed, in the ield,
in vitro or as cryopreserved collections often have many descriptors
in common. Recent descriptor lists of similar crops can be used as a
reference basis for collections that are managed in ield genebanks
(e.g. Descriptors for Rambutan, and Descriptors for Jackfruit).
Typically, the management category is divided into two sections,
according to the crop being described:
• plant or seed management descriptors; and
• multiplication or regeneration descriptors.
Management descriptors provide information on the amount of
seed available and the viability of the seed, along with the date of
the germination test. It also provides information on the number
of replicates of an accession in a ield genebank. The location of
an accession in the genebank and the places to where it has been
distributed are usually provided, as well as the location of an
accession in a ield genebank. When relevant, cryopreservation and
in vitro descriptors are also included.
Example #13
Sowing date
[YYYYMMDD]
Harvest date
[YYYYMMDD]
Seed germination at storage
[%]
3.1.3 Environment and site category
Descriptors in this category describe environmental and site-speciic
parameters, particularly in association with characterization and
evaluation trials. They are important for interpreting the results of
those trials due to genotype × environment interaction. However,
the level of detail needed for describing the site and environment
of the characterization and evaluation will vary according to the
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crop, and users will select only those relevant to the crop being
described.
Environment and site category are usually divided into two
sections:
• characterization and/or evaluation site descriptors; and
• site environment descriptors.
Descriptors for the characterization or evaluation site are the
same for all crops, and any recent descriptor lists can be used for
reference (e.g. Descriptors for Citrus). They typically include the
country of characterization and/or evaluation, the location (latitude
and longitude), elevation, and planting and harvest dates of the
characterization or evaluation trials.
Example #14
Country of characterization and/or evaluation
Site
Latitude
Longitude
Elevation
The descriptors listed under Site environment will be useful during
collecting activities in order to describe the collection or sampling
source environment, and the characterization and evaluation site
environments. They include standard descriptors for soil [matrix
colour, depth, pH, texture class(es)], topography, slope and climatic
information such as rainfall and temperature. Site environment
descriptors can be found in Appendix IV.
Example #15
Topography
Higher-level landform
Slope
Slope aspect
3.1.4 Characterization category
Describing plants is one of the most important ways that plant
genetic resources users can contribute to germplasm utilization and
conservation efforts.
Descriptors in this category are observations about plant
characteristics that can be used for diagnostic purpose to describe
the plants or trees of an accession and differentiate them from those
belonging to another accession. Therefore, data gathered during
Developing crop descriptor lists
characterization are used for distinguishing accessions. They provide
information on the type of plants that are in a collection, and information
potentially useful in crop development. They may also provide a tool
to evaluate claims of novelty (helpful for variety protection or plant
patents, as in the case of the UPOV Technical Guidelines).
Descriptors included under characterization can be considered as
the basis for taxonomic classiication, since they are mostly related
to botanical characteristics. Nevertheless, some of them have agroeconomic signiicance as well, for example colour of mango fruit is
an important market trait.
Characterization descriptors pertain to those traits that tend to
be highly heritable traits (i.e. traits that do not change with different
environments, that means they show none or low genotype ×
environment interactions). The characters scored are visible to
the naked eye, allow for quick and easy discrimination between
accessions, and are generally controlled by major genes. They often
provide additional information that assists in the identiication or
maintenance of the material (e.g. growth habits, leaf shapes, seed
shapes).
Characterization descriptors may also include a limited number
of additional traits considered to be desirable by a consensus of
users of a particular crop.
3.1.5 Evaluation category
Evaluation descriptors are of great interest to plant breeders and are
useful in crop improvement and the domestication of new crops. They
include descriptors such as yield, agronomic and other economically
important traits, biochemical traits (content of speciic chemical
compounds, dry matter content, etc.), and reaction to biotic and abiotic
stresses. It should be noted that, until 2004, crop descriptors included
a biochemical and molecular section describing the basic methods
most commonly used. With the release of the list of descriptors for
Genetic Markers Technologies (see http://www.bioversityinternational.
org/Publications/pubile.asp?id_pub=913) in February, 2004, those
sections are no longer included in the crop-speciic descriptors. The
user is encouraged to follow the most recent list of descriptors for
markers published on the Bioversity Web site.
The expression of many characteristics in the evaluation category
is subject to genotype and environment interactions and usually
shows high genotype × environment interactions relecting the
inluence of the environment in which they are grown on the
expression of gene(s), and are usually multigenic, involving minor
genes, (where the genetic control of a trait results in the phenotypic
expression varying from place to place and over seasons and years).
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Observation of these descriptors may involve the use of simple to
complex techniques and equipment.
To score evaluation descriptors, it is often necessary to use
appropriate experimental designs and statistical analyses trials
that are much more complex and resource intensive than is
necessary for characterization. Since evaluation descriptors
are influenced by environmental conditions, curators, breeders
and researchers conduct replicated trials over years to obtain
objective results for these traits. Evaluation is generally carried
out as part of a breeding programme and in collaboration with
other crop improvement scientists, such as pathologists and
entomologists, and also with farmers (various participatory
methods of crop improvement), where germplasm undergo
evaluation for specific traits. Ideally, these results are then
fed back to the originating genebank in order to complement
existing data.
Descriptors listed under biotic stress susceptibilities (pests and
diseases) should include both speciic and common names.
Example #16
Fungi
Alternaria sesami
Leaf spot and blight
Cercospora sesami
Leaf spot
Colletotrichum spp.
Anthracnose
Recently published descriptor lists are comprehensive, with
asterisked characterization and evaluation descriptors indicating
the minimum set of highly discriminating characteristics that
should be recorded for each accession. Asterisked descriptors are
particularly useful indicators of diversity in collections and for
international harmonization of documentation systems.
4. Similarities to and differences from other
technical guidelines
Over the years, different guidelines for plant genetic resources
documentation have been developed by UPOV, COMECON, USDAGRIN and others, in addition to those developed by Bioversity and
its predecessors. In addition, several national programmes have been
developing descriptors for crops of national interest and for which
internationally accepted lists were not available. Below is a short
summary and description of the more commonly used descriptor
lists.
Developing crop descriptor lists
4.1 Union Internationale pour la Protection des
Obtentions Végétales
The Technical Guidelines developed by the Union Internationale pour
la Protection des Obtentions Végétales (UPOV) have been developed
speciically for testing the distinctness, uniformity and stability (DUS)
of new cultivars of crops (UPOV 1989, 1993). DUS traits are central to
the breeder’s work since they are necessary to obtain legal protection
for a bred variety.
UPOV descriptor lists are constructed with the thoroughness of
legal documents. Requirements for the minimum amount of seed,
number of vegetation periods, minimum number of plants, and
maximum number of aberrant plants are deined. Precise rules for
scoring are given, along with example varieties for each trait and
level of manifestation. Many countries have adopted the UPOV
guidelines for identifying and registering new plant varieties.
UPOV lists contain data that correspond to Bioversity categories
of characterization and preliminary evaluation. The objective and
interpretable scoring of traits is a clear advantage of this system
(van Hintum et al. 1995). Nevertheless, use of the UPOV Technical
Guidelines by the plant genetic resources community is limited due
to the high number of standard cultivars used and the fact that these
standards are based on modern cultivars, making comparison with
exotic material or wild species dificult.
4.2 Council for Mutual Economic Aid
In 1977, the member countries of the Council for Mutual Economic
Aid (COMECON) joined forces to develop descriptor lists for crops
of primary economic importance. By 1990, 48 bilingual (Russian/
English) descriptor lists had been published.
The passport category of these descriptor lists contained 13 ields.
In addition to descriptive data, the characterization category (six
ields) contained detailed geographical information on the location
of collections in eight COMECON countries: Bulgaria, Cuba,
Czechoslovakia, Hungary, Mongolia, Poland, Romania and USSR.
The characterization descriptors included data on morphology,
biology, disease and pest resistance, chemical composition,
economic utilization and other descriptors; botanical keys were
also included.
An international databank was planned that would be accessible
to all plant germplasm users within the framework of COMECON
activities. After the abolition of COMECON, the N.I. Vavilov AllRussian Scientiic Research Institute of Plant Industry (VIR) used
the experience to develop a databank for the worldwide collections
conserved at the institute.
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4.3 United States Department of Agriculture Genetic
Resources Information Network (USDA-GRIN)
The US National Plant Germplasm System (NPGS) has developed
descriptor lists for many major food plants. Descriptor lists allow
NPGS curators to enter plant trait data into the Genetic Resources
Information Network (GRIN) database (see USDA-GRIN, no date,
in references).
These lists match the Bioversity International format for
characterization and evaluation categories and for use of the
descriptors. They are linked to accession numbers, but do not
contain descriptors for passport data (accession and collecting).
They also omit management, site and environment data.
Developing crop descriptor lists
Gathering and analysing data
When deining descriptors, there are a range of criteria that can be
applied to select the most appropriate or practical descriptors. Among
these, the following should be considered:
• Type of data.
• Type of scales.
• Resolution, complexity and cost.
• Methods for collecting data.
• Experimental design.
• Scoring, coding and recording of descriptors.
• Numerical versus alphanumeric coding schemes.
5. Types of data
When determining how a certain characteristic or trait should be
scored (that is, the different states of expression a descriptor can take),
it is useful to classify them into two broad categories:
• qualitative data; or
• quantitative data.
It is sometimes desirable or necessary to convert or transform
the data between the two categories, such as for statistical analysis
purposes. However, it should be noted that when quantitative data
are converted to qualitative data, commonly used information items
such as shape, colour and texture are lost, yet these are the most
commonly used descriptors. Studies conducted on scoring show
that scoring and conversion methods using qualitative data may
be problematic and can create bias (except for experts). As such,
readers should be cautious when converting data.
5.1 Qualitative data
Qualitative data, such as type of sample received, are not computable
by arithmetic calculations and are expressed in discontinuous states.
They are self-explanatory and independently meaningful labels or
names that determine the class or category in which an individual,
object or process falls. All possible states are necessary to describe
the full range of a characteristic, and every form of expression can
be described by a single descriptor state; the order of states is not
important.
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Example #17
Type of material received
1
Seed
2
Seedling
3
Fruit
4
Shoot
5
Pollen
For some qualitative descriptors, such as colour descriptors, it is
important to know whether:
• a inite number of states exist;
• all states need to be separately recorded; or
• all states can be ranked in a meaningful way that will merge a
group of states under one name.
In other cases, the range of expression is at least partly continuous,
but varies in more than one dimension:
Example #18
Leaf colour
1
Green
2
Yellow
3
Brown
4
Bluish green
Example #19
Seed coat texture
1
Smooth
2
Partially rough
3
Radially rough
4
Partially radially rough
5
Reticulately rough
6
Partially reticulately rough
99
Other
(specify in descriptor Remarks)
In the examples above, where the level of detail can be open
to interpretation by different users and can complicate future
statistical analysis, it is recommended to carefully select the most
representative states or include colour chart codes, reference
standards or drawings, as in the examples below.
Developing crop descriptor lists
23
Including the most representative states of expressions and splitting the
descriptor:
In some situations, it may also be possible to split the qualitative
characteristic into a qualitative and a pseudo-quantitative characteristic,
such as in the following situation:
Example #20
Flower colour
1
Light yellow
2
Medium yellow
3
Dark yellow
4
Green
5
Light pink
6
Medium pink
7
Dark pink
It is advisable to split this descriptor into the following
characteristics:
Example #21
Flower colour
1
Yellow
2
Green
3
Pink
Intensity of flower colour
3
Weak (Light)
5
Medium
7
Strong (Dark)
Including RHS colour chart codes:
Example #22
Leaf colour
(RHS colour chart code)
1
Green yellow
(145-B)
2
Yellow green
(150-A)
3
Green
(128-A)
4
Bluish green
(120-B)
5
Dark green
(135-B)
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Including reference standards:
Example #23
Leaf colour
(Reference standard)
1
Green yellow
Deglet nour
2
Yellow green
Mejhoul
3
Green
Besser Helou
4
Bluish green
Ammari, Menakher
5
Dark green
Ghars
Including drawings:
Example #24
Seed coat texture
(See Figure 3)
1
Smooth
2
Partially rough
3
Radially rough
4
Partially radially rough
5
Reticulately rough
6
Partially reticulately rough
99
Other (specify in descriptor Remarks)
1
2
3
4
5
6
Figure 3. Seed coat texture.
Developing crop descriptor lists
Decisions on whether descriptor states need to be recorded separately
or can be merged into a group will depend on the importance of the
state in describing (within and between accessions), the diversity of
the crop or gene pool. In general, the descriptor states of qualitative
characteristics are given consecutive numbers starting with ‘1’ and
often have no upper limit.
With emerging imaging techniques, it is possible to convert the
qualitative data (where the range of expression is continuous) to
quantitative data, such as in colour and texture descriptors. In this
case, the data can also be analysed quantitatively.
5.2 Quantitative data
Quantitative data consist of measures or counts that use numerical
values, allowing statistical analyses, for which descriptions such as
means and standard deviations are meaningful.
Quantitative descriptors are those in which the expression
covers the full range of variation from one extreme to the other.
Different states of expression of quantitative data can be recorded
using discrete (countable data, such as “number of plants”), or
continuous (measurable data, such as plant height, weight, length)
scales.
Many quantitative characters that are continuously variable are
recorded on a 1 to 9 scale, in which ‘1’ stands for ‘very short’ or
‘very low’, and ‘9’ corresponds to the highest expression such as
‘very high’ or ‘very long’ (see Section 10).
Nevertheless, the use of exact measurements is highly
recommended, especially for easily measurable characteristics
such as length or width, because there is no room for subjective
interpretation. The use of ‘classes’ can prevent or complicate
considerably statistical analysis of data. Such analysis is becoming
increasingly important as many genebanks are now focusing
on the use of conserved germplasm and on measuring withinaccession (within-population) variation. It is easy to re-classify
after measurements have been made, but it is not possible to
translate those classes back to the exact data.
Sometimes only a selection of the states is described (e.g. 1, 3,
5, 7 and 9) for such descriptors. Where this occurs, the full range
of codes is available for use by extension of the given codes or by
interpolation between them.
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Example #25
(A full scale)
Length of peduncle
1
Very short
(<3 cm)
2
Very short to short
(3-5 cm)
3
Short
(6-8 cm)
4
Short to intermediate
(9-10 cm)
5
Intermediate
(11-13 cm)
6
Intermediate to long
(11-13 cm)
7
Long
(14-16 cm)
8
Long to very long
(17-19 cm)
9
Very long
(>19 cm)
Example #26
(A reduced scale)
Length of peduncle
1
Very short
(<3 cm)
3
Short
(6-8 cm)
5
Intermediate
(11-13 cm)
7
Long
(14-16 cm)
9
Very long
(>19 cm)
6. Types of scales
There are several types of scales used for creating scoring methods.
The use of a particular scale will depend on the type of data
(qualitative or quantitative) to be recorded. The scale level will
depend on the different states of expression of the characteristic,
and on how they are recorded.
The most commonly used scales in the descriptors series are:
nominal, ordinal (discrete), continuous and binary scales (See
Figure 4).
The new techniques becoming available for converting qualitative
to quantitative data based on computer-image analysis have the
potential to exert a signiicant inluence on selecting the type of
scale to use in particular contexts.
Developing crop descriptor lists
27
DATA AND SCALES
QUANTITATIVE
QUALITATIVE
NOMINAL
ORDINAL
BINARY
CONTINUOUS
Figure 4. Types of data and scales.
6.1 Scales for qualitative characteristics
Qualitative characteristics can be measured using nominal, ordinal or
binary scales. Within the continuum view, some descriptors, such as
shape and texture, can be measured (quantitatively) using continuous
scales. Their states of expression are often coded with sequential
numbers, whereby special groups, such as ‘Others’, are given a special
(’99’) value to set them apart from other descriptor states in order to
accommodate new descriptor states if new germplasm is collected
that exhibits a new form of a particular characteristic. The descriptor
state ‘Others’ (listed last) is usually listed when it is presumed that
other states may exist in other collections; further information may
also be added in the ‘Remarks’ ield. In the following example, room
has been left under ‘99’ to accommodate further shapes, currently
unknown but that might exist in other collections.
Example #27
Fruit shape
1
Round
2
Ovate
3
Oblong
4
Elliptic
99
Other (specify in the descriptor Remarks)
If a new shape is discovered in new germplasm collected (such
as ‘obovate’), a new sequential code number should be assigned
(see the example below, where ‘99’ might be used as the code for
potential new shapes until they are conirmed).
DISCRETE
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Example #28
Fruit shape
1
Round
2
Ovate
3
Oblong
4
Elliptic
5
Obovate
99
Other (specify in the descriptor Remarks)
The states can be better deined by adding standards or check
cultivars to the descriptor states to clarify the different states of
expression of each trait.
6.1.1 Qualitative descriptors using nominal scale
Nominal scales provide code numbers for traits that are deined
by text (names or labels). They do not follow a numerical or logical
order or ranking sequence and the codes are arbitrary numbers (e.g.
pubescence, colour, shape).
Example #29
Fruit colour
1
Yellow
2
Orange
3
Red
4
Brown
5
Purple
99
Other (specify in the descriptor Remarks)
Example #30
Leaf type
1
Tendril
2
Phyllody
3
Simple (lamina not bifurcated into lealets)
4
Bipinnate
5
Multipinnate
99
Other (specify in the descriptor Remarks) )
Developing crop descriptor lists
29
6.1.2 Qualitative descriptors using ordinal scale
These scales are similar to nominal scales, but have an order (e.g.
data values are ranked in a numerically meaningful way). Ordinal
scales rank traits from low to high. They result from visually assessed
quantitative traits.
Example #31
Intensity of anthocyanin coloration
1
Low
2
Intermediate
3
Strong
Example #32
Plant growth habit
Recorded at the beginning of lowering period. (See Figure 5)
1
Erect
2
Semi-erect
3
Spreading
4
Prostrate
1
2
3
4
Figure 5. Plant growth habit.
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6.1.3 Qualitative descriptors using a binary scale
Qualitative characteristics with only two categories (absent vs.
present) are described by a special form of nominal scale. They can be
scored on a binary scale (yes/no; absent/present) and the following
standard coding should be used:
Example #33
Leaf colour variegation
0
Absent
1
Present
Example #34
Fruit cracking
0
No
1
Yes
Example #35
Leaf glands
0
Absent
1
Present
Here, ‘0’ is used to indicate the absence of the characteristic or
attribute, or that the trait is not observed.
6.2 Scales for quantitative characteristics
Quantitative characteristics are recorded by measuring, counting or
weighing, and can be recorded using continuous or discrete scales.
6.2.1 Quantitative descriptors using a continuous scale
Continuous scales refer to the exact measurement of a trait and can
assume an ininite number of real values. The best way of recording
quantitative descriptors is by scoring the measurement in exact
units, using the international unit system (Système International
d’Unités – SI) (see Appendix II).
Example #36
Peduncle length [cm]
Developing crop descriptor lists
31
Quantitative data for such descriptors are measured on a continuous
scale with well-deined units of measurement. As noted earlier,
quantitative data recorded on continuous scales have a greater
potential for statistical analysis than those recorded on discrete scales.
Conversion from a continuous scale to a discrete scale is possible, but it
is not possible to convert from a discrete scale to a continuous scale.
Example #37
Peduncle length
30 cm
= very small
Peduncle length
very small
= ????
6.2.2 Quantitative descriptors using a discrete scale
Quantitative descriptors can be scored on a discrete scale and can
take a inite or countable number of values. This is useful when one
wants to use bar or pie charts to describe the variation found. This
also allows the visualization of variation in a very simple way. This
system is only used when precision is not required and the objective
is only visualization of variation present. In these cases, a certain
range of (continuous) values is grouped into discrete classes. These
descriptor states, representing discrete classes, are a good measure
for describing diversity within a crop or gene pool.
Example #38
Number of stolons
The discrete quantitative data of this descriptor are assessed by
counting rather than measuring using a metric scale. An accession’s
value is determined by comparing it with a set of values assigned
to that trait.
For some descriptors, the fact that they can be ordered from ‘very
low’ to ‘intermediate’ to ‘very high’ is suficient, without exactly
deining the distances between the classes. However, these states
are only possible after counting and knowing what is, for example,
the minimum and maximum number of stolons.
In a common coding scheme for this type of scale, the descriptor
state is scored between ‘1’ (weakest expression) and ‘9’ (strongest
expression), as shown below. As a general rule, descriptor states are
formed in such a way that for comparing expressions, a reasonable
word pair is chosen (e.g. Weak/Strong; Short/Long; Small/Large).
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Example #39
Quantitative descriptors using a discrete scale
1
Very low
2
Very low to low
3
Low
4
Low to intermediate
5
Intermediate
6
Intermediate to high
7
High
8
High to very high
9
Very high
Sometimes this list is abbreviated by listing only states 3, 5, and
7. Where this has occurred, the full range of codes is available for
use by extension of the codes given or by interpolation between
them.
Example #40
Density of oil glands on fruit surface
3
Low
5
Intermediate
7
High
[no. per sq. cm]
(< 40/cm2)
(50 – 80/cm2)
(>90 cm2)
The validity of exact measurements should be emphasized
again because of their potential for data analysis and because
transformation is minimal compared with discrete scale data.
There is also a ‘limited’ range of states comprising a 1 to 5 scale. It
is used where the range of expression of a trait is physically limited
at both ends and it is not appropriate to divide the expression into
more than three intermediate states.
Example #41
Stem growth habit
1
Erect
3
Semi-erect
5
Prostrate
When deining descriptors for different intensities of the same
colour hue, the descriptor and descriptor states may be presented
as pseudo-quantitative data (if they fulil the requirements for a
quantitative characteristic).
Developing crop descriptor lists
33
Example #42
Intensity of green colour
3
Light
5
Intermediate
7
Dark
Example #43
Intensity of anthocyanin coloration
3
Weak
5
Intermediate
7
Strong
Although this type of scheme allows a ranking of scores, it is not
as precise and objective as measurement on a continuous scale. This
is especially true when dealing with observations made by different
observers, as individual bias leads to differences in scoring of traits.
More deinition may be added by providing examples or
standards to deine each category in more detail, such as standard
references.
Example #44
Number of lobes in mature leaf
Standard reference
3
Few
Chardonnay
5
Intermediate
Chasselas blanc
7
Many
Hebron
7. Resolution, Complexity and Costs
7.1 Level of precision required
The preferred way of describing, for example, plant height, is by
actual values measured in metres, cm or mm. It is essential to specify
the unit of measurement in all cases.
Plant height can also be described in terms of discrete classes:
Example #45
Plant height (range)
3
Short
5
Intermediate
7
Long
(<20 cm)
(30 – 50 cm)
(>60 cm)
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Quantitative data on a continuous scale has a greater potential
for allowing statistical analysis than quantitative data measured
on a discrete scale, and the use of exact measurements avoids
differences in interpretation by different users. This does not mean
that characteristics described using only discrete scale are less
valuable; they are important in being diagnostic in nature, but could
complicate future statistical analysis. The unit of measurement is
also an indication of the level of resolution that is required.
If diversity of a speciic trait (e.g. plant type) can be described by
two very distinct states (dwarf type, tall type), a visual scoring of
the two descriptor states could be suficient and may be preferable
to measuring every accession and recording the plant height in cm;
this will save time and work.
It is good practice to keep observations and measurements as
simple as possible. The objective of measurements is to determine
how the trait of a speciic accession compares with the diversity of
the collection. When developing descriptors, one should remember
that specialist knowledge and specialist equipment could be readily
available at a particular institution, but this might not be the case
for other institutions. In addition, methodologies that might be
executed at one institution without problems, might present
extraordinary logistical problems for institutions dealing with
different combinations of crops or climatic environments (e.g. an
institution working with one crop in comparison with a multicrop
institution).
Where a term is open to interpretation, it is best to try to make a
direct comparison with a well known standard or to use an absolute
measurement. It is also essential to evaluate the trait in a number
of randomly selected plants or a representative sample to ensure
that the full range of variation present is described.
7.2 Complexity of the measurement or observation
The complexity of measurement or observation is dependent on
extent of priming, special equipment or speciic expertise required to
execute a method of measurement. The more complex a procedure,
the greater the chance of making mistakes during its execution,
requiring greater care and attention to detail.
7.3 Cost per measurement
It is recommended that the costs for each measurement be
carefully analysed, in terms of both staff time and materials. To
have comprehensive minimum characterization data, the costeffectiveness of observing descriptors is an important consideration.
However, it must be noted that the value of data recorded is in the
Developing crop descriptor lists
accuracy of its recording. Hence, it may be best to focus on a few
priority measurements when funds are a major limitation.
8. Methods for collecting data
As a general rule, when developing descriptors, it is important to
determine which order or method should be followed. As a rule
of thumb, the order of descriptors should follow a botanical or a
chronological order.
Botanical order
• Seedling (e.g. hypocotyl colour, pubescence)
• Plant (e.g. growth habit, crown shape)
• Root (e.g. shape, surface, lesh colour, system)
• Stem (length, pubescence)
• Leaf (blade, petiole, stipule)
• Inlorescence
• Flower (calyx, sepal, corolla, petal, stamen, pistil)
• Fruit
• Seed/grain
Chronological order (order of development)
• Seedling stage
• Vegetative phase
• Reproductive phase
• Pre-harvest
• Post-harvest
Within these alternative ordering methods, it is suggested to
follow the most immediately visible characteristic, such as:
• Attitude
• Colour
• Shape
• Individual parts of the organ, such as base shape, apex shape
and margin
• Height
• Length
• Width
• Other characteristics
9. Experimental design
For a widely applicable, uniform and more meaningful information
system, the data need to be standardized, not just with regard to
terminology but also in terms of measurement. This encompasses
measurement techniques, data recording, units of measurement and
encoding methods – all of which are relevant to the experimental
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design – when assessing the descriptors and their diversity, and will
vary according to characterization or evaluation trials.
A useful guide for genebank managers who undertake evaluation
trials on their genetic resources collections is found in Technical
Bulletin No. 4 (IPGRI, 2001). The manual covers the stages involved
in an experimental programme, from the determination of objectives
for each trial, to the methods used for analysis, and provides general
guidelines for managers to adapt to speciic crops. It speciically
focuses on evaluation of large collections.
The main issues to consider in the design of an experiment
are:
• Set precise objectives (including background and justiication
for the proposed research).
• Experimental design.
• Decide on analysis strategy.
• Select treatments (number of accessions per trial, control
treatments).
• Specify sites (plots and layout).
• Indicate levels of measurement (individual plant, plot or trial
level).
• Collect data and analyse.
10. Scoring, coding and recording of descriptors
In defining individual descriptors, many aspects need to be
considered. The following internationally accepted norms for the
scoring, coding and recording of descriptor states are promoted
worldwide by Bioversity International.
• The Système International d’Unités (SI) units should be used;
the units to be applied for each descriptor are given in square
brackets following the descriptor name.
• The Royal Horticultural Society (RHS) Colour Charts for
colour descriptors is strongly recommended for all ungraded
colour characters (the precise chart should be speciied in the
section where it is used). The observation of colour by eye may
compromise accuracy in determining exact colours, depending
on each individual user; a colour chart is a useful tool for
assigning relevant colour codes to different colour states.
• For all quantitative descriptors, it is recommended to use actual
measurements. Where resources are insuficient to take actual
measurements, quantitative characters that are continuously
variable can be recorded on a 1–9 scale, as follows:
Developing crop descriptor lists
37
Example #46
Continuously variable attribute
0
Absent
1
Very low
2
Very low to low
3
Low
4
Low to intermediate
5
Intermediate
6
Intermediate to high
7
High
8
High to very high
9
Very high
These descriptor states (or states of expression) and corresponding
descriptor codes are provided to deine each characteristic and to
harmonize descriptions. Each state is allocated a corresponding
numerical code for ease of data recording and for consistency in
the production and exchange of the descriptions.
When a descriptor is scored using a 1–9 scale, such as in Example
46, ‘0’ would be scored when the character is not expressed or a
descriptor is not applicable. In the following example, ‘0’ will be
recorded if an accession does not have panicles:
Example #47
Panicle number per plant
3
Low
(5 – 10)
5
Intermediate
(15 – 20)
7
High
(25 – 30)
• Absence or presence of characters is scored as a simple binary 0 or 1:
Example #48
Terminal leaflet
0
Absent
1
Present
• Blanks are used for information not yet available.
• Dates should be expressed numerically in the format YYYYMMDD,
where:
– YYYY = 4 digits to represent the year
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– MM = 2 digits to represent the month
– DD = 2 digits to represent the day
If the month and/or day are missing, this should be indicated with
hyphens. Leading zeros are required (i.e. 197506--, or 1975----).The
date format listed above follows the ISO international format for
the representation of dates and times (see Bibliography and Further
Reference Sources).
10.1 Recording heterogeneous data
Landraces and wild populations are not as uniform as commercial
varieties. Many genebanks will therefore mainly handle accessions
that are heterogeneous for many traits (each accession is not
genetically uniform and contains a certain amount of variation).
Recording the average or most frequently occurring state does
not express the extent of variation nor its range within each
accession. To a certain extent, this can complicate documentation,
since special provision must be made to record the diversity. If
statistical studies are foreseen, the best approach is to record
actual measurements.
Nevertheless, several other approaches have been proposed to
address this issue. In crop descriptor lists, references are made to
different methodologies, as discussed below.
• For accessions that are not generally uniform for a descriptor
(e.g. a mixed collection, or genetic segregation), the mean and
standard deviation can be reported where the descriptor is
continuous. Where the descriptor is discontinuous, several codes
in order of frequency could be recorded.
• Another approach is the method developed by van Hintum
(1993), which has the following rules:
– record the scores in decreasing order of size; and
– add an equals sign (=) after the score if there is only one
fraction.
In this system, homogeneous populations are followed by the
‘=’ sign. For heterogeneous populations, the ratio between two
adjacent fractions is taken. If between 1.5 and 5.0, one ‘x’ sign is
placed between the two fractions; if the ratio is higher than 5.0,
two ‘x’ signs are placed.
• The method developed by Sapra and Singh (Rana et al. 1991),
proposes the use of numbering codes from 0 to 9 based on
frequency encountered (1=very low, 9=very high, with the same
scale used for quantitative characters):
– Three codes are placed in decreasing order of frequency
– The frequency codes are placed after each descriptor code
Developing crop descriptor lists
39
– For homogeneous populations, ‘9’ is placed after the irst
descriptor code and ‘0’ (indicating absence) after the other two
codes.
Example #49
Flower colour
1
White
2
Purple
3
Red
For a population with only white lowers, the scores would be
192030. For a population with few (very low) white lowers and
many (very high) red lowers, the scores would be 381120.
For descriptors with single digit states (e.g. 1–9 scale), the
systems for recording heterogeneity differ and are not completely
compatible. At this time, it is unclear to what extent these systems
are applied by genebanks.
• Another method, proposing how heterogeneity could be
documented for speciic traits of the crop, has recently been
under development by A. Alercia and co-workers, and is outlined
below.
If an accession shows high variation between plots and within
plants, such as the lower colour of Lathyrus, the method suggested
is to use different columns for each colour, estimate for each plot
the percentage of colours present, and record the average. Assign
numbering codes for each colour in order of frequency (increasing
order).
Example #50
Table 1. Flower colour
Plot No.
Accession No.
Yellow
White
Pink
Red
1
10123
50
10
15
25
2
10123
20
40
30
30
3
10123
30
20
25
25
4
10123
40
30
10
30
5
10123
70
10
10
10
Total
240
110
90
150
%
48%
22%
18%
30%
Assign numbering codes in increasing order using a 1–9 scale
(low to high scale), as follows:
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Example #51
1
(18%)
2
(22%)
3
(30%)
4
(48%)
• The descriptor will now will appear as:
Example #52
Flower colour
1
Pink
(18%)
2
White
(22%)
3
Red
(30%)
4
Yellow
(48%)
• If, in addition, lower characteristics also show variation between
them, it is recommended that they be recorded separately. For
example, in Lathyrus species there is a huge variation between
accessions, replications and even lowers in the same plot.
When this occurs, it is recommended that lower element data
be recorded separately:
Example #53
(i)
Standard colour on upper side
(ii)
Standard colour on lower side
(iii)
Keel colour
(iv)
Wing colour
(v)
Vein colour
• Sometimes, variation may be found in the distribution of colour
on standards. In this case, it is suggested to record the variation
as follows:
Example #54
Distribution of colour in the standards
1
Colour present on margins
2
Colour present in the centre
3
Colour present along the veins
Developing crop descriptor lists
41
It is recommended that the Royal Horticultural Society Colour
Chart be used for colour descriptors. However, in case RHS charts
are not available or unaffordable (for example, small collections),
using any other standard colour charts or generating one using
computer tools is acceptable. When standards different from RHS
charts are used, the standards used should be clearly mentioned
along with information on colour and in some instances when the
charts are uncommon, the chart itself may have to be provided along
with the information.
11. Numeric versus alphanumeric coding schemes
In its descriptor lists, Bioversity promotes the use of numeric coding
systems for descriptors rather than alphanumeric systems. The
main reason for this choice is that crop descriptors are aimed at an
international audience, and numerical codes do not need translation.
Additionally, the use of numerical codes substantially facilitates the
simple and accurate scoring of descriptors; updating and modiication
are easier and quicker as well.
The use of alphanumeric coding or short-hand codes may
lead to confusion, making data retrieval and exchange extremely
dificult (different users have different approaches for the coding
and interpretation of data).
Example #55
Table 2. Numeric codes linked to multilingual descriptor states
Numeric Code
Fruit: apex
Fruit: sommet
1
Indented
Déprimé
Fruto: ápice
Hundido
2
Rounded
Arrondi
Redondeado
3
Pointed
Pointu
Puntiagudo
99
Other
Autre
Otro
With numeric scoring, different language versions score traits
in a compatible and consistent way. This makes the use of numeric
codes a convenient way to exchange data internationally.
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Developing crop descriptor lists
Making descriptors work
12. The development process
Bioversity works closely with crop experts in the development of
descriptor lists to ensure that the inal product provides optimal
support to all who work on particular crops.
Bioversity coordinates and manages the production of its
descriptor lists through a number of activities, and the discussion
below summarizes the process of developing a crop-speciic
descriptor list.
The drafting of crop descriptors is led by an expert, who is the main
author of the characterization and evaluation descriptors. Bioversity
then prepares a draft version applying its internationally accepted
format for descriptor lists. A larger group of scientists from different
countries is then invited to provide scientiic advice and comments to
ensure that the full extent of knowledge and expertise is relected in
the draft. At this stage, Bioversity scientists are also consulted for their
technical comments and scientiic advice. Relevant and substantiated
comments provide input in developing the draft list to achieve a
consensus document, after which the main author receives the text
for inal approval. Finally, the list is formatted for publication, and
any necessary igures are drawn and positioned.
One of the main reasons for the success of the descriptor
programme is that the process involves broad consultation, enabling
Bioversity International to take into consideration comments from
various regions and experts. Producing these lists to the required
standard is time consuming, but cannot be compromised.
There are many aspects of crop descriptors for which the individual
drafter’s experience and knowledge are essential in preparing the
irst draft. This includes the selection of appropriate terminology,
experimental design, the identiication of characteristics and the
selection of check cultivars, if required. In such situations, general
guidance and experience are provided by Bioversity through a series
of guidelines and steps, which are presented below.
13. A few basic rules
There are a number of options when someone is making a decision
on which descriptors to include and how to deine them. Below are
a few basic guidelines:
• Keep the descriptors as simple as possible so that they are
understood and can easily be used by a wide range of users.
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• Use images and drawings to support textual descriptions and
to clarify complex descriptors.
• Provide clear deinitions of descriptors to enable others to apply
them.
• Analyse carefully the unit costs per measurement (or set of
measurements), in terms of both staff time and materials.
• Specify, when relevant, the unit of measurement.
• Avoid ambiguities. If a descriptor appears to be ambiguous,
include references on methodology or standards. Colour is an
attribute that beneits from an absolute comparator value, such
as a standard colour chart value.
• Have the experimental design ready prior to assessing descriptors
and their diversity.
• Consult widely among crop and genebank specialists in order to
achieve a comprehensive and understandable list of descriptors
that can be widely accepted.
Once the above simple rules have been followed, crop descriptor
lists can function as tools to assist genebanks and other collection
curators in documenting germplasm in a consistent manner and
ensuring the continued use of the germplasm by the plant genetic
resources community.
14. Step-by-step checklist for defining descriptors
Step 1: Investigate the range of diversity for the trait
• What kind and level of diversity is known for this trait?
• Is it relevant to discriminating accessions?
Next Step:
– If no diversity is known, no descriptor is necessary!
– Otherwise, go to Step 2.
Step 2: Provide a name for the descriptor
• A descriptor name should be:
– Descriptive
– Unambiguous, and
– Compact.
• Descriptor names are frequently composed of:
– An object or item, plus a trait name.
Example #56
Accession number
Leaf colour
Soil fertility
Developing crop descriptor lists
Next Step:
– Go to Step 3
Step 3: Is the descriptor dealing with one or more traits?
• Avoid developing descriptors that describe more than one
characteristic at the same time.
Example #57
Leaf-blade colour
1
White and striped
2
Pink and mottled
In this example, it would be better to split this descriptor up into
’leaf-blade colour’ and ‘leaf-blade variegation’.
Next Step:
– If more than one characteristic is involved, split the descriptor
into separate descriptors, and go back to Step 2.
– If only a single characteristic is described, go to Step 4.
Step 4: Decide how to record the descriptor
• Deine how the trait should be recorded (visual assessment,
measured), what tools are needed and under what conditions it
should be recorded.
• Add images if necessary to support the description.
Next Step:
– If the characteristic is qualitative, go to Step 5.
– If the characteristic is quantitative, go to Step 6.
Step 5: Define qualitative descriptors
• List the distinct descriptor states you want to use. Determine
whether states can be merged or grouped.
• If possible, add references or standards that illustrate the different
descriptor states.
• Number the states starting with ‘1’. If there is a need for space
to list potential further states, add ‘99 Other’.
• Use image analysis to eventually convert qualitative data to
quantitative data.
Next Step:
– Go to Step 9.
Step 6: Define quantitative descriptors
• For quantitative traits, determine whether the values should be
scored on a continuous or a discrete scale.
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Next Step:
– For continuous scales, go to Step 7.
– For discrete scales, go to Step 8.
Step 7: Use continuous scales
• Determine the level of resolution needed: whenever possible
include the actual value of measurements and specify the units
to be used (SI units).
Next Step:
– Go to Step 9.
Step 8: Define states on discrete scales
• Deine the descriptor states you need and number these
sequentially starting from ‘1’.
• States on a 1 to 9 scale (from weak to strong expression of the trait).
Include if necessary more deined references or standards.
Next Step:
– Go to Step 9.
Step 9: References and standards used
• If reference is made to a speciic method or a reference system,
provide the relevant bibliographical references and give a full
citation in an appendix.
• If check cultivars or reference varieties are included, they should
be available and widely known.
Next Step:
– Go to Step 10.
Step 10: Is the descriptor highly discriminatory?
If the descriptor is discriminatory, mark it with an asterisk (*). This
will indicate that this descriptor is particularly useful as an indicator
of diversity in the collection, but also for international harmonization
of documentation systems, if any.
Developing crop descriptor lists
Looking forward
The increasing attention given to molecular and biochemical
characterization is relected in the latest descriptor lists. Bioversity
International recognizes the complementarity of innovative
approaches with classical agro-botanical analysis. The List of
Descriptors for Genetic Marker Technologies developed by IPGRI,
now Bioversity International, in consultation with international
experts, CGIAR Centres and research organizations was published
in February 2004. Standardizing this information will facilitate the
development of data exchange encoding formats, such as Extensible
Markup Language (XML) and Document Type Deinitions (DTD), for
dissemination of information on markers and the creation of a global
registry containing a full and accurate inventory of species-speciic
reference markers already published.
Because of the high demand from Bioversity’s partners for
descriptor standards, some ideas to expand the work on descriptor
development are listed below:
• Develop standards for new areas (in situ collections, including
farmer descriptors related to indigenous and traditional
knowledge; forest species).
• Emphasize conservation for use (‘conservation and use’ of plants)
instead of simply conservation.
• Develop descriptors that beneit people (such as the use of crops
to combat desertiication or soil erosion).
• Develop descriptors that beneit environment (such as the use of
crops for bioenergy production).
• Apply the emerging imaging techniques for the description of
complex traits, such as those of shape and texture.
• Future descriptor lists may also incorporate reinements based
on the methodologies used by the biological ontology research
community (Plant Ontology Consortium, see http://www.
plantontology.org/), such as the assignment of a term accession
identiier to each descriptor deinition and placement of the terms
into a structured ontology.
• Web-enabling the available descriptors.
• Electronic descriptor system. The next stage is to develop
databases based on descriptors and on-line consultation in the
development of new and revised descriptors. This is discussed
below.
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
Electronic-descriptor system: a new development
process
In addition to the electronic versions of descriptors (PDF and HTML
iles) listed on Bioversity’s Web site, there is a new production process
for descriptor development. Testing is underway, and a number of
issues still need to be analysed.
In the future, this system will allow for a moderated real-time
electronic consultation in descriptor development by an expert
community, with instant feedback.
Some of this system’s features include:
• on-line descriptor development;
• electronic delivery and reuse;
• representation of descriptors in XML;
• format extended to include database ield deinition and XML
element name; and
• generation of electronic forms and database deinitions.
The system will have an impact on:
• standardization of descriptor structures;
• harmonization of descriptors across crops;
• harmonization of descriptor states;
• support to communities of experts; and
• number of descriptors produced.
Developing crop descriptor lists
Bibliography and further references
Alercia A, Diulgheroff S, Metz T. 2001. List of Multi-crop Passport Descriptors.
FAO/IPGRI, Rome. Available from: http://www.bioversityinternational.
org/Publications/pubile.asp?ID_PUB=124
Bartz AE. 1988. Some thoughts on measurement. In: Basic statistical concepts (3rd
ed.). MacMillan, New York, NY, USA. pp. 1–21.
CAB International. 1999. Crop Protection Compendium. CD-ROM. CAB
International, UK.
De Vicente C, Metz T, Alercia A. 2004. Descriptors for Genetic Markers Technologies.
IPGRI, Rome, Italy. Available at: http://www.bioversityinternational.org/
Publications/pubile.asp?id_pub=913
FAO [Food and Agriculture Organization of the United Nations]. 1990. Guidelines
for Soil Proile Description (3rd edition rev.). International Soil Reference
Information Centre (ISRIC), Land and Water Development Division, FAO,
Rome, Italy.
FAO. 2006. Guidelines for soil description. (4th edition, rev.). World Soil Resources
Report. 110 p. FAO Doc. no. A0541/E. Available from: ftp://ftp.fao.org/docrep/
fao/009/a0541e/a0541e00.pdf
FAO. 1996. Report on the State of the World’s Plant Genetic Resources for Food
and Agriculture, prepared for the International Technical Conference on Plant
Genetic Resources, Leipzig, Germany, 17-23 June 1996. Food and Agriculture
Organization of the United Nations, Rome, Italy.
FAO. No date. List of Institute Codes. These codes are available from http://apps3.
fao.org/wiews/ for registered WIEWS users. From the Main Menu select:
“PGR” and “Download”. If new Institute Codes are required, they can be
generated online by national WIEWS administrators, or by the FAO WIEWS
administrator [Stefano.Diulgheroff@fao.org].
Plant Ontology Consortium. Available at: www.plantontology.org/
USDA-GRIN. No date. US Department of Agriculture Genetic Resources Information
Network database. Available at: www.ars-grin.gov.
Harris JG, Harris MW. 1994. Plant Identiication Terminology: An Illustrated
Glossary. Spring Lake Publishing, Spring Lake, Utah, USA.
Henderson IF. 1989. Henderson’s Dictionary of Biological Terms (10th ed.). Edited
by E. Lawrence. Longman Scientiic & Technical, Harlow, Essex, England, UK.
Greuter W, Mcneill J, Barrie FR, Burdet HM, Demoulin V, Filgueiras TS, Nicolson DH,
Silva PC, Skog JE, Trehane P, Turland NJ, Hawksworth DL. (Editors & Compilers).
2000. International Code of Botanical Nomenclature (Saint Louis Code) adopted
by the Sixteenth International Botanical Congress, St. Louis, Missouri, July–
August 1999. Koeltz Scientiic Books, Königstein. (Regnum Vegetabile, 138). See:
http://www.bgbm.org/iapt/nomenclature/code/default.htm
IPGRI [International Plant Genetic Resources Institute]. 2001. The design and
analysis of evaluation trials of genetic resources collections. A guide for
genebank managers. IPGRI Technical Bulletin, No. 4.
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
ISO 8601:2000. Data elements and interchange formats – Information interchange
– Representation of dates and times.
ISO 6709:1983 Standard representation of latitude, longitude and altitude for
geographic point locations.
ISO 3166 Codes for the representation of names of countries. The ISO 3166-1: Code List
can be found at: http://www.un.org/Depts/unsd/methods/m49alpha.htm
ISO 3166-3:1999. Codes for the representation of names of countries and their
subdivisions – Part 3: Code for formerly used names of countries. This List is not
available on line, but can be obtained from IPGRI [ipgri-mcpd@cgiar.org].
Kornerup A, Wanscher JH. 1984. Methuen Handbook of Colour. 3rd edition.
Methuen, London, UK.
Laliberté B, Withers L, Alercia A, Hazekamp T. 1999. Adoption of Crop Descriptors
– IPGRI. In: A Synthesis of Findings concerning CGIAR Case Studies on the
Adoption of Technological Innovation. IAEG Secretariat, May 1999.
Munsell Color. 1975. Munsell Soil Color Chart. Munsell Color, Baltimore, MD, USA.
Munsell Color. 1977. Munsell Color Charts for Plant Tissues, 2nd edition, revised. Munsell
Color, Macbeth Division of Kollmorgen Corporation, Baltimore MD, USA.
Painting KA, Perry MC, Denning RA, Ayad WA. 1995. Guidebook for Genetic
Resources Documentation. IPGRI, Rome, Italy.
Purdy LH, Loegering WQ, Konzak CF, Peterson CJ, Allen RE. 1968. A proposed
standard method for illustrating pedigrees of small grain varieties. Crop
Science 8:405–406.
Rana R.S, Sapra RL, Agrawal RC, Rajeev Gambhir. 1991. Plant Genetic Resources.
Documentation and Information Management. National Bureau of Plant Genetic
Resources (Indian Council of Agricultural Research), New Delhi, India.
RHS [The Royal Horticultural Society]. 1966, 1986, 1995. R.H.S. Colour Chart (edn.
1, 2, 3). The Royal Horticultural Society, London.
SI Base Units (Système International d’unités). No date, See: http://www.bipm.
fr/enus/3_SI/base_units.html
Stearn WT. 1995. Botanical Latin. Fourth Edition. David & Charles Publishers,
Newton Abbot, UK.
UPOV [Union Internationale pour la Protection des Obtentions Végétales]. 1989.
Guidelines for the Conduct of Tests for Distincness, Homogeneity and Stability.
Triticale (×Triticosecale Witt.). Geneva, Switzerland.
UPOV. 1993. Draft Guidelines for the Conduct of Tests for Distinctness, Homogeneity
and Stability. Wheat (Triticum aestivum L. emend. Fiori et Paol.). Geneva,
Switzerland.
van Hintum ThJL. 1993. A computer compatible system for scoring heterogeneous
populations. Genetic Resources and Crop Evolution 40:133–136.
van Hintum ThJL, Jongen MWM, Hazekamp Th. (editors). 1995. Standardization
in Plant Genetic Resources Documentation. Report of the Second Technical
Meeting of Focal Points for Documentation in East European Genebanks.
Centre for Genetic Resources, The Netherlands (CGN), Wageningen, The
Netherlands.
Developing crop descriptor lists
51
Appendix I – Contributors
Coordinators
Ms Adriana Alercia
Germplasm Information Specialist
Bioversity International HQ
Via dei Tre Denari 472/a
00057 Maccarese (Rome)
Italy
E-mail: a.alercia@cgiar.org
Mr Samy Gaiji
Project Coordinator, UMBP
Bioversity International HQ
Via dei Tre Denari 472/a
00057 Maccarese (Rome)
Italy
E-mail: s.gaiji@cgiar.org
Dr Ramanatha Rao
Project Coordinator, Facilitating Use of
Genetic Resources
Bioversity International
P.O.Box 236, UPM Post Ofice, Serdang
43400 Selangor Darul Ehsan
Malaysia
E-mail: r.rao@cgiar.org
Mr Luigi Guarino
Honorary Research Fellow
Secretariat of the Paciic Community, Suva
Fiji
E-mail: luigiG@spc.int
Reviewers
Dr Abdallah Bari
Scientist, PGR Information/Data
Management and Analysis
Methodologies
CWANA
Bioversity International c/o ICARDA,
PO Box 5466, Aleppo
Syria
E-mail: a.bari@cgiar.org
Dr Jan Engels
Genetic Resources Management Advisor
Bioversity International HQ
Via dei Tre Denari 472/a
00057 Maccarese (Rome)
Italy
E-mail: j.engels@cgiar.org
Ir Tom Hazekamp
Consultant
Bioversity International HQ
Via dei Tre Denari 472/a
00057 Maccarese (Rome)
Italy
E-mail: t.hazekamp@cgiar.org
Dr Annie Lane
Global Project Coordinator
Crop Wild Relative Project
Bioversity International HQ
Via dei Tre Denari 472/a
00057 Maccarese (Rome)
Italy
E-mail: a.lane@cgiar.org
Dr Stefano Padulosi
Senior Scientist, Integrated Conservation
Methodologies and Uses
Bioversity International HQ
Via dei Tre Denari 472/a
00057 Maccarese (Rome)
Italy
E-mail: s.padulosi@cgiar.org
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
Dr Paul Quek
Scientist, Documentation/Information
Bioversity International c/o Stesen Kuarantin
Lepas Masuk
Jabatan Pertanian,Bangunan JKR (P) 1746
P.O.Box 236, UPM Post Ofice, Serdang
43400 Selangor Darul Ehsan
Malaysia
E-mail: p.quek@cgiar.org
Dr Xavier Schelderman
Scientist, Conservation and Use of
Neotropical PGR
Bioversity International c/o CIAT
Apartado Aereo 6713, Cali
Colombia
E-mail: x.schelderman@cgiar.org
Developing crop descriptor lists
Appendix II – Standard reference sources
A2.1 References and standards used in developing
crop descriptor lists
Category of
descriptors
References
Passport
FAO/IPGRI List of Multi-crop Passport Descriptors (2001)
Country names:
— ISO 3166 Codes for the representation of names of countries,
particularly the ISO 3166-1:1999 Code List
— ISO 3166-3 Codes for the representation of names of
countries and their subdivisions – Part 3: Code for formerly used
names of countries.
Institute codes:
FAO codes should be used. These codes are available from
http://apps3.fao.org/wiews/ for registered WIEWS users. If
new Institute Codes are required, they can be generated online
by national WIEWS administrators, or by the FAO WIEWS
administrator.
Date format – use ISO date format (ISO 8601).
Site and
Environment
FAO. 1990. Guidelines for Soil Proile Description.
FAO. 2006. Guidelines for Soil Description.
Munsell Color. 1975. Munsell Soil Color Chart.
UNESCO System for Classifying Vegetation See: http://wwweosdis.ornl.gov/source_documents/unesco.html
Characterization
and Evaluation
Methuen Handbook of Colour (Kornerup A, and Wanscher JH.
1984)
Munsell Color Charts for Plant Tissues (Munsell Color, 1977).
Documentation and Information Management. Plant Genetic
Resources. NBPGR (ICAR)
Royal Horticultural Society Colour Chart (RHS, 1986)
SI Units (Système Internationale d’Unités) (see http://www.bipm.
fr/enus/3_SI/base_units.html)
A computer compatible system for scoring heterogeneous
populations (Van Hintum 1993).
A proposed standard method for illustrating pedigrees of small
grain varieties (Purdy et al. 1968).
Glossary of terms
Plant Identiication Terminology; An Illustrated Glossary. (Harris
and Harris 1994)
Henderson’s dictionary of biological terms- 10th edition.
(Henderson 1998)
Botanical Latin. (4th edition) (Stearn 1995)
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
A2.2 Base units – Système International d’Unités (SI)
Physical quantity
Base unit [symbol]
Length
metre [m]
Mass
gram [g]
Time
second [s]
Substance
mole [mol]
Temperature
kelvin [K] or degree Celsius [ºC]*
Electrical current
ampere [A]
Luminous intensity
candela [Cd]
Note: (1) *degree Celsius is common referred to as Centigrade (= K -273)
(2) These base units can be preixed by factors such as kilo (k), centi (c) or milli (m) to scale
the units.
Developing crop descriptor lists
Appendix III – FAO/IPGRI Multi-Crop Passport Descriptors
The list of multi-crop passport descriptors (MCPD) was developed
jointly by IPGRI and FAO to provide international standards
to facilitate germplasm passport information exchange. These
descriptors aim to be compatible with IPGRI [Bioversity International]
crop descriptor lists and with the descriptors used for the FAO World
Information and Early Warning System (WIEWS) on plant genetic
resources (PGR).
For each multicrop passport descriptor, a brief explanation of
content, coding scheme and suggested ield name (in parentheses)
is provided to assist in the computerized exchange of this type of
data. It is recognized that networks or groups of users may want
to further expand this MCPD List to meet their speciic needs. As
long as these additions allow for an easy conversion to the format
proposed in the multi-crop passport descriptors, basic passport data
can be exchanged worldwide in a consistent manner.
General comments
• If a ield allows multiple values, these values should be separated
by a semicolon (;) without space(s), (e.g. Accession name:
Rheinische Vorgebirgstrauben;Emma;Avlon).
• A ield for which no value is available should be left empty e.g.
Elevation). If data are exchanged in ASCII format for a ield
with a missing numeric value, it should be left empty. If data are
exchanged in a database format, missing numeric values should
be represented by generic NULL values.
• Dates are recorded as YYYYMMDD. If the month and/or day are
missing, this should be indicated with hyphens. Leading zeros
are required (i.e. 197506--, or 1975----).
• Latitude and longitude are recorded in an alphanumeric format.
If the minutes or seconds are missing, this should be indicated
with hyphens. Leading zeros are required.
• Country names: Three letter ISO codes are used for countries. The
ISO 3166-1: Code List and the Country or area numerical codes
added or changed are not available on-line, but can be obtained
from IPGRI [ipgri-mcpd@cgiar.org]
• For institutes, the codes from FAO should be used. These codes are
available from http://apps3.fao.org/wiews/ for registered WIEWS
users. From the Main Menu select: ‘PGR’ and ‘Download’. If new
Institute Codes are required, they can be generated online by national
WIEWS administrators, or by the FAO WIEWS administrator [at the
time of writing: <Stefano.Diulgheroff@fao.org>].
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
• The preferred language for free-text ields is English (i.e.
‘Location of collecting site’ and ‘Remarks’).
MULTI-CROP PASSPORT DESCRIPTORS
1. Institute code
(INSTCODE)
Code of the institute where the accession is maintained. The codes consist of the 3letter ISO 3166 country code of the country where the institute is located plus a number.
The current set of Institute Codes is available from the FAO website (http://apps3.fao.
org/wiews/).
2. Accession number
(ACCENUMB)
This number serves as a unique identiier for accessions within a genebank collection,
and is assigned when a sample is entered into the genebank collection.
3. Collecting number
(COLLNUMB)
Original number assigned by the collector(s) of the sample, normally composed of the
name or initials of the collector(s) followed by a number. This number is essential for
identifying duplicates held in different collections.
4. Collecting institute code
(COLLCODE)
Code of the institute collecting the sample. If the holding institute has collected the
material, the collecting institute code (COLLCODE) should be the same as the holding
institute code (INSTCODE). Follows INSTCODE standard.
5. Genus
Genus name for taxon. Initial uppercase letter required.
(GENUS)
6. Species
(SPECIES)
Speciic epithet portion of the scientiic name in lowercase letters. The following
abbreviation is allowed: ‘sp.’
7. Species authority
Provide the authority for the species name.
(SPAUTHOR)
8. Subtaxa
(SUBTAXA)
Subtaxa can be used to store any additional taxonomic identiier. The following
abbreviations are allowed: ‘subsp.’ (for subspecies); ‘convar.’ (for convariety); ‘var.’ (for
variety); ‘f.’ (for form).
9. Subtaxa authority
Provide the subtaxa authority at the most detailed taxonomic level.
(SUBTAUTHOR)
10. Common crop name
(CROPNAME)
Name of the crop in colloquial language, preferably English (i.e. ‘malting barley’,
‘caulilower’, or ‘white cabbage’)
11. Accession name
(ACCENAME)
Either a registered or other formal designation given to the accession. First letter
uppercase. Multiple names separated with semicolon without space. For example:
Rheinische Vorgebirgstrauben;Emma;Avlon
12. Acquisition date [YYYYMMDD]
(ACQDATE)
Date on which the accession entered the collection where YYYY is the year, MM is the
month and DD is the day. Missing data (MM or DD) should be indicated with hyphens.
Leading zeros are required.
13. Country of origin
(ORIGCTY)
Code of the country in which the sample was originally collected. Use the 3-letter ISO
3166-1 extended country codes.
Developing crop descriptor lists
MULTI-CROP PASSPORT DESCRIPTORS
14. Location of collecting site
(COLLSITE)
Location information below the country level that describes where the accession was
collected. This might include the distance in kilometres and direction from the nearest
town, village or map grid reference point, (e.g. 7 km south of Curitiba in the state of
Parana).
15. Latitude of collecting site (see note 1)
(LATITUDE)
Degrees (2 digits), minutes (2 digits) and seconds (2 digits) followed by N (north) or S
(south) (e.g. 103020S). Every missing digit (minutes or seconds) should be indicated with
a hyphen. Leading zeros are required (e.g. 10- - - -S; 011530N; 4531- -S).
16. Longitude of collecting site (see note 1)
(LONGITUDE)
Degrees (3 digits), minutes (2 digits) and seconds (2 digits) followed by E (east) or W
(west) (e.g. 0762510W). Every missing digit (minutes or seconds) should be indicated
with a hyphen. Leading zeros are required (e.g. 076- - - -W).
17. Elevation of collecting site [masl]
(ELEVATION)
Elevation of collecting site expressed in metres above sea level. Negative values are
allowed.
18. Collecting date of sample [YYYYMMDD]
(COLLDATE)
Collecting date of the sample where YYYY is the year, MM is the month and DD is the
day. Missing data (MM or DD) should be indicated with hyphens. Leading zeros are
required.
19. Breeding institute code
(BREDCODE)
Institute code of the institute that has bred the material. If the holding institute has bred
the material, the breeding institute code (BREDCODE) should be the same as the holding
institute code (INSTCODE). Follows INSTCODE standard.
20. Biological status of accession
(SAMPSTAT)
The coding scheme proposed can be used at 3 different levels of detail: either by using
the general codes (in boldface) such as 100, 200, 300, 400, or by using the more speciic
codes such as 110, 120, etc.
100) Wild
110) Natural
120) Semi-natural/wild
200) Weedy
300) Traditional cultivar/landrace
400) Breeding/research material
410) Breeder’s line
411) Synthetic population
412) Hybrid
413) Founder stock/base population
414) Inbred line (parent of hybrid cultivar)
415) Segregating population
420) Mutant/genetic stock
500) Advanced/improved cultivar
999) Other (Elaborate in REMARKS ield)
21. Ancestral data
(ANCEST)
Information about either pedigree or other description of ancestral information (parent
variety in case of mutant or selection). For example, a pedigree ‘Hanna/7*Atlas//
Turk/8*Atlas’ or a description ‘mutation found in Hanna’, ‘selection from Irene’ or ‘cross
involving amongst others Hanna and Irene’.
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MULTI-CROP PASSPORT DESCRIPTORS
22. Collecting/acquisition source
(COLLSRC)
The coding scheme proposed can be used at 2 different levels of detail: either by using
the general codes (in boldface) such as 10, 20, 30, 40, or by using the more speciic
codes such as 11, 12, etc.
10) Wild habitat
11) Forest/woodland
12) Shrubland
13) Grassland
14) Desert/tundra
15) Aquatic habitat
20) Farm or cultivated habitat
21) Field
22) Orchard
23) Backyard, kitchen or home garden
(urban, peri-urban or rural)
24) Fallow land
25) Pasture
26) Farm store
27) Threshing loor
28) Park
30) Market or shop
40) Institute, Experimental station,
Research organization, Genebank
50) Seed company
60) Weedy, disturbed or ruderal habitat
61) Roadside
62) Field margin
99) Other (Elaborate in REMARKS ield)
23. Donor institute code
Code for the donor institute. Follows INSTCODE standard.
(DONORCODE)
24. Donor accession number
(DONORNUMB)
Number assigned to an accession by the donor. Follows ACCENUMB standard.
25. Other identiication (numbers) associated with the accession
(OTHERNUMB)
Any other identiication (numbers) known to exist in other collections for this accession.
Use the following system: INSTCODE:ACCENUMB;INSTCODE:ACCENUMB;…
INSTCODE and ACCENUMB follow the standard described above and are separated
by a colon. Pairs of INSTCODE and ACCENUMB are separated by a semicolon without
space. When the institute is not known, the number should be preceded by a colon.
26. Location of safety duplicates
(DUPLSITE)
Code of the institute where a safety duplicate of the accession is maintained. Follows
INSTCODE standard.
27. Type of germplasm storage
(STORAGE)
If germplasm is maintained under different types of storage, multiple choices are
allowed, separated by a semicolon (e.g. 20;30). (Refer to FAO/IPGRI Genebank
Standards (1994) for details on storage type.)
10) Seed collection
11) Short-term
12) Medium-term
13) Long-term
20) Field collection
30) In vitro collection (Slow growth)
40) Cryopreserved collection
99) Other (elaborate in REMARKS ield)
28. Remarks
(REMARKS)
The remarks ield is used to add notes or to elaborate on descriptors with value 99 or 999
(=Other). Preix remarks with the ield name they refer to and a colon (e.g. COLLSRC:roadside).
Separate remarks referring to different ields are separated by semicolons without space.
Note 1: To convert from longitude and latitude in degrees (º), minutes (‘), seconds (‘’) and a hemisphere
(North or South; East or West) to decimal degrees, the following formula should be used:
dº m’ s’’=h *(d+m/60+s/3600) where h= +1 for the Northern and Eastern hemispheres, and h= –1 for the
Southern and Western hemispheres, i.e. 30º30’0’’ S= –30.5 and 30º15’55’’ N=30.265.
Developing crop descriptor lists
59
Appendix IV – List of standard descriptors for site
environment
A4.1 Site environment
A4.1.1 Topography
This refers to the proile in elevation of the land surface on a broad
scale. The reference is FAO (1990).
Numeric Descriptor state
code
1
Flat
0 – 0.5%
2
Almost lat
3
Gently undulating
4
Undulating
5
Rolling
11 – 15.9%
6
Hilly
16 – 30%
7
Steeply dissected
>30%
moderate elevation range
8
Mountainous
>30%
great elevation range (>300 m)
99
Other
0.6 – 2.9%
3 – 5.9%
6 – 10.9%
specify in the appropriate section’s Notes
A4.1.2 Higher-level landform (general physiographic features)
The landform refers to the shape of the land surface in the area in
which the collecting site is located (adapted from FAO, 1990).
Numeric Descriptor state
code
1
Plain
2
Basin
3
Valley
4
Plateau
5
Upland
6
Hill
7
Mountain
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
A4.1.3 Land element and position
Description of the geomorphology of the immediate surroundings
of the collecting site (adapted from FAO, 1990). (See Figure A4.1)
Numeric Descriptor state
code
Numeric
code
Descriptor state
1
Plain level
17
Interdunal depression
2
Escarpment
18
Mangrove
3
Interluve
19
Upper slope
4
Valley
20
Midslope
5
Valley loor
21
Lower slope
6
Channel
22
Ridge
7
Levee
23
Beach
8
Terrace
24
Beachridge
9
Floodplain
25
Rounded sumit
10
Lagoon
26
Summit
11
Pan
27
Coral atoll
12
Caldera
28
13
Open depression
Drainage line (bottom position
in lat or almost-lat terrain)
14
Closed depression
29
Coral reef
15
Dune
16
Longitudinal dune
99
Other (specify in appropriate
section’s Notes)
Developing crop descriptor lists
Figure A4.1. Land element and position
A4.1.4 Slope [°]
Estimated slope in degrees of the collecting site.
A4.1.5 Slope form
It refers to the general shape of the slope in both vertical and
horizontal directions (FAO 1990).
Numeric code
Descriptor state
1
Straight
2
Concave
3
Convex
4
Terraced
5
Complex (irregular)
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
A4.1.6 Slope aspect
The direction that the slope on which the accession was collected
faces. Describe the direction with symbols N, S, E, W (e.g. a slope
that faces a south-western direction has an aspect of SW).
A4.1.7 Crop agriculture (Adapted from FAO 1990)
Numeric
code
Descriptor state
1
Annual Field cropping
2
Perennial field cropping
3
Tree and shrub cropping
A4.1.8 Overall vegetation at and surrounding the collecting
site (Adapted from FAO 1990)
Numeric
code
1
Descriptor state
Herbaceous
1.1
Grassland
1.2
Forbland
2
Closed forest
Continuous tree layer, crowns overlapping, large
number of tree and shrub species in distinct layers
3
Woodland
Continuous tree layer, crowns usually not touching,
understorey may be present
4
Shrub
5
Dwarf shrub
99
Other
Specify in appropriate section’s Notes
A4.1.9 Soil parent material
Two lists of examples of parent material and rock are given below.
The reliability of the geological information and the knowledge of
the local lithology will determine whether a general or a speciic
deinition of the parent material can be given. Saprolite is used if the
in situ weathered material is thoroughly decomposed, clay-rich but
still showing rock structure. Alluvial deposits and colluvium derived
from a single rock type may be further speciied by that rock type.
Developing crop descriptor lists
63
A4.1.9.1 Unconsolidated material (Adapted from FAO 1990)
Numeric
code
Descriptor state
Numeric
code
Descriptor state
1
Aeolian deposits
(unspeciied)
10
Volcanic ash
2
Aeolian sand
11
Loess
3
Littoral deposits
12
Pyroclastic deposits
4
Lagoonal deposits
13
Glacial deposits
5
Marine deposits
14
Organic deposits
6
Lacustrine deposits
15
Colluvial deposits
7
Fluvial deposits
16
In situ weathered
8
Alluvial deposits
17
Saprolite
9
Unconsolidated
(unspeciied)
99
Other (specify in
appropriate section’s
Notes)
A4.1.9.2 Rock type (Adapted from FAO 1990)
Numeric
code
Descriptor state
Numeric
code
Descriptor state
1
Acid igneous/
metamorphic rock
17
Dolomite
2
Granite
18
Sandstone
3
Gneiss
19
Quartzitic sandstone
4
Granite/gneiss
20
Shale
5
Quartzite
21
Marl
6
Schist
22
Travertine
7
Andesite
23
Conglomerate
8
Diorite
24
Siltstone
9
Basic igneous/
metamorphic rock
25
Tuff
10
Ultra-basic rock
26
Pyroclastic rock
11
Gabbro
27
Evaporite
12
Basalt
28
Gypsum rock
13
Dolerite
14
Volcanic rock
99
Other (specify in
appropriate section’s
Notes)
15
Sedimentary rock
16
Limestone
0
Not known
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
A4.1.10 Stoniness/rockiness/hardpan/cementation
Numeric code
Descriptor state
1
Tillage unaffected
2
Tillage affected
3
Tillage dificult
4
Tillage impossible
5
Essentially paved
A4.1.11 Soil drainage (Adapted from FAO 1990)
Numeric code
Descriptor state
3
Poorly drained
5
Moderately drained
7
Well drained
A4.1.12 Soil salinity (dissolved salts)
Numeric code
Descriptor state
1
<160 ppm
2
161 – 240 ppm
3
241 – 480 ppm
4
481 – 800 ppm
5
>800 ppm
A4.1.13 Groundwater quality
Numeric code
Descriptor state
1
Saline
2
Brackish
3
Fresh
4
Polluted
5
Oxygenated
6
Stagnating
A4.1.14 Soil depth to groundwater table (Adapted from FAO 1990)
The depth to the groundwater table, if present, as well as an estimate of
the approximate annual luctuation, should be given. The maximum
rise of the groundwater table can be inferred approximately from
changes in proile colour in many, but not all, soils.
Developing crop descriptor lists
Numeric code
65
Descriptor state
1
0 - 25 cm
2
25.1 - 50 cm
3
50.1 - 100 cm
4
100.1 - 150 cm
5
> 150 cm
A4.1.15 Soil moisture
Moisture conditions prevailing in the soil at the time of collecting
should be given together with the depth. Attention should be paid
to unusual moisture conditions caused by unseasonal weather,
prolonged exposure of the proile, looding, etc. (from FAO 1990).
Numeric code
Descriptor state
1
Dry
5
Slightly moist
7
Moist
9
Wet
A4.1.16 Soil matrix colour (Adapted from FAO 1990)
The colour of the soil matrix material in the root zone around the
accession is recorded in the moist condition (or both dry and moist
condition, if possible) using the notations for hue, value and chroma
as given in the Munsell Soil Color Charts (Munsell Color 1975). If
there is no dominant soil matrix colour, the horizon is described as
mottled and two or more colours are given and should be registered
under uniform conditions. Early morning and late evening readings
are not accurate. Provide depth of measurement [cm]. If a colour chart
is not available, the following states may be used:
Numeric code
Descriptor state
Numeric code
Descriptor state
1
White
9
Yellow
2
Red
10
Reddish yellow
3
Reddish
11
Greenish, green
4
Yellowish red
12
Grey
5
Brown
13
Greyish
6
Brownish
14
Blue
7
Reddish brown
15
Bluish black
8
Yellowish brown
16
Black
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
A4.1.17 Soil organic matter content
Numeric code
Descriptor state
1
Nil (as in arid zones)
3
Low (as in long-term cultivation in a tropical setting)
5
Medium (as in recently cultivated but not yet much depleted)
7
High (as in never cultivated, and in recently cleared forest)
9
Peaty
A4.1.18 Soil pH
Actual pH value of the soil around the accession
A4.1.18.1 Root depth [cm]
Indicate the root depth at which the soil pH is being measured
A4.1.19 Soil erosion
Numeric code
Descriptor state
3
Low
5
Intermediate
7
High
A4.1.20 Rock fragments (Adapted from FAO 1990)
Large rock and mineral fragments (>2 mm) are described according
to their abundance by soil volume.
Numeric code
Descriptor state
1
0 – 2%
2
2.1 – 5%
3
5.1 – 15%
4
15.1 – 40%
5
40.1 – 80%
6
> 80%
A4.1.21 Soil texture classes (Adapted from FAO 1990)
For convenience in determining the texture classes of the following
list, particle size classes are given for each of the ine earth fraction
listed below (Figure A4.2):
Developing crop descriptor lists
Numeric code
67
Descriptor state
Numeric code
Descriptor state
1
Clay
12
Coarse sandy loam
2
Loam
13
Loamy sand
3
Clay loam
14
Loamy very ine sand
4
Silt
15
Loamy ine sand
5
Silty clay
16
Loamy coarse sand
6
Silty clay loam
17
Very ine sand
7
Silt loam
18
Fine sand
8
Sandy clay
19
Medium sand
9
Sandy clay loam
20
Coarse sand
10
Sandy loam
21
Sand, unsorted
11
Fine sandy loam
22
Sand, unspeciied
10
100
20
90
30
80
50
pe
rce
nt
cla
y
60
si
nt
rce
pe
40
70
lt
50
5
60
8
40
6
70
3
30
80
9
20
10
2
90
7
10
10
0
13
10
20
30
Figure A4.2. Soil texture classes
40
50
60
70
80
90
0
10
percent sand
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
A4.1.22 Soil particle size classes (Adapted from FAO 1990)
Numeric code
Descriptor state
1
Clay
<2 µm
2
Fine silt
3
Coarse silt
4
Very ine sand
5
Fine sand
6
Medium sand
201 – 630 µm
7
Coarse sand
631 – 1250 µm
8
Very coarse sand
3 – 20 µm
21 – 63 µm
64 – 125 µm
126 – 200 µm
1251 – 2000 µm
A4.1.23 Soil taxonomic classification
As detailed a classiication as possible should be given. This may
be taken from a soil survey map. State class (Alisols, Spodosols,
Vertisols, etc.).
A4.1.24 Water availability
Numeric code
Descriptor state
1
Rain-fed
2
Irrigated
3
Flooded
4
River bank
5
Sea coast
99
Other (specify in appropriate section’s Notes)
A4.1.25 Soil fertility
General assessment of the soil fertility, based on existing
vegetation.
Numeric code
Descriptor state
3
Low
5
Moderate
7
High
A4.1.26 Climate of the site
Should be assessed as close to the site as possible (state number of
recorded years)
• Temperature [ºC]
Provide either the monthly or the annual mean.
Developing crop descriptor lists
• Rainfall [mm]
Provide either the monthly or the annual mean (state number
of recorded years).
• Wind
Annual average (state number of years recorded)
– Frequency of typhoons or hurricane force winds
Numeric code
Descriptor state
3
Low
5
Intermediate
7
High
– Date of most recent typhoon or hurricane force wind
[YYYYMMDD]
– Annual maximum wind velocity [m/s]
• Frost
– Date of most recent frost [YYYYMMDD]
– Minimum temperature [ºC]
Specify seasonal average and minimum survival
temperature
– Duration of temperature below 0ºC [days]
• Relative humidity
– Relative humidity diurnal range [%]
– Relative humidity seasonal range [%]
• Light
Numeric code
Descriptor state
1
Shady
2
Sunny
• Day length [hours]
Provide either the monthly (mean, maximum, minimum) or
the seasonal (mean, maximum, minimum).
69
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BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
Appendix V – Example Collecting form
COLLECTING FORM for Allium spp.
=====================================================================================
SAMPLE IDENTIFICATION
-----------------------------------------------------------------------------------------------------------------------------------COLLECTING INSTITUTE(S) (2.1):
-----------------------------------------------------------------------------------------------------------------------------------COLLECTING No. (2.2):
PHOTOGRAPH No. (2.16):
-----------------------------------------------------------------------------------------------------------------------------------COLLECTING DATE OF SAMPLE [YYYYMMDD] (2.3):
-----------------------------------------------------------------------------------------------------------------------------------SPECIES (1.7):
SUBTAXA(1.8):
----------------------------------------------------------------------------------------------------------------------------------------COMMON NAME (1.11):
1. Dry bulb onion
2. Shallot
3. Japanese bunching onion/Welsh onion 4. Garlic
5. Leek
6. Kurrat
7. Great-headed garlic/elephant garlic
8. Chive
9. Rakkyo
10. Chinese chive/Oriental garlic/Nira
99. Other (specify)
=====================================================================================
COLLECTING SITE LOCATION
-----------------------------------------------------------------------------------------------------------------------------------COUNTRY OF ORIGIN (2.4):
-----------------------------------------------------------------------------------------------------------------------------------LOCATION (2.5):
km:
direction:
from:
-----------------------------------------------------------------------------------------------------------------------------------LATITUDE (2.6):
LONGITUDE (2.7):
ELEVATION (2.8): m asl
=====================================================================================
COLLECTING SITE ENVIRONMENT
-----------------------------------------------------------------------------------------------------------------------------------COLLECTING / ACQUISITION SOURCE (2.9):
10. Wild habitat
20. Farm or cultivated habitat
30. Market or shop
40. Institute, Exp. Station, Research Org., Genebank
50. Seed company
60. Weedy, disturbed
99. Other (specify):
or ruderal habitat
-----------------------------------------------------------------------------------------------------------------------------------HIGHER LEVEL LANDFORM (6.1.2):
-----------------------------------------------------------------------------------------------------------------------------------1. Plain
2. Basin
3. Valley
4. Plateau
5. Upland
6. Hill
7. Mountain
-----------------------------------------------------------------------------------------------------------------------------------SLOPE [°] (6.1.4):
SLOPE ASPECT (6.1.5; code N,S,E,W):
=====================================================================================
SAMPLE
-----------------------------------------------------------------------------------------------------------------------------------BIOLOGICAL STATUS OF ACCESSION (2.12):
100. Wild
200. Weedy
300. Traditional cultivar/Landrace
400. Breeding/research material
500. Advanced/improved cultivar
999. Other (specify):
-----------------------------------------------------------------------------------------------------------------------------------TYPE OF SAMPLE (2.13):
1. Vegetative
2. Seed
99. Other (specify)
-----------------------------------------------------------------------------------------------------------------------------------NUMBER OF PLANTS SAMPLED (2.14): PREVAILING STRESSES (2.15.7):
Mention the types of major stresses, i.e. abiotic (drought), biotic (pests, diseases, etc.)
=====================================================================================
ETHNOBOTANICAL DATA
-----------------------------------------------------------------------------------------------------------------------------------ETHNIC GROUP (2.15.1):
-----------------------------------------------------------------------------------------------------------------------------------LOCAL/VERNACULAR NAME (2.15.2):
------------------------------------------------------------------------------------------------------------------------------------
Developing crop descriptor lists
Plant uses (2.15.3)
1. Food uses
1.1 Raw salad
1.4 Freezing
1.5 Pickling
3. Ornamental
4. Forage
71
1.2 Fresh cooked
1.6 Dehydrated
99. Other (specify)
1.3 Stored/cooked/bottled/canned
2. Medicinal
-----------------------------------------------------------------------------------------------------------------------------------PARTS OF THE PLANT USED (2.15.4)
1. Seed
2. Root/rhizome
3. Bulb/clove
4. Leaf sheath/pseudostem
5. Leaf
6. Scape
7. Flower/inlorescence
99. Other (specify)
=====================================================================================
CHARACTERIZATION
-----------------------------------------------------------------------------------------------------------------------------------PLANT DESCRIPTORS
Foliage colour (7.1.1):
1. Light green
2. Yellow green
3. Green
4. Grey-green
5. Dark green
6. Bluish green
7. Purplish-green
99. Other (specify)
-----------------------------------------------------------------------------------------------------------------------------------LEAF LENGTH [cm] (7.1.2):
-----------------------------------------------------------------------------------------------------------------------------------FOLIAGE ATTITUDE (7.1.5):
3. Prostrate
5. Intermediate
7. Erect
-----------------------------------------------------------------------------------------------------------------------------------CROSS-SECTION OF LEAF (7.1.7):
1. Circular
2. Semi-circular
3. Square
4. Pentagonal
5. V-shaped
99. Other (specify)
-----------------------------------------------------------------------------------------------------------------------------------DEGREE OF LEAF WAXINESS (7.1.8)
3. Weak
5. Medium
7. Strong
-----------------------------------------------------------------------------------------------------------------------------------SHAPE OF MATURE DRY BULBS (7.1.11):
1. Flat
2. Flat globe
3. Rhomboid
4. Broad oval
5. Globe
6. Broad elliptic
7. Ovate
8. Spindle
9. High top
99. Other (specify)
-----------------------------------------------------------------------------------------------------------------------------------BULB SKIN COLOUR (7.1.15):
1. White
2. Yellow
3. Yellow and light brown 4. Light brown
5. Brown
6. Dark brown
7. Green (chartreuse)
8. Light violet
9. Dark violet
10. Mixed population
99. Other (specify)
-----------------------------------------------------------------------------------------------------------------------------------NATURE OF STORAGE ORGAN (7.1.11)
1. Bulb, single large
2. Bulbs, several small
3. Rhizomes
4. Cloves
5. Foliage leaf bases
99. Other (specify)
-----------------------------------------------------------------------------------------------------------------------------------INFLORESCENCE/FRUIT
Ability to lower (7.2.1):
0. No
1. Yes
-----------------------------------------------------------------------------------------------------------------------------------GENERAL FERTILITY (7.2.5):
1. Sterile
2. Male sterile
3. Female sterile
4. Fertile
-----------------------------------------------------------------------------------------------------------------------------------Flower number in umbel (7.2.6):
0. Absent
1. Few (<30)
2. Many (>30)
-----------------------------------------------------------------------------------------------------------------------------------Date of 50% flowering [YYYYMMDD] (7.2.8):
=====================================================================================
COLLECTOR’S NOTES:
IPGRI and INIBAP
operate under the name
Bioversity International
Supported by the CGIAR
ISBN: 978-92-9043-729-1