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8/9/2019 Home Gardens & in Situ Conservation of Plant Genetic Resources in Farming Systems; Gardening Guidebook

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Proceedings of the Second International Home GardensW orkshop , 17 –1 9 July 20 0 1 , W itzenhausen, Fede ra l Repub lic o f G erm anJ .W. Watson and P.B. E yzaguirre, e d i t o r s

Home gardens andi n s i t u conservation of plant genetic resourcesin farming systems

IPG RI isa Future Harvest Centresupported by theCons ultative Group onInternationa l AgriculturalResearch (CGIAR)

DeutscheGesellschaft fürTec hnisc heZusammenarbeit(G TZ) Gm bH


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Proceedings of the Second International Home GardensW orkshop , 17 –1 9 July 20 0 1 , W itzenhausen, Fede ra l Repub lic of G erm anJ .W. Watson and P.B. E yzaguirre, e d i t o r s

Home gardens andi n s i t u conservation of plant genetic resourcesin farming systems


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The International Plant Genetic Resources Institute (IPGRI) is an autonomous international scientific organization,supported by the Consultative Group on International Agricultural Research (CGIAR). IPGRI’s mandate is toadvance the conservation and use of genetic diversity for the well-being of present and future generations. IPGRI’sheadquarters is based in Maccarese, near Rome, Italy, with offices in another 19 countries worldwide. The Instituteoperates through three programmes: (1) the Plant Genetic Resources Programme, (2) the CGIAR Genetic Resources

Support Programme and (3) the International Network for the Improvement of Banana and Plantain (INIBAP).The international status of IPGRI is conferred under an Establishment Agreement which, by January 2001, had been signed and ratified by the Governments of Algeria, Australia, Belgium, Benin, Bolivia, Brazil, Burkina Faso,Cameroon, Chile, China, Congo, Costa Rica, Côte d’Ivoire, Cyprus, Czech Republic, Denmark, Ecuador, Egypt,Greece, Guinea, Hungary, India, Indonesia, Iran, Israel, Italy, Jordan, Kenya, Malaysia, Mauritania, Morocco,Norway, Pakistan, Panama, Peru, Poland, Portugal, Romania, Russia, Senegal, Slovakia, Sudan, Switzerland, Syria,Tunisia, Turkey, Uganda and Ukraine.

In 2000 financial support for the Research Agenda of IPGRI was provided by the Governments of Armenia,Australia, Austria, Belgium, Brazil, Bulgaria, Canada, China, Croatia, Cyprus, Czech Republic, Denmark, Estonia,F.R. Yugoslavia (Serbia and Montenegro), Finland, France, Germany, Greece, Hungary, Iceland, India, Ireland, Israel,Italy, Japan, Republic of Korea, Latvia, Lithuania, Luxembourg, Macedonia (F.Y.R.), Malta, Mexico, the Netherlands,Norway, Peru, the Philippines, Poland, Portugal, Romania, Slovakia, Slovenia, South Africa, Spain, Sweden,Switzerland, Thailand, Turkey, Uganda, the UK and the USA and by the African Development Bank (AfDB), AsianDevelopment Bank (ADB), Center for Development Research (ZEF), Center for Forestry Research (CIFOR), Centrede Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), Centro AgronómicoTropical de Investigación y Enseñanza, Costa Rica (CATIE), Common Fund for Commodities (CFC), Technical Centrefor Agricultural and Rural Cooperation (CTA), European Environmental Agency, European Union, Food andAgriculture Organization of the United Nations (FAO), Food and Fertilizer Technology Center for the Asia andPacific Region (FFTC), Future Harvest, Global Forum on Agricultural Research (GFAR), Instituto Colombiano parael Desarollo de la Cienca y la Technología (COLCIENCIAS), Inter-American Drug Abuse Control Commission(CICAD), International Association for the Promotion of Cooperation with Scientists from the New IndependentStates of the former Soviet Union (INTAS), International Development Research Centre (IDRC), InternationalFoundation for Science (IFS), International Fund for Agricultural Development (IFAD), International Service forNational Agricultural Research (ISNAR), Japan International Research Centre for Agricultural Sciences (JIRCAS),National Geographic Society, Natural Resources Institute (NRI), Programme on Participatory Research and GenderAnalysis for Technology Development and Institutional Innovation (PGRA), Regional Fund for AgriculturalTechnology (FONTAGRO), Rockefeller Foundation, Taiwan Banana Research Institute (TBRI), Technova, UnitedNations Development Programme (UNDP), UNDP Global Environment Facility (UNDP-GEF), United NationsEnvironment Programme (UNEP), UNEP Global Environment Facility (UNEP-GEF), United States Department of Agriculture (USDA), Vlaamse Vereiniging voor Ontwikkelingssasamenwerking en Technische Bijstand (VVOB) andthe World Bank.

The geographical designations employed and the presentation of material in this publication do not imply theexpression of any opinion whatsoever on the part of IPGRI or the CGIAR concerning the legal status of any country,territory, city or area or its authorities, or concerning the delimitation of its frontiers or boundaries. Similarly, theviews expressed are those of the authors 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 :Watson, J.W. and P.B. Eyzaguirre, editors. 2002. Proceedings of the Second International Home Gardens Workshop:Contribution of home gardens to in situ conservation of plant genetic resources in farming systems, 17–19 July2001, Witzenhausen, Federal Republic of Germany. International Plant Genetic Resources Institute, Rome.

ISBN 92-9043-517-8

IPGRIVia dei Tre Denari 472/a00057 Maccarese (Fiumicino)Rome, Italy

© International Plant Genetic Resources Institute, 2002

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C o n t e n t s

Acknowledgements v

Foreword vi

IntroductionOpening remarks 1

G. Fischbeck Home gardens—a genetic resources perspective 3

J. Engels Home gardens agrobiodiversity: an overview across regions 10

P.B. Eyzaguirre and J . Watson

Technical contributionsHome gardens and the maintenance of genetic diversity 14

T. Hod gkin Documentation of plant genetic resources in home gardens 19

H. Knüpffer Contributions of home gardens to our knowledge on cultivated plant species:the Mansfeld approach 27K. Hamm er

Characterizing genetic diversity of home garden crop species: 34some examples from the AmericasM. Hoogendijk and D. Williams

Contributions of home gardens agrobiodiversity to development, nutrition and livelihoods 41P.B. Eyzaguirre and M . Fernandez

Project reportsContribution of home gardens to in situ conservation of plant genetic resources 42in farming systems —Cuban componentL. Casti ñ eiras, Z. Fundora Mayor, T. Shagarod sky, V. M oreno , O. Barrios,L. Fern

á ndez and R. Crist

óbal

Contribution of home gardens to in situ conservation 56in traditional farming systems —Guatemalan componentJ. M . Leiva, C. Azurdia, W. Ovando , E. L ó pez and H . Ayala Home gardens and in situ conservation of agrobiodiversity —Venezuelan component 73C. Quiroz, M. Guti é rrez, , D. Rod r í guez, D. P é rez, J. Ynfante, J. G á mez, T. P é rez de Fernandez,A. Marques and W. Pacheco

Contribution of home gardens to in situ conservation of plant genetic resources 83in farming systems in GhanaS.O. Bennett- Lartey, G.S. Ayernor, C.M . M arkwei, I.K. Asante, D.K. Abb iw, S.K. Boateng,

V. M. Anc hirinah and P. EkpeRole of home gardens in the conservation of plant genetic resources in Vietnam 97L.N. Trinh, N.T.N. Hue, N.N . De, N. V. Minh and P.T. Chu

C O N TE N TS iii


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Case studiesHome gardens in Nepal: status and scope for research and development 105P. Shrestha, R. Gautam, R.B. Rana and B. Sthapit

Home gardens in Ethiopia: some observations and generalizations 125

Z. AsfawHome gardens in the Upper Citarum Watershed, West Java: a challenge for in situ 140conservation of plant genetic resourcesO.S. Abd oellah, Parikesit, B. Gunaw an and H .Y. Hadikusumah

Working group reportsPlant genetic resources conservat ion in home gardens: ecosystems and key species 148

Group AIn situ conservation strategies for home gardens as components 151of complementary conservation and use strategies for plant genetic resources

Group B

Documentation and measurement of genetic diversity in home gardens 155Group C

Mainstreaming contributions from the project: follow-up actions andpriorities for future work on managing home gardens ’ agrobiodiversity for development

Group A 156Group B 158Group C 161

Poster presentationsTemperate home gardens of small alpine farmers in Eastern Tyrol (Austria): 163their value for maintaining and enhancing biodiversityB. Vogl-Lukasser and C R. Vogl

Mansfeld ’s Encyclopedia and Database on Agricultural and Horticultural Crops 165J. Ochsmann, H. Kn ü pffer, N. Biermann and K. Bachm annThe home garden database and information system —technical aspects 168V. Afanasyev, J. Ochsmann and H . Kn ü pfferHome gardens in Kerala as an efficient agroecosystem for conservation 169and sustainable management of biodiversity

K. PushkaranEthnobotany of genetic resources in Germany —diversity in city gardens 171of immigrantsTh. Gladis

Summary and recommendationsConclusions 175P.B. Eyzaguirre

Appendix I. Workshop Agenda 176

Appendix II. List of Participants 179

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A C K N O W LE D G EM E N TS v

A c k n o w l e d g e m e n t s

The Home Gardens Workshop documented in these Proceedings was made possible by theconceptual guidance, financial and logistical support of the German Foundation for International

Development (DSE). In particular, Eckard Hehne, Wolfgang Zimmermann, Theda Kirchner, andWaltraude Michaelis should be singled out for their contributions in assuring the high quality andpartnership that was achieved at this event. DSE was first involved in identifying home gardenagrobiodiversity as an important issue for in situ conservation at an earlier workshop in Bonn in 1995and we are grateful for their long-term support. In addition, the contributions of the University of Kassel, Witzenhausen and of the International Centre for Advanced Training at Witzenhausen(IBZW) to the organization of the Workshop are duly acknowledged. We are grateful that our researchpartners and scientists from several institutions in Germany and around the world were able toparticipate; their contributions greatly enriched the discussion. We also thank the team that producedthis volume, in particular Annie Huie for compiling the manuscript. The funding for the researchphase of the Home Gardens Project was provided by the Federal Ministry for Economic Co-Operationand Development (BMZ) through the Deutche Gesellschaft fuer Technische Zusammenarbeit (GTZ)and implemented by the International Plant Genetic Resources Institute (IPGRI).


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Foreword

The roots of this Home Gardens Workshop go back to at an earlier meeting organized by theGerman Foundation for International Development (DSE) and its Food and Agriculture Development

Centre (ZEL) in Bonn, Germany in 1995 to identify priority issues for conservation and use of plantgenetic resources in developing countries. IPGRI and various German partners considered a range of problems that developing countries face in managing and conserving plant genetic resources. Themeeting also suggested priorities and strategies to increase the contribution of agrobiodiversity andgenetic resources to food security and economic development of the rural poor and established a jointpriority research agenda. Home gardens, a globally distributed system managed by rural householdsto maintain and utilise plant diversity, were highlighted as an important system for in situconservation strategies. Focusing on home gardens was also an opportunity to show howagrobiodiversity contributes to better livelihoods for the rural poor and increases productivity inecosystems.

In 1998, the priorities established at the aforementioned DSE in situ workshop were put intopractice in partnership with genetic resources scientists and institutions in developing countries withthe support of the German Federal Ministry for Economic Cooperation and Development (BMZ)through GTZ (Deutsche Gesellschaft für Technische Zusammenarbeit). A three-year IPGRI researchproject on agrobiodiversity in home gardens has been implemented in partnership with nationalplant genetic resources programmes in five countries: Ghana, Vietnam, Guatemala, Cuba andVenezuela. The Institute of Plant Genetics and Crop Plant Research (IPK-Gatersleben) has served asthe partner German institution working in the areas of genetic resources documentation andcharacterization.

The results of the Home Garden Project presented in these Workshop Proceedings contributeto national and global strategies for including home gardens as a distinct and important componentof in situ conservation of agrobiodiversity. The national and comparative studies have also begun toestablish a clear link between home garden diversity and household livelihoods and food security.IPGRI will continue to build the global research partnerships that provide national programmes andlocal organizations with the tools to include genetic resources management at the household andecosystem levels in national biodiversity conservation and development strategies and policies. Wethank the many institutions, communities, and individuals that have contributed to the research onhome gardens genetic resources and Germany for its financial support of the Workshop and theresearch activities.

Geoffrey Hawtin, PhDDirector General, IPGRI


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IN TR O D U C TIO N 1

Int roduct ion

Opening remarks

Gerhard FischbeckEmeritus Professor of Plant Breeding, University of Munich-Weihenstephan

The purpose of this international workshop is to address the topic ‘Contribution of Home Gardens tothe In Situ Conservation of Plant Genetic Resources in Farming Systems’. As a former universityprofessor of Agronomy and Plant Breeding and one of the early Board members of IBPGR (nowIPGRI), I have been interested and engaged in plant genetic resources work for quite some time.

Many of the readers will know about, or may even have participated in, the ‘Fourth InternationalFAO Conference on Plant Genetic Resources for Food and Agriculture’ that was held in Leipzig in1996. At this occasion, the status of plant genetic resources was reviewed on a worldwide basis andsignificant gaps, inherent risks, and tremendous costs became clearly apparent, confounding aconservation strategy mainly focused on ex situ gene bank conservation of plant genetic resources. Itwas not difficult to conclude that opportunities for in situ conservation of plant genetic resourcesdeserved much more interest than they had received before; even more so, since the erosion of geneticdiversity in cultivated plants did not proceed with the speed and intensity that had been fearedduring the early phases of the Green Revolution. Apparently, there are structures and/or conditionsin developing countries that support the maintenance of diversity within traditional crop speciesdepending on the needs and preferences of rural communities. Inevitably, such forms of in situconservation contain dynamic possibilities for genetic change. Such elements may result in adaptivechanges in gene frequencies without much danger of loss of genetic diversity; these may even containpositive aspects from a breeders view. In contrast, depending on the size and structure of thepopulation as well as differences in the mating and propagation system for a species, it is also possiblethat genetic drift will occur, which can result in sizable losses in genetic diversity from the originalgene pool.

IPGRI and GTZ were among the first research and donor organizations to initiate a pilot project tostudy the role of home gardens in genetic diversity conservation, and I am very glad to serve aschairman to this Second International Home Gardens Workshop, convened to derive conclusionsfrom the preceding three-year research project. Besides delegations from the five countriesparticipating directly in the project, the attendance of colleagues from at least 10 more countriesdemonstrates the increasing worldwide interest in assessing home garden diversity. Experts fromIPGRI, IPK Gatersleben and the University of Kassel are also attending, among which I want tomention personally Prof. Hammer, who pioneered the scientific interest in home gardens. The

combination of country research partners, home garden experts from around the world, andrepresentatives from international research and development institutions will hopefully provideopportunities for broad-based discussions.

This workshop intends to concentrate more on technical than on scientific questions. Within aframe of more general lectures related to principles of in situ conservation and home gardencharacteristics, the first objective of this workshop is to provide a summary of the Home GardensProject results obtained by the five participating countries during their three-year research phase.These results form the experimental basis upon which any of the other objectives of the workshopneed to be based.

The second objectivestill concentrates on the individual country results but, in addition, calls for thecountry teams to elucidate from their results in situ conservation issues and to present ideas for

management systems that suit conservation purposes.Results and ideas from country reports together with principles demonstrated in the framework lectures will form the basis for the third objective: to provide guidelines for extended efforts in the


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2 H O M E G A R D E N S A N D IN SITU C O N S E R VA TIO N O F P G R

utilization of home garden potential for in situ conservation. This objective will be achieved withinputs from all participants and aims at formulating project follow-up actions and more generalrecommendations that include relevant ties with the Convention on Biodiversity (CBD).

To this end, several working groups have been formed to discuss major issues and conclusions, as

well as to formulate proposals for follow-up actions that will hopefully emanate from this workshop.In this way, the publication of the proceedings of this workshop may form a milestone in expandingthe interest in home gardens and increasing their utilization for in situ conservation.


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Home gardens—a genetic resources perspective

Jan EngelsInternational Plant Genetic Resources Institute, Rome, Italy

In t roduc t ion The importance of home gardens in the production of food, medicine and other useful products forhuman beings is widely recognized; consequently, regular attempts to improve the productivity of this widespread agro-ecosystem have usually been initiated with specific objectives in mind. Theimportance of the contribution of home gardens to the improvement of the nutritional status of ruraland urban families and the increase of vegetable production in the tropics are two examples of previous home garden research. The realization that this ‘farming’ system is also an importantreservoir of unique genetic diversity has more recently led to initiatives to study this system morecarefully in order to obtain a better understanding of the role of home gardens in the managementand conservation of genetic diversity in situ .

This overview paper is intended to assess how different aspects related to genetic diversitymanagement may contribute to or have an influence on the in situ conservation of agro-biodiversityin home gardens from a genetic resources perspective. However, before starting this assessment itwould be advantageous to provide some information on the general ‘philosophical’ context in whichthis home garden research is being implemented at IPGRI.

IPGRI’s mandate is “To advance the conservation and use of genetic diversity for the well-being of presentand future generations” which places IPGRI’s programmatic work clearly in the development context.This aspect is further underlined in its mission statement: “To encourage, support and undertake activitiesto improve the management of genetic resources worldwide so as to help eradicate poverty, increase food securityand protect the environment. IPGRI focuses on the conservation and use of genetic resources important todeveloping countries and has an explicit commitment to specific crops”(IPGRI 1999).

Conservation efforts can only be based on a sustainable footing if and when the targeted geneticdiversity is utilized. Therefore, it can be concluded that it is not only important to understand thegenetic diversity as such, but also its role in agro-ecosystems as well as the role and function of human beings in the management of genetic diversity. Only a holistic research approach, actively involvingall the relevant ‘stakeholders’ in a participatory manner and examining all components of theagroecosystem that influence diversity management will lead to meaningful results.

Closely related to the agroecosystem approach, it will be important to place the conservation in awider context in order to achieve a sustainable conservation effort; all possible options and methodsavailable should be considered to conserve the genetic diversity within the home garden agro-ecosystem. Good links with national conservation programmes will be as important as a close

collaboration with other supporting research activities in the country or region, incorporatingdisciplines such as plant taxonomy, plant breeding, nutrition, socio-economic and policy aspects.Through a better understanding of the role of farmers and their families as the producers of garden

products, it will be possible to improve the management of genetic diversity in home gardens,resulting in a better and more sustainable production combined with the maintenance of a high levelof genetic diversity. Targeted and well-planned ‘interventions’ from the outside, i.e. the introductionof new crops, improved varieties and/or of specific characteristics that are missing in a given homegarden system can further strengthen the importance of this production system and allow a naturallink between conservation and development.

In the following, the different approaches to conservation will be examined followed by a brief treatment of ways and means to encourage an increase of genetic diversity within home gardens.

Than we will have a closer look at the important aspects of home gardens from a plant geneticresources perspective and, finally draw a few conclusions.



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Approaches to conservat ion

Agroecosystem approachHome gardens can be regarded as microenvironments within the agroecosystem that preserve the

function and resilience of the larger ecosystem. It is important to think of these microenvironments inthe aggregate when determining optimum conservation units for a conservation strategy, for instancewhen selecting gardens, deciding on the number to be included in a conservation strategy,determining population sizes of plant species, etc.

Home gardens as an ecosystem contain multiple levels of diversity, including cultural, genetic andagronomic diversity. They are valued for different reasons, for instance: one can distinguish anintrinsic value related to its aesthetic value, religious value, etc.; an ecosystem value as mentioned before; and a value in its contribution to livelihoods. Closely related to these different types of valueis the fact that genetic diversity managed by people has a close and direct linkage with the culturaldiversity. Therefore, while purposefully conserving one aspect of diversity, it is impossible to avoidconsidering the others. One important element of this genetic diversity–cultural complex is theindigenous knowledge that is entirely interwoven with these two components. It is an integral andessential part of the genetic diversity, and consequently, the diversity can only be used as a geneticresource if both the biological and the information/knowledge components are available.

From a genetic and agronomic diversity point of view, it is often the strong influence of human beings managing the gardens that leads to increased diversity. As will be discussed below, homegardens are important centers of experimentation, plant introduction, and crop improvement as wellas refuges for unique genetic diversity. The latter diversity exists at the “ecosystem” level (i.e. thewider ecological environment within a geographic region in which individual gardens exist), thespecies level and within species levels. It is especially the genetic diversity in the two last levels thatis of interest for conservation efforts.

Holistic conservation approachIn broad terms, one can divide genetic conservation into two approaches. One approach deals withgenetic diversity occurring in its natural environment, e.g. the plant, animal and microbial diversityin natural habitats and the crop, animal and wild relatives in farmers’ fields and their surroundings.This form of conservation is called in situ . The other approach, the most common method for plantgenetic resources for food and agriculture (PGRFA), is to collect the genetic diversity from its naturalsurrounding or from research programmes and store the seed, vegetative parts or even the entireplant in a man-made infrastructure, i.e. a genebank. This way of conserving genetic diversity is calledex situ conservation.

In view of the fact that each of these broad conservation approaches mentioned above can be

subdivided into more specific methods, largely developed to deal with the specific biologicalrequirements of the material to be conserved, it will be important to carefully consider theserequirements in order to choose the most suitable ones. Besides the fact that each of these methods issuitable for specific types of biological material, they possess also other strengths and weaknesses thatone needs to consider when conserving genetic resources. These considerations may include theduration of the conservation exercise, the access to the conserved material, administrative andpolitical issues, questions of ownership and sovereignty, among other questions. Therefore, whensearching for the best method, it will be relatively easy to see how two or more methods should beused in combination in order to fit these variables and, thus, to provide for the most effective andefficient conservation strategy. The right combination of conservation methods can significantlyincrease the total genetic diversity conserved, its security, accessibility, and cost-efficiency. In selecting

the appropriate conservation methods it is important to take a holistic view of the overall objectivesof the conservation effort and to place it in a wider context, whenever possible, as part of adevelopment process.



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While the Convention on Biological Diversity (CBD) emphasizes the in situ approach toconservation, it views both in situ and ex situ conservation as complementary. In the case of both plantand animal genetic resources for food and agriculture, ex situ conservation has been the customarypractice to date. Germplasm collections are maintained in genebanks and are, thus, readily accessible

for use in plant and animal improvement programmes. This perspective has now broadened to takeaccount of the role of in situ conservation, which allows the process of crop evolution and adaptationto continue.

In situ and ex situ methods are thus increasingly viewed as mutually supportive options availablefor conserving different elements of a given genepool to include traditional and modern crop varietiesas well as animal breeds, wild relatives and genetic stocks. Selection of the appropriate methodshould be based on a range of criteria, including: the biological nature of the species in question; thepracticality and feasibility of the particular method chosen (which depends on the availability of thenecessary infrastructure and the necessary human and financial resources); and the efficiency, cost-effectiveness and security afforded by its application. In many instances, the development of appropriate complementary conservation strategies requires further research to define the criteria,refine the method and test its application for a range of genepools and situations. An important aspectto consider in linking in situ and ex situ components in the conservation strategy is the dynamic natureof the former and the static, but potentially more secure approach, of the latter.

In the case of crop plants, selection of the appropriate ex situ method (seed, pollen, in vitro , field,DNA conservation) will depend largely on the biological nature of the germplasm material. Whereverpossible, preference is given to the storage of orthodox seeds under low temperature and seedmoisture content regimes as this method is best researched, easy to apply and relatively cheap. If thespecies in question does not produce orthodox seeds or is propagated vegetatively, the material can be maintained either in field genebanks or as tissue in reagents tubes, i.e. in vitro . Alternatively, pollencan also be considered for storage. Such ex situ efforts can be complemented by approaches such ason-farm management of the valuable genetic diversity inherent in traditional crop varieties andlandraces and in situ conservation of their wild relatives in protected areas. Engels and Wood (1999)provide more details of the individual methods, including the pros and cons.

Thus, with growing recognition that sustainable and adequate conservation of the world’s geneticresources cannot be achieved through any single approach or method, complementary strategies areincreasingly being adopted by conservation programmes around the world. Moreover, in recognitionthat lasting conservation efforts of any kind can only be achieved through the active participation of all stakeholders, both national and international conservation efforts are increasingly being integratedinto broader development objectives and processes. Details of organizational and institutional aspectsof conservation activities at the national and international level can be found in Spillane et al. (1999).

Linking conservation with developmentIn complementary conservation, it is important to give due consideration to the utilization of thegermplasm conserved, either by the household using the resource as the foundation for foodproduction, or by the plant breeder in improvement efforts. It will be important that home gardenmaterial is made available for research as a basis for the improvement process. Therefore, establishinglinks between local communities that depend on home gardens and the formal research andconservation system is an essential pre-condition for increasing the benefits of managing diversitywithin home gardens.

Another related aspect is the establishment of linkages with extension services, as part of a widercollaboration between home garden farmers on the one side and the research and conservationsystems on the other. Such a link will be essential to the research community, providing the means to

inform them of the needs and problems that occur at the grassroots level; it would also be essential tothe home gardeners themselves because they might benefit more directly from new developments inthe agricultural sector that are being disseminated by the extension service.



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Another dimension of linking the home garden community with the outer world is theinvolvement of the public and private sectors as well as civil society in the conservation anddevelopment projects. This will ensure that the aforementioned needs of home garden owners can bevoiced, and that influence can be asserted where and when it is necessary on their behalf.

Encouraging/facilitating the increase of genetic diversityTo maintain genetic diversity at the species and within species level, it is important to continue theprocess of evolution through farmer selection within crop diversity to obtain suitable types under theprevailing conditions, ensuring the crop’s ability to adapt to changing conditions or requirements. Itis also widely accepted that genetic diversity within a farming system provides more crop stability interms of yield security and encourages more sustainable production methods, because thedependency on outside-farm inputs is much lower. Therefore, especially in marginal environmentswhere the predictability of growing conditions is low, the use of more genetic diversity tends to be beneficial to the people. It is assumed that this very situation is also applicable to home gardenproduction.

However, in order to ensure the long-term and broad-based suitability of the genetic diversitymanagement and conservation practices in home gardens, it will be indispensable to create awarenessof the role and importance of genetic diversity in production systems as well as in crop evolution atlarge. In particular, the relationship between crop evolution and the role of the individual is importantto understand.

In order to further strengthen the genetic base of the crops grown and bred within the gardens, itis important to facilitate access to species and varietal diversity in communities, introducing specificcharacteristics in particular crops according to the local needs. A close link with the national geneticresources programme will be beneficial.

Organizing diversity fairs and demonstration plots are two of many more approaches that willfacilitate the creation of awareness and the exchange of genetic diversity and management/usepractices among the owners of individual gardens. A related activity is the creation of opportunitiesto market the produce of the gardens in order to generate additional income for gardeninghouseholds.

Impor tan t aspec ts o f hom e gardensf rom a p lan t gene t ic resource perspec t ive

Plant domesticationPlant domestication most likely began around the dwellings of human settlements. The immediatearea around the homestead offers increased availability of water, better soil fertility due to organic

waste inputs, and easier protection of the crop against animals (Harlan, 1975). Facilitated by the closeinteraction between humans and plants within a home garden setting, many new crops have beendeveloped in home gardens. This process continues, especially in parts of the world where there isstill ample plant diversity available and where a ‘natural’ link between gardens and nature exist.

Very diverse selection pressures, such as significant differences in micro-environments and acontinuous flow of germplasm between gardens, affect the evolution of crop species, especially of vegetables and other minor crops. Human selection of plant diversity within the genepool is one of the driving forces of crop evolution, a process that is being fueled by the availability and creation of genetic variability.

As the process of plant domestication and crop evolution is ongoing it can be expected thatcontinuously new germplasm will develop. Consequently, home gardens contain unique and rare

genetic diversity that has evolved or be developed locally and that is of interest not only to thedevelopers but also to the conservationists within a given country as well as internationally.



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Plant introduction and distribution centreHome gardens can collectively be regarded as informal ‘plant introduction and distribution’

centers, and the permanent contacts between gardens—facilitated through the strong links betweengardens, families, and local markets—as well as the great diversity in individual gardens lead to

continuous germplasm and information exchange among them. These activities are of criticalimportance for plant domestication and crop evolution and also give rise to a dynamic situation inwhich new and unique genetic diversity can evolve.

Wherever the home garden is linked to a farm it has been regularly observed that the homegarden plays the role of a nursery where seedlings and plantlets are produced for transplanting,diseased plants are nurtured, and vegetatively propagated material is multiplied.

Experimentation centreClosely linked to some of the aforementioned points the garden is also a place for experimentation andeven fundamental research. The ground breaking genetic research of the monk Gregor Mendel duringthe 19th century in the Tjech Republic was done in the home garden of the monastery and resulted inthe formulation of the genetic laws that, among other advances, greatly facilitated plant breeding!

Experimentation with growing new species and varieties is a well-known aspect of home gardensand is in fact an important contribution to crop improvement and evolution. Human curiosity is animportant factor that stimulates experimentation and encourages rare plants to be introduced,grown and used. Information sharing on plant production increases the efficiency of experimentation and builds on experiences of others.

Important production centreHome gardens are the logical production system for crop plants that are eaten fresh, used on a daily basis, consumed only in small quantities, or that need specific attention such as vegetables, spicesand herbs, medicinal plants. Species such as minor fruits, root and tubers, ornamentals and othersalso fall into this category. The types of crops grown and the closeness of the garden to the house andkitchen assure that home gardens contribute significantly to food security, especially because theyare an important source of micro-nutrients and vitamins, and therefore play a critical role in thenutritional balance of the human diet.

From a plant genetic resources perspective, it is obvious that that the home garden is an importantlocation for the cultivation of so-called neglected and underutilized species (neglected from aresearch perspective and underutilized from a broader economic perspective). Such species have sofar not received much attention from conservationists, botanists and agronomists, and they aresignificantly under-represented in genebanks. Therefore, integrating home gardens into a nationalconservation strategy would most likely lead to increased research, better conservation and to a

strengthened basis for the improvement of these species.Refuge for genetic diversityAs already mentioned, home gardens are a ‘window’ for introduction of, and experimentation with,genetic diversity. Consequently, they harbour significant amounts of genetic diversity, partly uniqueand sometimes rare. This diversity exists both at the species and within species (or varietal) level andtends to be greater in tropical gardens. In order to provide a possibility for comparison, the authorcounted the species and varietal diversity in the home garden of a friend in the central part of Germany (i.e. Heidelberg). A total of 12 crop/species groups and 105 species and varieties werecounted in an area of approximately 750 square meters. From my own observations in CentralAmerica, East Asia and southern Ethiopia it can be concluded that the genetic diversity at the variety

level within a garden is relatively limited but between gardens within a local community thisdiversity is high or very high. In contrast, the diversity at the species level in temperate gardens isrelatively high within a garden and more limited between gardens within a given community.



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Therefore, when planning a conservation strategy it is important to duly consider these aspects.Sometimes the site of the house itself is selected based on the presence of particular wild tropical

fruit trees, so the home garden then becomes a refuge for them. It was observed in Central Americathat in several instances the location of the house was determined by the presence of one or more

wanted fruit trees in the forest not only for its fruits but also for shade. Therefore, in areas withrelatively recent human settlement, matured fruit trees of indigenous species frequently representthe original genotypes of a naturally distributed and usually non-domesticated species.

Home gardens and cultural heritageAs previously mentioned, there exists a close relationship between a home garden and the culture of the surrounding community, and in fact the two are completely interwoven. One very striking aspect,related to the traditions of a family as part of a larger community, is the key role of women inmanaging the garden and utilizing its produce, either in her own kitchen or by selling it in the market.

Strong links can be observed between culinary and botanic diversity, and a good understandingof both aspects is important to proper conservation management. The inclusion of women in theconservation strategy is obvious and needs to be given due attention during the preparatory andimplementation phases.

Another dimension of the close relationship between house, garden and family is the role thehome garden plays in terms of security. The garden is frequently part of the protected area aroundthe homestead, which often includes a fence in order to keep children and livestock in and othersout, thus also protecting genetic diversity.

Linking home gardens to research or extensionThe absence of formal or informal links between the home gardens on the one side and the nationalresearch and extension service on the other does not allow this important production system to benefit from the outcome of research or from the services of the extension system. Furthermore, theproblems encountered within home gardens are neither addressed by public- or private-sector-funded research nor is the production of food in any way reflected in the national statistics. Thissituation leads to a continued neglect of the home gardens, excluding them from national or regionalconservation efforts, and requiring due attention and improvement.

Another consequence of this situation is that, without information on home gardens and links tothe national system, they can’t be a factor in the development or implementation of new legislationor policy, a situation that could easily result in laws and policies that are not beneficial for the homegarden system. One example of a possible negative consequence is the introduction of plant varietyprotection law in many developing countries that typically results in national seed laws that arerather restrictive to the flow of seed and planting material. For instance, in Europe it is not

permissible to exchange bigger quantities of seed or planting material when the material is notregistered as a protected variety. The latter can only be done when the material is sufficientlyuniform, stable and distinct as well as having a proven use value. These requirements can hardly beachieved for the small numbers of plants that are grown in gardens and that will not becommercialized. Therefore, such a policy could have a negative impact on the flow of germplasmand, thus, possibly undermine the home garden system.

Linkages with the marketplaceThe market place plays an important social and economic role in many rural areas of the world.Within the context of home gardens and from a genetic diversity perspective, the marketplace iscrucial in facilitating the exchange of germplasm among the members of a community as well as

between communities. We have already seen how important such exchange is for crop evolution andimprovement as well as for the continued and sustainable production of food in the home gardens,even if the exchange of genetic diversity may be restricted to the local market. The market can also



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be an important entrance point for new crops or varieties and, in this way, can link the individualgarden to a larger network.

Another aspect of the marketplace is the opportunity to sell or barter the surplus produce of thegarden, thus generating additional income for the family. The fact that women typically market the

surplus produce has the advantage that the exchange of genetic diversity is driven by the needs of the housewife and, consequently, may reflect important needs such as food security. Furthermore,the additional income will more likely benefit the family and/or contribute to a more balanced diet(Talukder et al. 2000); therefore, the agrobiodiversity present in home gardens has importantdevelopment as well as conservation contributions.

ConclusionsHome gardens are an important production system of food and other essential products, harbouringunique and sometimes rare genetic diversity of our crop plants and some of their wild relatives. Inaddition, as centers of experimentation, species domestication, crop improvement as well as of plantintroduction and exchange they deserve the highest possible attention in genetic resourceconservation and use programmes.

• Home gardens provide a unique opportunity to clearly explain and demonstrate theimportance of genetic diversity for crop improvement and evolution as well as the relevanceof linking conservation of agro-biodiversity with development.

• Home gardens are an important agro-ecosystem that provides national programmes andIPGRI with unique opportunities to study conservation efforts in a holistic sense, inparticular to develop complementary conservation strategies.

• It is important to link conservation efforts in home gardens with national programmes and,thus, allow the necessary integration of the home garden system in the national research andextension system.

• More targeted research support is needed to utilize the opportunities that home gardensoffer to food security and agro-biodiversity conservation.

ReferencesEngels, J.M.M. and D. Wood. 1999. Conservation of agrobiodiversity. Pp. 355–385 in Agrobiodiversity:

Characterization, Utilization, and Management (Wood and Lenne, eds.). CABI Publishing, Wallingford, UK.Harlan, J.R. 1975. Crops and man. American Society of Agronomy, Madison, Wisconsin, USA.IPGRI, 1999. Diversity for development. The new strategy of the International Plant Genetic Resources Institute.

IPGRI, Rome, Italy.Spillane, C., J. Engels, H. Fassil, L. Withers and D. Cooper. 1999. Strengthening national programmes for plant

genetic resources for food and agriculture: planning and coordination. Issues in Genetic Resources no. 8.IPGRI, Rome, Italy.

Talukder, A., L. Kiess, N. Huq, S. de Pee, I. Darnton-Hill and M.W. Bloem. 2000. Food and Nutrition Bulletin21(2):165-172.



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Home gardens and agrobiodiversity: an overview across regions

Pablo Eyzaguirre and Jessica WatsonInternational Plant Genetic Resources Institute, Rome, Italy

Biodivers ity conserva t ion and deve lopm ent in h ome gardens Home gardens are microenvironments containing high levels of species and genetic diversity withinlarger farming systems. These gardens are not only important sources of food, fodder, fuel, medicines,spices, construction materials and income in many countries around the world, but are also importantfor in situ conservation of a wide range of plant genetic resources. Home gardens are dynamicsystems; their structure, composition, and species and cultivar diversity are influenced by changes inthe socioeconomic circumstances and cultural values of the households that maintain these gardens.Understanding the factors and decision-making patterns that affect the management of home gardensis crucial for including home gardens as a strategic component of in situ conservation of agrobiodiversity.

The conservation of agrobiodiversity is inseparable from the sustainable use of plant geneticresources in agriculture. Thus agrobiodiversity conservation is both a goal and a means to secure thelivelihoods and well being of farming communities in poorer regions of the developing world. Homegardens are clear examples of diversity rich production systems that serve both a development and aconservation function. In order to strengthen this link between biodiversity conservation anddevelopment, IPGRI received the support of the German Federal Ministry for Economic Cooperationand Development (BMZ) through GTZ (Deutsche Gesellschaft für Technische Zusammenarbeit) tocarry out a three-year research project on plant genetic resources in home gardens. This project has been implemented in partnership with national plant genetic resources programmes in five countries,Ghana, Vietnam, Guatemala, Cuba, and Venezuela. The Institute of Plant Genetics and Crop PlantResearch (IPK-Gatersleben) has served as the partner German institution working in the areas of genetic resources documentation and characterization. Based on the results that are emerging, theproject is providing a framework for including home gardens as a distinct and important componentof in situ conservation of agrobiodiversity. The case studies have also begun to establish a clear link between home garden diversity and household livelihoods and food security.

The chapters that follow contain important research findings that should also be assessed in adevelopment perspective. This is particularly important in light of the project’s overall goal, to“promote the development of tropical farming communities through the conservation and use of diversity in home gardens”. In light of this goal, several research objectives were elaborated andagreed at the First International Home gardens and Agrobiodiversity Workshop in Cali, Colombia, in

September of 1999. These research objectives are to:• document genetic diversity in home gardens and the ecological, socio-cultural, and economicfactors that govern its distribution and maintenance

• develop methods to include home garden systems in national agrobiodiversity strategies andprogrammes

• develop strategies for home gardens linked to ecosystem conservation, livelihoods, and culturalvalues.

The results of the studies have clearly met the first two objectives and as the project moves towardscompletion, several activities are planned with policy-makers, communities and other developmentand conservation agencies to mainstream the results of the studies into national conservation and

development programmes. In order to assess how the various national studies have addressed theobjectives, this presentation reviews the coordinated steps that were carried out across the fivecountries.



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Sam pl ing hom e gardens and k ey spec ies The first step was to establish a common set of sampling procedures to assess how much crop andtree diversity home gardens maintain and what would be the best ways to monitor this diversity aspart of national strategies for agrobiodiversity conservation. The key factor in the analysis was to

consider the home garden as a niche or sub-system within a larger agro-ecosystem. No singlegarden or even type of garden could be considered as a conservation unit without referring first tothe larger farm and ecosystem in which it is located. The sampling strategy was also designed tolook at the dynamics of home garden systems within and among ecosystems. In each country a setof sites were selected to reflect the farming systems and ecologies of the more importantagroecological zones that also contained significant biological diversity. These sites then weresurveyed to select a sample of home gardens for monitoring and in-depth study. The followingpoints were applied in identifying the sites and sample sizes.

• Sites selected reflect major agroecological zones (AEZ) in each country.• Broad site survey of home garden diversity to identify ‘typical’ gardens per AEZ.• Unrepresentative (newly established or commercial vegetable plots) gardens eliminated.• Key informants help select representative gardens.• Final selected sample per site n=30–50 gardens covers essential biodiversity in home gardens.

Some species were present in most home gardens within a country and even across countriesand regions—peppers, taro or sweet potato, banana and papaya. For these there were uniquevarieties found in home gardens and in several cases the home garden serves as the germplasm bank or source for planting material or where new types are developed and introduced. These ‘keyhome garden species’ merited in-depth genetic diversity study. In order to select the key homegarden species with high diversity the following selection criteria were applied:

• the species has unique varieties found in home gardens• there are significant levels of varietal diversity of the species• households attach sociocultural importance to the species• the species is economically important both for consumption and/or sale.

The species were then characterized using agromorphological traits and descriptors, as well asethnobotanical diversity indicators based on farmers’ local taxonomy and local germplasmmanagement systems. In some cases the national teams were able to use DNA markers to measure thegenetic diversity of one key species in the home garden and compare it with the diversity that has been already measured and maintained in ex situ genebanks. Genetic diversity in key species is linkedto unique uses even for crops that are widely distributed and present both in large stands or fieldsand in home gardens. For example, Vietnamese home gardens were an important source of banana

diversity even though banana is also an important commercial and plantation crop. The home gardencultivars were distinctive and used for special purposes such as dried and pickled bananas formedicinal uses, and green bananas used ceremonially (Tet shrine).

The key species in home gardens of the five countries are listed below. The number of farmervarieties is being evaluated to confirm their uniqueness.

Vietnam• Pomelo (9–14 varieties per ecosystem): Do, Thanh tra, Bien Hoa, Chum, Bi, Ngot, Oi, Nam roi,

Hong, DHNN1, Phuc trach, Chua, Son, Dao.• Banana ( Musa spp.) (9–12 varieties): Xiem, Su, Gia, Hot, Cau, Samp, Tieu, Ta qua, Do, Ngu, Lan,

Chua.

• Luffa ( Luffa cylindrical) (6 varieties): Trau, Huong, Khia, Dai, Den, Tay.• Taro ( Colocasia esculenta) (8–17 varieries): So, Sap, Tim, Ngua, Nuoc, Cao, Ngot, Mung.

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Ghana• Yam: Dioscorea alata (4), rotundata (15), praehensilis (1), cayenensis (1), bulbifera (2), dumetorum (1),

esculenta (1), burkiliana (1), one wild species• Plantain: Musa spp. 15 local varieties

• Pearl Millet: Pennisetum glaucumi 3–4 varieties

Guatemala• Zapote/Sapota ( Pouteria sapota).• Chillies ( Capsicum spp .).• Huisquil/Chayote ( Sechium edule).

Cuba• Lima bean ( Phaseolus lunatus ): 16 agro-morphological descriptors, 3 cultivated groups, 1 wild.• Zapote ( Pouteria sapota): 11 AMI, no clear varieties.• Chilli ( Capsicum): frutescens (10–18),chinense (7–11),annuum (5–10).

Venezuela• Papaya ( Carica papaya): 5.• Avocado ( Persea americana): 18, with more variety in size and shape than ex situ• Chilli ( Capsicum sp.): 11.• Beans ( Phaseolus vulgaris): 14, with disease resistance found in 2–3.

Conservat ion va lue of hom e gardensThe case studies analysed the various ways that home gardens contribute to biodiversity, at theecosystem, species and genetic levels. At the ecosystem level, the home garden provides a complexmicroenvironment that links more complex natural ecosystems with agricultural systems. It has beennoted that home gardens mimic the natural structure of forest systems, with the crucial difference thatnearly all the species found in a home garden are used. Thus a valuable conservation role for homegardens is as a sustainable use system within or around protected forest areas. This function was wellstudied and confirmed in Cuba, and could apply to other countries where natural forests areimportant sources of income and are also being threatened with overexploitation of outrightconversion. Biodiversity conservation in home gardens can be linked to protected areas verysuccessfully according to these studies.

Home gardens are often the focal point of a household’s social interactions within the family andwith visitors. One of the important functions that home gardens perform is to keep knowledge of varieties and uses of diversity alive from generation to generation. In home gardens children and

visitors can learn from the family experts in different types of diversity and its uses. These can benutritional, commercial, aesthetic, and spiritual. Home gardens in all the countries served as refugesfor the ‘heirloom crop varieties’ that were valued and maintained in the family but had little place incommercial markets. Households were also able to exchange their home garden varieties as part of the social visits. Sharing and exchanging plant genetic resources are common features of visits between households.

In several countries and ecosystems the home garden was where germplasm from the wild was brought under cultivation. This complex ecosystem close to the house where plants can be closelyobserved and managed makes it a convenient site for traditional plant experimentation anddomestication. For some of the root crops such as taro and yams, ruderal material from the wild iscontinually brought under cultivation in home gardens to renew the vigour of the germplasm for

planting in larger fields. Some home garden species that exist in both cultivated and uncultivatedforms are also income earners. The study in Guatemala focused attention on loroco ( Fernaldia pandurata ), a wild species that is also cultivated and widely commercialized as a vegetable for use in



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tamales, the production being almost entirely from home gardens. Similarly varieties of eggplantsand peppers appear in both cultivated and uncultivated forms in home gardens.

Ecosystem services that home gardens provide to the larger agricultural systems and the healthand well being of the household were often noted in the interviews with farmers. The home gardens

provided protected and enriched environments for varieties that may have been more susceptible to biotic and abiotic stresses in the fields. Among the services they provided were soil enrichment,improved water retention, a habitat for pollinators. Home gardens are a good example of howhumans cause niche differentiation that can increase the total productivity of agroecosystems.

The five national studies were able to bring the diversity analyses at the different levels togetherand link it to development actions and policy. This forms the basis of in situ conservation strategiesthat give prominence to the contribution of home gardens. The specific elements for implementingthat strategy are first, to identify those species and varieties that are best conserved in home garden based on the following features:

• Occurring only in gardens.• Being replaced by improved varieties.• Undergoing process of domestication.• Wild species or variety whose environment is threatened.• Identify possible links to ex situ conservation in genebanks particularly for rare crop varieties.

In situ conservation in genebanks as several of the studies described.

The second element in that strategy is to develop a sampling and monitoring strategy for geneticresources that are typical and mainly found in home gardens. Several of the countries were able toidentify empirically the optimal number of gardens and their linkages to each other and surroundingecosystems as the basis for a monitoring strategy that is cost effective and builds upon the existinginstitutions in both nature conservation, local community development and agricultural research andextension. These low cost sampling approaches are best suited to the conditions of tropicaldeveloping countries. In addition, links to ex situ conservation programmes in genebanks wereparticularly valuable in targeting the varieties and zones where home gardens complement in situconservation in crop fields and in genebanks.

The role of formal genetic resources programmes in the work of in situ conservation was variableacross countries. It was clear however that home garden biodiversity could benefit from formal linksto genetic resource conservation programmes. Home gardens are increasingly institutionalized inCuba as the key element in the national in situ conservation strategy. In Vietnam, the focus on homegardens has helped to further a growing understanding of the complementarity between ex situ andin situ conservation in Vietnam. In Guatemala, home gardens agrobiodiversity is best maintained anddeveloped as part of a broad based strategy linking to community development associations and

NGOs. In Ghana, building policy support and public awareness of agrobiodiversity and the need toconserve it was achieved by linking home gardens to traditional foods and income opportunities forrural households. In Venezuela, the conucos , or home garden can be closely linked to growing supportfor traditional foods and ecological agriculture. In sum, the home garden proved to be a natural andeasy way to focus attention on the role of agrobiodiversity in food security and healthy environments.Because the garden is close to home, we were able to bring these agrobiodiversity issues to people’sattention in a humane and understandable way.

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Technical contr ibut ions

Home gardens and the maintenance of genetic diversity

Toby HodgkinInternational Plant Genetic Resources Institute, Rome, Italy

Summary Home gardens contribute to the conservation of biodiversity at the ecosystem, species and withinspecies levels. They provide complex, multi-layered environments in which farmers can maintain largenumbers of useful plant species over many years. They may also provide a basis for the maintenance insitu of significant amounts of intra-specific (genetic) diversity of useful plant species.

The maintenance of genetic diversity in home gardens will depend on farmer management, theenvironmental characteristics of the garden and species biology. The amount and distribution of thegenetic diversity of different characters (e.g. agromorphological, biochemical or molecular), within and between gardens, will also vary with the characters measured and the ways in which each is affected byfarmer management, environment and species biology. Understanding the ways in which farmersmanage planting materials, maintain identifiable populations and varieties, and exchange or mixmaterials will be especially important to analysing and understanding observed patterns of diversity.

From a conservation perspective, key concerns of those investigating the maintenance of geneticdiversity in home gardens have included the small population sizes maintained by farmers, therelatively high levels of selection intensity that may be practiced and the vulnerability of individualgarden populations to random events causing loss of whole populations. Determining the contributionthat home gardens can make to in situ conservation requires an understanding of the amount anddistribution of genetic diversity of different species in home gardens and of the ways in which selection,gene flow and other processes affect its maintenance over time. This understanding needs to beintegrated with an analysis of farmer management practices and of the needs and objectives of the homegarden owners.

In t roduc t ion Home gardens have characteristics that present particular challenges and opportunities for thoseinterested in the maintenance of genetic diversity within production systems. They are complex,multi-storeyed environments with very high species diversity and a wide range of very variedecological micro-niches (Eyzaguirre, this volume). They are clearly important targets for agro-ecosystem conservation, in that they provide a wide range of ecological benefits and services and avaluable set of products for the rural poor. They are also important in the conservation of useful plant

species since they contain very large numbers of species which are often absent or disappearing fromother production systems (e.g. Phaseolus lunatus in Cuba, Castineiras et al. this volume) or have yet to be introduced to agriculture (e.g . Fernaldia pandurata in Guatemala, J. M. Leiva et al. this volume).The role of home gardens in the conservation of within species variation (genetic diversity) is lessobvious. Population sizes of most home garden crops are extremely small, varying from a fewindividuals to, at most, a few hundred plants. The materials are often ephemeral, frequently being lost by the owners and having to be reintroduced. These, and other factors, would seem to mitigateagainst home gardens playing a significant part in conservation of intra-specific diversity. In thispaper, I hope to provide an overview of some of the issues involved in determining the role of homegardens in conserving crop diversity from a genetic diversity perspective.

Conservat ion and produ c t ionCrop diversity is maintained in home gardens when it meets producers’ needs. It may be maintainedover long periods, and in this sense, it may be said to be conserved in situ . However, conservation is



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rarely (if ever) the actual objective. Farmers who maintain diversity do so because they find it useful.Thus, any evaluation of in situ conservation of crop diversity in home gardens has to place the desiredconservation objectives (the amount of diversity maintained, the duration of maintenance etc.) in thecontext of farmers’ production objectives.

Three groups of interacting factors will affect the maintenance of crop genetic diversity in homegardens: the biological characteristics of the crops; the way in which farmers manage the productionand reproduction of the material; and, the way in which environmental factors affect crop production.Reproductive biology, and the way in which planting material is maintained, will be among the mostsignificant biological characteristics. Outbreeders and inbreeders often have markedly differentamounts of diversity in local cultivars, with hotspots of high diversity in some inbreeders (Schoen andBrown 1991). The patterns of diversity distribution are also usually very different, as is also the casefor clonally propagated crops such as Musa or taro. Farmer management determines what is sown,what planted, the size of the population and what is saved for future seed. Farmers provide the majorsources for the effects of selection and gene flow on diversity. The environment provides anothermajor source of the effects of selection. Temperature, moisture availability, day length, biotic andabiotic stresses will all have an impact of gene frequency and on the nature and amount of diversitymaintained within a crop population.

In trying to determine how home gardens can best contribute to conservation, it is necessary tounderstand the ways in which environment, crop biology and farmer management are affecting theextent and distribution of genetic diversity. This involves determining what diversity is maintained by farmers, where and when it is maintained, and how and by whom. It also involves exploring whyfarmers choose to maintain the cultivars they do, in the ways that they do. The next sections of thispaper consider some aspects of determining the amount, distribution and maintenance of diversitythat are particularly relevant to home gardens.

The amoun t o f gene t ic d ivers ity There is a range of different approaches to describing the amount of genetic diversity present in a cropin a home garden or group of home gardens. Whichever methods are used, the three most importantfeatures that are measured are the richness, evenness and distinctness of the characteristics. Richnessis a measure of the number of different types, while evenness describes their distribution within and between the different populations (cultivars, home gardens, areas etc.). Distinctness provides usefuladditional information on how different the types are and can be particularly important for assessingwhether some populations or areas have unique types.

Richness, evenness and distinctness can, with suitable adjustments, be measured using almost anycharacters, which seem to be biologically or genetically meaningful. Afirst approach might be simply

to record the numbers of local cultivars and the extent to which the same ones occur in different homegardens. Further studies might determine differences with respect to important morphological traits(e.g. seed colour, root flesh colour, plant height) or performance traits (yield, stress or diseaseresistance etc.). The trouble with agromorphological measures is often that their expression depends,at least in part, on the environment and that they do not provide a completely accurate picture of genetic differences. For this reason, studies of biochemical differences (isozymes) can be useful ormolecular markers can be used (see also Frankel et al. 1995, Karp et al. 1997, Jarvis et al. 2000).

Numbers and identities of local cultivars present in home gardens provide an obvious startingpoint to determining the amount of diversity. However, some caution may be needed in analysingsuch data. The names given by farmers may be different for the same local cultivar or the same fordifferent cultivars. This has been demonstrated in specific farming situations but similar information

for home gardens is lacking. It may be more difficult to obtain a clear classification of local cultivarsand their identities in home garden production systems than it is in other farming systems. Sizes of populations are much smaller and cultivar identity may be more personalized or more casual. There

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is evidence from farming situations that, even when names differ, farmers recognize the sameimportant distinguishing attributes between local cultivars. In such cases, these characters can beused to establish identities and determine numbers and patterns of distribution of local cultivars,providing that the analysis frameworks developed for traditional farming situations are valid for

home garden systems.Analysis of many morphological and performance related traits is frequently used to determine

variation in home garden materials and to compare local cultivars from different gardens,communities or areas. For some traits, which show little variation with environment, it may bepossible to do this, using measures taken in home gardens. In other cases, trials on a single site will be needed and collection of planting material will be required. This may be difficult for some cropssuch as taro where only one or two plants of each type are maintained in any garden. Wherequantitative traits are analysed (time to flower, height) measures such as coefficient of variation willgive an estimate of richness. Using multivariate statistics it may be possible to detect quite distinctpatterns of variation and combinations of traits in specific areas or communities, which cansignificantly help understanding how evenness and distinctness are expressed in the crop.

Molecular markers are increasingly used to investigate genetic diversity distribution and they areincreasingly replacing the use of isozymes (although the latter remain useful, functional andinexpensive). Molecular markers such as RAPDs can give inconsistent results (Karp et al. 1997) whileother approaches (AFLPs, microsatellites) require more investment or more expertise. However, theymay be especially useful when only small amounts of material can be obtained and they certainly givevery substantial amounts of information on patterns of neutral diversity.

The information obtained in this way can begin to answer some important conservation relatedquestions. If all farmers or communities maintain the same diversity, it may be less important, whichones continue to grow local cultivars while if some have unique varieties their continued interest inthese cultivars may be very important. Information on gene flow can indicate that there is significantexchange of materials between farmers and communities and that we have a meta-population of thecrop. This would indicate that the small size in any one garden is not necessarily a conservationconstraint. In contrast, evidence of genetic drift or of significant bottlenecks in some local materialsmay suggest that they are very vulnerable and may need additional ex situ conservation measures ormultiplication.

The dis t r ibut ion o f divers ity In analysing diversity, the way it is distributed - between local cultivars, between cultivars in differentgardens, between communities and areas—is as important as the simple description of the amount of diversity. Again, the information can come from local cultivar numbers and identities,agromorphological characters or molecular markers. It can also be linked with ways of analysing

geographical information such as DIVA (Hijmans et al. 2001).One important question is the extent to which local cultivars in home gardens, or the geneticcharacters they possess are unique. Does the same variation exist in the wild? Or in other productionsystems? Thus, a semi-cultivated tree species such as sapote may occur also in the wild but the typesmaintained in home gardens may have unique flavour, maturity or yield traits. Since the species isunlikely to be maintained on any scale in ex situ collections, home gardens may be the only reasonableway of maintaining the traits and diversity found. Similarly, the types of Capsicum maintained inhome gardens may be quite different from those grown for commercial production and provideunique flavour, quality, season or other characteristics. Answering these questions will require thatthe diversity found in home gardens is compared with that found from other sources such as samplesfrom the wild or ex situ collections.

The way in which diversity is partitioned within and between home gardens, communities orareas, provides the necessary information for determining not only where diversity is maintained butalso who maintains it and how. Do certain farmers or certain areas tend to maintain higher levels of



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diversity and if so why? Because of their production environment, or for other reasons? The answersto these questions are important for the information they can give on the ways in which conservationparticular objectives might be achieved. They can help identify unique diversity and the reasons itcontinues to exist in some home gardens. This can lead to identifying measures to promote

maintenance or situations where continued in situ maintenance is unlikely.Preliminary evidence suggests that there are substantial differences in distribution of crops. Thus,

home gardens can often maintain many more local cultivars of some crops than might be found inlarger scale production systems (e.g. Capsicum) or can maintain specific types that are not grown ona larger scale. Some crops such as lima bean in Cuba or sponge gourd in Nepal are only grown inhome gardens and are unique to that production system. However, there is much less information onhow these differences are reflected in terms of genetic diversity. Whether the alleles and traits in homegarden populations are very substantially different or whether they also occur in other productionsystems but at different frequencies or in different combinations.

In understanding the patterns of diversity found in home garden cultivars it may be important tounderstand why specific local cultivars are being grown in the garden. Is it for convenience? Becauseit is new? Because it won’t grow anywhere else? The answers to these questions will affect both theamounts and types of diversity found.

The mainten ance of diversi ty From a conservation perspective, the population sizes of a local cultivar in a home garden are usuallywell below that which would be desirable. Even for the most important crops there will seldom bemore than a few hundred plants, even of a relatively important legume, and often population sizeswill be below 10. There are two interacting elements that need to be explored—the way in whichfarmers maintain such small populations and the genetic implications of the small populationsthemselves

Most farmers are likely to save their own seed or planting material over longer or shorter periods.Since populations are small, this is likely to be a fairly unstable process and seasons in whichparticular types can no longer be maintained are likely to occur quite frequently. However, there havecertainly been situations where farmers have maintained special types for many decades and some of the crops are themselves very long lived.

While short maintenance periods may appear to make the conservation of material very unstablethis may not be the case. It depends on the way farmers meet their needs for new or replacementmaterials and the extent to which communities or even regions maintain a common range of materialsthat are exchanged or passed on. The information that is needed to determine whether this is the casecan come from a variety of sources.

The processes of maintenance and the genetic consequences of different practices have not been

studied to any great extent. Some kind of selection process will be involved in choosing what plantswill provide future planting material. A very substantial reduction in population size may also occur.The planting material will usually be stored in some way and may lose viability during this process.It may be mixed with materials from other sources so as to permit gene flow to occur.

ConclusionsHome gardens seem to provide environments in which part of the genetic diversity of many cropspecies can be maintained. The important questions that need to be answered from a conservationperspective relate to the amount and character of that diversity and to the ways in which it changesover time. Answering these questions requires the planned investigation of the amount and

distribution of genetic diversity. Analysis of richness, evenness and distinctness can provideinformation both on the amount and distribution of diversity present and on the portion that isunique to local home gardens. Ideally these studies will include information from both



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agromorphological characters and molecular markers but even a study of the number anddistribution of cultivars can provide useful information.

Together with information on the amount and distribution of diversity, it will be increasinglyimportant to try and understand the genetic consequences of the maintenance procedures used by

farmers. This will provide the necessary information on the significance of random or stochasticevents in the maintenance of local populations and cultivars. It will also allow us to determine whatare the genetic diversity consequences of the small apparent size of most home garden populationsand whether we are in fact dealing with meta-populations of some type.

Home gardens are dynamic production systems in which farmers probably make changes everyseason that affect the cultivars grown, the sizes of populations and the characteristics of the materials.Their contribution to conservation is dynamic and ensures the maintenance of adapted materials,which provide direct benefits to the owners and to the users of home garden products. The geneticdiversity maintained is part of this contribution and can also make a further contribution to widerconservation objectives.

ReferencesFrankel, O. H., A.H.D. Brown and J.J. Burdon. 1995. The Conservation of Plant Biodiversity. Cambridge

University Press, UK.Hijmans, R.J., L. Guarino, M. Cruz and E. Rojas, E. 2001. GIS software for PGR research: 1. DIVA-GIS. Plant

Genetic Resources Newsletter 127:15-19. Jarvis, D.I., L. Myer, H. Klemick, L. Guarino, M. Smale, A.H.D, Brown, M. Sadiki, B. Sthapit and T. Hodgkin.

2000. A Training Guide for In Situ Conservation On-farm. IPGRI, Rome, Italy.Karp, A., S. Kresovich, K.V. Bhat, W.G. Ayad and T. Hodgkin. 1997. Molecular tools in plant genetic resources

conservation: a guide to the technologies. IPGRI Technical Bulletin No. 2. IPGRI, Rome, Italy.Schoen, D.J. and A.H.D. Brown. 1991. Intraspecific variation in population gene diversity and effective

population size correlates with the mating system. Proc. Nat. Acad. Sci. USA 88:4494-97.



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Documentation of plant genetic resources in home gardens

Helmut Knüpffer

Genebank Department, Institute of Plant Genetics and Crop Plant Research (IPK),Gatersleben, Germany

In t roduc t ion Home gardens often contain a significant part of the crop plant biodiversity in tropical countries.Compared to other agricultural or horticultural ecosystems, home gardens are very species-rich, andthey are an ecosystem well suited for in situ conservation of plant genetic resources (cf., e.g. Esquiveland Hammer 1992, 1994). There is often no clear border between wild plants and cultivated plants.

The IPGRI project ‘The contribution of home gardens to in situ conservation of plant geneticresources in farming systems’ is aimed at investigating the possible role of home gardens inpreserving plant genetic resources and at producing an overview of the inter- and infraspecificdiversity of cultivated plants in five selected tropical countries, namely, Cuba, Ghana, Guatemala,Venezuela and Vietnam, as an example for the situation in the tropics worldwide. National teamswere investigating the species cultivated in selected home gardens in selected regions of thesecountries. One of the aims was to compile species lists of the countries involved, cross-referenced withavailable information on the taxonomy, vernacular names, distribution, uses and other aspects of thespecies.

The Institute of Plant Genetics and Crop Plant Research (IPK) in Gatersleben, Germany, started todevelop a database for the cultivated plant species diversity data compiled by the national projectteams. The ‘Database for Checklists of Cultivated Plants’ (Knüpffer 1992, Knüpffer and Hammer 1999,Hammer et al. 2000) was taken as the basis for the documentation system development. This systemand its present situation are described in the present paper.

Background Following the Rio Conference in 1992, in situ conservation began to receive increasing attention. It became obvious that documentation of PGR in in situ agroecosystems needed new approaches, andIPGRI soon declared its readiness to take a lead in this field: “Meeting the information needs of in situconservation work will require a substantial programme to consider both what information is neededand how it can best be maintained and used” (Iwanaga 1995). In 1995, information systems for in situconservation did not exist (Stützel 1995). The concepts had thus to be developed on the basis of ex situcollection documentation systems, but additional descriptors would need to be developed. Brockhaus

and Oetmann (1996) proposed a system of descriptors for in situ conservation of plant geneticresources, based on a comparison with ex situ descriptors.A number of actual approaches to document in situ conservation are reported by Jarvis and

Hodgkin (1998). In Appendix II of this report, various data collecting forms are reproduced which can be used as a basis for developing such a descriptor list. An IPGRI workshop (Laliberté et al. 2000, pp.61–63) addressed the need for descriptors for the documentation of on-farm conservation andmanagement.

Thormann et al. (1999) divided the information necessary for the development of conservationstrategies for wild plant species into four categories, which apply also for the conservation of PGR inhome gardens:

1. species information including taxonomy, biology, conservation, distribution and use

2. size and type of protected areas3. physical environment of species’ distribution areas4. organizations and resource people.


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