D. I. Jarvis

A global perspective of the richness and evenness of traditional crop-variety diversity maintained by farming communities

Varietal data from 27 crop species from five continents were drawn together to determine overall trends in crop varietal diversity on farm. Measurements of richness, evenness, and divergence showed that considerable crop genetic diversity continues to be maintained on farm, in the form of traditional crop varieties. Major staples had higher richness and evenness than nonstaples. Variety richness for clonal species was much higher than that of other breeding systems. A close linear relationship between traditional variety richness and evenness (both transformed), empirically derived from data spanning a wide range of crops and countries, was found both at household and community levels. Fitting a neutral “function” to traditional variety diversity relationships, comparable to a species abundance distribution of “neutral ecology,” provided a benchmark to assess the standing diversity on farm. In some cases, high dominance occurred, with much of the variety richness held at low frequencies. This suggested that diversity may be maintained as an insurance to meet future environmental changes or social and economic needs. In other cases, a more even frequency distribution of varieties was found, possibly implying that farmers are selecting varieties to service a diversity of current needs and purposes. Divergence estimates, measured as the proportion of community evenness displayed among farmers, underscore the importance of a large number of small farms adopting distinctly diverse varietal strategies as a major force that maintains crop genetic diversity on farm.

Wild relatives and crop cultivars: detecting natural introgression and farmer selection of new genetic combinations in agroecosystems

Whether new combinations of genes that result from hybridization and introgression between wild and cultivated taxa are maintained, with the resultant development of populations with new characteristics, depends on natural selection, and in the case of crops, on human selection. While many cases of deliberate introgression of desirable traits into crop cultivars as part of breeding programmes are known, the extent and significance of natural or farmer‐assisted introgression is uncertain. A range of techniques have been used to document natural hybridization and introgression of agricultural crops and their wild relatives in many crops including maize, wheat, barley, oats, pearl millet, foxtail millet, quinoa, hops, hemp, potato, cocona, casava, common bean, cowpea, pigeon pea, carrots, squash, tomato, radish, letuce, chilli, beets, sunflower, cabbage, and rasberries. However, the majority of these studies are based on morphological characters, and few have investigated the frequency with which such new types are produced and retained in natural and agroecosystems for farmer selection. Even more limited is information on the role of farmers in recognizing and selecting new genetic variation from the natural introgression of crops with their wild relatives, and the impact, once selected, of these new genetic combinations on the crop diversity. Molecular evaluation of natural introgression linked to investigations of farmer recognition and use of introgressed types provide ways of evaluating whether farmer selection for introgressed types is a significant process in increasing the genetic diversity of crop plants.

An Heuristic Framework for Identifying Multiple Ways of Supporting the Conservation and Use of Traditional Crop Varieties within the Agricultural Production System

This paper reviews and discusses how studies on (i) on-farm diversity assessment, (ii) access to diversity and information, (iii) extent of use of available materials and information, and (iv) benefits obtained by the farmer or farming community from their use of local crop diversity, are necessary to identify the different ways of supporting farmers and farming communities in the maintenance of traditional varieties and crop genetic diversity within their production systems. Throughout this paper two key themes are emphasized. First, any description or analysis within the four main areas (assessment, access, use and benefit) can, and most probably will, lead to a number of different actions. Second, the decision to implement a particular action, and therefore its success, will depend on farmers and the farming community having the knowledge and leadership capacity to evaluate the benefits that this action will have for them. This in turn emphasizes the importance of activities (whether by local, national and international organizations and agencies) of strengthening local institutions so as to enable farmers to take a greater role in the management of their resources.

Seed exchange networks for agrobiodiversity conservation. A review.

The circulation of seed among farmers is central to agrobiodiversity conservation and dynamics. Agrobiodiversity, the diversity of agricultural systems from genes to varieties and crop species, from farming methods to landscape composition, is part of humanity’s cultural heritage. Whereas agrobiodiversity conservation has received much attention from researchers and policy makers over the last decades, the methods available to study the role of seed exchange networks in preserving crop biodiversity have only recently begun to be considered. In this overview, we present key concepts, methods, and challenges to better understand seed exchange networks so as to improve the chances that traditional crop varieties (landraces) will be preserved and used sustainably around the world. The available literature suggests that there is insufficient knowledge about the social, cultural, and methodological dimensions of environmental change, including how seed exchange networks will cope with changes in climates, socio-economic factors, and family structures that have supported seed exchange systems to date. Methods available to study the role of seed exchange networks in the preservation and adaptation of crop specific and genetic diversity range from meta-analysis to modelling, from participatory approaches to the development of bio-indicators, from genetic to biogeographical studies, from anthropological and ethnographic research to the use of network theory. We advocate a diversity of approaches, so as to foster the creation of robust and policy-relevant knowledge. Open challenges in the study of the role of seed exchange networks in biodiversity conservation include the development of methods to (i) enhance farmers’ participation to decision-making in agro-ecosystems, (ii) integrate ex situ and in situ approaches, (iii) achieve interdisciplinary research collaboration between social and natural scientists, and (iv) use network analysis as a conceptual framework to bridge boundaries among researchers, farmers and policy makers, as well as other stakeholders.

Traditional maize storage methods of Mayan farmers in Yucatan, Mexico: implications for seed selection and crop diversity

For small-scale farmers who maintain genetically diverse crop populations, aspects of the storage of their seeds and harvest may be just as important for successful farming as those related to productivity. The community of Yaxcaba, Yucatan, Mexico was studied to understand how the conditions under which Maya farmers store their maize harvests influence their seed selection practices and the diversity of maize varieties grown. Most farmers select their maize seed based primarily on ear characteristics and secondarily on grain characters. Farmers incorporate storability concerns by selecting for an archetypal healthy ear and by conducting selection in several steps between harvest and planting of the subsequent crop generation. Most farmers store their maize harvest in the husk, initially in the field and then in rustic granaries constructed of logs and palm thatch, in which farmers conserve separately their different seed lots. All local landrace populations show morphological adaptation (principally husk characteristics) for local storage conditions, indicating that storability has been an important selection pressure on traditional maize. Storability also appears to be a key factor working against the straightforward adoption of improved maize seed in Yaxcaba. Local farmers value many qualities of improved maize varieties, but their principal complaint is that improved maize cannot be conserved reliably under local storage conditions. Nearly all farmers who utilize improved seed stock in Yaxcaba grow locally adapted or ‘creolized’ versions of improved varieties, displaying characteristics of local maize landraces that facilitate their storage.

The value of plant genetic diversity to resource-poor farmers in Nepal and Vietnam

Genetic resources for food and agriculture are the biological basis of world food and nutrition security; and they directly or indirectly support the livelihoods of over 2.5 billion people. Genetic diversity gives a species or a population the ability to adapt to changing environments. For resource-poor farmers, adaptive animal breeds, crop varieties and cultivars adapted to particular micro-niches, stresses or uses are the main resources available to maintain or increase production and provide a secure livelihood. The economic value of genetic diversity for productivity and yield traits is discussed in the literature. However, it is difficult to value many other aspects of agricultural biodiversity as these have both direct and indirect values in terms of qualitative traits such as food, nutrition and environmental uses that include adaptation to low input conditions, co-adaptive complexes, yield stability and the consequent reduction of risk, specific niche adaptation, and in meeting socio-cultural needs. Together, the direct and indirect values of genetic resources for resource-poor farmers are expressed in a range of options in the form of the crop varieties and species they use for managing changing environments. The value of genetic diversity to resource-poor farmers is seldom captured by markets or addressed by the international research agenda. This paper presents lessons learned from our work over 5–10 years in the Asia and Pacific Ocean (APO) region on participatory crop improvement, home gardens and on-farm management of agricultural biodiversity. The lessons illustrate how farmers adapt genetic resources to suit local environmental conditions. The paper focuses on the value of genetic diversity of selected crop species to meet peoples food and other needs. Genetic diversity valued by resource-poor farmers is often maintained, selected and exchanged by local social seed networks. Identification of such genetic resources and their custodians is important if international agricultural research is to contribute to the reduction of poverty. The paper highlights some good practices from case studies that illustrate how such genetic resources could be exploited by informal research and development strategies or participatory plant breeding or for marketing value-added products.

Participatory crop improvement and formal release of Jethobudho rice landrace in Nepal

Jethobudho is an aromatic rice landrace of the Pokhara valley in middle hills of Nepal. Although local consumers are willing to pay a high price for its purchase, the landrace has a problem with quality variation. Decentralized participatory population improvement for specific market-identified traits was conducted on “Jethobudho” populations collected from farmers’ fields in seven geographic regions of the valley in Nepal. The preferred post harvest quality traits, field tolerance to blast and lodging, and superior post harvest quality traits of Jethobudho were established by a consumer market survey. These traits were used for screening the materials. 338 sub-populations of Jethobudho were evaluated for yield, disease, lodging resistance, and post harvest quality traits. Significant variation was found for culm strength, neck blast tolerance, awn characteristics, panicle length, number of grains per panicle, test grain weight and post harvest quality traits, whereas no significant variation was found in grain yield, plant height, tiller number, maturity period and leaf blast. Based on these identified traits and micro-milling evaluations, 183 populations were screened in on-farm and on-station nurseries, and in succeeding years populations were further screened by plant breeders and expert farmers in research trials, resulting in the selection of 46 populations for post harvest quality traits. Six accessions with similar agronomic traits, field tolerance to blast and lodging, and superior post harvest quality traits, were bulked and evaluated on-farm using participatory variety selection (PVS). The enhanced Jethobudho accessions were also evaluated for aroma using simple sequence repeat (SSR) and found to have unique aromatic genetic constitution. Community based seed production groups were formed, linked to the Nepal District Self Seed Sufficiency Programme (DISSPRO), and trained to produce basic seeds (truthfully labeled) of Jethobudho. The National Seed Board of Nepal released the enhanced landrace in the name of “Pokhareli Jethobudho” in 2006, as the first bulk variety of traditional high quality aromatic rice improved through participatory plant breeding to be formally released in Nepal for general cultivation under the national seed certification scheme. Landrace improvement is shown as an important option for supporting programmes for in situ conservation of landraces on-farm.

The maintenance of crop genetic diversity on farm: Supporting the Convention on Biological Diversity's Programme of Work on Agricultural Biodiversity

Abstract Over the last decade, Bioversity International has worked with national, regional and local partners in eight countries (Burkina Faso, Ethiopia, Hungary, Mexico, Morocco, Nepal, Peru, and Vietnam) on the maintenance and use of crop genetic diversity on farm, particularly that found in traditional varieties (or landraces). The work has involved investigating the extent and distribution of diversity in over 27 crops and exploring with farmers and rural communities the management practices used to maintain traditional varieties. The results of this collaboration have (i) provided tools to assess the amount and distribution of crop genetic diversity in production systems (ii) increased our understanding of when, where and how this diversity will be maintained, (iii) identified practices, communities and institutions that support maintenance and evolution of crop genetic diversity in production systems, and (iv) provided possible mechanisms for ensuring that the custodians of these systems and genetic materials will benefit from their actions. This international collaboration has provided significant contributions to the four elements of the Convention on Biological Diversitys Programme of Work on Agricultural Biodiversity: (i) assessment of diversity; (ii) adaptive management; (iii) capacity building; and (iv) mainstreaming.

All Maize Is Not Equal: Maize Variety Choices and Mayan Foodways in Rural Yucatan, Mexico

Foodways have changed substantially over the past several centuries in the Yucatan Peninsula and other areas of Mesoamerica, but one constant is the presence of maize (Zea mays) at the heart of rural economy, ecology, and culture. The domestication and diversification of maize – the world’s most productive grain crop – by indigenous farmers ranks as one of the greatest accomplishments of plant breeding. Remains of ancient maize cobs in the archeological record suggest that maize was first brought into cultivation roughly 7,000 years ago in the highlands of central Mexico, where its closest wild relative, teosinte (Zea mays ssp. parviglumis), also grows (Wilkes 1977; McClung de Tapia 1997; Smith 2001; Piperno and Flannery 2001; Matsuoka et al. 2002.). From that starting point, maize was gradually selected and diversified over time by farmers into an impressive array of different forms, sizes, and colors. Maize appears to spread out of central Mexico rapidly in the context of regional trade and exchange networks, and farmers selected and adapted maize populations to thrive in new environments. Archeobotanical evidence from northern Belize suggests maize arrived in the Yucatan Peninsula by about 5,000 years B.P. (Colunga-Garcia Marin and Zizumbo-Villarreal 2004).

The agricultural biodiversity policy development process: Exploring means of policy development to support the on-farm management of crop genetic diversity

Developments in international and national law and policy over the last two decades have changed the working environment for those in charge of managing and making decisions about genetic resources, including those held on-farm by farming communities. A collaborative programme with national partners in Vietnam, Mexico, Peru, Burkina Faso, Morocco and Hungary, and Bioversity International (formerly the International Plant Genetic Resources Institute (IPGRI) has designed tools to assist scientists and decision-makers to understand how scientific and institutional information about in situ conservation of agricultural biodiversity on-farm can be integrated and inform policy choices. This paper shares information about the critical components of the policy development process and how the process might enable a participatory, bottom-up approach for supporting the conservation and use of agricultural biodiversity on-farm.