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.

A questionnaire survey of 408 households explored the role of socio-economic and cultural factors in rice (Oryza sativa L.) varietal diversity management on-farm in two contrasting eco-sites in Nepal. Multiple regression outputs suggest that number of parcels of land, livestock number, number of rice ecosystems, agro-ecology (altitude), and use of chemical fertilizer have a significant positive influence on landrace diversity on-farm, while membership in farmersÕ groups linked to extension services has significant but negative influence on landrace diversity. Factors with significant positive influence on diversity of modern varieties on-farm were number of parcels of land and of rice ecosystems, access to irrigation, membership in farmersÕ groups, and use of insecticide. Within communities, resource-endowed households maintain significantly higher varietal diversity on-farm than resource-poor households and play a significant role in conserving landraces that are vulnerable to genetic erosion and those with socio-cultural and marketpreferred traits. Resource-poor households also contribute to local diversity conservation but at lower richness and area coverage levels than resource-endowed households. Households where a female had assumed the role of head of household due to death or migrant work of her husband had less diversity due to lower labor availability. Landraces with socio-cultural and market-preferred traits are few in number but have potential to be conserved on-farm.

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This poster is dedicated to the memory of Alfredo Riesco, valued collaborator and friend, who died on 23 August, 2005 in an aeroplane crash near Pucallpa, Peru

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 people's food and other needs. Genetic diversity valued by resourcepoor 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.

To enhance the diversi®cation of rice varieties for the speci®c needs of farmers through a participatory varietal selection (PVS) approach, four pre-release and one released chaite rice varieties were distributed in 20 villages of the Western Hills of Nepal in 1991. A survey conducted during June 1993 found that varietal diversity increased in all locations and in 80% of the study area at least two new rice varieties were reported where only CH 45 was grown before the distribution. On-farm varietal diversity was further enhanced by farmer-to-farmer dissemination of new rice varieties. All the rice varieties tested were adopted, but the adoption level varied between locations. Of the households surveyed 37% were growing the new rice varieties and a further 57% were aware of those varieties within two years of introduction. The PVS approach provided farmers with the bene®ts of new genetic materials ®ve to six years in advance of the formal system and with minimum eort. Institutionalization of the PVS approach and the use of the farmers' network of information and seed exchange, involving relevant grassroots level institutions, can improve the eectiveness of the variety evaluation system.

There has been very little comparative research on farmers' and scientists' theoretical or conceptual knowledge, sometimes leading to reliance on untested assumptions in plant breeding projects that attempt to work with farmers. We propose an alternative approach that is inductive, based on a very basic biological model of plant-environment relationships, and on a holistic model of knowledge. The method we use was developed in Oaxaca, Mexico, and is based on scenarios involving genotype × environment interactions, heritability, and genetic response to selection. It is being modified and applied in a research project with collaborating scientists and farmers in Syria (barley), Cuba (maize) and Nepal (rice). We are testing the ideas that: (i) farmers' knowledge is complex, and includes conceptual knowledge of genotypes and environments; (ii) farmers' knowledge is both similar to and different from scientists' knowledge; and (iii) a generalizable methodological approach permitting inclusion of farmers' conceptual knowledge in research design and execution can form the basis for enhanced farmer-scientist collaboration for crop conservation and improvement. Results to date suggest that farmers have conceptual knowledge of their genotypes and environments that is congruent with the basic biological model also used by scientists, but that their knowledge is also influenced by the specific, local characteristics of their genotypes and environments, and by their social contexts. Some examples of the practical utility of these research results are given.

In Nepal, in traditional rice farming systems many diverse landraces are grown in all of the rice agro-ecosystems from low to high altitude. Three case study sites were selected to represent the major rice agro-ecozones: Bara (100-150 m) for the low-altitude terai (plain); Kaski (700-1,206 m) for the mid-hill zone; and Jumla (2,200-3,000 m) for the high-hill zone. The diversity in rice varieties was compared in these three sites and nine survey villages in a series of surveys conducted in 1998, 1999 and 2006. The level and distribution of diversity on farm varied with the physical and socio-economic settings of the farming communities. The mid-hill site (Kaski) had the highest rice landrace diversity. This was adapted to the diverse agro-ecosystems found there and there was equal diversity in Kule khet (irrigated lands by seasonal canals) and Sim khet (marshy wet land). The next most diverse system was Nicha khet (irrigated lowlands) in Bara, the low-altitude site. The high-hill site (Jumla) had the lowest rice diversity. Across all sites many of the landraces were rarely grown and then only in small areas, reflecting the specialized uses to which they were put. At all sites the most common single landrace occupied less than half of the rice area. Resource-rich farmers were the more important custodians of on-farm rice varietal diversity across the sites. There was more rice diversity in favourable environments than in less favourable ones. This was true whether diversity was measured across sites or across rice domains within sites.