It does not make economic sense to trade productivity for biological diversity when it means thwarting the opportunities of poorer farmers in less-industrialized economies. "Promising candidates" for on-farm management of crop biodiversity are sites where the local crop genetic resources are ranked highly with respect to both farmer utility and their biological diversity, and where empirical analysis predicts that farmers are likely to continue cultivating them.

When genetic analyses confirm that relatively high levels of diversity are found in a location where farmers are choosing to specialize in fewer modern varieties for commercial sale, programs to conserve landraces may be costly in terms of private opportunities foregone and public expenditures. Instead, careful introduction of larger numbers of modern types with distinct agronomic and consumption attributes, or participatory variety selection, may both benefit farmers and contribute to productivity enhancement over the longer term. Remaining landraces might be conserved ex situ following the criteria recommended for optimal sampling. In order to save misdirected public funds, it is equally important to know in which locations remaining landraces have little genetic interest. Not all landraces embody potentially valuable diversity. If farmers care about them, they will continue to grow them. If not, they will discard them, with few implications for society.

On a global scale, for highly bred, staple food crops (e.g., rice, wheat, and maize), historical factors such as labor to land ratios, agroecological features, and commercialization explain to a large extent in which regions landraces are still grown and will continue to be grown. At a more localized scale of analysis, studies suggest that, while the effects of incomplete local markets for crop products and market distance are fairly predictable, the effects of other economic variables, such as the extent of off-farm employment, income and wealth status, are not easy to predict a priori unless researchers already have extensive knowledge about farmer decision-making and local economies among candidate sites. Typically, it will therefore be necessary to undertake more empirical research at the household and community level once candidate sites have been identified, while controlling statistically for the regional-level factors described above. Only as more case studies accumulate can generalizations be drawn. Though some of the policy instruments mentioned here have been designed to support on-farm conservation through enhancing either the demand for or supply of diverse seed types, the balance sheet from the field has not yet been tallied.

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