Plant breeders make a distinction between 'quantitative' characteristics of rice cultivars and specific traits. Quantitative characteristics or traits describe the biological performance of the cultivar and are governed by a number of genes. The semi-dwarf plant type as typified by the first generation of modern rice varieties (e.g. IR8) is a quantitative characteristic. Specific traits are usually controlled by a single gene (or very few genes) and are typically found in plants (usually in landraces or wild species) that do not themselves have valuable quantitative characteristics. Through backcrossing and other methods, breeders can incorporate these specific traits into modern cultivars with valuable quantitative characteristics.
Important qualitative traits include the following: (i) resistance to insect damage; (ii) resistance (tolerance) to disease damage; (iii) tolerance of ecological stresses (cold, heat, flood, drought); and (iv) grain quality and agroeconomic features (e.g. ease of harvesting).
The first two categories are directly related to crop-loss evidence. Crop-loss data showing estimates of farm losses from specific insect pests and diseases are now available for several countries. Some of these loss data cover losses due to ecological stress as well. Crop-loss data can then at least potentially be linked with varietal trait data in a 'hedonic' type regression to estimate the value of varietal traits.
This chapter reports hedonic value estimates based on crop-loss data from Indonesia. A short review of crop-loss evidence for rice is first presented. Then rice productivity and varietal change data in Indonesia are reviewed. A short methodology section discusses the hedonic methods both for crop-loss and productivity specification. Estimates for Indonesia are presented and discussed. The final section discusses the limitations and promise of crop-loss data for trait value estimation.
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