1. The number of generations is a useful index of genetic complexity.
2. Approximately 100 of the 306 varieties released since 1966 were planted in 1984. Of these 306 varieties, 118 were released after 1980. Thus, a high proportion of released varieties were actually important varieties.
3. IRRI has been the major source of the foreign germplasm.
4. The genetic evaluation unit at IRRI has sought to combine multiple traits in advanced lines and varieties.
5. Ninety were planted in the 250 districts analysed. Approximately 100 were planted in all districts.
6. Very high costs associated with collecting the 'last few' plants would probably not be justified.
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