Abstract
The role of international agriculture research institutions could be limited to the collection, maintenance and distribution of basic germplasm materials if the research capacity of national programs were satisfactory. However, the research capacity in many tropical countries was far from this and it was necessary that international institutions such as CIAT upgraded the immediate usefulness of germplasm materials to be offered to national programas. In cassava, there was no major complication with the breeding method per se and following the orthodox breeding scheme promised steady progress in yield improvement. The CIAT/Colombia breeding program started with the enhancement of basic physiological yied capacity of the breeding population in a low stress environment and accomplished a 100% increase in the yied capacity of the breeding population compared with that of the original unselected population thanks largely to improved harvest index. A simultaneous selection in a high stress environment added tolerance to numerous diseases and pests as well as adaptation to infertile and acid soils. The selection and population improvement by the CIAT/Thai collaborative program in a semi-arid environment further upgraded the total biomass production, root dry matter content and tolerance to drought of the breeding population. Thus, I consider that the current CIAT cassava breeding materials provide national program breeders with immediate selection opportunities for higher yielding capacity and adaptation to high stress growing environments.
