"Green revolution" and cassava breeding

If a wholesale yield improvement of major crops by new high yielding cultivars was the definition of "Green Revolution", it was also a tacit expectation that a success similar to that in rice or wheat would be repeated in cassava when a cassava varietal improvement program was established at CIAT twenty years ago. It soon became clear that genetic improvement of yield in this crop would be a slow process because a multi-genic scheme controlled the yielding ability, as opposed to the basically single-gene scheme in rice and wheat. Technology adoption would also be slow because the main clients were small farmers in low-input environments and varietal improvement alone would not solve the problem; an integrated approach was required to diffuse the improved technology. One positive aspect was that working on cassava would contribute less to the widening of the gap between rich and poor farmers, the major negative-effect of the "Green Revolution". Thanks mainly to the improvements in harvest index in the early years and in biomass and root dry matter content in later years, significant yield upgrading (up to 100 percent) of breeding populations took place virtually for all the major cassava growing environments. After a long gestation period, the number of cultivars released and the area planted are finally increasing rapidly. Earlier cultivars are contributing to enhancing production efficiency in some areas in Thailand and Indonesia. Later cultivars are poised to make major contributions in Thailand, Indonesia, China and Vietnam. A "Green Revolution" in cassava may be in the making in its own way