The successes of the so-called “Green Revolution” of the 1960’s in obviating eminent famines in highly populated developing countries across continents stemmed from the development of high yielding semi-dwarf wheat cultivars at CIMMYT, the International Maize and Wheat Improvement Center established in 1963, Mexico, and the semi-dwarf rice cultivars at IRRI, the International Rice Research Institute established in the Philippines in 1960. These new highly productive cereal cultivars, under high fertilization application supplemented with irrigation, stimulated the formation in 1971 of the CGIAR, the Consultative Group on International Agricultural Research. More international research centers were established to expand activities on other staple food crops, cropping systems and natural resources management covering the most important agro-ecological zones in various developing countries .

In the humid and sub-humid tropics of Africa and Latin America, two new research centers concerned with cassava research were established in late 1960’s: IITA, the International Institute of Tropical Agriculture, located in Nigeria, and CIAT, Centro Internacional de Agricultura Tropical, located in Colombia. Given the necessary financial support, international multidisciplinary teams of scientists were able, for the first time, to conduct extensive research on cassava. They collaborated with the few, already existing, national research programs to improve germplasm collection and characterization, breeding, agronomy, cropping systems management, pest-and-disease control, and crop use. Various researchers reviewed results on many aspects of cassava research in Africa, Asia, and Latin America over the last 3 decades . In the following sections we review and highlight some of the eco-physiological research conducted at CIAT, particularly under relevant field conditions where most cassava is grown, in relation to breeding improved cultivars for both favorable and stressful environments . The research had laid the foundations for cassava breeding and selection of adaptable cultivars under both environments.

At first, breeding objectives were directed towards developing high-yielding cultivars for favorable conditions where biotic and abiotic stresses were absent . This strategy focused on selecting for high yield per unit land area and comparing with traditional vigorous cultivars and/or landraces suitable for intercropping. Another trait selected for was high dry matter content in storage roots. Harvest indexes , were selected to be higher than those of common landraces and traditional cultivars . However, most cassava production occurs in environments with varying degrees of stresses and with little, or no, production inputs from resource-poor farmers. Hence, later breeding strategy goals centered on selecting and developing cultivars with adequate and stable yields, and able to adapt to a wide range of biotic and abiotic stresses . This strategy was stimulated by cassava’s inherent capacity to tolerate adverse environments, particularly those where other major staple food crops such as cereals and grain legumes would fail to produce.

The strategy also aimed to avoid and/or reduce the negative consequences on the environment caused when highinput production systems are adopted . In light of this environmentally sound breeding strategy, research on cassava physiology has focused on both basic and applied aspects of the crop under prevailing environments. The goal was to better understand and elucidate the characteristics and mechanisms underlying productivity and tolerance of stresses . The remarkable predicted suitability of cassava to possible increases in average surface Earth’s temperatures caused by expected rises in atmospheric CO2 in the year 2030 and beyond is substantiated by the experimental data on the responses of cassava photosynthesis to temperature and CO2. Research on cassava physiology at CIAT had shown that maximum cassava growth and productivity requires high temperature , high solar radiation, high air humidity and sufficient rainfall during most of the growth period .Also, representative responses of these sets of leaves to measuring PAR are shown in one cultivar, M Col 2059. In these trials, 8 cultivars representing cassava ecosystems, that is: hot humid low-land, hot-dry low-land, humid high altitude, and sub-tropic cool eco-zones, were tested and all had shown the same responses, indicating cassava resilient response to varying climatic conditions.