内容简介：
This volume reports the findings of a study of the productivity impacts of varietal improvements research conducted at a number of international centres affiliated with the Consultative Group on International Agricultural Research. Such centres have been at the forefront of the "Green Revolution" which resulted in the breeding of new crop varieties of the world's staple food crops. The study was initiated and supported by the Impact Assessment and Evaluation Group of the CGIAR. Econometric models are used to evaluate investment in these cases of agricultural research, and to analyze impact in selected countries (Brazil, China and India).