ABSTRACT
Rice germplasm collections, varying in size from a few hundred to several thousand accessions, are maintained in various countries by national research programs and by International Agricultural Research Centers of the Consultative Group on International Agricultural Research. Utilization of the genetic diversity which exists in rice has been economically profitable. Economic analyses indicate that the breeding and utilization of planthopper- rice hoja blanca virus resistant cultivars is highly profitable. The various rice germplasm collection and conservation programs have been successful on a global basis and have provided a large number of accessions for use in insect resistance screening and breeding programs. West Africa dominates the sub-Saharan rice sector with 60% of the rice area and 56% of the production. In Asia, where rice is mostly grown under irrigated conditions, modern cultivars have rapidly spread. Rice is a major food crop in Latin America where pest control expenses contribute to increasing costs and decreasing profitability of rice production.
