Breeding Rice for Resistance to Pests

Abstract

Rice (Oryza sativa L.) is grown on more than 147 million hectares worldwide, primarily in countries where human population densities are extremely high. The crop is well adapted to flooded soils and high temperatures, conditions common in vast areas of Asia and under which no other cereal crop can thrive (58). Current global rice production is 520 million tons, or approximately 57 kg of milled rice per capita, sufficient to provide 20% of the total global human caloric requirement (58). In terms of producing calories for human consumption, rice is probably the world's most important food crop (24). Insects and diseases are important constraints to rice production, and breeding pest-resistant rice cultivars is one of the primary aims of rice improvement programs worldwide (77). Most rice producers live on small farms in Asia and either do not presently have access to purchased inputs for pest management, or lack the knowledge to use such inputs effectively. Consequently, pest management in rice depends to a great extent on the genetic resistance of rice cultivars. Pest resistance is advantageous in developing countries because there is no cost to farmers and resistant cultivars are easily adopted and disseminated, unlike knowledge-based technologies. Also, concern for the environment is becoming an important public policy issue in developing countries, and pest