Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 2004
Publication Date: November 15, 2004
Citation: Rutger, J.N. 2004. The future of rice research in the united states from a plant breeding perspective. 2nd International Rice Functional Genomics meeting. Abstract p. 32. Technical Abstract: Rice breeding invariably has involved and will continue to involve one or more of the "Big Four" goals common to all crop breeding programs: yield, quality, pest resistance, and stress tolerance. Standard methods -- pedigree, backcrossing, induced mutation --will continue to be the backbone, although they may be revolutionized, possibly in ways that today are inconceivable. Certainly the standard methods will be supplemented by molecular technologies and expansion of multidisciplinary research teams. For example, the recent establishment of the RICECAP is expected to aid in development of biotechnology-based tools to enhance two characters that have been difficult to improve through conventional breeding, milling quality and sheath blight disease resistance. Higher yields are considered essential for virtually all crops, including rice. At 7.4 mt/ha, US rice yields on its 1.2 million hectares are well above the world average of 3.8 mt/ha on 153 million hectares. In fact US national rice yields are exceeded only by those of Australia at 8.6 mt, in an environmental production area of 150,000 hectares which is favored by the same type of Mediterranean climate enjoyed by California, which has similar or higher yields on 200,000 hectares. It is essential that pursuit of ever-higher yields continue, in order to keep the US rice industry competitive in the global marketplace. Rice breeders in the US focus on grain quality, especially since the US rice industry has a well-earned reputation for producing the best quality rice in the world. However, the grain quality of US rice has not gone unnoticed by rice breeders in Asia, many of whom are pursuing the very same quality factors considered important for US rice: translucent long grains with intermediate amylose levels and high whole-grain milling yields which constitute some 80% of southern long grain production, and translucent medium grains with low amylose levels and high whole grain milling yields which constitute virtually all of California production. And, in fact in production of aromatic rices Asian rices are considered superior to current US varieties, resulting in imports of 14% of the rice being eaten in this country today, up from zero imports two decades ago. Therefore most US breeding programs now include development of aromatic rices. The US, and indeed the entire western hemisphere, is fortunate to have relatively few of the traditional disease and insect pests common to Asian rice production. A restrictive quarantine import procedure, which often frustrates US rice scientists, is an integral key to keeping out introduced diseases and pests. Within the US, continued progress is being realized on developing blast resistant varieties, and efforts on developing sheath blight resistance are intensifying. Among insect pests, several programs continue to seek resistance to the rice water weevil, an insect indigenous to the US. Resistance to another insect, rice stink bug would be desirable, but sources of major resistance have not been found. Stress tolerance research is being pursued for improved cold tolerance, especially in California, and in Arkansas. Promising levels of improved tolerance to straighthead, which is often referred to as a physiological disease and is a problem in some southern rice areas, have been found in newer indicas. Drought tolerance, important in many rainfed areas of the world is not a major objective in the US, since high production costs dictate that rice must be grown under optimal conditions, which means full flood. Salinity tolerance is pursued from time to time, but is not a major breeding objective in the relatively land-rich US rice production areas. The germplasm base of US rices is relatively narrow, and as recently as 1990 all southern US varieties traced back to 22 accessions, while California varieties traced back to 23 accessions. In recent years some broadening of germplasm has occurred, almost all in the tropical japonica long grains, or in the temperate japonica medium grains. Only one indica variety, Jasmine 85 is grown in the US, and that on a limited area. In the last two decades some rather spectacular yield increases, as well as better disease resistance, have been observed in indicas from China, although grain quality is not acceptable for US markets. Therefore a base-broadening effort, concentrating on indicas, has been launched at the Dale Bumpers National Rice Research Center.