Arkansas Agricultural Experiment Station, University of Arkansas Division of Agriculture
Dale Bumpers College of Agricultural, Food and Life Sciences
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Indica rice lines released to broaden benetic base The Agricultural Research Service, USDA, and the Arkansas Agricultural Experiment Station, U of A Division of Agriculture, have announced the release of three indica germplasms of rice, indica-16 through indica-18. These mutants are part of a base broadening effort to develop indicas for the US, where very narrow genetic bases, essentially all in japonicas, have evolved because of need for adaptation to temperate climates. There are three different types of rice: japonica, indica and javanica. Japonica rice varieties are high yielding and tend to be resistant to disease. Although quite hardy, indica yield less than japonica types and are most often grown in the tropics. Javanica types of rice fall between japonica and indica varieties in terms of yield, use and hardiness. The new lines are induced early flowering mutants of Oryzica llanos 5 (PI 584668, henceforth abbreviated as OL5), a highly blast disease [Pyricularia grisea (Cooke) Sacc.] resistant cultivar from Colombia, which in itself is a month too late in maturity for the US. These three germplasm lines are 24 to 36 days earlier than the parent, making them 6 to 18 days later than the southern tropical japonica long grain cultivar Francis (PI 632447). These germplasms retain the blast resistance of the OL5 parent. Their early maturity and blast resistance make them useful sources of indica diversity for US rice improvement programs. The lines were derived by gamma radiation of OL5 in late 1999 at rates of 270, 300, and 320 Grays (Gy). The M1 generation was grown in the 1999/00 Puerto Rico winter nursery. Germplasm amounts of seed (ca 5 grams) of the above lines may be obtained by writing to: J. Neil Rutger, Dale Bumpers National Rice Research Center, USDA-ARS, P.O. Box 1090, Stuttgart, AR 72160. Requests from outside the US must be accompanied by an import permit. Seed also will be placed in the National Small Grains Collection, USDA-ARS, 1691 South 2700 West, Aberdeen, ID 83210, where it is available for research purposes, including development and commercialization of new cultivars. If this germplasm contributes to the development of new cultivars it is requested that appropriate recognition be given to the source. |