J.N. Rutger, M.L. Peterson, and C.H. Hu2
`Calrose 76' rice (Oryza sativa L.), CI 9966, is a true-breeding, induced short stature mutant (experimental designation D7) from the cultivar `Calrose'. The parent cultivar has been described3 and is grown extensively in California. Calrose 76 was selected in 1971 at Davis, Calif., as a single short stature M2 generation plant grown from Calrose seed exposed to 25 kR of Cobalt-60 gamma radiation.
Calrose 76 is similar to its parent cultivar Calrose except that its straw is about 25 cm shorter at maturity and has more awning. Average mature height of Calrose 76 in 3 years of tests was 87 cm. Genetic studies have shown that Calrose 76 carries a single recessive gene for short stature4. Calrose 76 is more resistant to lodging than Calrose and `CS-M3', another tall medium-grain cultivar widely grown in California. In 2 years of tests at Davis, awn length of Calrose 76 averaged 5.0 mm compared to 2.0 for Calrose. In a test at Biggs, Calrose 76 awn length was 12.0 mm compared to 8.7 mm for Calrose. Like its parent, Calrose 76 has pubescent leaves and hulls. No differences have been noted in disease reaction of Calrose 76 and Calrose. Its short stature distinguishes Calrose 76 from other medium grain cultivars grown in California.
In 19 agronomic tests conducted cooperatively with the California Agriculture Extension Service and the California Cooperative Rice Research Foundation from 1973 to 1975, yields of Calrose 76 equalled those of CS-M3, a check cultivar very similar to Calrose in yield and adaptation. Average lodging of Calrose 76 was 18% compared to 45% for CS-M3. Seedling vigor of Calrose 76 closely approached that of CS-M3. Calrose 76 headed about 1 day later than CS-M3. Because of its shorter stature and lodging resistance, Calrose 76 is expected to replace a portion of acreage of the tall, medium grain cultivars currently grown in California.
Kernels of Calrose 76 are nonaromatic and have light brown pericarp color and white nonglutinous endosperm. Brown rice seeds average 5.8 and 2.7 mm in length and width, respectively, compared to 6.0 and 2.7 mm for CS-M3. Respective milled kernel weights of Calrose 76 and CS-M3 were 2.00 and 2.04 g/100. Head rice milling yields of Calrose 76 were similar to those of Calrose and CS-M3. In tests at the Cooperative Regional Rice Quality Laboratory at Beaumont, Tex., Calrose 76 showed characteristics typical of U.S. medium-grain cultivars, specifically, the amylose content of Calrose 76 was 18.4% compared to a mean value of 18.9% for Calrose and CS-M3. Alkali reaction values of Calrose 76 were similar to those of Calrose and CS-M3, indicating a low-gelatinizing-temperature type. Taste panelists at the Western Regional Research Center at Albany, Calif., could detect no differences in cooked samples of Calrose 76 and Calrose.
Calrose 76 was jointly released on 1 June 1976, by the ARS, USDA, the California Agricultural Experiment Station, and the California Cooperative Rice Reserach Foundation. Classes of seed will be breeder, foundation, registered, and certified. Breeder and foundation seed of Calrose 76 will be maintained by the California Cooperative Rice Research Foundation, Inc., P.O. Box 306, Biggs, CA 95917. Germplasm amounts of seed (=<25g) are available from the senior author.
1 Registered by the Crop Sci. Soc. Am. Cooperative investigations by the ARS, USDA; the Calif. Agric. Exp. Stn.; and the California Coop. Rice Res. Found., Inc. Accepted 10 May 1977.
2 Research genetics, ARS, USDA, Davis, CA 95616; professor, Dep. of Agronomy & Range Science, Univ. of California,, Davis, CA 95616; formerly professor, Dep. of Agronomy, National Chung-Hsing Univ., Taichung, Taiwan. Present address of C.H. Hu: N.F. Davis Drieder and Elevator, Inc., Firebaugh, CA 93622.
3Johnston, T.H. 1958. Registration of rice varieties. Agron. J. 50:694-700.
4 Rutger, J.N., M.L. Peterson, C.H. Hu, and W.F. Lehman. 1976. Induction of useful short stature and early maturing mutants in two japonica rice (Oryza sativa L.) cultivars. Crop Sci. 16:631-635.