New Guest Blog- Calrose Rice, A California Legacy

By Kent McKenzie and Carl Johnson

Commercial rice production in California was established 1912 along with the founding of the Rice Experiment Station (RES) near Biggs. In the previous few years, scientists with the USDA’s Bureau of Plant Industries tested and indentified a few plant introductions that successfully produced a rice crop in small plantings in the heavy clay soils of the Northern Sacramento Valley. Not only were the yields so high that their validity was questioned by rice producers elsewhere in the United States, but the grain quality was good enough to win awards at some agricultural expositions. In the following few years, selections of twoshort grain introductions were identified and named Caloro and Colusa. Because or their adaption and productivity they became the predominant California rice varieties for the next 50 years.

Calrose was developed by Jenkins W. Jones and Loren L. Davis and released from RES to growers in 1948 to complement the California short-grain varieties. It was a selection made from a cross of Caloro to Calady that was backcrossed to Caloro. Calady was a medium-grain selection developed in California from a cross of Caloro and Lady Wright. The latter was long-grain variety released by S. L. Wright of Louisiana, the developer of the medium-grain Blue Rose that was the predominant medium grain in the Southern United States until the late 1940s. Calrose is similar to Caloro in agronomic characteristics but the kernels are more transparent than Caloro, have better milling quality, and have a vitreous texture similar to Blue Rose. The name “rose” indicates medium-grain shape and “Cal” to indicate California origin and production.

Calrose acreage began increasing rapidly after a very cool year in 1954 that was a yield disaster for Caloro. Fortunately, Calrose had very acceptable cooking and taste properties. By 1960 Calrose was grown on 30 percent of California rice acreage and by 1975 70 percent. Today it constitutes more than 80 percent of the California rice crop. Its success can be attributed to a combination of its adaptation, productivity, grain quality,the California climate, and successful marketing. Thus, Calrose allowed California to transition to a medium-grain type, capture the western Blue Rose market, become the dominant U.S. medium-grain rice producing state, and achieve world market recognition.

With Calrose as a foundation variety and the establishment in 1969 of a grower-funded accelerated rice breeding program at RES, breeders began to improve the adaptation and productivity of Calrose as well other rice varieties for the other market classes. Major improvements included development of smooth hulls that improve handling, short strawheight that produces more grain and less straw, earlier maturing varieties, and most recently improvement is milling yield and stability. With each trait addition, incremental improvements were made in field performance while maintaining the Calrose quality. This grain quality is the combination of physical and chemical quality characteristics passed down and enhanced from Calrose and the climate, soils, and water of California rice growing regions. New releases from RES are subject to physicochemical and cooking tests, grower and marketer input, and evaluation to ensure new varieties remain true to type.

Over the years new varieties with the same or improved cooking properties as Calrose were released and then replaced the older medium-grain varieties in commercial production. Calrose, as a medium-grain class, was established and is still used to identify California medium-grain quality. After 64 years we have reached Calrose XX, have no interest in its retirement, and look forward to future improvements.

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Kent McKenzie is Director of the Rice Experiment Station near Biggs.

Carl Johnson served as the Calrose rice breeder at the station from 1974 until his retirement in 2008.