Crop Management and
Environmental Effects on Rice
Milling Quality and Yield - 2007



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Project Leader and Principal  Investigators

Randall "Cass" Mutters, farm advisor, UC Cooperative Extension, Butte County

James Thompson, extension specialist, Dept. of Biological and Agricultural Enginering, UC Davis

Richard Plant, professor, Dept. of Plant Sciences, UC Davis


This is the fifth year of a project examining how rice moisture at harvest affects head rice yield and ultimately grower profitability.

A plot at the Rice Experiment Station was divided into three basins and planted with M-202, M-205 or M-206 rice at a seeding rate of 150 pounds per acre. The rice was grown under identical cultural practices. One basin was drained seven days after 50% heading, while the other two basins were drained 14 days and 21 days after heading, respectively. A portion of each basin was harvested on September 27 and October 1, 4, 15, 18, 22, and 26. Samples were then analyzed for rice moisture, head rice quality, and yield. Similar plots were grown, harvested, and evaluated from locations in Colusa and Natomas (Sacramento County).

Results from all three locations demonstrated that M-206 maintains high head-rice quality over a wide range of harvest moisture contents, even down to 15% moisture content. The RES test also showed high head-rice quality and high yield when draining fields 14 days after 50% heading, about a week earlier than normal.

Average head rice quality from Sept. 27 to Oct.26 for rice drained 21 days after heading

Variety M-205 has better stability in head rice quality than M-202 but not quite as good as M-206. The stability of M-206 would allow the industry to harvest at lower moisture content and reduce the need for column drying. If validated in additional seasons over a wider range of soil and weather conditions, this could potentially revolutionize the management of rice harvest and drying. The ability to harvest M-206 and M-205 at lower moisture contents and still maintain high head-rice yield will allow growers to reduce drying costs and increase returns per acre. It will also reduce the consumption of natural gas for column drying and decrease the carbon dioxide emissions associated with rice production. Harvesting at lower moisture content may also decrease the potential for off-odor development in handling before drying.

This research also showed that basing drain timing on days after 50% heading, rather than the appearance of panicles, is a useful index. Heading date is a more consistently definable and easily observable condition than the color or shape of panicles, and it allows harvest date to be predicted several weeks in advance.


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