UC Cooperative Extension collaborates with the California Rice Experiment Station to evaluate commercial varieties and advanced breeding lines. The San Joaquin County Delta location was one of nine locations in the 2023 statewide trial. The Delta is a test site for very-early maturing varieties because it has cooler growing conditions than other rice growing regions of the state.

The trial was drill-seeded on April 27^th at a rate of 150 lb/acre, and varieties were replicated four times as 150 ft² plots. The trial was planted in a field of M-206, and fertility and pests were managed by the grower in the same manner as the field. We harvested the trial on October 12^th, and yield was determined by hand-harvesting a 15 ft² area from each plot.

Table 1 shows results from the Delta location (advanced breeding lines omitted). Among the entries, M-206 is the most commonly planted variety in the Delta and across the state. It has good agronomic characteristics and consistent quality across different harvest moistures. Some Delta growers also plant M-105, which is a very-early variety that has yielded well in Delta trials but may be slightly more susceptible to rice blast disease than M-206. Among the newer varieties, M-210 is early maturing, blast resistant, and may be a good option for the Delta. While variety M-211 performed well in 2023, it is not as well adapted to cooler environments as M-210 and has had variable performance over the last three years (Table 2). Also, M-211 quality tends to decrease below 18 percent harvest moisture. Statewide results of all nine testing locations will be available soon from the UC Rice Research and Information Center.

Special thanks go to the cooperating grower. Thanks also go to Bruce Linquist and Ray Stogsdill, UC Davis, for coordinating the statewide effort, and the CA Rice Research Board for funding. If you have questions about the trial or about Delta rice production, please don't hesitate to reach out to me, and good luck in 2024!

Table 1. 2023 Delta rice variety trial results.

Table 2. Three-year Delta trial yield summary (lb/acre at 14% moisture).