Last year, we reinstituted the San Joaquin County Delta rice variety trial, after a four-year break. San Joaquin County is one of twelve locations of the statewide trial that evaluates commercial varieties and advanced breeding lines. San Joaquin County is a test site for very early maturing varieties because the Delta is cooler than other rice growing regions of the state. The trial was drill-seeded on April 16^th at a rate of 150 lb/acre and harvested on October 7^th.

Statewide results will be available from the UC Rice webpage (https://rice.ucanr.edu/Reports-Publications/Agronomy_Papers/). Table 1 (below) shows the San Joaquin County results. Among the entries, M-206 is the most commonly planted variety in the Delta, followed by M-105. The average yield across all commercial varieties and advanced lines was 10,129 lb/ac. When interpreting the results, the CV, or coefficient of variation, is a measure of variability in the data in relation to the mean. The LSD (.05), or least significant difference at 95%, is used to compare means of different varieties. When the difference between two varieties exceeds the LSD value, we are 95% certain that the two varieties performed differently; the results are not due to random chance.

This trial helps to support the Delta rice industry, which has a different production system from the Sacramento Valley. We plan to continue trialing rice varieties in the Delta again in 2022. Please don't hesitate to reach out if you have questions about Delta rice production, and good luck this season!

Table 1. 2021 San Joaquin County very early rice variety test (advanced lines and varieties).