Bruce Linquist, UCCE specialist, Dept. of Plant Sciences, UC Davis

Sixteen on-farm rice variety trials were conducted throughout the rice growing regions of California in 2018 by UC Cooperative Extension scientists in cooperation with plant breeders at the Rice Experiment Station (RES). Standard varieties were compared with preliminary and advanced lines in these tests to measure performance across a range of environments, farmer practices, and disease levels.

Six similar tests were conducted at RES—two from each maturity group. Average yields across varieties and locations in the advanced-line tests ranged from 9,390 pounds/acre in the very early tests to 9,180 pounds/acre in the early tests. In the intermediate/late tests, the advanced lines average yield was 9,900 pounds/acre.

Field preparation and planting were completed in May. Several advanced lines in 2018 produced high yields, as well as demonstrating important breeding goals aside from yield, such as disease resistance, grain quality, and specialty types. Testing advanced and preliminary lines under a variety of conditions remains a critical aspect of releasing new varieties adapted to changing cultural practices, markets, and pests.

Rice variety evaluations

Eight uniform, advanced breeding-line trials and eight preliminary breeding line trials were conducted throughout the major rice producing areas of California. The RES breeders conducted six additional tests—two from each of the three maturity groups. Many of the experimental lines have been tested and screened in previous years and were advanced for further testing. The RES provided the seed for public varieties and experimental cultivars. No proprietary lines were tested. Agronomic performance for these tests follows.

Very early maturity

Four advanced breeding lines and eight commercial varieties were compared in four very early advanced tests. The preliminary tests evaluated eight commercial varieties and 36 preliminary lines evaluated in separate tests at each location. Commercial varieties at each location included S-102, CA-201, CH-201, CH-202, CM-101, CM-203, M-104, M-105, M-205, M-206, M-209, M-210, A-202, CJ-201, L-206, and L-207.

Grain yields in the advanced tests averaged 9,390 pounds/acre overall, 9,530 pounds/acre at RES, 9,810 pounds/acre at Sutter, 10,450 pounds/acre at Yolo, and 7,810 pounds/acre at south Yolo. The three highest-yielding entries on average were short grain line 10Y2043 (10,260 pounds/acre), long grain line 14Y1006 (10,260 pounds/acre), and long grain L-207 (9,940 pounds/acre. Top-yielding commercial varieties included L-207,

CJ-201, M-201, and M-105. Averaged across four locations, yields for lines in the preliminary tests ranged from 9,700 pounds/acre to 5,780 pounds/acre.

Average grain moisture at harvest was 18.2%, average lodging 8%, average days to heading was 84, average seedling vigor 4.7, and average plant height was about 37 inches. Field preparation and planting were average, with all trials completed in late May. Harvest was completed within the normal time frame. Yields were up 4.6% from 2017.

Comparing commercial standard entries over a five-year period and across locations, M-104, M-105, and S-102 were the highest yielding varieties at 9,263 pounds/acre, 9,067 pounds/acre, and 8,907 pounds/acre, respectively.

Early maturity

Four advanced breeding lines and eight commercial varieties were compared in four early advanced tests. Preliminary tests included eight commercial varieties and 40 preliminary lines evaluated in separate tests at each location. Commercial varieties at each location included S-102, CA-201, CH-201, CH-202, CM-101, CM-203, M-104, M-105, M-205, M-206, M-209, M-210, A-202, CJ-201, L-206, and L-207.

Yields in the advanced lines averaged 9,180 pounds/acre overall, 9,850 pounds/acre at RES, 8,630 pounds/acre at Butte, 9,040 pounds/acre at Colusa, and 9,190 pounds/acre at Yuba. Advanced long grain line 14Y1006 was the highest yielding entry (9,930 pounds/acre) averaged over four locations in 2018. Advanced short grain line 10Y2043, long grain L-207, and medium grain premium quality 12Y2175 yielded second, third, and fourth, respectively. Top-yielding commercial varieties included CJ-201, M-209, M-206, M-210, and M-105.

Average number of days to 50% heading was 82. The commercial standard M-206 averaged 81 days over four locations. In the preliminary tests, CM-203 was the highest yielding commercial variety, with 12 experimental lines yielding higher.

Over a five-year period and across locations, L-207 was the highest yielding commercial variety at 10,080 pounds/acre, followed by M-209 at 9,422 pounds/acre, and M-206 at 9,356 pounds/acre.

Intermediate/late maturity

Four advanced experimental lines and eight commercial varieties were compared in three intermediate/late tests. Preliminary tests included six commercial varieties and 18 preliminary lines evaluated in separate tests at each location. Commercial varieties at each location included S-102, CA-201, CH-201, CH-202, CM-203, M-105, M-205, M-206, M-209, M-210, A-202, CJ-201, L-206, and L-207.

Yields in the advanced lines averaged 9,900 pounds/acre overall, 9,970 pounds/acre at RES, 10,030 pounds/acre at Butte, and 9,740 pounds/acre at Glenn. The 2018 advanced over-location yield increased 920 pounds/acre (9.3%) compared to the 2017 season average. In the advanced tests, L-207 was the highest yielding commercial variety (10,440 pounds/acre). CJ-201 and M-209 were the next highest yielding commercial varieties. The medium grain entry 12Y2175 was the highest yielding advanced entry across locations at 10,960 pounds/acre.

Average number of days to 50% heading was 82. Advanced line 12Y2175 was the latest variety at 86 days to reach 50% heading at all locations. Over a five-year period and across locations, L-206 is the highest yielding commercial variety in this group at 9,469 pounds/acre, followed closely by M-209 at 9,420 pounds/acre.

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