Rice Breeding Program, 2019


Kent McKenzie, Director

Virgilio Andaya, director of plant breeding; plant breeder, Clarose medium grains

Teresa De Leon, plant breeder, short grains

Shyamal Talukder, plant breeder, long grains

Cynthia Andaya, research scientist, DNA marker laboratory

The California public rice breeding program has developed 51 improved rice varieties in 11 different market types since accelerated research began in 1969. Foundation seed of 15 public varieties and three experimental lines were produced on 132 acres at the Rice Experiment Station (RES) in 2019.

Our Thanks to a Steady Hand

Rice Experiment Station Director Kent McKenzie will be retiring in December 2020 after many years at the helm of California’s premier rice breeding program. He joined RES in 1988 and soon took leadership for the short grains and premium quality project. He became RES director after the sudden passing of his predecessor, D. Marlin Brandon, in January of 2000. McKenzie is proud of his role in keeping RES on course the last 20 years and is grateful for the unwavering support of the growers and the California rice industry.

“I feel very fortunate that for the last 32 years I have been able to participate in the RES Rice Breeding Program, which has released some 30 new rice varieties and brought improved yield, quality, disease resistance, and market types,” he said. “I was not the lead breeder for most of those releases but did support them as a member of the program, in their intellectual property protection, and in seed production.”

Thank you, Kent. We wish you all the best in retirement!

The rice breeding program’s primary research objective is the development of high-yielding, superior rice varieties that are commercially competitive in the world market. Other specific breeding objectives include grain quality and milling yield, cold tolerance and seedling vigor, early maturity and strong culm, and disease resistance.

Virgilio Andaya is director of plant breeding and is responsible for building the breeding and research team and for providing guidance to achieve goals for all grain types and market classes. He primarily breeds medium grains.

Teresa De Leon leads the short grain program and participates in the medium grain program. She temporarily has taken charge of rice disease screening and quarantine of introductions.

Shyamal Talukder leads the long grain program. He also participates in medium grain breeding and is the liaison to breeding programs in the Southern U.S. and handles screening of the Uniform Rice Regional Nursery.

Cynthia Andaya is in charge of the DNA marker laboratory and the grain quality lab. The lab supports all breeding projects with marker-aided selection, genotyping, and DNA fingerprinting.

Director Kent McKenzie oversees administration of the Rice Experiment Station, providing logistical support and guidance on variety releases, market evaluation, funding, and recommendations to the board of directors. He also has provided leadership in the discovery and evaluation of novel sources of herbicide resistance.

Breeding nurseries

The breeding nursery in 2019 was composed of 50% medium grains, 25% short grains, and 25% long grains. Based on market class, about half is conventional rice and half is specialty types. A total 1,231 crosses were made in 2019, bringing the total to 51,439 since 1969.

Drill-seeding of second generation populations was done on May 4 and 5. Drill seeding of seed maintenance was done May 13 and 14. Water-seeding of progeny rows, preliminary yield tests, advanced yield tests and other breeding lines started on May 13 and were completed on May 24.

A total of 274 entries were evaluated in the advanced yield tests and 871 entries in the preliminary yield tests. Preliminary yield tests are the initial step of replicated large-plot testing for experimental lines and superior entries before being advanced to statewide yield tests.

The breeding nursery included 37,589 water-seeded pedigree rows, 631 drill-seeded second-generation plots, and 15,015 drill-seeded seed maintenance rows. Headrows of 12Y2175 and 14Y006, proposed for release in 2020, were also grown for foundation seed increase.

Crosses made in early spring 2019 were grown during the summer at RES to produce second-generation seed. Crosses made in summer were planted in the Hawaii winter nursery or in the RES greenhouse to accelerate the selection process.

The 2019-20 winter nursery consisted of 7,280 regular rows and 521 transplanted rows. The rows were dry-seeded November 5 and 6. Seedlings were transplanted December 10 and 11. Selection in the Hawaii nursery took place in March. Harvested seeds are to be planted in the 2020 breeding nursery at RES.

The 2020 San Joaquin cold tolerance nursery was planted in cooperation with a local rice grower. The three-acre, drill-seeded nursery included 3,840 rows and 444 second-generation plots.

Foundation seed headrows were grown for breeder seed of A-202, Calaroma-201, M-210, M-104, and Calamylow-201. Headrows of experimental line 10Y2043, released as S-202 in early 2019, as well as headrows of 12Y2175 (M-211) and 14Y1006 (L-208), recommended for foundation seed increase, were also grown.

The 2018–2019 Hawaii winter nursery consisted of 7,860 regular rows (including checks), 600 first-generation transplanted rows, and seed multiplication plots for six ROXY™ lines. The rows were dry-seeded between October 30 and November 1. First-generation seeds were planted October 30, while seedlings were transplanted December 10. Selection and harvest was set for April 2019, with seed to be returned for processing and planting in the RES breeding nursery.

The 2019 San Joaquin cold tolerance nursery was planted in cooperation with a local grower. This three-acre, drill-seeded nursery included 3,600 rows, and 405 second-generation plots. Weed control was good, although damage from geese caused some stand establishment problems. Minimal cold-induced blanking was observed in the rows and the second-generation populations.

Statewide yield tests

Statewide yield tests were conducted in grower fields and at the RES in 2019 to evaluate promising advanced selections from all three maturity groups—very early, early, or intermediate/late. More details can be found in in the Rice Variety Trials section of this annual report.

Calrose medium grains

The predominant rice varieties planted in California are medium grains, commercially and internationally known as Calrose rice, and account for more than 80% of California rice acreage. Breeding for medium grain rice comprises about half the rice breeding program. A significant portion of this project is devoted to premium-quality medium grains.

The main goal of the medium grains breeding project is to develop new rice varieties with high, stable grain and milling yields without sacrificing the excellent grain quality of the Calrose varieties. Breeding materials are planted mostly by hand at the RES breeding nursery the second Monday in May, while the second-generation nursery and seed maintenance plots are drill-planted in the first week of May. Seed increase and generation advance also take place at the Hawaii Winter Nursery.

Average grain yield and agronomic characteristics of medium grain check varieities grown at the Rice Experiment Station in 2019 for the statewide variety trial tests
Variety Grain Yield
Harvest MC% Seedling vigor Days to Heading Plant Height (cm) Lodging (percent)
M-104 8,890 17 4.9 72 100 20
M-105 9,653 18 4.8 76 101 16
M-205 8,863 18 4.9 83 96 0
M-206 9,133 19 4.9 77 103 33
M-209 9,603 20 4.8 83 100 0
M-210 8,843 18 4.9 75 103 20

Check variety performance

Calrose varieties in commercial production are used as checks in preliminary and advanced yield tests. In 2019, these included M-104, M-105, M-205, M-206, M-209, and M-210. There was an overall average yield reduction in California last year.

M-105 was the highest yielding variety in statewide yield tests at 9,653 pounds/acre. M-209 was the second highest at 9,603 pounds/acre average grain yield. For the last six years, the yield performance of M-209 has been better than M-206 and M-205. M-206 is still the most widely grown rice variety in California because of its superior adaptability to different environments.

New Calrose medium grain

In early 2020, the experimental line 12Y2175 was approved for release as M-211. It is a high-yielding, semi-dwarf, early maturing, glabrous, high-quality medium grain developed as an alternative to M-209 and as a replacement for M-205. It has excellent cooking characteristics and is close to M-401 premium quality.

The three-year average grain yield was 9,712 pounds/acre for 12Y2175, compared to 9,196 pounds/acre for M-209 and 9,129 pounds/acre for M-206. It performed best in Butte, Sutter, Colusa, and Yolo counties. Seedling vigor is similar to M-206 and M-209, and it is more lodging resistant than M-206.

Milled grains of 12Y2175 are heavier and slightly longer than M-206 but slightly shorter than M-209. It is perfectly suited for comingling with other Calrose types.

Head rice yield of 12Y2175 harvested at 18% to 22% is 61/67 (head/total), compared to 62/68 for M-209 and 64/69 for M-206. Head rice yield was lowest when cut at moistures below 18%.

Graded for grain appearance characteristics such as aroma, taste, and softness by external evaluators, 12Y2175 was found to be highly acceptable to the rice market.

Promising medium grains

Twelve promising lines showed higher yield compared to check varieties in statewide yield tests.

In the very early group, 17Y3158 yielded the highest at 10,410 pounds/acre, which is 8.5% higher than the top-yielding check variety, M-105, at 9,590 pounds/acre. Another line, 17Y3047, registered grain yield of 10,000 pounds/acre.

In the early group, 18Y3098 yielded the highest at 10,310 pounds/acre, higher than any of the check varieties. Line 18Y3102 registered grain yield of 10,090 pounds/acre at RES and averaged 10,050 pounds/acre statewide, the highest in this group.

In the intermediate/late group, 18Y3215 had the highest yield at 10,490 pounds/acre. Other promising lines in this group are18Y3292 and 18Y3141.

Long grains

The long grain breeding project focuses on four major rice types—conventional, jasmine, basmati, and aromatics. Milling and cooking quality improvements of conventional long grains and specialty types remain major priorities, followed by resistance to cold-induced blanking and other agronomic and disease resistance traits.

Conventional long grains

In conventional long grains, extensive cooking quality screening and selection efforts have eliminated the majority of texture softness from California long grain breeding material. Consequently, the primary focus is on milling yield and cold tolerance.

L-206 has been the standard check since its release in 2006. It is an early maturing, high-yielding, conventional long grain with good cooking quality. L-207, released in 2016, is a high-yielding, intermediate height, and early maturing variety with Southern long grain cooking quality. It is adapted to most areas except the San Joaquin region.

A-202 is a conventional aromatic variety released in 2014 as a replacement for A-301. A-202 heads nine days earlier than A-301, is taller, has higher seedling vigor, and retains the same flavor sensory profile. Milled kernels of A-202 are slightly bolder than A-301. Starch characteristics are typical of other conventional long grains like L-206 and L-207. It is not recommended for cooler regions.

In 2019 statewide tests at RES, grain yield of L-207 was 10,747 pounds/acre—compared to 9,770 pounds/acre for L-206, 9,930 pounds/acre for Calaroma-201

(CJ-201) and 9,790 pounds/acre for A-202. Key agronomic performance characteristics of long grains in statewide tests are summarized in the table below.

New long grain variety

The advanced conventional long-grain line, 14Y1006, an early maturing sister line of L-207, is being released in 2020 as L-208. It was evaluated in the three maturity groups and compared to L-206 and L-207.

Overall results indicate that 14Y1006 is an excellent high-yielding conventional long grain with a 13% yield advantage over L-206 in all locations and has a 3.4% higher yield than L-207. In statewide tests in 2019, 14Y1006 yielded 10,340 pounds/acre—compared to 10,000 pounds/acre for L-207 and 9,190 pounds/acre for L-206. Mean heading was 81 days, four days earlier than L-207 and two days earlier than L-206. It has shown improved lodging resistance, blanking resistance, milling yield, and cooked grain texture. It is best suited to the warmer rice growing areas of the Sacramento Valley.

The length of milled 14Y1006 is shorter than L-207 but longer than L-206. Grain width is narrower than both L-207 and L-206. Head rice yield when harvested at 18% to 22% moisture was 62/69 (head/total), compared to 62/69 for L-207 and 58/67 for L-206. Percentage of total rice is also higher.

Internal and external cooking and tasting evaluations confirmed the acceptability of 14Y1006 in the long grain market.

Promising long grain lines

In addition to 14Y1006, several other promising lines produced high yields and have performed consistently well for the last four years.

In the very early tests, 17Y1027 had a mean yield of 10,450 pounds/acre at RES and 9,260 pounds/acre statewide. Compared to L-207, it had a 1% yield advantage at RES but a 3.5% disadvantage in statewide tests. It also registered a 5% to 11% yield advantage over L-206, CJ-201, and A-202 at RES and 2% to 6% statewide.

Average grain yield and agronomic characteristics of long grain check varieities grown at the Rice Experiment Station in 2019 for the statewide variety trial tests
Variety Grain Yield
Seedling vigor Days to Heading Plant Height (cm) Lodging (percent) Stem Rot Score
A-202 9,790 4.8 80 102 6 2.5
CJ-201 9,930 4.8 82 95 1.5 4.0
CT-202 7,180 4.8 83 96 1.3 1.0
L-206 9,770 4.8 77 92 8.8 2.5
L-207 10,750 4.8 81 111 1.5 3.8

This line also performed especially well in the early group, both at RES and statewide. It yielded 11,790 pounds/acre at RES and 11,040 pounds/acre statewide. Compared to L-207, 17Y1027 had a 13% yield advantage at RES and 4.5% statewide. Compared to L-206, CJ-201 and A-202, it showed a 19% to 26% yield advantage at RES and 13% to 18% yield advantage statewide.

In the intermediate/late group, 17Y1027 had slightly lower yield than L-207 at RES and a slightly higher yield statewide. Compared to other check varieties, it had a 9% to 14% higher yield at RES and 8% to 11% higher yield statewide. In addition, 17Y1027 exhibited no lodging in any RES tests and proved to be better adapted to warmer regions.

Another line, 16Y1154, had lower yield (9,010 pounds/acre) than the checks at RES in very early tests but yielded 2% to 6% higher than L-206, CJ-201, and A-202 in statewide tests (9,260 pounds/acre). In early tests, this line outperformed all check varieties at RES (11,130 pounds/acre) and statewide (10,760 pounds/acre). Compared to L-207, it had a 7% yield advantage at RES and 2% statewide. In both RES and statewide tests, 16Y1154 had a 10% to 19% yield advantage over L-206, CJ-201, and A-202. In the intermediate/late group, this line had an average yield of 11,140 pounds/acre at RES and 10,290 pounds/acre statewide. It also produced a 7% to 11% higher yield than L-206, CJ-201, and A-202 at RES and statewide. No lodging was found in any of the tests at RES.

Short grains

The short grain project includes conventional short grains and specialty types such as waxy rice, low amylose short grains, waxy short grains, Arborio types, and premium short grains. New lines are bred and selected for improved, stable grain yield and yield-related traits, milling and cooking quality, blanking resistance, lodging resistance, very early to early and uniform maturity, short flowering duration, and resistance to diseases. The project is approximately 30% conventional short grains, 35% waxy, 20% premium short grains, 10% Arborio, and 5% low amylose.

New short grain variety

S-202, formerly designated as the experimental line 10Y2043, was released in 2019 for California commercial rice production. This new conventional short grain variety is a very high-yielding, early maturing, semi-dwarf, with glabrous grains. S-202 consistently outperformed S-102 and M-206 in 2019 yield tests, with an overall grain yield of 9,870 pounds/acre,

compared to 8,520 pounds/acre and 8,970 pounds/acre, respectively. Seedling vigor of S-202 is comparable to that of S-102, with slightly shorter plant height and slightly longer days to flower.

Head rice yield of both S-202 and S-102 averaged 62% when harvested at moistures greater than 19% and dropped to 58% and 54%, respectively, at moistures below 17%. Cooking and sensory evaluations taken internally and externally for several years indicate an overall market acceptability for S-202. The new variety also has better cold tolerance.

Because of its outstanding yield potential and grain quality, S-202 is an excellent replacement to S-102 but may not be comingled with the latter because of its significantly smaller grain size.

Short grain yield tests

Experimental lines in nurseries and yield tests are compared to standard short grain check varieties: • S-102, released in 1996, has been the standard short-grain check. It is very early maturing, with large seeds, pubescent, and has good cold tolerance.

• Calhikari-202 (CH-202), released in 2012, is the latest premium quality variety. It is early, short, pubescent, yields higher than Calhikari-201, has better eating quality, smaller grains, and higher milling yields.

• Calmochi-203 (CM-203), released in 2015, is the latest waxy or sweet rice. It is a high-yielding, glabrous, early maturing variety released as an alternative to Calmochi-101.

• Calamylow-201 (CA-201) is a low amylose variety developed from Calhikari-201. It is an early maturing pubescent rice, ideal for making sushi and is the only low-amylose rice variety released by RES.

Among the short grain checks in 2019 statewide yield tests, S-202 had the highest yield at 10,157 pounds/acre, followed by CM-203 at 9,913 pounds/acre. S-102 had an average yield of 7,083 pounds/acre, while the premium short grain CH-201 and CH-202 yielded 7,483 pounds/acre and 8,707 pounds/acre, respectively. CA-201 had the lowest yield at 6,200 pounds/acre.

Conventional short grains

Released for foundation seed production in 2019, S-202 consistently yielded higher than S-102 in all three maturity groups at RES and statewide. Experimental line 18Y117 is promising and yields higher than either check in the very early group at RES. This line also preformed well in statewide tests with an average yield of 9,400 pounds/acre in the very early group, 10,020 pounds in the early group, and 9,550 pounds/acre in the intermediate/late group. It has excellent adaptation to all rice growing areas of California. Overall, 18Y117 is better than S-102 but yielded less than S-202 in the early and intermediate/late tests.

Specialty short grains

Large drying and storage bins hold foundation seed of the rice varieities developed by the Rice Experiment Station. Foundation seed is allocated by the California Crop Improvement Association to seed growers for commercial production. Fifteen varieties and three experimental lines were produced in 2019.
Premiums—Two lines were entered into statewide evaluations in 2019. Line 15Y2112 has been in yield tests since 2015 and continues to perform well. Its average yield ranged from 9,020 pounds/acre in the RES early group to 9,650 pounds/acre in the RES very early group. It performed better than CH-201 and CH-202 in the very early and early groups but is only comparable to CH-202 in the statewide intermediate/late group.

The experimental line 17Y2087 is another promising premium quality short grain rice. It performed well in the very early group with an average yield of 9,650 pounds/acre at RES and 8,920 pounds/acre in statewide tests.

Waxy—More than 30% of the short grain project is devoted to the improvement of sweet or waxy short grains. In 2019, nine experimental lines were entered in the statewide tests for waxy short grains, with at least three of them deemed promising.

In the very early group, 17Y2142 had an average yield of 9,900 pounds/acre at RES, compared to CM-101 and CM-203 yields of 6,170 pounds/acre and 9,840 pounds/acre, respectively. However, this line had an average yield of 9,440 pounds/acre in the early group and 9,670 pounds/acre in the intermediate/late group tests at RES. It showed consistent high yields in all locations of the statewide tests, giving an average yield of 9,323 pounds/acre.

Compared to the waxy check varieties, CM-203 continues to be the highest yield waxy rice. However, this line and 15Y2135 have other desirable characteristics, such as better lodging resistance and lower cold-induced panicle blanking.

Low amylose and Arborio types—Currently only one low amylose variety, CA-201, is in commercial production, but it is low yielding—6,200 pounds/acre at RES and 7,000 pounds/acre statewide. A promising alternative is experimental line 15Y2100, with an average yield of 9,250 pounds/acre in the RES early group and 9,520 pounds/acre in the RES intermediate/late group. Statewide, 15Y2100 has an overall mean yield of 9,056 pounds/acre, a 30% yield advantage over CA-201.

A line designated as 16Y2028 is another promising low amylose short grain. It outperformed 15Y2100 with a grain yield of 10,110 pounds/acre and 9,600 pounds/acre in the RES very early and early groups, respectively.

Of the Arborio types typically used in risotto recipes, the previously released germplasm 89Y235 yielded 7,240 pounds/acre. Two promising lines in the pipeline, 18Y2070 and 18Y2045, had significantly higher yields. Line 18Y2070 registered an average yield of 9,550 pounds/acre in the early group at RES and 9,350 pounds/acre in statewide early group testing.

DNA marker laboratory

The role of the DNA marker laboratory is constantly evolving with the needs of the RES rice breeding program. It has been renamed the RES Genetics Lab to reflect the larger function it now plays. The Genetics Lab will continue the research tasks the DNA marker lab was created for, as well as handle new areas of research.

A 2,200 square-foot RES Genetics Building was constructed in 2019 with funds from the Rice Research Trust. Equipment from the DNA marker lab was transferred into this new facility in December. Additional equipment also was purchased by the Rice Research Trust.

The lab supports the different breeding programs and special projects. The lab is involved in marker-aided selection for blast resistance, grain quality, aroma, and herbicide resistance; DNA fingerprinting and purity testing of advanced lines; genetic mapping of stem rot resistance genes and herbicide tolerance to oxyfluorfen; and the development of mutant populations using both irradiation and chemical mutagenesis. Emphasis varies from year to year depending on the needs of the breeding program.

Marker-aided selection

Marker-aided selection for both blast resistance and grain quality is now a routine part of genetics work. The lab played a major role in the release of M-210, which has improved blast resistance over M-208. Other markers are being used to predict grain quality parameters such as starch characteristics in the long grain program. One marker is being used to detect the presence of fragrance genes in breeding materials.

Most of the marker-aided selection work in 2019 focused on blast resistance and herbicide tolerance. About 3,000 lines from the medium grain project were screened for both. These materials contain multiple blast resistance genes, as well as herbicide resistance. Breeding material and headrows were analyzed with microsatellite markers and single nucleotide polymorphisms (SNP) markers for oxyfluorfen tolerance in rice.

DNA fingerprinting

Another important function of the genetics lab is to assist in variety identity and purity assessment—DNA fingerprinting that distinguishes medium grain, long grain, and short grain varieties. The lab keeps a marker database of all rice varieties released at RES, as well as other rice variety introductions.

ROXY™ materials planted in the greenhouse and the field were also fingerprinted for identity. As the ROXY™ trait is being transferred to different varieties, fingerprint profiles can distinguish resistant plants in different genetic backgrounds.

The DNA lab also received requests from different entities for identity and purity issues. In one case, a private company sought to determine whether milled samples marketed as Calrose were really a California variety. DNA marker analysis showed that the samples were not one of California’s Calrose varieties but were actually a medium grain from the southern U.S.

Herbicide tolerance

An oxyfluorfen tolerant mutant was isolated from treated M-206 several years ago. The DNA lab was tasked to determine the genetics of the herbicide tolerance and to identify what gene is responsible for this trait.

Genetic mapping studies identified the location of herbicide tolerance with a multi-pronged approach. This fine mapping effort identified the genes controlling the trait that are associated with particular molecular functions such as lipid binding and transporter activity. Four SNP markers for oxyfluorfen resistance detection are now being used for marker-aided selection in the RES breeding program. This detailed investigation into the genetics of the ROXY™ trait will be useful in understanding the tolerance mechanism, supporting the intellectual property protection, and the eventual commercialization of this non-GMO herbicide resistant rice as a weed control tool for growers.

Rice pathology

The rice pathology project is an integral part of the rice breeding program. Research in this area and breeding focuses on developing rice varieties with resistance to stem rot, aggregate sheath spot, and blast diseases. Kernel smut is another, more recent, area of research.

Stem rot

Even without a full-time plant pathologist, RES continues work on stem rot by screening breeding lines for sources of resistance. In 2019, a total of 2,916 rows were evaluated in the disease nursery field. Breeding materials evaluated for stem rot resistance included 107 statewide entries, 287 advanced yield tests, 187 recombinant inbred lines, 203 uniform regional rice nursery entries from southern universities, and 372 entries for genomic selection study. Only 10 lines were found to be highly resistant and 51 lines were resistant. While some lines show promise, finding sources of stem rot remains elusive. More basic research is needed to better understand the disease and resistance.


Panicle and leaf blast were observed at RES and in a ROXY™ field trial near Colusa. The outbreak was minimal, however, and did not affect grain yield. RES is continuing efforts to incorporate multiple sources of rice blast resistance into medium, short, and long grain varieties. Several crosses were made and some blast-related genes are being targeted with gene editing techniques. M-210—a blast resistant M-206—is now available to growers who desire a blast resistant variety.

Aggregate sheath spot

Some aggregate sheath spot was observed in RES fields, but not in the statewide field test locations. No greenhouse or field evaluations were conducted in 2019 because of the lack of a full-time plant pathologist. Backcross populations previously developed to incorporate resistance genes from Teqing, Jasmine 85, and MCR10277 to M-206 and L-206 are kept in cold storage for future reference and use.

Quarantine introductions

The building blocks for any breeding program are cultivars with traits desirable in commercial production. In 2019, 239 lines were received from the Uniform Regional Rice Nursery. Of these, only 152 passed the brown rice protocol and were planted in the greenhouse. Seeds of clean and healthy plants were harvested and kept in the cold room for future use. An additional 2,139 rice accessions were obtained from other sources, including some from Japan, China, Italy, Hungary, and Romania. Fourteen of these were used in short and medium grain crosses. In 2020, 136 accessions will be characterized for agronomic traits, yield, grain quality, greenhouse cold stress, and stem rot.

All plant introductions grown and released for breeder use are done so under procedures developed and approved by the U.S. Department of Agriculture and the California Department of Food and Agriculture to prevent introduction of exotic insect pests and diseases, as well as weedy red rice in California.

Herbicide tolerant rice

These are the people who make the Rice Experiemnt Station run, captured all together before the opening of the 2019 Rice Field Day. A relatively small but very diverse and dedicated group, providing administrative, field operations, facilities maintenance, seed production, rice breeding and genetics expertise. Their skills and efforts successfully bring together three complex activities - growing a rice crop, producing foundation seed, and developing improved rice varieties for California.

ROXYTM is a heritable non-GMO rice trait that provides tolerance to the post-patent herbicide ALB2023 (oxyfluorfen) and has been recovered in the variety M-206, California’s most widely grown Calrose variety. The backcross selection to M-206 (17Y3000) has been tested in 2017–19 University of California yield tests, and the seed has been increased and purified.

Five years of research in multiple locations shows that the herbicide applied preplant in a water-seeded system provides high levels of rice weed control with the ROXY™ trait. It is also effective in drill-seeded rice with a preplant and preflood application and may have potential in other rice growing regions.

Extensive research and discovery by the Rice Experiment Station has been underway on the genetics and mechanism of this trait since its discovery (see DNA Marker Laboratory section). The trait is controlled by a single recessive gene and is a new mechanism for rice herbicide tolerance.

A provisional US patent for this trait was filed in 2016 and expanded in 2019, providing additional information on gene(s), mutation sequences, new data, and a biochemical pathway in support of the patent application. A shared partnership with Albaugh LLC is underway to pursue registration and commercialization of the exclusive herbicides ALB2023 and ALB2024 for rice weed control and will be known as the ROXY™ Rice Production System.

The registration process with the federal Environmental Protection Agency was initiated in 2019. Some of the activities involved in this process include aquatic dissipation testing, herbicide efficacy testing, and developing a production system and herbicide brands.

The breeding and introgression of the ROXY™ trait will follow the same RES breeding program protocols for adaptation, yield, and quality as conventional varieties. New crosses have been generated and advanced, including experimental lines 17Y3000 and 19Y4000.

Breeding with genomic selection

Almost all the national and international rice breeding programs use conventional breeding schemes—the pedigree method, a very time-consuming approach. Advances in molecular genetics have been incorporated into plant breeding programs in recent years. However, this approach is limited by the number of useable molecular markers.

A new approach called genomic selection shows enormous potential to significantly enhance breeding efficiency and is being integrated into the RES rice breeding program. In 2018, a rice population was developed to analyze the variability of all the advanced lines from the last five years. This population consists of 210 medium grains, 64 long grains 73 short grains and 13 compound grain types. All the varieties released by RES are included in this population. The training population was transplanted at RES in 2019 for line purification, seed multiplication, and agronomic study.