Herbicide-resistant rice shows promise in field trials

A new herbicide-resistant rice line that shows promise for use by the state's rice growers was highlighted at this year's California Rice Field Day.

"The rice breeding program would like to deliver that technology to California growers as an option for weed control," Kent McKenzie, director of the California Rice Experiment Station in Biggs, said. "A patent has been filed and efforts are being pursued to obtain registration for this herbicide for use on rice in California."

The herbicide-tolerant line is called ROXY, which is an acronym for resistance to oxyfluorfen.

McKenzie reported on the station's discovery of and research on the ROXY trait. Oxyfluorfen (GoalTender and Goal 2XL by Dow AgroSciences) is a contact herbicide that controls broadleaves and provides partial control of some grass species and sedges. In California, it is widely used in orchard crops, grapes and strawberries. The herbicide provided "exceptional" control of broadleaf weeds in rice plots at the experiment station, he said.

"Greenhouse and field testing with pre-plant applications of oxyfluorfen have demonstrated the herbicide tolerance of the mutant lines and first-generation breeding materials. Promising levels of weed control were also demonstrated in 2015 to 2017 field tests," McKenzie noted.

He explained that mutations are induced from chemicals or irradiation to create breeding material for new varieties. It is the same technology that was used to develop one of the state's first semi-dwarf varieties, Calrose 76, in 1976.

More than 300 people attended the 105th annual field day to learn about the latest research on rice varieties and pest control. The half-day event, held at the Rice Experiment Station, was sponsored by the California Cooperative Rice Research Foundation, the University of California and the U.S. Department of Agriculture.

Field day participants toured the breeding nursery aboard canopied, flatbed trucks, where they learned about the latest research on rice varieties.

Virgilio Andaya, director of plant breeding, discussed research that focuses on different rice types, including short-, medium- and long-grain; aromatic; and premium-quality varieties.

"The California rice cropping season started a bit late in 2017, due to delayed land preparation brought about by extended rain events up until the end of April to early May," Andaya stated. "Rice acreage this year did not pick up, as some farmers opted to fallow rice fields rather than risk lower yields due to late planting, even with the abundance of water. The Rice Experiment Station managed to plant and set up all the yield trials, pedigree nurseries and seed maintenance plots at the station by May 26. Late or not, everything got planted."

A promising medium-grain variety being developed is called 12Y3097, which is a blast disease-resistant variety.

"Breeder and foundation seeds are being grown in 2017 and will be available for sale in 2018 if the line is approved for release," Andaya said. "It is intended as a replacement for M-208."

In addition, "The medium-grains project has started to explore the use of unique traits that may add value to Calrose as a brand. One of the traits being looked at is aroma similar to the one found in the long-grain aromatic rice or the Jasmines," he noted. "By 2017-2018, the project hopes to get enough seed of aromatic Calrose for grain-quality and grain-yield evaluation, and market testing."

In terms of long-grain rice, a promising variety is 15Y84, a Jasmine-type experimental line that showed superior agronomic performance and grain-quality characteristics.

"If released, this will be the first Jasmine-type rice to be developed by the station that has quality characteristics that are similar to the imported Jasmine," Andaya said.

Paul Sanchez, UC plant pathologist, discussed his research on developing rice varieties with disease resistance to rice blast, stem rot and aggregate sheath spot.

"The Pathology Project handles rice germplasm requests by the breeders, which must go through quarantine," Sanchez stated. "All received germplasm materials were grown and evaluated inside the station's quarantine greenhouse. Materials are then released for use in the breeding program. The station's plant quarantine and rice germplasm conservation procedures ensure that the breeders have access to traits important to the continuing improvement of California varieties."

The station's DNA Marker Lab, headed by Cynthia Andaya, is involved in marker-aided selection for blast resistance, grain quality, aroma and herbicide resistance; genetic mapping studies; and generation of new populations using both irradiation and chemical mutagenesis.

Field day attendees also toured the Hamilton Road Facility to learn about weed research. The weed control project seeks to assist California rice growers in the prevention and management of herbicide-resistant weeds, and to achieve broad-spectrum weed control.

UCCE weed specialist Kaseem Al-Khatib talked about ROXY rice, new herbicides and herbicide-resistant weeds.

Al-Khatib said that ROXY rice was built on the M-206 variety.

"ROXY was evaluated for crop tolerance and weed control with oxyfluorfen applied alone or in combination with several other rice herbicides," he noted. "Oxyfluorfen did not cause damage on the rice. We have good safety with oxyfluorfen, and also there are no interactions with other herbicides that can make this technology unfit. It has very good weed control."

Butte herbicide, a granular mixture of benzobicyclon and halosulfuron, was registered for use in rice this year. The active ingredient, benzobicyclon, adds a new mode of action to the herbicide portfolio for water-seeded rice in California.

In research trials, Butte showed excellent control of ducksalad, monochoria, ricefield bulrush, smallflower umbrellasedge and sprangletop weeds. It provided good control of watergrass and barnyardgrass, and fair control of redstem. Overall, Butte alone provided a broad spectrum of weed control and offered an exceptional level of crop safety, Al-Khatib said, adding that greater grass-weed control was provided when Butte was used in sequence with other herbicides that have different modes of action. Butte was developed by Gowan Co.

Experimental herbicides are being tested at the facility, including NAI-1777, which Al-Khatib called "a very promising tool for weed control in California rice, most importantly for controlling and managing a variety of herbicide-resistant weeds in California rice fields."

An assortment of rice-farm equipment and supplies were exhibited during the event. There was a weedy red rice display and update, and posters highlighted research on topics such as controlling tadpole shrimp and improving irrigation efficiency.

Rice farmers, scientists, government officials and agricultural business people attended the annual field day for various reasons.

"I grew up on a peach farm in Yuba City," John Karnegis, certified crop advisor with Valley Truck & Tractor Co. in Yuba City, said. "A lot of what we do involves equipment for rice, so I came to learn more about the new rice varieties and about the industry as a whole."

Rice grower Ryan Lundberg of RL Rice in Richvale, said, "I like to look at all the new varieties, see what new chemicals are coming out and see what's working. Last year, we got to see what the new chemical Butte was doing—it had not been released yet. It was interesting to come out and see how it worked in relation with other chemicals, to develop a plan. It came out this year, so maybe we will use this new chemical."

Rice producer Rick Nelson of Pleasant Grove said, "I came here to see the different varieties being developed at the rice research station. As time goes on, we just have to keep developing better-performing as well as more saleable rice varieties that are popular not just in California or the U.S., but worldwide. If we can do that, it sort of assures our future in the rice business here, so the competition doesn't take over."

Shawn Yarnes of Winters, regional deployment manager for the Mexico-based Integrated Breeding Platform, said, "I was invited to Rice Field Day because the Rice Research Foundation is considering the breeding management system software platform that we've developed to help manage their breeding data."

(Robyn Rominger is a reporter in Winters. She may be contacted at robynrominger@hotmail.com.)