New rice breeds can fight disease and preserve taste

Plant breeders at the Rice Experiment Station in Biggs continue to roll out new varieties that should make growers' work a little easier or more profitable.

Some of the varieties offer better resistance of common diseases. One brings herbicide tolerance through conventional breeding. All of them figure to produce better yields of high-quality rice.

"Our varieties are all high yielding and high quality," said Teresa De Leon, a rice breeder at the experiment station.

California rice values stand at $700 million to $900 million annually, second nationally to Arkansas. Growers need high quality to maintain their export markets, especially Japan, which buys around a billion pounds of the state's rice.

Growers support and control research at the station through the California Cooperative Rice Research Foundation.

Participating at the annual Rice Field Day, De Leon stood in plots of medium-grain varieties, including the recently released M-211.

"M-211 is a very high-yielding variety," De Leon said. "It is premium quality, but you have to handle it with tender loving care."

In statewide tests last year, M-211 produced greater yields than all other medium-grain varieties, at 9,600 pounds per acre. It is particularly well suited for the warmer areas of the Sacramento Valley.

Rice breeders noted that the most important characteristic of this new variety is its cooking quality, which qualifies it as the first premium Calrose variety.

The Achilles' heel of M-211, however, is its susceptibility to blast, a common fungal disease that impacts rice. When severe, it can cause significant injury to the crop.

Because variety resistance is important in controlling blast, breeders said it is critical to begin with clean seed and manage nitrogen and crop residue carefully when growing a variety such as M-211.

The experiment station next year is poised to release a breakthrough rice variety with herbicide tolerance from conventional breeding methods.

"19Y400 will probably be released next year as our first ROXY variety," said Kent McKenzie, who recently retired as director of the station. He continues to work as a consultant on herbicide-tolerant rice to the California Cooperative Rice Research Foundation and the crop protection company Albaugh.

The line of rice known as ROXY, which stands for resistant to oxyfluorfen, are herbicide-tolerant rice varieties. They began as a variant trait of M-206 medium-grain rice that can be crossed into other varieties using conventional methods and not genetic engineering.

Conventional breeding methods are essential to California rice growers because they rely heavily on the Japanese market, which has been slow to accept biotech crops.

"This is not GMO. This is conventional breeding," said Kassim Al-Khatib, University of California Cooperative Extension weed specialist. "ROXY is tolerant of oxyfluorfen, which is an old material. It is good on grasses except sprangletop. You apply it before planting, and once you get to 1-1/2 pints, you get good control. We did see some stunting, but the plants came back. All the herbicides cause stunting."

In addition to herbicide tolerance, 19Y400 has resistance to blast, according to McKenzie. That's because it is a cross between M-210 and the variant trait originally discovered in M-206.

With its anticipated release next year, 19Y400 is likely to be the first of nearly 60 advanced ROXY lines.

M-210 is the only medium-grain variety grown commercially with resistance to blast. It is widely used as an alternative to M-206 in areas with that disease problem.

"Some years, blast is pretty serious," said Luis Espino, UCCE rice advisor in Butte and Colusa counties. "I've seen some this year but not as bad as last year. A lot of growers have switched to M-210, which is resistant."

Rice researchers have studied the ROXY herbicide-tolerance trait since 2014 and filed for a patent in 2017. They found it does not impact yield and can be used in effective weed-control systems for both water-seeded and drilled rice.

UC publishes up to five years of medium-grain variety rice yields in all the growing regions of the Sacramento Valley. Information is available at the UC Rice Blog, which includes the article "Considerations for choosing the right medium-grain rice variety."

While around 80% of California rice is medium grain, researchers at the experiment station are also working with conventional, jasmine, basmati and aromatic long-grain varieties and have a number of promising lines.

Among the short-grain varieties, Calhikari-202 has excellent cooking and eating qualities, breeders said. But it is subject to lodging and has relatively low yields.

An experimental short-grain line, 17Y2087, has significantly higher yields than Calhikari-202, including as much as 35% higher yields in Glenn and Colusa counties. Other short-grain lines show higher yield potentials.

Researchers are also evaluating rice lines for tolerance of cold, drought or salinity stress and studying approaches to diseases such as blast and stem rot.

(Bob Johnson is a reporter in Sacramento. He may be contacted at bjohn11135@gmail.com.)