Tuesday, May 28, 2024

UA field tours showcase varieties, nitrogen management and weed control

university of arkansas aromatic rice
14AR1105 is an aromatic long-grain rice from Debbie Ahrent’s program nearing release.

Diamonds may be a girl’s best friends, but Diamond — University of Arkansas’ new long-grain variety — is shaping up to be a producer’s best friend.

“It has an extremely high yield potential, and people who have it are excited about it because it looks good in the field,” says Dr. Karen Moldenhauer, a UA rice breeder in Stuttgart.

Diamond was grown for registered seed for the first time this year, occupying about 9 percent of the Arkansas’ rice acreage. The new variety also has a clear kernel and low chalk.

Moldenhauer’s comments came during field tours that were part of the university’s recent annual Rice Expo.

Titan, a medium-grain released the same year as Diamond, continues to garner interest from Kellogg’s, she says. The Battle Creek, Mich., cereal manufacturer has requested enough Titan to run through two pilot plants for a month to determine how it puffs.

“Kellogg’s hasn’t made a decision on it but they’re very interested,” Moldenhauer says.

With a large kernel, Titan has quality similar to Bengal, a Louisiana State University medium-grain released in the early 1990s.

Dr. Xueyan Sha, another UA breeder, also has a number of varieties in the pipeline, including a Clearfield medium grain and a Clearfield long grain. In addition, Sha has a few lines imported from India he is using to try to improve heat tolerance in new varieties.

Debbie Ahrent is close to releasing a new aromatic rice, known under its experimental number as 14AR1105. It has a stronger aroma than the current U.S.-grown jasmine-type rices, along with a nice looking kernel, pretty good yields and good milling.

Ahrent has it in about 3 acres for seed increase, Moldenhauer says.

Green is the color

jarrod hardke
Extension rice agronomist Dr. Jarrod Hardke provided attendees an overview of how the rice season was progressing.

With the continued stream of new varieties coming from breeders, agronomists have revisited fertility, says Dr. Rick Norman, a UA agronomy professor in Fayetteville.

“Varieties we have now are ifferent than ones in the ’90s and ’70s,” he says.

In the past, the university recommended growers put out about two-thirds of their nitrogen pre-flood, with the remainder coming at midseason between the start of internode elongation and 1/2-inch internode.

After four years of trials, Norman says the mid-season timing may be too early. Instead, the data suggest that two weeks after the beginning of IE or one week after 1/2-inch internode can maximize yield potential.

“It looks like a little later is better than a little earlier,” Norman says.

Drs. Trent Roberts and Jarrod Hardke also have been working with the Greenseeker, a hand-held device that measures light wavelengths reflected from plants. It then converts that information into a number that growers can use to determine whether their crop needs mid-season nitrogen.

This year, Roberts and Hardke have several field-scale trials putting the Greenseeker to the test. Each field has a 5-foot-by-5-foot reference plot that has received a small bagful of extra nitrogen.

Users first scan the reference plot and record the reading. Then they randomly scan at least 10 locations in the field and average those numbers. By dividing the average into the reference plot number, they obtain a ratio that should tell them whether mid-season nitrogen will pay.

If, for example, the result is 1.1, Norman says there’s a 10 percent chance they’ll see a yield improvement with additional nitrogen. But if the result is 1.2, then there’s a 90 percent chance they’ll get a yield increase with added nitrogen.

“We have N-STaR for nitrogen pre-flood, then we have this to determine if we need any N mid-season,” he says.

Developed by the University of Arkansas, N-STaR is a field-specific soil N intended to provide a prescription N rate.

Weed relief

rogue herbicide Bob Sott
Dr. Bob Scott points out the aquatic weed control provided by Rogue herbicide, which is not yet registered for use in rice. Note the weed-free water around the rice plots.

Rice producers should receive some relief from herbicide-tolerant weeds in the coming months with a handful of new herbicide registrations, says Dr. Bob Scott, UA Extension weed specialist.

Loyant with Rinskor active from Dow AgroSciences is one product high on Scott’s list. With registration expected “any day now,” he predicts  the herbicide to be used on a lot of acres next season.

“We expect good things out of this product,” Scott says.

He says Loyant also should fit well into row-rice systems, since it is “outstanding” on Palmer pigweed. Pigweed has difficulty germinating through water, such as the flooding held on conventional rice fields. But it has no problems in row rice fields since they are regularly flushed.

Rogue herbicide is another product that Scott’s excited about. With registration anticipated in 2019, the herbicide is strong on sprangletop with some activity on barnyardgrass. Rogue also is strong on aquatic weeds.

Unlike many other herbicides, Rogue is used post-flood. To be most effective, the flood must be held on the field for at least seven to 10 days.

“So it’s going to be a great fit for zero-grade or straight levee fields that where you can manage the water well,” Scott says, adding it will not have a place in row rice.

Rogue from Gowan Co. contains the active ingredient benzobicyclon.

Three or four other herbicides also are in the pipeline, although a bit further back.

“It’s a very exciting time to be working in rice,” Scott says. “But with the (weed) resistance, we need these new products.”

— Vicky Boyd

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