A gem of a variety

New ‘Diamond’ lives up to expectations with strong yields and excellent grain quality.

diamond rice variety
2017 was the first season that the University of Arkansas long-grain variety, Diamond, was in commercial production — photos by Vicky Boyd

By Vicky Boyd

After the first year of commercial production, the Diamond variety has proven to be a gem with average statewide yields topping nearly all conventional varieties in University of Arkansas and Mississippi Sate University field trials.

“All of our growers are really happy with it,” says Dr. Jarrod Hardke, rice Extension agronomist at the University of Arkansas Rice Research and Extension Center in Stuttgart.

Dr. Bobby Golden, a rice Extension agronomist with Mississippi State University’s Delta Research and Extension Center in Stoneville, says he’s heard similar sentiments from his growers.

“In farmers’ fields this year, the early reports are that Diamond yields are excellent,” he says. “In my trials, I’ve had it top out at 203 bushels per acre.

“It looks to be a really strong conventional variety on par with Rex for Mississippi. I don’t have any milling data in from this year yet. But from everything I’m hearing in Mississippi, across the board the milling quality has been good.”

Nevertheless, at least one grower who planted Diamond had some blast issues and recommends putting it in fields without a blast history and where you can maintain water.

“I had mixed emotions about it,” says Korey Randleman, who farms in Greene County, Arkansas, along the St. Francis River. “I liked it all year long until the very end. I had three fields. Two fields were exceptional, and one field was my very worst.”

Even with what he described as a Cadillac fungicide treatment on all three fields, Randleman says the one on sandy ground had bad blast.

“I gave it every opportunity to do something great,” he says. “In places it did, in places it didn’t. But I know that as a producer, in the field that didn’t do well, I probably shouldn’t have planted it there. I’d tell other growers, ‘Just plant it where you don’t have a history of blast problems.’”

Good yield potential

Named after the Arkansas state gem, the Diamond long-grain variety is from the program of Dr. Karen Moldenhauer, a University of Arkansas rice breeder at the Rice Research and Extension Center in Stuttgart.

Diamond has the parentage of Francis and Roy J but with better yield potential and improved straw strength, Hardke says. LaKast, another University of Arkansas release, had significant lodging this season whereas Diamond did not.

Moldenhauer attributes Diamond’s standability to its Roy J parentage.

“Diamond can lodge, but it’s not bad for lodging,” Moldenhauer said. “But it’s not Roy J, which only lodges under extreme conditions like strong winds and rain.”

This was the first year Diamond was available for commercial production, occupying about 100,000 acres or 10 percent of Arkansas’ rice acreage, Hardke says.

In 2016, Diamond was only grown for seed production. The new variety has excellent grain quality with low chalk. It also has typical Southern long-grain cooking quality and average overall milling yields.

In three years of data from Arkansas Rice Performance Trials and Producer Rice Evaluation Program on-farm trials, Diamond had an average milling yield of 55-69 (head rice/total rice). During those three years, its grain yield ranged between 193 bushels and 209 bushels per acre, with a mean of 200 bushels per acre.

By comparison, LaKast had average milling yields of 55-70 and a mean grain yield of 189 bushels per acre.

Diamond and LaKast also are two of 11 University of Arkansas recommended long-grain cultivars for 2018.

Fertility recommendations

University of Arkansas Extension recommends a single pre-flood nitrogen application of 130 pounds per acre. For growers going with a two-way split, Extension recommends 105 pounds N pre-flood, followed by 45 pounds mid-season.

Early nitrogen applications should be increased by 30 pounds N per acre for clay soils and by 20 pounds N per acre for fields where rice follows rice.

Like many other Arkansas varieties, Diamond tends to be taller than varieties with semi-drawf lineage. Nevertheless, Hardke says, it does stand pretty well.

“But like anything, you can overfertilize it,” he says.

Golden says Diamond’s good straw strength is attractive to Mississippi producers as well.

“So far for us, it doesn’t tend to lodge as bad as LaKast, and that’s good because even if the yield is good, growers don’t like anything that tends to go down over here,” he says.

Golden had Diamond in his variety-by-nitrogen trials, where he applied nitrogen at various rates up to 240 units per acre. Even then, Diamond didn’t go down.

On the slightly heavier Mississippi soils, he says 180 pounds actual N should maximize yield potential.

An upright architecture

diamond rice variety
Diamond is from the breeding program of Dr. Karen Moldenhauer, with the University of Arkansas.

Diamond is susceptible to most rice diseases, except false smut, to which it is very susceptible, according to University of Arkansas ratings.

“My main overall concern is false smut, which we don’t have a lot of,” Hardke says. “We only get a minimum suppression from fungicides, so we strongly caution people from planting it in fields with a history of false smut.”

Depending on the year and growing environment, Diamond may have awns, something that surprised some Mississippi producers this season, Golden says.

The new variety also has an upright architecture, which is different than more robust Mississippi varieties, such as Rex or Thad.

“It’s a little more erect, a little more upright,” he says. “It’s not a big, bushy type variety that our growers are used to.”

That led some growers to be skeptical of Diamond’s yield potential until they put the combine in the field. Golden says they were pleasantly surprised.

“I’ve not had a single grower who said, ‘Why did you tell me to plant Diamond?’” he says. “But I’ve had more phone calls from growers who said, ‘Diamond did very well on my farm.’ It’s good to hear another conventional variety that performs as well as Rex and Thad in Mississippi to aid conventional producers by spreading out risk.”

Moldenhauer says the upright architecture dates back to her days as a graduate student in Iowa where the new highest-yielding corn hybrids had upright leaves. An upright architecture increases light penetration into the canopy and photosynthesis, which can boost yield potential. In rice, more upright plants also allow for better air movement and theoretically less disease, she says.

Another promising line

But Moldenhauer isn’t stopping at Diamond. She has another promising line in trials that could be released commercially as soon as 2021, providing everything goes well between now and then.

2017 was the first year the experimental variety was in statewide ARPT trials, and it topped 200 bushels per acre across the board. She had it at Stuttgart and Pine Tree in 2016.

“I think what really caught our eye with this variety is it has fairly good yield stability over all locations,” she says. “This is the first line I’ve had that yielded above 200 in all locations, even Pine Tree.”

The experimental line has Roy J as the mother and a mix of genetics, including Katy, Newbonnet, Wells and LaGrue, on the father’s side.

Breeder head rows are planned for 2018. If the experimental line continues to perform as it has, a foundation seed block is planned for 2019, with seed grower production in 2020.

Even if the new line falters along the way, Moldenhauer says she can use it in a future cross, so her time hasn’t been wasted.

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