Cut seeding rate, maintain yields

Growers attending the Delta Research and Extension Center's Rice/Soybean Field Day received a generous dose of traditional production advice, but with transgenic rice varieties and hybrids gaining popularity in Mississippi, they also got cutting edge, research-based advice for the new technology options.

One such advance is the Clearfield technology, planted on about 25 percent of the state's rice acreage. Tim Walker, DREC agronomist and researcher, says growers have two seed options with Clearfield rice.

“CL-161 is the variety currently grown and Clearfield XL8 is a hybrid tolerant to the Newpath herbicide,” says Walker. “In side-by-side comparisons across various soil types during the past three years, Clearfield XL8 yielded 213 bushels per acre and CL-161 yielded 186 bushels an acre.”

In verification trials, Clearfield XL8 produced 58 percent whole grains, and CL-161 produced 61 percent whole grains.

“Both products offer opportunities to produce above average yields while decreasing problems associated with red rice,” says Walker.

In other efforts on behalf of rice producers, Walker and Jay Barnett, research associate, are attempting to draw conclusive information from their research to determine if growers can cut seeding rates and still expect top yields.

“As seed costs increase, which will be the case as more technology is carried within or on the seed, optimum seeding rates for best yields and agronomic performance are critical,” says Walker. “Seeding rate are being evaluated on five of the most popular rice varieties grown in Mississippi.”

He reports that in each of the varieties — Cheniere, Cocodrie, Francis, Priscilla and Wells — exceptional yields are being achieved with as few as 40 pounds of seed per acre, about one-half of the seed usually planted in a production field.

“Lower seeding rates increased the standability of Francis in 2003 without sacrificing yields,” says Walker. “In years when environmental conditions are conducive for sheath blight, thinner stands increase airflow through the rice canopy and can decrease sheath blight pressure.”

Walker is continuing research into nitrogen use and replacement on rice fields and fields in rotation with other crops and on the use of foliar fungicides.

“To maximize rice yields with the varieties and hybrids grown in Mississippi, sufficient nitrogen has to be supplied to the plant in the early vegetative stages of growth,” says Walker. “This increases tillering, an important yield component. Nitrogen fertility studies indicate at least two-thirds of the total nitrogen should be applied to dry soil prior to establishing a permanent flood for most semi-dwarf varieties.”

In recent years, more growers have included foliar fungicides in rice programs. “Because weather conditions were conducive for sheath blight on susceptible rice varieties in 2004, a large amount of acreage was treated with a foliar fungicide,” he says. “As a means of determining the effectiveness of a preventive foliar fungicide application, a large field study is being conducted on a sheath blight-susceptible variety. Quadris, Quilt, Stratego and Moncut were applied at labeled rates two weeks after panicle differentiation.”

Walker says yield monitor data from the trials will be correlated to the various treatments, and an economic analysis will determine the cost effectiveness of foliar fungicides as preventive applications. That information will be released to growers as soon after harvest as possible.

Eva Ann Dorris is an ag journalist from Pontotoc, Miss. She can be reached at 662-419-9176 or [email protected].

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