Arkansas Rice Expo shows N tests and more
Field trials of NST*R in farmers' fields have verified that the site-specific nitrogen rates recommended provide optimum yields and that they frequently vary significantly from the rates a farmer would have otherwise applied, Roberts said.
Richard Norman, professor of soil fertility, who has worked on the project for some 20 years, said nitrogen exists in many organic forms in a constant state of change in the soil. The amount actually available to plants has been hard to pin down.
Norman credits Roberts, who was his graduate student, with helping to solve the chemistry puzzle by identifying measurable soil nitrogen fractions that reliably predict the amount of soil nitrogen available to plants.
Karen Moldenhauer, who directs the Division of Agriculture's rice breeding program, said a very promising long-grain rice breeding line is about two years from possible release as a new variety. So far, breeding line 142-AR has produced very high yields and matures a week earlier than current high-yielding varieties.
The breeding line appears to have a high level of resistance to bacterial panicle blight, which was a major disease problem in 2010 and may be again in 2011. "We are very excited about that," Moldenhauer said.
Yeshi Wamishe, a new assistant professor of plant pathology based at the rice center, said her first priority is identifying sources of genetic resistance to bacterial panicle blight.
"This bacteria thrives in heat," Wamishe said. The disease is likely to occur at an "epidemic" level again this year if excessive heat conditions persist, said Richard Cartwright, former extension plant pathologist and now associate director for agriculture and natural resources in the Cooperative Extension Service.
Genetic resistance is the best way to manage this and other bacterial plant diseases, Wamishe said. She said her research is focused on identifying "durable" resistance through a combination of genes that can be bred into future varieties.
Bob Scott, a weed scientist based at the Lonoke Extension and Research Center, said a comprehensive rotation study is underway to help producers avoid creating herbicide-resistant populations of the red rice weed.
Clearfield rice plants are resistant to Newpath herbicide, which kills red rice and other weeds. Clearfield varieties are currently planted on 60 to 70 of the Arkansas acreage, Scott said.
"We do see a build-up of red rice in continuous Clearfield plots," Scott said, which means red rice weeds develop resistance to Newpath herbicide when exposed to it year after year.
Red rice infestation is 80 to 90 percent lower in test plots where Clearfield rice is rotated with either Liberty Link or Roundup Ready soybeans and in plots left fallow for a year and treated to prevent red rice germination, Scott said.
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