Frances Gould | 1/17/2014 10:29:39 PM
LSU AgCenter agronomist Dr. Dustin Harrell is participating in a multistate study on arsenic in rice to determine if levels of the element are higher in different varieties and to see if various flooding methods affect arsenic content.
"Can we change the water management practices to alter the uptake and accumulation of arsenic in rice? That’s what we are investigating," said the LSU AgCenter scientist based at its Rice Research Station.
All plants naturally absorb arsenic from the soil, but rice tends to absorb more because it is growing in flooded, anaerobic conditions, and that make arsenic more available for uptake by the plant, Harrell explained.
The different flooding regimes being used include:
Traditional drill-seeded, delayed-flood management practices, where a flood is applied after the rice reaches the three- to four-leaf stage of development and is left until two weeks before harvest.
Intermittent flooding, where the initial flood is held for two to three weeks and then allowed to evaporate until mud is exposed, followed by pumping water to a 2- to 4-inch depth.
Semiaerobic rice management, where flushing is conducted regularly, but aerobic conditions are allowed to persist.
Straighthead management, where the rice is flooded for 10 days to two weeks, followed by draining until the soil cracks and then flooding again until it is drained for harvest.
The testing is being conducted in all rice-growing states, including Texas, California, Mississippi, Arkansas, Missouri and Louisiana.
Harrell said the flooding practices that allow the field to drain typically will require more weed management, which will increase herbicide expenses, increase disease pressure and reduce grain yield.
Varieties being tested are CL151, Cheniere, Presidio and Jupiter, along with hybrids CLXL729 and CLXL745.
Harrell said all rice samples will be milled at the Rice Research Station and then sent to a lab for determining inorganic and organic arsenic content. He said results should be available by spring 2014.
The FDA recently reported the results of testing and concluded there are no health issues associated with arsenic in rice and rice products.
"This study is simply long-term research to allow Louisiana rice producers to produce the safest, most nutritious rice available for our customers," said Dr. Steve Linscombe, director Rice Research Station.
This article was published in the 2014 Louisiana Rice Research Board Annual Report.