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| Bitter panicum is one of the plants used in coastal restoration projects. (Photo by Michael Materne) |
In an effort to stem the relentless erosion of Louisiana's coastal wetlands, researchers at the LSU AgCenter are applying proven plant breeding and genetic techniques to improve native marsh plants that can withstand the troublesome coastal environment.
Coastal restoration is important for Louisiana. Although the state boasts 15,000 miles of shoreline and 40 percent of the nation's wetlands, it also loses an average of one acre of marsh lands every 20 minutes.
Coastal marshes protect against storms and provide important biological diversity.
AgCenter researchers are trying to reverse the land loss by planting Spartina alterniflora, also called smooth cordgrass.
Vegetation helps build marshes. Plants growing in the water trap sediment and cause it to settle and accumulate. A single Spartina plant, for example, will grow to cover a 10-foot circle in one year.
"Spartina seems to be the most obvious species to deal with. It's very adaptable and very productive," said Stephen Harrison, a plant breeder with the School of Plant, Environmental and Soil Sciences.
The marsh plant tolerates a complete range of salinity from seawater to fresh water, and it can withstand water depths to about 1 foot.
"Plants are needed to establish permanent protection of coastlines and canal banks to stop and even reverse erosion," Harrison said. "Our task is to improve plant species to allow commercialization of marsh re-vegetation on a large scale. We're helping the system establish equilibrium."
A vigorously growing perennial grass that tolerates a wide range of conditions, Spartina can be planted in shallow water just off the shoreline to slow down wave action and trap sediments suspended in the water.
"Spartina can catch soil and hold it as well as generate new organic matter from decomposition," Harrison said.
One of the Spartina's drawbacks is its inability to produce large quantities of viable seed.
"Over time Spartina has been adapted to vegetative reproduction," Harrison said. "Because it propagates primarily through shoots, it doesn't produce a lot of seed."
Early work with Spartina included producing plants using biotechnology cloning techniques. Resear
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| Spartina seedlings growing in an LSU AgCenter greenhouse. (Photo by Prasanta Subudhi) |
chers use tissue culture to produce large numbers of plants--some for transplant and some encapsulated in a protective gel as artificial seeds.
"We're working with applied, proven plant-breeding techniques to further develop a plant that can be propagated by seed rather than vegetatively," Harrison said. "We need to develop the ability to produce seed en masse so seed companies can produce and market seed for coastal preservation and restoration."
The researcher's goal is to develop a nursery collection of promising material to develop varieties that could be planted by seed and meet the requirements of coastal restoration.
Because Spartina suffers from disease and pest problems, AgCenter researchers are working with the plant the same way they would work with wheat or pasture grasses.
"There also are seed dormancy questions that need to be addressed," Harrison said. "We want to develop the ability to harvest seeds and store them dry and be able to spread seed, perhaps by air, and have seeds germinate and develop plants."
Based on experience with rice production, air seeding can plant an acre in 8 seconds, achieving an equivalent planting rate with transplants would require 20,000 hours of labor.
Researchers are looking at other grass species that also have potential for controlling wetlands erosion. These include black mangrove (Avicennia germinans), marshhay cordgrass (Spartina patens), salt grass (Distichlis |
| Researchers are working with sea oats, a plant well-adapted to holding onto the coast. (Photo by Prasanta Subudhi) |
spicata), big cordgrass (Spartina cynosuroides), California bulrush (Schoenoplectus californicus), seashore paspalum (Paspalum vaginatum), bitter panicum (Panicum amarum), sea oats (Uniola paniculata) and several woody plant species occupy different niches in marsh environments depending on salinity, elevation and other factors.
"This is a comprehensive, multidisciplinary approach to addressing a problem that's important for the people of the state of Louisiana as well as the entire United States," said David J. Boethel, vice chancellor for research and director of the Louisiana Agricultural Experiment Station. "It's not just an agricultural problem and not just a coastal problem. This program will provide protection for all the state and stem the loss of land."
(Updated March 23, 2007, by Linda Benedict)