Title page for ETD etd-04042007-213813


Type of Document Master's Thesis
Author Robertson, Clark Lane
Author's Email Address crobe13@lsu.edu
URN etd-04042007-213813
Title Pathology and Seedling Nutrition of Spartina alterniflora (Smooth Cordgrass)
Degree Master of Science (M.S.)
Department Plant Pathology & Crop Physiology
Advisory Committee
Advisor Name Title
Raymond W Schneider Committee Chair
Irv Mendelsshon Committee Member
Marc A Cohn Committee Member
Stephen A Harrison Committee Member
Keywords
  • stalled seedling growth
  • coastal restoration
  • coastal marshgrass
Date of Defense 2007-03-21
Availability unrestricted
Abstract
Transplants of Spartina alterniflora Loisel. (smooth cordgrass, Poaceae) are effective in stabilizing and protecting vulnerable coastal wetlands from erosion. However, the expense and labor associated with propagation and transplanting restrict the widespread use of S. alterniflora in coastal restoration and protection projects. As an alternative, seeding of S. alterniflora by aircraft has been proposed as a more useful and economical approach for revegetating denuded marsh sites. However, a period of stalled growth, which lasts for 12 or more weeks, has been observed in smooth cordgrass seedlings, and this increases their susceptibility to being washed away by inundating tides. This stalled growth period must be overcome before aerial seeding can be implemented.

As with any plant species, it is reasonable to assume that S. alterniflora has optimal nutritional requirements for seedling and mature plant growth. Previous nutritional research has involved only mature smooth cordgrass plants. These studies showed that applications of nitrogen and phosphorus fertilizers increased plant growth. The objectives of this study were to document the lag phase of seedling growth observed in field and greenhouse conditions; determine the possible role of soil microbes, including seed and seedling pathogens and mycorrhizal fungi, as a cause of delayed seedling growth; and investigate the role of nutrition in seedling growth.

This study confirmed the existence of stalled seedling growth in S. alterniflora and concluded that pathogens are not the cause of this lag period. Furthermore, supplemental N and P (240 kg N ha-1, 49.5 kg P ha-1) reduced the lag phase from over 100 days to less than 50 days under ideal greenhouse conditions. However, nutrient additions did not completely overcome stalled seedling growth. Future research possibilities include investigating the effects of plant growth regulators (hormones) and seed preconditioning treatments on seedling growth.

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