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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Candidate halophytic grasses for addressing land degradation: Shoot responses of Sporobolus airoides and Paspalum vaginatum to weekly increasing NaCl concentration

Pessarakli, Mohammad, Breshears, David D., Walworth, James, Field, Jason P., Law, Darin J. 28 February 2017 (has links)
In many arid and semiarid regions worldwide, high levels of soil salinity is a key driver of land degradation, as well as a key impediment to re-establishing plant cover. Combating land degradation and erosion associated with soil salinity requires experimental determination of plant species that can grow in soils with high levels of salinity and can be used to re-establish plant cover. Herein, we evaluated the responses of untested candidate cultivars of two halophytic grass species to high soil salinity: alkali sacaton (Sporobolus airoides Torr.) and seashore paspalum (Paspalum vaginatum Swartz). We evaluated the growth responses of both species in a greenhouse under control (no-salt) and various levels of NaCl salinity (EC 8, 16, 24, 32, 40, and 48dSm(-1)) using Hoagland solution in a hydroponics system in a randomized complete block design trial. At all salinity levels, sacaton grass had a greater shoot height, shorter root length, lower shoot fresh and dry weights, and poorer color and general quality compared to seashore paspalum. The shoot fresh and dry weights of both grasses were greatest at the low to medium levels of salinity, with the greatest response observed at EC 16dSm(-1). At the highest level, salinity significantly reduced shoot fresh and dry weights of both grasses. Because growth of both halophytic species exhibited high tolerance to salinity stress and were stimulated under low to medium levels of salinity, both species could be considered suitable candidates for re-establishing plant cover in drylands to combat desertification and land degradation associated with high levels of soil salinity.
2

Investigating Cold Hardiness and Management Practices of Warm-season Putting Green Species in the Transition Zone

Kauffman, John M 01 August 2010 (has links)
Warm-season turf species are becoming increasingly popular for putting green use in the transition zone. Ultradwarf bermudagrass (Cynodon dactylon (L.)  C. transvaalensis Burtt-Davy) is the prevalent warm-season putting green species, but seashore paspalum (Paspalum vaginatum Swartz) and ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.] may also be grown in the transition zone. Warm-season species are susceptible to winter injury and may require different management regimes than cool-season species. Therefore, the objectives of this research were to assess the impacts of various management practices on warm-season putting green species and characterize the physiological basis for differences in freeze tolerance of various warm-season putting green species. Field studies determined sampling procedures form thatch-mat depth and soil organic matter content of warm-season putting greens and assessed the impact of various management practices on different warm-season putting green species/varieties. The relative freeze tolerance of ‘Champion’ and ‘TifEagle’ ultradwarf bermudagrass cultivars, ‘SeaDwarf’ seashore paspalum, and Diamond zoysiagrass were determined, along with the accumulation of proline and polyamines during cold acclimation, in growth chamber studies. All species/varieties required different sampling numbers for determination of thatch-mat depth and soil organic matter. More sand was incorporated into the turf canopy and surface hardness was increased with brushing and vibratory rolling TifEagle putting greens after sand topdressing application than either treatment alone. Putting green management programs with lower mowing heights and increased mowing frequencies increased ball roll distance on a MiniVerde putting green without negatively affecting turf quality. Weekly vertical mowing + daily grooming on TifEagle reduced thatch depth and turfgrass quality, while increasing topdressing incorporation over either treatment alone. Diamond was the most freeze tolerant species/variety, followed by TifEagle, Champion, then SeaDwarf. Cold acclimation increased proline concentration for all species/varieties except SeaDwarf, but had inconsistent effects on polyamines. Spermidine and putrescine concentrations differed with species/variety, but were not correlated to freeze tolerance.

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