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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

Variation in ecogeographical traits of pecan cultivars and provenances

Sagaram, Madhulika 15 May 2009 (has links)
Pecan [Carya illinoinensis (Wangenh.) C. Koch] is a species distributed over an area of varied geographic and climatic variation in the Unites States and Mexico providing a potential for anatomical and physiological adaptation within the cultivars and provenances (i.e., the area of origin of seed). An assessment of leaf anatomical traits of pecan cultivars (Pawnee, Mohawk and Starking Hardy Giant) collected from three locations (Tifton, GA., Chetopa, KS., and Stillwater, OK.) was conducted to provide an understanding of patterns of ecogeographic variation within the natural range. The stomatal density 'Pawnee’ (404 stomata/mm2) was intermediate between that of ‘Mohawk’ (363 stomata/mm2) and ‘Starking Hardy Giant’ (463 stomata/mm2). There were differences among the three pecan cultivars at the same location but there were no differences in stomatal density within the same cultivar grown at three distinct locations. The study suggested that differences in stomatal density in pecans are cultivar-specific rather than being determined by environmental factors. The stability of certain leaf anatomical characteristics, such as stomatal density, for pecan cultivars grown at different locations confirms that these traits can be used for screening provenances with desirable leaf anatomical characteristics for breeding and cultivar development. To achieve the objective of studying anatomical, morphological and physiological traits, Mexican and U.S. provenances grown at the Pecan Genetics and Breeding Program facility in Somerville, Texas were used. The prominent results from the provenance study indicate the presence of intra-specific variation in pecan provenances for the morphological and anatomical traits along the east-west gradient. It is also interesting to note that western provenances displayed the least stomatal density (350 stomata/mm2) while an eastern provenance showed the greatest stomatal density (728 stomata/mm2). This trend may be explained with the gradient in moisture availability from the wetter conditions in the east to the arid conditions in the west in North America. Most of the physiological traits measured did not show any distinct differences between the provenances. There is a great possibility that anatomical traits like stomatal density are genetically controlled to a great extent in pecan in comparison to the physiological traits.
2

Variation in ecogeographical traits of pecan cultivars and provenances

Sagaram, Madhulika 15 May 2009 (has links)
Pecan [Carya illinoinensis (Wangenh.) C. Koch] is a species distributed over an area of varied geographic and climatic variation in the Unites States and Mexico providing a potential for anatomical and physiological adaptation within the cultivars and provenances (i.e., the area of origin of seed). An assessment of leaf anatomical traits of pecan cultivars (Pawnee, Mohawk and Starking Hardy Giant) collected from three locations (Tifton, GA., Chetopa, KS., and Stillwater, OK.) was conducted to provide an understanding of patterns of ecogeographic variation within the natural range. The stomatal density 'Pawnee’ (404 stomata/mm2) was intermediate between that of ‘Mohawk’ (363 stomata/mm2) and ‘Starking Hardy Giant’ (463 stomata/mm2). There were differences among the three pecan cultivars at the same location but there were no differences in stomatal density within the same cultivar grown at three distinct locations. The study suggested that differences in stomatal density in pecans are cultivar-specific rather than being determined by environmental factors. The stability of certain leaf anatomical characteristics, such as stomatal density, for pecan cultivars grown at different locations confirms that these traits can be used for screening provenances with desirable leaf anatomical characteristics for breeding and cultivar development. To achieve the objective of studying anatomical, morphological and physiological traits, Mexican and U.S. provenances grown at the Pecan Genetics and Breeding Program facility in Somerville, Texas were used. The prominent results from the provenance study indicate the presence of intra-specific variation in pecan provenances for the morphological and anatomical traits along the east-west gradient. It is also interesting to note that western provenances displayed the least stomatal density (350 stomata/mm2) while an eastern provenance showed the greatest stomatal density (728 stomata/mm2). This trend may be explained with the gradient in moisture availability from the wetter conditions in the east to the arid conditions in the west in North America. Most of the physiological traits measured did not show any distinct differences between the provenances. There is a great possibility that anatomical traits like stomatal density are genetically controlled to a great extent in pecan in comparison to the physiological traits.
3

Ekonomi eller politiska beslut : Vad styr fristående gymnasieskolors lokalisering?

Dahlén, Ewa January 2012 (has links)
In the beginning of the 1990s the responsibility for the schools shifted from the government to the local authorities. This started an era with a freedom of choice for students where they themselves could choose which school to go to. The new system also opened up the possibility for independent private schools to exist side by side with local authority held schools. The overall aim of this study is to determine the factors that affect the location of these independent schools and the geographical pattern these independent schools create. The study in this paper is based on materials from statistics and interviews. The statistics is from SCB (Statistics Sweden), Skolverket (a government agency that work for the Ministry of Education) and Skolinspektionen (a government agency that supervises that schools follow laws and regulations) and the interviews are with principals and owners of independent schools and representatives from Skolverket, Skolinspektionen and Friskolornas riksförbund (The national association for independent schools). Since the 1990s the independent schools have become nearly as many as the local authority held schools, but are concentrated to 41 percent of Sweden’s municipalities. When comparing this to the local authority held schools that are in 96 percent of Sweden’s municipalities means that the independent schools are in high numbers in a few municipalities. The study shows a geographical pattern of independent schools mainly in large cities. In this paper I examine if the concentration of independent schools in a small part of Sweden’s municipalities is due to political reasons or economical reasons. In conclusion the study indicates that economical factors is the main reasons for their geographical location. The main reasons for locating in urban areas are based on the number of students, diversity, opportunity, and the closeness to universities but also the closeness to entertainment as cafés.

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