Browsing by Subject "Seeds"
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Item Controlling seal formation and improving seedling emergence using polyacrylamide polymers(Texas Tech University, 1997-05) Perkins, Clinton ToddSoils from arid and semiairid regions are often structurally unstable and seal. This surface sealing phenomenon negatively effects many components of the soil-plant system, thereby limiting crop production. Delayed or erratic plant emergence are direct effects of the surface sealing and subsequent crusting phase of the soU. Increased water runoff loss, decreased water infiltration, and enhanced wind erosion are all negative indirect effects of surface seals. Since the 1980's, there has been renewed interest in the use of water soluble polymers for enhancing soil physical properties. Several factors contributing to this use are more efficient application strategies, availability of inexpensive and, more effective polymers. Better understanding of the beneficial effects of using polymers on surface sealing (increased infiltration and reduced surface strength and hardening) and on the emergence and development of various crops will make crop growing more economical and profitable in soils susceptible to seal formation. Subsequently, farmers (especially from the Southern High Plains of Texas) will benefit from a wider range of crops that they could grow and thus improve productivity and profits. This project investigated polymer addition to the soil surface to (i) decrease soil sealing and (ii) enhance seedling emergence. Polymers of differing charges and molecular weight were sprayed on the soil surface at several rates.Item Humble alchemy(2014-05) White, Shalena Bethany; Williams, Jeff, M.F.A.This master's report addresses the conceptual and material investigations that were explored within my artistic research made at the University of Texas at Austin between 2011 and 2014. These works are a confluence of adornment, sculpture and installation art. These pieces incorporate ancient and contemporary metalworking techniques with raw, organic material. The notion of elegant ornamentation is expanded beyond the body into the adornment of architecture. The potential for transformation and reinvention within found elements is explored within this work. The natural resources I work with have gone through a cycle, which is interrupted when the objects are removed from the earth. I see my process in relationship to alchemical concepts of transmutation. Through manipulation, common matter evolves into precious material. The refined, meticulous craftsmanship conveys a sense of reverence and honor towards the common material. This intervention with the material is an act of preservation and veneration. This work explores my sense of intrigue about the extraordinary potential of mundane materials, and investigates conventional notions of material value.Item Plant community dynamics governed by red harvester ant (Pogonomyrmex barbatus) activities and their role as drought refugia in a semi-arid savanna(Texas A&M University, 2005-11-01) Nicolai, Nancy CarolThis study examined modifications made by Pogonomyrmex barbatus, by their processes of granivory and nest construction, to forb and grass dynamics under large-scale disturbances of fire, recent drought and long-term, large-mammalian herbivory using comparative studies, field experimental manipulations, and a simulation model on the Edwards Plateau, Texas. Ant nests are refugia for grass survival during extreme droughts as demonstrated during the drought of 1998 to 2002. Significantly greater cover of grasses and lower abundance and cover of forbs was found beside nests compared with surrounding habitat throughout the drought and recovery. Grasses near nests may be the seed source for surrounding habitats during recovery. Seeds were differentially collected among most forbs and grasses despite seed abundance. Harvest was significantly reduced in the fall relative to spring. During preference experiments, harvest differences were found between grazing treatments for two of four species, but only during the spring. High lipid content seeds were unpreferred in fall compared to high protein and carbohydrate content seeds. Granivory influences on seedling establishment were studied by comparing seedling recruitment among sown and naturally occurring seeds excluded and open to foragers. Exclosures were placed in three nest densities and two burn treatments. Seeds in exclosures produced significantly more seedlings than open arenas only during the first year of drought recovery. Densities of grasses and annual forbs were higher in open arenas the second year due to indirect effects of granivory. By reducing seeds ants release seedlings from competition. Sown seedling abundance was unaffected by colony density and fire. Colony density and distribution were influenced by topography, soil types, soil depth and woody cover, but not by historical grazing treatments. Cleared vegetation on nest disks impacted less than 1% of total surface area and losses were compensated by greater basal cover of grasses next to disks compared to surrounding habitats. Foraging areas influenced 17.3-73.6% of surface area and could diminish seed populations for potential seedlings. Model results agree with experimental observations that communities may be modified by P. barbatus presence due to differential responses of grass species to interaction between nests or granivory and rainfall amounts.Item The Effects of Certain Plant Growth Stimulants as Seed Treatments on the Germination and Yield of Cotton and a Grain Sorghum(Texas Tech University, 1944-07) Ayres, Cecil INot Available.