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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.
61

Seedling age relationships of sugar maple, Acer saccharum Marsh

Hett, Joan Margaret, January 1967 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
62

Localization of Expansin Expression During Adventitious and Lateral Rooting in Response to Auxin in Loblolly Pine

Xu, Fuyu January 2002 (has links) (PDF)
No description available.
63

Effects of site preparation in interior plateau clearcuts on the soil water regime and the water relations of conifer seedlings

Fleming, Robert LeSueur January 1993 (has links)
Site preparation effects on growing season soil water regimes were investigated on three clearcut, grass-dominated sites in the Interior Douglas-fir (IDFdk), Montane Spruce (MSxk) and Engelmann spruce-Subalpine fir (ESSFxc) Biogeoclimatic Subzones, near Kamloops, British Columbia. The response of newly planted Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and lodgepole pine (Pinus contorta Dougl.) to these treatments was determined at the IDFdk site. Soil water regimes were measured in scalped, ripped and herbicide site preparation treatments and in an untreated control using a neutron moisture meter, a two-probe gamma-density gauge, tensiometers and thermocouple psychrometers. At the IDFdk, seedlings were spring planted in each of the treatments and control to determine whether microclimate modification by site preparation would improve seedling water relations, growth and survival during the first growing season. Root zone soil water content was most limited at the low-elevation site (IDFdk) and least limited at the high-elevation site (ESSFxc). The different site preparation treatments provided similar increases in root zone soil water content, profile water storage and drainage at each site. This resulted in substantial increases in soil water supply at the lowest two sites. Site preparation resulted in increased Douglas-fir and lodgepole pine stomatal conductance (gs), transpiration (E), leaf area, root egress, root collar basal area and dry matter production. Survival of both species was high in the control and in all site preparation treatments. Both species had similar seasonal patterns of gs and E in the control. In the site preparation treatments, lodgepole pine had greater gs, and by late summer, greater E than Douglas-fir. Although lodgepole pine had substantially higher twig xylem pressure potentials and lower soil-plant liquid flow resistances than Douglas-fir, both species appeared well adapted to survive drought. First growing season stomatal responses of both species to environmental conditions, including normalized vapor pressure deficit at seedling height (Ds/P), solar irradiance (Rs) and root zone extractable water (Φe), were similar when normalized against annual maximum conductance (gsmax ). A multiplicative model with non-linear least squares optimization (NLLS) of response functions to Rs, Ds/P and Φe provided a simple, reasonably accurate description of gs/gsmax for both species, and accounted for differences in gs between the control and ripped treatment. In most cases, the NLLS models developed for a given species and year resulted in relatively precise (R²>0.60) and unbiased estimates of gs /gsmax, and yielded estimates of mean daily stomatal conductance (Gs ) and total daily transpiration (T) within 20% of measured values, for the same species in other years. / Land and Food Systems, Faculty of / Graduate
64

Resistance to water uptake by conifer seedlings

Dosskey, Michael Gordon January 1978 (has links)
Water availability for uptake by tree seedlings is determined both by the soil water potential in relation to seedling needle water potential and by the resistance to flow of water through the soil, root and stem, to the needles. This study was designed to focus principally on water uptake resistances. The effects of soil texture and tree species on this water uptake resistance were quantified through the use of an Ohm's Law model suited to water flow through the soil-plant system. The study was conducted on one-year-old potted seedlings in a controlled environment growth chamber. Needle water potential (ΨN) of Douglas-fir is not much affected by soil water potential (Ψs) down to about -2.5 MPa, where the calculated water uptake rate becomes very small. However, soil texture does significantly affect the resistance to flow into the seedling and thus affects the water uptake rate by the seedling. The total resistance to water uptake increases as the soil dries. Coarser textured soils show consistently higher water uptake resistances over the soil water potential range -0.5 to -2.5 MPa. It is inferred that differences in resistance are associated with unsaturated, hydraulic conductivity characteristics of the soil and soil-root contact. Unlike Douglas-fir, both western and mountain hemlock show a large decrease in needle water potential as the soil dries down to a Ψs of about -3.0 MPa. The water potential difference (Ψs - ΨN) for hemlocks is less where Ψs is higher than -1.8 MPa, and greater where Ψs is less than -1.8 MPa, than (Ψs - ΨN ) for Douglas-fir in these s s N experiments. Despite these differences, the resistance to water uptake for both hemlock species is much greater over the soil water potential range -0.5 to -2.5 MPa, and thus the water uptake rates are much less than for Douglas-fir with the same soil, even though root densities and root surface areas are much larger for the hemlocks. This behavior is most pronounced with mountain hemlock. These differences are thought to be related to higher tissue and (perhaps) soil-root contact resistances in the hemlock species. The soil resistance appears to be small, at least down to Ψs of about -2.0 MPa, in these experiments. However, root densities are probably much greater than one might expect in the field. / Forestry, Faculty of / Graduate
65

Survival and growth of three oak planting stocks on Hurricane Katrina disturbed lands

Hollis, Damon 06 August 2011 (has links)
Three types of oak planting stock were evaluated to determine their influence on survival and initial growth. Planting stocks utilized include conventional containerized seedlings with a 240 cm3 container, 1-0, bare-root seedlings, and Root Production Method (RPM™) seedlings with a 11.4 L container. Initially after outplanting and at the conclusion of the first and second growing seasons, height, groundline diameter (GLD), and survival were assessed. Study sites are located in southern Mississippi on lands disturbed by Hurricane Katrina. Species planted were swamp chestnut oak (Quercus michauxii Nutt.) and Nuttall oak (Q. texana Palmer). A total of 3,600 seedlings were planted in this study: 300 seedlings for each of the six planting stock/species combinations per site. Statistical comparisons of growth and survival among species and planting stock types were performed. RPM™ and bare-root planting stocks exhibited similar growth and survival, while the conventional container stock had significantly lower growth and survival.
66

Modeling of bending stresses generated in soil crusts by emerging seedlings /

Hanegreefs, Paul R. January 1985 (has links)
No description available.
67

Effects of soil amendments on crusting, seedling emergence and yield of onion, tomatoes and peppers.

Yacoub, Mohamed Mohamed. January 1991 (has links)
The effects of sulfur-containing amendments (H₂SO₄,Al₂(SO₄)₃ and gypsum) or crust formation, soil chemical properties, seedling emergence and yields of onions (Allium cepa), tomatoes (Lycopersicum esculentum) and chili peppers (Capsicum sp.) were studied on a Pima clay loam soil. Treatments were surface applied on a strip above the seeds. The chemicals influenced the penetrometer index, soil-pH, electrical conductivity, DPTA-extractable soil Fe, Cu, Zn, Mu and seedling emergence in two greenhouse experiments. Gypsum and H₂SO₄ increased seedling emergence while Al₂(SO₄)₃ reduced the soil-pH and EC more than H₂SO₄ and gypsum. Based upon penetrometer readings, H₂SO₄ was the best anti-crusting agent tested followed by gypsum and Al₂(SO₄)₃. At the end of the study, all soil samples were very low in KCl extractable Al, showing that Al toxicity was not responsible for seedling damage. Gypsum decreased levels of Mn and Zn but did not affect Fe and Cu. Al₂(SO₄)₃ increased Fe and Zn, decreased Cu but did not affect Mn. H₂SO₄ did not affect extractable Mn, Cu, Zn and Fe levels. In a field study using two water qualities at Safford, gypsum produced the most tomato seedlings whereas Al₂(SO₄)₃ and H₂SO₄ produced the least. Onion stand counts were not affected by the chemicals with either water. Gypsum, H₂SO₄ and Al₂(SO₄)₃ polymer produced the highest pepper stand counts with the saltier water but there were no differences with lower salt water. Tomatoes produced the highest yield with gypsum and lowest with H₂SO₄ and Al₂(SO₄)₃ with saltier water. With lower salt water, gypsum produced highest yield, followed by the H₂SO₄. Both H₂SO₄ treatments produce low yields. Onions showed no treatment response under lower salt water, while with saltier water, gypsum and H₂SO₄ produced the highest yields. Pepper yields were not affected by amendments with the lower salt water. Al₂(SO₄)₃ polymer, H₂SO₄ and gypsum increased yields with the saltier water. Varieties of peppers and tomatoes produced different yields in response to water quality in a supplementary field study.
68

Assessing Two Year Growth and Survival of Two Oak Species and Three Planting Stocks on Hurricane Katrina Damaged Land

Hall, Andrew Taylor 06 May 2017 (has links)
Hurricane Katrina made landfall in 2005 damaging 1.2 billion cubic meters of timber including 48 million cubic meters of hardwood. An economically efficient method of artificial oak regeneration is necessary in many areas to restore this high value resource. Bareroot, conventional containerized, and EKOgrown® seedlings of Quercus shumardii and Q. texana were planted on two sites in south Mississippi. Growth and survival were evaluated for two years. Survival was assessed monthly and at the end of each growing season. Height and groundline diameter were assessed initially after planting and the end of each growing season. After two growing seasons, Q. Nuttallii exhibited superior performance generally when compared to Q. Shumardii. Conventional containerized had poor survival and initial growth likely caused by freeze damage in the nursery. EKOgrown® seedlings performed better than other planting stocks, however, high seedling cost makes them less cost-effective than bareroot seedlings which exhibited acceptable performance overall.
69

Assessing the Early Growth Performance and Survival of Two Oak Species and Three Planting Stocks on Hurricane Katrina Damaged Land

Miles, Charles Holden 03 May 2019 (has links)
Hurricane Katrina had a devastating impact on bottomland hardwood forests in 2005 resulting in damage to nearly 1.2 billion cubic meters of timber. Following such a natural disaster, natural regeneration is typically not a viable option because the seed source has been destroyed on site. Therefore, an economically efficient method of artificial regeneration is considered the most appropriate technique for reforesting these damaged areas. However, few studies have evaluated comparative research that examined early survival and growth performance of various oak species and stock types in such planting settings. This project was implemented in an effort to expand upon what is already known from previous artificial regeneration attempts on Hurricane Katrina damaged lands. Bareroot, conventional containerized, and large potted EKOgrownTM seedlings of cherrybark oak (Quercus pagoda Raf.) and willow oak (Quercus phellos L.) were planted on two sites located in south Mississippi. Survival was assessed monthly and at the end of each growing season, whereas height and groundline diameter (GLD) were measured immediately post planting and at the end of each growing season. Analysis of variance (ANOVA) and Tukey-Kramer multiple comparisons procedure (MCP), where appropriate, were performed to determine any significant differences. After the first growing season, cherrybark oak did not exhibit a substantial difference regarding survival performance when compared to willow oak (75.5 percent and 76.5 percent, respectively). After two growing seasons, willow oak exhibited considerably greater survival (74.0 percent) overall when compared to cherrybark oak (70.5 percent). Bareroot seedlings had the highest survival (87.2 percent). Conventional containerized seedlings had unacceptable survival (47.5 percent) and EKOgrownTM seedlings had acceptable survival (82.0 percent). EKOgrownTM seedlings demonstrated the best overall GLD growth of all planting stocks (3.9 mm respectively). Bareroot seedlings had the second best overall GLD growth (1.5 mm) and conventional containerized had the least amount of overall GLD growth (0.8 mm). Overall height growth when comparing all three planting stocks bareroot, conventional containerized, and EKOgrownTM were similar to one another (-3.5cm, -0.8cm, and -3.6cm respectively). Therefore, based on an overall consideration of cost and performance, bareroot seedlings are considered the most effective option of the two species considered for artificial regeneration utilized in this study.
70

THE MECHANISM OF ACTION OF FLUAZIFOP-BUTYL, HALOXYFOP-METHYL, AND SETHOXYDIM HERBICIDES ON WHEAT (TRITICUM AESTIVUM L.) SEEDLINGS (CHLOROPLAST DEVELOPMENT).

SATTI, MOHAMED AHMED EISA. January 1985 (has links)
Haloxyfop-methyl 2-[4-[ [3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoate, fluazifop-butyl (±)-2-[4-[ [5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoate, and sethoxydim 2- [1-(ethoxyimino)butyl]-5- [2-(ethylthio)propyl] -3-hydroxy-2-cyclohexen-1-one modified chloroplast pigment, growth, anatomy, and ultrastructure of pre- and postemergent-treated wheat (Triticum aestivum 'Pavon 76') seedlings. Seedlings were grown under 16 h photoperiod (105 μE/M²/S) at 32/24 C day/night temperature. Pigment, growth and anatomical studies were made on pre- and postemergent-treated seedlings. Postemergent treatments were applied to 6-day-old seedlings. Carotenoid levels were reduced by 90 to 94% in preemergent-treated seedlings at 5 x 10⁻⁵ M for each herbicide. Postemergent application of 10⁻³ M haloxyfop-methyl and sethoxydim caused a reduction of 11 and 15% in carotenoid concentration than the control, respectively. Also, they produced a significant reduction in chlorophyll a and total chlorophyll concentration. Preemergent treatment with 5 x 10⁻⁶ M of each herbicide caused a reduction of 78 to 91% in leaf fresh weight and 72 to 84% reduction in root dry weight as compared to the control. Height of the seedlings was reduced by 79 to 86% of the control. Postemergent treatments with 10⁻³ M of each herbicide reduced the length of the second leaf by 98%, whereas length of the first leaf was reduced by 36% following haloxyfop-methyl treatment and 45% following fluazifop-butyl or sethoxydim treatments. Fresh weight of leaf tissue treated with 10⁻³ M of each herbicide was reduced by 40%. Preemergent treatment of the seedlings with 3 x 10⁻⁶ and 5 x 10⁻⁶ M haloxyfop-methyl or with 5 x 10⁻⁶ M fluazifop-butyl or sethoxydim caused 35 to 50% enlargement of mesophyll cells as compared to the control. These cells appeared to contain less cytoplasm. Post- emergent application of 10⁻³ M of each herbicide caused swelling of mesophyll cells. Ultrastructural studies showed that plastids of seedlings germinated in 5 x 10⁻⁶ M of each herbicide were disrupted, swollen, and lacked internal thylakoids but contained masses of plastoglobuli. The chloroplasts of postemergent-treated seedlings had fewer granal and intergranal thylakoids, but the injury to plastids was less severe than in preemergent treatments.

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