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1
Sill, David W., Barry Tickes, and Lisa A. Carey. "Field Emergence and Seedling Growth of Lettuce as Affected by Pre-Plant/Pre-Emergent Herbicides." College of Agriculture, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/221599.
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Pre plant and pre- emergence herbicides are commonly used in lettuce production. We investigated possible effects the herbicides benefin (Balan), pronamide (Kerb) and bensulfide (Prefar) had on emergence and seedling growth of several iceberg lettuce varieties that had been primed and pelleted by seed enhancement companies The herbicide Prefar and a mixture of Balan + Prefar had the greatest impact on dry weight regardless of variety, while seedlings grown on Kerby plots were not significantly different than seedlings from untreated plots. Dry weight accumulation and field emergence were influenced significantly by pellet types and priming methods.
2
Roman, Erivelton Scherer. "Modelling seedling emergence of common lambsquarters in corn." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq31897.pdf.
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3
Sinclair, John. "Crusting, soil strength and seedling emergence in Botswana." Thesis, University of Aberdeen, 1985. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU363198.
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This thesis gives the results of an investigation of the strengths and particularly the crust forming potential of arable soils from Botswana and the relationship to seedling emergence of sorghum, the most important crop in Botswana and one that because of its small seed weight (about 2 0 mg) can fail to emerge through a hard soil crust. A review of the literature suggested that the soil factors which had to be considered were dispersibility of clay and factors which affect this, and the bulk density of the soils. Soils which are found in many tropical and sub-tropical regions, with low organic matter and inactive clays can set hard after a simple wetting and drying cycle. In these soils, the strength is very strongly dependent on the water content, showing a hyperbolic or exponential relationship-, and the strengths when dry may be very greatly increased by remoulding the wet soil. The crust strength required to prevent seedling emergence varies with the size of the seedling and for cotton (seed weight about 80 mg), 1-3 MPa penetration resistance measured with a penetrometer is sufficient to prevent emergence. Seedlings exert a total force proportional to their number. In the experimental programme, seedlings' forces were measured, seedling emergence observed in a field experiment under crusting conditions, and the strength characteristics of a group of soils, representative of arable soils in Botswana, studied. A sorghum seedling was found to exert a maximum force of about 1 N or dividing by the area of the plumule, a pressure of about 0,5 MPa. The field experiment showed that much better emergence was obtained from planting 15 seeds together than from planting 4 seeds together when a crust formed after planting. A study of 32 soils, most of them sand to sandy loam in texture but with a few clays and hydroirorphic soils, from arable areas in Botswana showed the sandy to sandy loam soils to have high bulk densities ( 1,45-1 ,75 Mg/m3) and extremely low organic carbon contents (0,12-0,85 g/100g). The bulk densities of all the soils were inversely related to the organic carbon content and this was itself related to the clay content of the soils. The bulk densities of the sands were dependent on the grading of the sand fraction. Many of the soils were sensitive to remoulding in the Emerson test and the sands to loany sands had 0,4-1,0 g/100 g water dispersible clay. Measurements of tensile strength on air-dry samples showed that all the soils, except for one sand, set hard after a wetting and drying cycle, giving for vacuum wet samples indirect tensile strengths 1,0-14,4 kPa. For the sands to sandy loams this strength was related to the water dispersible clay content. Samples wet at atmospheric pressure were weaker than the vacuum wet samples, the reduction in strength was related to the air porosity of the non-vacuum wet soils prior to drying. Remoulding the soils prior to drying them increased the strength by a factor of up to 50 times, giving strengths from 4 kPa to 600 kPa. The strength after remoulding was dependent on the Emerson index. Compacting the soils increased their strength greatly and to an extent that agreed with the hypothesis that the strength obtained was proportional to the area of contact between the particles. Experiments on penetration resistance at a range of water contents were performed on a few soils. A hyperbolic relationship between water content and penetration resistance of the surface soil was found for sand to sandy loam soils, with the maximum resistance of dry soils above 2 MPa. The penetration resistance of the sandy loam soil was Increased three times by disturbing it when wet. Sprinkler wetting the sieved soils was not found to affect the penetration resistance by a large amount compared and other methods of welting. Penetration resistance was measured on air-dry samples of most of the main group of soils following varying degrees of wetting with a rainfall simulator. The clays and hydromorphic soils gave very low values of penetration resistance under these conditions, showing that at organic carbon contents of about 1% and clay contents from 20 to 30%, the decreased bulk density and tendency to form aggregates' on drying overcame the tendency to set hard. The mean values for the sands to sandy loams were from 1 to 6 MPa so all these soils could offer significant resistance to a sorghum seedling. The penetration resistance of the sands and loam/ sands depended on their bulk densities and water dispersible clay contents, while the penetration resistance of the sandy loams depended only on the water dispersible clay content.
4
Alves, Fernanda Vieira. "Composição química e qualidade fisiológica de sementes de girassol de plantas submetidas à competição intraespecífica." Universidade Federal de Uberlândia, 2010. https://repositorio.ufu.br/handle/123456789/12139.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>The great number of seeds in the sunflower head and the temporal distribution of its
maturation cause the competition between whorls because of nutritional resources and,
consequently, differences in the seed chemical composition from the head regions. As the
competition among plants in the sowing line can influence seeds nutrient drainage, this
work aimed at evaluating both the chemical composition and the physiologic quality of
sunflower plants seed coming from different regions of the sunflower head and plants
stemming from high, low vigor seeds that partook of intra-specific competition. Three
experiments constituted dealing with seeds coming from one third of the head (peripheral,
median and central) were carried out. The experimental design was in randomized blocks
with four repetitions, each experiment treatment being distributed on a subdivided plot. In
the plots, it was evaluated five proportions of high-vigor seeds placed in the sowing line as
it follows: 0,75 (3A:1B); 0,67 (2A:1B); 0,50 (1A:1B); 0,33 (1A:2B), and 0,25 (1A:3B). In
the subplot, it was evaluated plants stemming from seeds of high and low vigor and two
additional treatments (all plants coming from seeds of high or low vigor, 1A:1A and 1B:1B,
respectively). After that, an analysis relating vigor proportions to the head thirds was made.
It was evaluated the percentage of proteins, lipids, total carbohydrates, ashes, moisture
degree, the weight of a thousand seeds, emergency measures (its initial, ending, and middle
times, emergence and average velocity, uncertainty, synchronicity, time variation
coefficient and emergency) obtained through emergency test in the sand. It concludes that:
a) the proportion of vigor of the seeds in the sowing line interfere in performance of the
plants and in seed quality resultant, being that the plants coming of seeds put in major
proportion in the line, independently of the vigor have major competitiveness; b) the
chemical composition of the sunflower seeds ranged with the position of the seeds in the
head. Higher content of carbohydrates and weight of thousand seed were observed in the
peripheral third, while the higher content of protein and lipids were obtained of the seeds in
the middle third; c) the position of the seed in the head interfered in the variables of
germination. Although sunflower head s third peripheral seeds showed a higher emergency
ignition in the sand, it showed a lower final time and time variation coefficient, besides
being having a higher emergency homogeneity and synchrony. The middle third seeds, on
the other hand, showed low emergency homogeneity and synchrony, being more distributed
in time.<br>O grande número de sementes presentes no capítulo de girassol e a distribuição
temporal da maturação delas geram a competição entre os verticilos por recursos
nutricionais e, logo, diferenças na composição química entre sementes das regiões da
inflorescência. Como a competição de plantas na linha de semeadura pode influenciar
na drenagem de nutrientes para as sementes, este trabalho objetivou avaliar a
composição química e a qualidade fisiológica de sementes de girassol oriundas de
diferentes regiões do capítulo e de plantas-mãe originadas de sementes de alto vigor e
de baixo vigor que sofreram competição intraespecífica. Foram conduzidos três
experimentos constituídos por sementes oriundas dos terços do capítulo (periférico,
mediano e central). O delineamento experimental foi em blocos casualizados com
quatro repetições. Os tratamentos em cada experimento foram distribuídos em parcelas
subdivididas, na quais se avaliaram cinco proporções de sementes com alto vigor
colocadas na linha de semeadura: 0,75 (3A:1B); 0,67 (2A:1B); 0,50 (1A:1B); 0,33
(1A:2B) e 0,25 (1A:3B). Nas subparcelas, foram avaliadas as plantas oriundas das
sementes de cada nível de vigor (alto e baixo) e dois tratamentos adicionais (todas as
plantas oriundas de sementes de vigor alto ou vigor baixo, 1A:1A e 1B:1B,
respectivamente). Depois foi feita a análise relacionando-se as proporções de vigor
avaliadas e os terços do capítulo. Foram avaliadas a porcentagem de proteínas, lipídeos,
carboidratos totais, cinzas, grau de umidade e peso de mil sementes, além das medidas
de emergência (tempos inicial, final e médio de emergência, velocidades média e de
emergência, incerteza, sincronia, coeficiente de variação do tempo e emergência),
obtidas por meio do teste de emergência em areia. Conclui-se que: a) a proporção de
vigor das sementes na linha de semeadura interfere no desempenho das plantas e na
qualidade das sementes resultantes, e as plantas oriundas de sementes colocadas em
maior proporção na linha, independentemente do vigor, têm maior competitividade; b) a
composição química das sementes de girassol variou com a posição das sementes no
capítulo. Maior teor de carboidratos e peso de mil sementes foram observado no terço
periférico, ao passo que maior teor de proteína e lipídeos foi obtido das sementes do
terço central; c) a posição da semente no capítulo interferiu nas variáveis da
germinação. Embora apresentem maior tempo inicial de emergência em areia, as
sementes do terço periférico do capítulo de girassol apresentam menor tempo final e
menor coeficiente de variação do tempo, tendo maior homogeneidade e sincronia de
emergência. As sementes do terço central, em contrapartida, apresentam menor
homogeneidade e sincronia de emergência, sendo mais distribuídas no tempo.<br>Mestre em Agronomia
5
Schutte, Brian J. "Biology and ecology of Ambrosia Trifida L. seedling emergence." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1181937971.
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6
Fessehazion, Melake Kessete. "Predicting and improving seedling emergence of three vegetable crops." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-02092006-130454.
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7
Welling, P. (Pirjo). "Regeneration by seeds and vegetation structure in alpine plant communities, subarctic Finland." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:951426861X.
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Abstract
The aims were to examine the importance of regeneration by seeds, the
influence of plant traits and disturbances, and the role of seed-seedling
conflicts in regeneration and in the determination of vegetation structure.
The study was carried out at in a subarctic alpine area (Kilpisjärvi
69°01'N 20°50E', Finland).
Seed bank and seedling densities were high in many plant communities
(ranges 99 -1109 viable seeds/m2 and 0.2-227
seedlings/m2, respectively). Effective seedling
recruitment is reflected in vegetation as a high proportion of plants with
poor or no vegetative reproduction ability. This development may take place
in meadows and snowbeds where herbs (e.g. Gnaphalium
supinum, Sibbaldia procumbens,
Veronica alpina and Viola
biflora) are abundant. On the other hand, the low proportion of
these plants in heath vegetation reflects ineffective seedling
recruitment.
Floristic similarities between the consecutive phases in the
regeneration pathway may be low despite effective seedling recruitment.
Clonality, large and small seed sizes and appendaged diaspores limit the
movement of species from phase to phase.
Generally, disturbances facilitate effective regeneration by seeds.
Grazing promotes species with large seed banks and is therefore one reason
for high seed bank densities. Freezing and melting processes negate a
negative influence of altitude on seed bank densities in the phase of
seedlings. However, if disturbances are severe and continuous and the soil
is compact, unstable or dry, disturbances are not beneficial. The same is
true if there is a shift in the species composition of seedlings from gaps
to closed vegetation. This phenomenon occurred in a rich meadow.
Seed-seedling conflicts limit regeneration by seeds in low-herb
snowbeds and Ranunculus glacialis-Gymnomitrion
snowbeds. Vegetative reproduction and infrequent pulses of seedling
recruitment negate an influence of short-term seedling recruitment on the
spatial structure of vegetation. Extreme conditions, such as low
temperatures, instability of the soil and late snowmelt modify the
influence of factors that are important in more moderate conditions.
To conclude, all transitions limit regeneration by seeds. However,
favourable conditions (e.g. moist conditions in a meadow) partly eliminate
the obstacles against seedling emergence. Regeneration by seeds therefore
has a major impact on the dynamics and structure of vegetation. In heath
vegetation, where bare soils are dry and the moss cover is thick, large
seed banks and seed rains do not guarantee effective seedling recruitment.
The regeneration process is reduced in the early phases, and plants that reproduce primarily by seeds have a minor role in vegetation. The accumulation of seed banks is effective in these circumstances.
8
Kittock, David L., Wallace C. Hofmann, B. Brooks Taylor, Joel Malcuit, Carl Michaud, and Peter T. Else. "Seedling Emergence Studies on Upland Cotton in Arizona in 1984." College of Agriculture, University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/203916.
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9
Kittock, D. L., W. C. Hofmann, J. Malcuit, P. Else, and C. Michaud. "Seedling Emergence Studies on Upland Cotton in Arizona in 1985." College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/219703.
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The 1985 and 1986 Cotton Reports have the same publication and P-Series numbers.<br>Seed of 19 upland cotton varieties was planted early in the season at 3 locations to evaluate relative emergence. Variety comparisons for seedling emergence were consistent at the 3 locations. Comparison of performance of older varieties with past years showed consistent relative emergence in 7 comparisons and an apparent weak seed lot for one variety in 1985 and apparent weak seed lots for another variety in past years. Deltapine 41 has consistently been near the bottom in early season seedling emergence over years and Deltapine 61 has been below average.
10
Trimble, Loren Ambrose. "Genetic improvement of seedling emergence of low-phytate soybean lines." [Ames, Iowa : Iowa State University], 2009.
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11
Clarke, Jodie Johnson. "Development of a Greenhouse Tobacco Seedling Performance Index." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33863.
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Tobacco seed performance is traditionally measured as percentage
germination at 14 d under controlled laboratory conditions. However, under
greenhouse conditions, seed lots with equal 14-d germination may exhibit
substantial differences in uniformity of early seedling growth and spiral root
incidence that impact the number of usable transplants. A seedling performance
index (SPI) was developed to quantitatively describe greenhouse tobacco seedling
performance. The 14-d emergence, relative leaf area uniformity, and seedling leaf
area determined by computer image analysis were used to calculate the index.
Greenhouse tobacco seed trials demonstrated that seed with the Rickard pellet had
higher emergence, but the higher spiral root incidence associated with the Rickard
pellet lowered the SPI compared to the Cross Creek pellet. Primed seed lots of
flue-cured cultivars (NC 72 and NC 71) had a significantly higher SPI than the
nonprimed seed lots at one location but not at a second location. Seed lots sown
in Premier Pro-Mix TA commercial medium had a higher spiral root incidence,
which resulted in a lower SPI compared to Carolina Choice, Carolina Gold, and
Sunshine LP5 commercial media. The index quantitatively determined
differences in seedling performance under greenhouse conditions not reflected by
standard germination tests. Significant differences in the SPI were observed
among seed lots with certified 90% germination. The SPI is a simple method to
describe seedling performance because the data used to calculate the SPI is
obtained from one seed tray image. In contrast, frequent counting and seedling
evaluations are involved with standard germination and vigor tests.<br>Master of Science
12
Sylla, Diaguely 1951. "EFFECT OF MICROPHYTIC CRUST ON EMERGENCE OF RANGE GRASSES." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276554.
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Field and greenhouse studies were conducted in 1986 and 1987 to determine the impact of disturbance of microphytic soil crust on emergence of two warm season grass species. In the greenhouse, emergence of seedlings sown on the top of undisturbed crust, under the crust, on disturbed crust, and on bare soil was studied. The mean number of seedlings of "Cochise" lovegrass (Eragrostis lehmanniana x Eragrostis tricophora) and Kleingrass (Panicum coloratum) was higher on disturbed field plots than undisturbed plots. Disturbance reduced the microphytic crust cover, and the crust did not recover throughout the growing season. Presence of seedlings in samples of litter washed off the plots and observation on ants showed that all the seeds sown did not remain on the plots during the growing season. In greenhouse flats the emergence of seedlings of both species was greater on disturbed microphytic crust and bare soil than when seeded on top of or under an intact crust. Undisturbed crust restricted penetration of roots and shoots when seeds were placed on or under the crust.
13
Spear, Jordan Dustin. "Genetic improvement of seedling emergence of soybean lines with low phytate." [Ames, Iowa : Iowa State University], 2006.
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14
Taki, Orang. "The improvement of seedling emergence by crack development in crusting soils." Thesis, Cranfield University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405235.
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15
Yacoub, Mohamed Mohamed. "Effects of soil amendments on crusting, seedling emergence and yield of onion, tomatoes and peppers." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185461.
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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.
16
Donath, Tobias W. [Verfasser]. "Effects of ground cover on seedling emergence and establishment / Tobias W. Donath." Gießen : Universitätsbibliothek, 2013. http://d-nb.info/1065184263/34.
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Hofmann, W. C., D. L. Kittock, J. Malcuit, P. Else, and C. Michaud. "Seedling Emergence and Lint Yield of DP-90 Seed of Different Densities." College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/219729.
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The 1985 and 1986 Cotton Reports have the same publication and P-Series numbers.<br>Six lots of Deltapine (DP) 90 of different seed densities were planted at three planting rates in four tests in Arizona in 1985. The lowest density seed lot had significantly lower standard germination, cold test germination, field emergence, and lint yield than other seed lots. The highest density seed lot had slightly higher lint yield and field emergence than other lots on an average.
18
Lorentz, Andrew. "Design, construction and testing of an ascending micropenetrometer to measure soil crust resistance." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/8511.
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The increasing world population is putting pressure on global food production.
Agriculture must meet these growing demands by increasing crop yields. One phenomenon
which prevents seedling emergence and damages crop yield is soil crusting. Understanding
of soil crusting and the factors which influence it is fundamental to ensuring good crop
production. An instrument which will test soil crust strength in a novel way, mimicking
seedling growth, may lead to pre-emptive agricultural soil management which could
increase crop production. This work details the process of design, construction and testing
of an ascending penetrometer to measure soil crust strength. The full design process is
discussed from concept generation and evaluation, using experimental methods and a
multi-criteria decision making tool, through to final design configuration, specification,
manufacture and testing.
Traditionally, soil penetrometers measure soil strength by forcing a probe from the surface
of the soil into the bulk soil below. To more accurately measure the direct impedance a
seedling would experience a device should measure impedance from the bulk soil upwards
and into the soil crust, mimicking what a growing seedling would experience. Results
prove that the manufactured ascending penetrometer with a force resolution of 0.01N and
displacement resolution of 0.0004mm is capable of detecting differences in soil crusts. At
these resolutions and accuracy to 0.1N and 0.1mm excellent repeatability was achieved.
The machine is therefore a useful and realistic tool for quantitatively comparing soil crusts
in soil. It is hoped that being able to compare soil crust strength will lead to improved soil
management techniques.
19
England, David M. "Seeding Treatments to Enhance Seedling Performance of the Bulrushes Bolboschoenus Maritimus, Schoenoplectus Acutus and S. Americanus in Wetland Restorations." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7659.
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A major goal in restoration is to reestablish native plant communities. There are several ways to reestablish species, but for large areas the most logistically feasible approach is to sow seed of desirable species. However, most wetland seeds are buoyant and are extremely difficult to establish in designated areas before floating away. In upland areas, tackifiers have been used to stabilize hill slopes from erosion and to keep seeds in place. The tackifier works as an adhesive that binds the seeds to the soil. However, the use of a tackifier has not been widely employed in wetland restorations, and prior to its broad implementation into wetland restoration practice, it is important to determine if tackifiers will hold up in wetland conditions. In greenhouse studies, we tested the effectiveness of different tackifier types and concentrations on Bolboschoenus maritimus seedling emergence, the influence of soil moisture and flooding on the duration of tackifier effectiveness, the effect of a mulch addition on tackifier effectiveness (Bolboschoenus maritimus, Schoenoplectus acutus and S. americanus), the effectiveness of pre-germination in enhancing Bolboschoenus maritimus seedling emergence using a tackifier, and the effectiveness of tackifier over time. We concluded that the use of a tackifier was effective at keeping seeds from washing away for at least 15 days, a mulch addition did not enhance tackifier effectiveness, and pre-germination did not benefit B. maritimus seedling emergence. The results from this study provide strong evidence that the use of a tackifier could be an effective solution to establish bulrush species in designated areas in wetland restorations.
20
Downs, Michael Paul. "Effects of leaf litter on seedling emergence of bull thistle, Cirsium vulgare (Savi) Ten." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq30786.pdf.
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21
Parks, Geoffrey Richmond. "Longleaf pine sandhill seed banks and seedling emergence in relation to time since fire." [Gainesville, Fla.] : University of Florida, 2007. http://purl.fcla.edu/fcla/etd/UFE0021193.
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22
Pamuk, Gunnar Sven. "Controlling water dynamics in Scots pine (Pinus sylvestris L.) seeds before and during seedling emergence /." Umeå : Dept. of Silviculture, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s305.pdf.
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23
Malcuit, Joel, David L. Kittock, B. Brooks Taylor, and Carl Michaud. "The Effect of Pregermination of Cotton Seed in Oxygen on Seedling Emergence and Lint Yield." College of Agriculture, University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/204033.
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Yacoub, M., L. J. Clark, and J. L. Stroehlein. "Effects of Soil Amendments on Crusting, Seedling Emergence and Yields of Onions, Tomatoes and Peppers." College of Agriculture, University of Arizona (Tucson, AZ), 1987. http://hdl.handle.net/10150/221239.
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Studies were carried out at the Safford Agricultural Center using some soil amendments as anti-crusting agents. The results are promising in terms of improved stands on soils subject to crusting. Additional research is needed in order to determine proper rates which will reduce crusting without being toxic to the emerging seedlings.
25
Mogollones, Barrera Sol C. "Seed dispersal, seedling emergence and bird community structure in a human-modified landscape mosaic in Sri Lanka." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=202126.
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Jäderlund, Anders. "Bilberry (Vaccinium myrtillus L.) in a boreal forest ecosystem : effects on tree seedling emergence and growth /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-6072-7.pdf.
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Khan, Mohammad Jamal 1960. "Evaluation of sulfur containing amendments for soil crusting, seedling emergence of tomato and DTPA extractable micronutrients." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278206.
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A greenhouse experiment was conducted to evaluate the effect of five amendments (H₂SO₄, Al₂(SO₄.18H₂O, FeSO₄.7H₂O, and CaS₅ and CaSO₄.2H₂O) on crust formation, seedling emergence, dry matter yield (DMY) of tomato and soil properties in a sodic soil from the Safford Agricultural Center. When applied in equivalent quantities (600 kg/ha S), sulfuric acid and Al-sulfate proved to be the best anti-crusting agents and gypsum the least. Tomato seedling emergence and DMY increased with addition of H₂SO₄ followed by gypsum. Sulfuric acid was superior in reducing ESP in 0-3 cm depth, while EC was increased with additions of all amendments. In 3-8 cm depth the amendments affected pH, EC and ESP less than at the 0-3 cm depth. DTPA extractable and plants concentrations of Zn, Fe and Mn significantly increased with the addition of various amendments, while Cu was not effected by any amendments.
28
Jernigan, Marcus Brendon. "Use of uprooted invasive buffelgrass (Pennisetum ciliare) parent plants as thatch to reduce progeny seedling emergence." Thesis, The University of Arizona, 2013. http://hdl.handle.net/10150/311668.
Full textAbstract:
Buffelgrass (Pennisetum ciliare) is a perennial bunchgrass native to Africa that has invaded ecologically intact areas of the Sonoran Desert in southern Arizona. It threatens many native plant species by means of competitive exclusion as well as increased fire frequency and intensity. Since the 1990s, efforts have been underway in southern Arizona to control buffelgrass using manual removal. A problem with this method is that the resulting bare, disturbed soil provides a favorable environment for buffelgrass seed germination. This study examined whether thatch composed of uprooted buffelgrass parent plants spread over disturbed areas reduces the density of progeny seedlings. A secondary goal was to determine whether light attenuation and/or autoallelopathy were major factors involved in the effect of thatch on buffelgrass seedling density. The effect of light attenuation on seedling density was tested in containers in the field and in the greenhouse. The propensity of thatch to produce autoallelopathic chemicals was tested in the greenhouse. Field plots with thatch had 1.9 buffelgrass seedlings/m² which was significantly fewer (p= 0.03) than the 2.9 seedlings/ m² in plots without thatch. These results suggest that the placement of thatch over areas disturbed during manual treatment of dense stands of buffelgrass will increase the efficiency of follow-up control of buffelgrass progeny seedlings in these areas. Results of the field container study suggest that light attenuation does not play a significant role (p= 0.39) in the reduction of seedling density by thatch, whereas those of the greenhouse shade treatment study indicated that light attenuation is a significant factor (p= 0.004). However, because percent germination was very low in the field container study, those results may be of little value compared to the greenhouse shade treatment study results which indicate that light attenuation is a mechanism by which thatch reduces buffelgrass seedling emergence. Chemicals leached from decomposed buffelgrass thatch did not have a significant effect (p= 0.09) on buffelgrass seedling density. Only the combination of thatch and leached chemicals significantly reduced (p= 0.014) seedling density. Thatch may also increase the activity of other factors that could reduce seedling density such as pathogens, and predators of seeds and seedlings.
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Jernigan, Marcus Brendon. "Use of uprooted invasive buffelgrass (Pennisetum ciliare ) parent plants as thatch to reduce progeny seedling emergence." Thesis, The University of Arizona, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1550441.
Full textAbstract:
<p> Buffelgrass (<i>Pennisetum ciliare</i>) is a perennial bunchgrass native to Africa that has invaded ecologically intact areas of the Sonoran Desert in southern Arizona. It threatens many native plant species by means of competitive exclusion as well as increased fire frequency and intensity. Since the 1990s, efforts have been underway in southern Arizona to control buffelgrass using manual removal. A problem with this method is that the resulting bare, disturbed soil provides a favorable environment for buffelgrass seed germination. This study examined whether thatch composed of uprooted buffelgrass parent plants spread over disturbed areas reduces the density of progeny seedlings. A secondary goal was to determine whether light attenuation and/or autoallelopathy were major factors involved in the effect of thatch on buffelgrass seedling density. The effect of light attenuation on seedling density was tested in containers in the field and in the greenhouse. The propensity of thatch to produce autoallelopathic chemicals was tested in the greenhouse. Field plots with thatch had 1.9 buffelgrass seedlings/m<sup>2</sup> which was significantly fewer (<i>p</i> = 0.03) than the 2.9 seedlings/m<sup> 2</sup> in plots without thatch. These results suggest that the placement of thatch over areas disturbed during manual treatment of dense stands of buffelgrass will increase the efficiency of follow-up control of buffelgrass progeny seedlings in these areas. Results of the field container study suggest that light attenuation does not play a significant role (<i>p</i> = 0.39) in the reduction of seedling density by thatch, whereas those of the greenhouse shade treatment study indicated that light attenuation is a significant factor (<i>p</i> = 0.004). However, because percent germination was very low in the field container study, those results may be of little value compared to the greenhouse shade treatment study results which indicate that light attenuation is a mechanism by which thatch reduces buffelgrass seedling emergence. Chemicals leached from decomposed buffelgrass thatch did not have a significant effect (<i>p</i> = 0.09) on buffelgrass seedling density. Only the combination of thatch and leached chemicals significantly reduced (<i>p</i> = 0.014) seedling density. Thatch may also increase the activity of other factors that could reduce seedling density such as pathogens, and predators of seeds and seedlings.</p>
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Borges, Kelly Cristiene de Freitas. "Maturação dos frutos na emergência de plântulas e no potencial frutífero de pitangueira-do-cerrado (Eugenia calycina Cambess)." Universidade Federal de Uberlândia, 2008. https://repositorio.ufu.br/handle/123456789/12102.
Full textAbstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>CHAPTER II: Eugenia calycina is a fruit bearing species which is present in areas of the Savannah,
whose fruit and seed morpho-physiological characteristics are rare. This being so, the
objectives of the study were to quantify the influence of fruit coloration in the morphophysiological
characters of fruit and seeds of the species; to determine pulp yield and to
indicate the potential of the species for genetic improvement programs. In November
2006, fruits in green, orange, bright-red and dark-red colorations, 50 of each coloration
were collected, their seeds extracted and both measured with relation to length and
width, as well as fresh and dry weight pulp. In November 2007, from 20 matrixes, the
number of fruits per plant and pulp yield was determined. The distribution for t
Student was used to build confidential intervals for length, width and fresh and dry
weight pulp and test the correlation coefficient between characters of the fruit and fresh
weight pulp. Frequencies asymmetry and kurtosis measurements indicated the nature of
the width and length distribution. Great ranges were observed in fruit size (8-20 mm
width; 10-30 mm length) and seeds (8-14 mm width; 7-14 mm length), within the same
maturation stage. The symmetrical and mesokurtic nature of the width and length
distributions of the fruit and seeds reveal their genetic potential for selection, even with
the anthropization of their area of occurrence. The production of fruit per plant was
variable (3 to 20), with pulp yield estimated at 59.1%. CHAPTER III: The occurrence of fruit bearing species extensively cultivated in Brazil gives evidence
to the need for a better knowledge of native flora and preservation of natural vegetable
resources. The aimed was quantifying the influence of the coloration of Eugenia
calycina Cambess. fruits in the emergency and development process of seedlings with
the purpose of production of same. For the collection, green, orange, bright-red and
dark-red coloring patterns of the fruit were established. These indicated the different
maturation stages. The emergency experiment was installed in randomized block
design, with four treatments (maturation stages) and seven repetitions of 28 seeds,
totaling 28 parcels. To evaluate the seedling development, two independent experiments
were installed both in randomized block design, using seedlings from the emergency
test. In the first experiment, the treatments consisted of seedlings from the emergency
test in different maturation stages (green, orange, bright-red and dark-red) and in the
second, they consisted of a mixture of substrata containing commercial, vermicular and
coconut peel substratum in different proportions. The fruit maturation stages did not
affect the emergency process significantly, not even with regards to the increments in
hypocotyls height, root length, stem diameter and number of leaves. The seedling
emergence capacity was high (83.67 to 90.31%), however, on average, less than one
seedling emerged per day (VE = 0.737 to 0.819 seedlings per day). Seedling growth was
slow, maximum of 7 cm in 210 days, even when substratum was supplemented with
chemical dressing (osmocote®), coconut peel and vermicular substratum.<br>CAPÍTULO II: Eugenia calycina é uma espécie frutífera de ocorrência em áreas de Cerrado, cujas
características morfofisiológicas de frutos e sementes são escassas. Diante disso, os
objetivos do trabalho foram quantificar a influência da coloração do fruto nos caracteres
morfofisiológicos de frutos e sementes da espécie; determinar o rendimento de polpa e
indicar o potencial da espécie para programas de melhoramento genético. Em novembro
de 2006, cinqüenta frutos, na coloração verde, laranja, vermelho-claro e vermelhoescuro,
foram coletados, extraídas suas sementes e ambos medidos quanto ao
comprimento e largura, além das massas das matérias fresca e seca da polpa. Em
novembro de 2007, de vinte matrizes, determinaram-se o número de frutos por planta e
o rendimento de polpa. A distribuição t de Student foi utilizada para construir
intervalos de confiança para comprimento, largura e massa das matérias fresca e seca de
polpa, e testar o coeficiente de correlação entre caracteres do fruto e a massa fresca de
polpa. Freqüências percentuais e medidas de assimetria e curtose indicaram a natureza
da distribuição da largura e do comprimento. Grandes amplitudes foram observadas na
morfometria dos frutos (8-20 mm de largura; 10-30 mm de comprimento) e das
sementes (8-14 mm largura; 7-14 mm comprimento), dentro do mesmo estádio de
maturação. A natureza simétrica e mesocúrtica das distribuições de largura e
comprimento dos frutos e sementes revelam seu potencial genético para seleção, mesmo
com a antropização de sua área de ocorrência. A produção de frutos por planta foi
variável (3 a 20), com rendimento de polpa estimado em 59,1%. CAPITULO III: A ocorrência de espécies frutíferas amplamente cultivadas no Brasil evidencia a
necessidade de melhor conhecimento da flora nativa e da preservação dos recursos
vegetais naturais. Diante disso, objetivou-se quantificar a influência da coloração dos
frutos de Eugenia calycina Cambess. no processo de emergência e no desenvolvimento
de plântulas para fins de produção de mudas. Na coleta foram estabelecidos os padrões
de coloração do fruto, verde, laranja, vermelho-claro e vermelho-escuro, indicando os
diferentes estádios de maturação. O experimento de emergência foi instalado em
delineamento de blocos casualizados, com quatro tratamentos (estádios de maturação) e
sete repetições de 28 sementes, totalizando 28 parcelas. Para avaliar o desenvolvimento
de plântulas, dois experimentos independentes foram instalados, ambos em
delineamento de blocos casualizados, usando plântulas do teste de emergência. No
primeiro, os tratamentos constaram de plântulas do teste de emergência em diferentes
estádios de maturação (verde, laranja, vermelho-claro e vermelho-escuro) e, no
segundo, constaram de mistura de substratos contendo substrato comercial, vermiculita
e casca de coco em diferentes proporções. Os estádios de maturação dos frutos não
afetaram significativamente o processo de emergência, nem mesmo os incrementos em
altura do hipocótilo, comprimento de raiz, diâmetro do caule e número de folhas. A
capacidade de emergência das plântulas foi alta (83,67 a 90,31%), porém, em média,
menos de uma plântula emergiu por dia (VE = 0,737 a 0,819 plântulas por dia). O
crescimento das plântulas foi lento, máximo de 7 cm em 210 dias, mesmo quando o
substrato foi suplementado com adubação química (osmocote®), casca de coco e
vermiculita.<br>Mestre em Agronomia
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Sagra, Javier, Daniel Moya, Pedro Plaza-Álvarez, et al. "Predation on Early Recruitment in Mediterranean Forests after Prescribed Fires." MDPI AG, 2017. http://hdl.handle.net/10150/625399.
Full textAbstract:
Wildfires play a significant role in many different elements of Mediterranean forest ecosystems. In recent years, prescribed fires have started being used more often as a fuel reduction tool, and also as silvicultural treatment to help the regeneration and health improvement of stands. Apart from the fact that fire may alter microsite conditions, very little is known about the impact of prescribed burning on natural regeneration or plant species renewal in Mediterranean pine forests. Likewise, knowledge about the influence of seedling predators on post-fire regeneration is still scarce. In this study, we aimed to compare the effects of seedling predation on recruitment in earlier stages after prescribed burnings in three pine stands in Central Spain: a pure stand of Pinus nigra; a mixed stand of Pinus halepensis and Pinus pinaster and a mixed stand P. nigra with P. pinaster. In situ we superficially sowed seeds from two different species. In the sowing experiment, we tested two different seed provenances (drier and more humid spanish regions) for each species. In all, 60 plots (30 burned, 30 unburned) per site, with 10 seeding units per plot and more than 20,000 seeds, were used in the whole study. Seedling predation was evaluated by replicating the seeding units inside and outside a wire cage as protection for rodents and birds. Our results showed that prescribed fires alter initial seedling predation intensity: predation was significantly higher in the seedlings grown in the plots affected by prescribed fire. The individuals sown before the fire passed showed slightly more predation than those sown after fire passage. Provenances did not appear as an important predation drive. Understanding the role of the predation associated with these treatments can help improve Mediterranean pine forest management.
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Winkel, Von Kenneth. "Effects of seedbed modification, sowing depth and soil water on emergence of warm-season grasses." Diss., The University of Arizona, 1990. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1990_108_sip1_w.pdf&type=application/pdf.
Full text
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Kittock, D. L., W. C. Hofmann, J. Malcuit, P. Else, and C. Michaud. "The Effect of Pregerminating DP-90 Cotton Seed in Oxygen and Drying on Seedling Emergence and Lint Yield." College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/219705.
Full textAbstract:
The 1985 and 1986 Cotton Reports have the same publication and P-Series numbers.<br>Partial pre-germination of Deltapine 90 seed under oxygen and then drying prior to planting tended to speed and increase emergence in two tests in 1985, but did not increase lint yield.
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Nelson, J. M., and C. C. Sharples. "Effect of Treatment of Lettuce Seeds with Fusicoccin and Other Growth Regulators on Seedling Emergence at High Temperature." College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/214109.
Full textAbstract:
Lettuce stand problems in desert production areas are, in many instances, related to high seedbed temperatures and the use of seed coatings. We evaluated the use of fusicoccin and other growth regulators to improve the performance of naked and coated lettuce seeds at high temperature. Treatment of both naked and coated seeds with fusicoccin markedly increased the rate and total emergence of seedlings incubated at 35 °C for 10 hours alternating with 23 °C for 14 hours.
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Magalhães, Stefânia Caixeta. "Disponibilidade de minerais, germinação e vigor de sementes de milho /." Jaboticabal : [s.n.], 2009. http://hdl.handle.net/11449/96797.
Full textAbstract:
Orientador: Francisco Humberto Dübbern de Souza<br>Banca: Roberval Daiton Vieira<br>Banca: Ana Dionísia da Luz Coelho Novembre<br>Resumo: A maioria dos métodos utilizados para estimar o vigor de amostras de sementes são qualitativos, portanto sujeito a erros do avaliador e de interpretação dos resultados. Metodologias quantitativas podem constituir alternativas mais confiáveis. Este trabalho teve como objetivo verificar se os níveis de alguns minerais armazenados nas sementes e disponibilizados durante etapas iniciais do processo de germinação constituem indicadores sensíveis e confiáveis do nível de vigor de sementes de milho. Vinte lotes de milho foram avaliados pelos testes de germinação, de condutividade elétrica, frio e de emergência da plântula. Após 12 h, 24 h, 36 h e 48 h do início da germinação, foram avaliados também as concentrações de fósforo inorgânico (Pi), fósforo, cálcio, potássio e magnésio por meio das técnicas de análise de injeção em fluxo (FIA) e de espectrometria de emissão ótica acoplada a plasma de argônio induzido (ICP-OES). Para estas análises, os minerais foram extraídos de amostras moídas com água a 95ºC, agitadas por 30 minutos e centrifugadas. Concluiu-se que as concentrações de Pi, P, Ca, Mg e K, extraídos pelo método da água aquecida, em sementes de milho híbrido após determinados períodos de germinação, permitiram agrupar amostras de lotes de sementes de forma idêntica à permitida pelos resultados obtidos com vários testes utilizados para avaliar o nível de vigor de amostras de sementes. Nesse trabalho isso foi verificado pelas avaliações dos níveis de Pi após 12 h e 48 h, de P após 12 h, 36 h e 48 h, de Ca após 24 h, 36 h e 48 h, de Mg após 36 h e 48 h e de K após 36 h e 48 h de germinação.<br>Abstract: Most of the traditional methods used for seed vigor evaluation are qualitative and, as such, prone to errors and results misinterpretation. Quantitative methods may constitute more reliable alternatives. The aim of this work was to verify if the concentrations of some minerals stored in the seeds and made available during the initial stages of the germination process constitute sensitive and reliable indicators of the level of corn seed vigor. Twenty seed lots were evaluated by means of the germination, electrical conductivity, cold and seedling field emergence tests. Additionally, the concentrations of inorganic phosphorus, phosporus, calcium, potassium and magnesium at 12 h, 24 h, 36 h and 48 h after the initiation of the germination process were also evaluated by means of the injection analysis in flow (FIA) and the spectrometry of optic emission coupled to plasma of induced argon (ICP-OES) techniques. For these analyses grinded seed samples were extracted with water at 95ºC, agitated for 30 minutes and centrifuged . It was concluded that the concentrations of Pi, P, Ca, Mg and K, extracted by the warm water method, in hybrid corn seeds after certain stages of the germination process, allowed the rating the of seed lots in a way similar to that obtained with the results of several other seed vigor tests. Specifically, this was achieved by evaluating the concentratrions of Pi after 12 h and 48 h, of P after 12 h, 36 h and 48 h, of Ca after 24 h, 36 h and 48 h, of Mg after 36 h and 48 h and of K after 36 h and 48 h after the beginning of the germination process.<br>Mestre
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Campbell, Diane R., Alison K. Brody, Mary V. Price, Nickolas M. Waser, and George Aldridge. "Is Plant Fitness Proportional to Seed Set? An Experiment and a Spatial Model." UNIV CHICAGO PRESS, 2017. http://hdl.handle.net/10150/626253.
Full textAbstract:
Individual differences in fecundity often serve as proxies for differences in overall fitness, especially when it is difficult to track the fate of an individual's offspring to reproductive maturity. Using fecundity may be biased, however, if density-dependent interactions between siblings affect survival and reproduction of offspring from high- and low-fecundity parents differently. To test for such density-dependent effects in plants, we sowed seeds of the wildflower Ipomopsis aggregata (scarlet gilia) to mimic partially overlapping seed shadows of pairs of plants, one of which produced twice as many seeds. We tested for differences in offspring success using a genetic marker to track offspring to flowering multiple years later. Without density dependence, the high-fecundity parent should produce twice as many surviving offspring. We also developed a model that considered the geometry of seed shadows and assumed limited survivors so that the number of juvenile recruits is proportional to the area. Rather than a ratio of 2:1 offspring success from high- versus low-fecundity parents, our model predicted a ratio of 1.42:1, which would translate into weaker selection. Empirical ratios of juvenile offspring and of flowers produced conformed well to the model's prediction. Extending the model shows how spatial relationships of parents and seed dispersal patterns modify inferences about relative fitness based solely on fecundity.
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Nciizah, Adornis Dakarai. "Aggregate stability, crust formation, steady state infiltration and mode of seedling emergence in soils with various texture and mineralogy." Thesis, University of Fort Hare, 2014. http://hdl.handle.net/10353/d1015539.
Full textAbstract:
The general objective of this study was to quantify the interactive effects of soil texture and mineralogy on soil crusting, infiltration and erosion and the subsequent effects on maize seedling emergence and early development using soils collected from 14 ecotopes in the Eastern Cape Province. The specific objectives were to determine; i) particulate organic matter, soil texture and mineralogy relations, ii) aggregate stability and breakdown mechanisms as affected by soil texture and organic matter, iii) crust formation and steady state infiltration, iv) rainfall pattern effects on crusting, infiltration and erodibility and v) rainfall intensity effects on crusting and mode of seedling emergence. Particulate organic matter (POM) was fractionated into litter POM, coarse POM and fine POM. Both total soil organic matter (SOM) and the POM in each fraction were determined using the weight loss on ignition procedure. Most ecotopes were either sandy loam or sandy clay loam and primary minerals especially quartz dominated the soil mineralogy. The clay content was significantly related to the total SOM (r = 0.78), hematite (r = 0.83) and quartz (r = -0.74). Aggregate stability was determined following methods described by Le Bissonnais (1996) i.e. fast wetting (FW), slow wetting (SW) and wet stirring (WSt). Aggregate breakdown followed the order; slaking < mechanical breakdown < micro-cracking for most ecotopes except Lujiko Leeufontein and Amatola Jozini where SW and WSt resulted in the least MWD respectively. Aggregate stability was significantly correlated to POM only for FW and SW and only positive but not significant for WSt. To study crust formation, aggregate sizes <2, 2 to 3, 3 to 5 mm were exposed to 60 mm hr-1 simulated rainfall. Sieving structural crusts, ~0.2 to ~0.8 mm thick with a surface layer of loose grains overlying a thin plasmic layer, formed in all ecotopes. Crusts with strengths between 0.25 and 3.42 10-4 kg m-2 developed on the <2 mm compared to <2.23 10-4 kg m-2 in the >2 mm aggregates. The reverse occurred in Alice Jozini, which had relatively low clay content of 120 g kg-1. Two significantly different groups of the SSIR were observed. The SSIR was between 1.24 and 3.60 mm hr-1 in the group of ecotopes dominated by primary minerals and relatively lower clay content. In the second group, consisting one ecotope dominated by kaolinite and relatively higher clay content, the SSIR was 15.23 mm hr-1. Rainfall pattern i.e. rainfall applied either as an eight minute single rainstorm (SR) or four-two minute intermittent rainstorms (IR) separated by a 48 h drying period significantly (p < 0.05) affected crust strength, SSIR and erosion. The IR resulted in higher crust strength and SSIR than SR. The effect of rainfall pattern on SSIR was mostly influenced by the primary minerals namely, quartz. Three maize seeds of equal size were planted in plastic pots, pre-wetted by capillary action and then subjected to simulated rainfall at three intensities for 5 min. Rainfall intensity (30, 45 and 60 mm h-1) significantly (P < 0.05) affected crust strength and mean emergence day (MED) but not emergence percentage (EMP) and shoot length (P > 0.05). The 60 mm h-1 rainfall intensity resulted in the highest crust strength and MED.
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Legras, Elaine C. "Microhabitat is critical for sugar pine seedlings emergence and survival in a xeric Jeffrey pine dominated forest /." abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1455660.
Full textAbstract:
Thesis (M.S.)--University of Nevada, Reno, 2008.<br>"May, 2008." Includes bibliographical references (leaves 39-44). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
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Magalhães, Stefânia Caixeta [UNESP]. "Disponibilidade de minerais, germinação e vigor de sementes de milho." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/96797.
Full textAbstract:
Made available in DSpace on 2014-06-11T19:28:27Z (GMT). No. of bitstreams: 0
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magalhaes_sc_me_jabo.pdf: 624079 bytes, checksum: 37a746a1dac768fd2d8f6dcc974b9b8d (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>A maioria dos métodos utilizados para estimar o vigor de amostras de sementes são qualitativos, portanto sujeito a erros do avaliador e de interpretação dos resultados. Metodologias quantitativas podem constituir alternativas mais confiáveis. Este trabalho teve como objetivo verificar se os níveis de alguns minerais armazenados nas sementes e disponibilizados durante etapas iniciais do processo de germinação constituem indicadores sensíveis e confiáveis do nível de vigor de sementes de milho. Vinte lotes de milho foram avaliados pelos testes de germinação, de condutividade elétrica, frio e de emergência da plântula. Após 12 h, 24 h, 36 h e 48 h do início da germinação, foram avaliados também as concentrações de fósforo inorgânico (Pi), fósforo, cálcio, potássio e magnésio por meio das técnicas de análise de injeção em fluxo (FIA) e de espectrometria de emissão ótica acoplada a plasma de argônio induzido (ICP-OES). Para estas análises, os minerais foram extraídos de amostras moídas com água a 95ºC, agitadas por 30 minutos e centrifugadas. Concluiu-se que as concentrações de Pi, P, Ca, Mg e K, extraídos pelo método da água aquecida, em sementes de milho híbrido após determinados períodos de germinação, permitiram agrupar amostras de lotes de sementes de forma idêntica à permitida pelos resultados obtidos com vários testes utilizados para avaliar o nível de vigor de amostras de sementes. Nesse trabalho isso foi verificado pelas avaliações dos níveis de Pi após 12 h e 48 h, de P após 12 h, 36 h e 48 h, de Ca após 24 h, 36 h e 48 h, de Mg após 36 h e 48 h e de K após 36 h e 48 h de germinação.<br>Most of the traditional methods used for seed vigor evaluation are qualitative and, as such, prone to errors and results misinterpretation. Quantitative methods may constitute more reliable alternatives. The aim of this work was to verify if the concentrations of some minerals stored in the seeds and made available during the initial stages of the germination process constitute sensitive and reliable indicators of the level of corn seed vigor. Twenty seed lots were evaluated by means of the germination, electrical conductivity, cold and seedling field emergence tests. Additionally, the concentrations of inorganic phosphorus, phosporus, calcium, potassium and magnesium at 12 h, 24 h, 36 h and 48 h after the initiation of the germination process were also evaluated by means of the injection analysis in flow (FIA) and the spectrometry of optic emission coupled to plasma of induced argon (ICP-OES) techniques. For these analyses grinded seed samples were extracted with water at 95ºC, agitated for 30 minutes and centrifuged . It was concluded that the concentrations of Pi, P, Ca, Mg and K, extracted by the warm water method, in hybrid corn seeds after certain stages of the germination process, allowed the rating the of seed lots in a way similar to that obtained with the results of several other seed vigor tests. Specifically, this was achieved by evaluating the concentratrions of Pi after 12 h and 48 h, of P after 12 h, 36 h and 48 h, of Ca after 24 h, 36 h and 48 h, of Mg after 36 h and 48 h and of K after 36 h and 48 h after the beginning of the germination process.
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Silva, Josué Bispo da. "Testes para avaliar o potencial fisiológico de sementes de beterraba /." Jaboticabal : [s.n.], 2006. http://hdl.handle.net/11449/105115.
Full textAbstract:
Orientador: Roberval Daiton Vieira<br>Banca: Teresinha de Jesus Deléo Rodrigues<br>Banca: Arthur Bernardes Cecílio Filho<br>Banca: Júlio Marcos Filho<br>Banca: Ana Dionisia da Luz Coelho Novembre<br>Resumo: O uso de testes de vigor é imprescindível na avaliação do potencial fisiológico das sementes produzidas e comercializadas por uma empresa. O trabalho, dividido em duas etapas, teve por objetivo estudar diferentes testes para avaliar o potencial fisiológico de sementes de beterraba. Com base nos resultados, concluiu-se que os testes de EA, EASS-20, EASS-40 e DC podem ser utilizados para avaliar o potencial fisiológico de sementes de beterraba; o uso de soluções salinas apresenta vantagem sobre o procedimento tradicional; o ajuste do TA das sementes no teste de deterioração controlada deve ser feito pelo método do substrato úmido.<br>Abstract: The use of vigor tests is essential to evaluate the physiological potential of seed lots produced and selled by a company. The work, separated in two stages, aimed to study different vigor tests to evaluate the physiological potential of beetroot seeds. With base in the results, it was concluded that EA, EASS-20, EASS-40 and DC tests can be used to evaluate the physiological potential of beet seeds; the use of solutions presents advantage on the traditional procedure; the adjustment of seed MC in the controlled deterioration test would be done by the method of humid substratum.<br>Doutor
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Taab, Alireza. "Seed dormancy and germination in Solanum nigrum and S. physalifolium as influenced by temperature conditions /." Uppsala : Dept. of Crop Production Ecology, Swedish University of Agricultural Sciences, 2009. http://epsilon.slu.se/200949.pdf.
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Silva, Josué Bispo da [UNESP]. "Testes para avaliar o potencial fisiológico de sementes de beterraba." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/105115.
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silva_jb_dr_jabo.pdf: 199072 bytes, checksum: 14fd74baadfa1ee3eebbb79f63e6a4fa (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA)<br>O uso de testes de vigor é imprescindível na avaliação do potencial fisiológico das sementes produzidas e comercializadas por uma empresa. O trabalho, dividido em duas etapas, teve por objetivo estudar diferentes testes para avaliar o potencial fisiológico de sementes de beterraba. Com base nos resultados, concluiu-se que os testes de EA, EASS-20, EASS-40 e DC podem ser utilizados para avaliar o potencial fisiológico de sementes de beterraba; o uso de soluções salinas apresenta vantagem sobre o procedimento tradicional; o ajuste do TA das sementes no teste de deterioração controlada deve ser feito pelo método do substrato úmido.<br>The use of vigor tests is essential to evaluate the physiological potential of seed lots produced and selled by a company. The work, separated in two stages, aimed to study different vigor tests to evaluate the physiological potential of beetroot seeds. With base in the results, it was concluded that EA, EASS-20, EASS-40 and DC tests can be used to evaluate the physiological potential of beet seeds; the use of solutions presents advantage on the traditional procedure; the adjustment of seed MC in the controlled deterioration test would be done by the method of humid substratum.
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Roso, Rodrigo. "Echium plantagineum L. (boraginaceae): superação da dormência, respostas à temperaturas, luz e profundidades de semeadura." Universidade Federal de Santa Maria, 2017. http://repositorio.ufsm.br/handle/1/11651.
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Echium plantagineum is considered an annual invasive ruderal plant, possibly biennial, originating in the Mediterranean region and Western Europe, of easy adaptation, with up to 1,5 m of height, reproduced by seeds, and with potential to become weed. Besides being easy to adapt to different environmental conditions. Besides being easy to adapt to different environmental conditions. In view of the above, the objective of the work is to evaluate methods of overcoming dormancy, light regimes, temperature variations and seeding depths in the physiological quality of E. plantagineum seeds. Three experiments were conducted, two in the laboratory, in which Experiment I evaluated seed dormancy overcoming treatments with high temperature exposure times (42 °C) and humidity [TU] (100%) (24, 48, 72 and 96 h), immersion times in potassium nitrate (PN) (0,2%) (6, 12, 18 and 24 h), immersion in concentrations of gibberellic acid [GA] (250, 500, 750, 1000 and 1500 mg L-1), and PN + GA (12 h) + (125, 250, 375, 500 and 625 mg L-1). In Experiment II the seeds were submitted to different constant temperatures (5, 10, 15, 20, 25, 30 and 35 °C) in the presence or absence of light. Experiment III was conducted in a greenhouse, in which the seeds were allocated to different soil depths (0,0, 1,0, 2,0, 3,0, 4,0, and 5,0 cm) in the presence or absence of plant cover with ryegrass straw (Lolium multiforum L.). In general, the pre-germination treatments using PN and GA applied sequentially are favorable for overcoming dormancy, allowing maximum expression of vigor and germination of the seeds, making it possible to generate seedlings with normal primary structures. Seeds of E. plantagineum can be classified as neutral photoblasts, having a temperature of 20 °C as optimum for germination, variable from 10 to 30 °C. When the seeds were submitted to depths in the soil, there was a significant decrease of the emergence with the increase of the depth, being the seeds located at the surface showed greater emergence, occurring positive influence of the soil cover with straw.<br>Echium plantagineum é considerada uma planta ruderal invasiva anual, eventualmente bienal, originária da região do Mediterrâneo e Europa Ocidental, de fácil adaptação, com até 1,5 m de estatura, reproduzida por sementes, e com potencial para se converter em planta daninha. Além de possuir fácil capacidade de adaptação a diferentes condições ambientais. Diante do exposto, o trabalho tem como objetivos avaliar métodos de superação da dormência, regimes de luz, variações de temperaturas e profundidades de semeadura na qualidade fisiológica de sementes de E. plantagineum. Foram conduzidos três experimentos, sendo dois em laboratório, em que no Experimento I avaliou-se tratamentos de superação de dormência de sementes com tempos de exposição a alta temperatura (42 °C) e umidade [TU] (100%) (24, 48, 72 e 96 h), tempos de imersão em nitrato de potássio [NP] (0,2%) (6, 12, 18 e 24 h), imersão em concentrações de ácido giberélico [AG] (250, 500, 750, 1000 e 1500 mg L-1), e NP+AG (12 h) + (125, 250, 375, 500 e 625 mg L-1). No Experimento II as sementes foram submetidas a diferentes temperaturas constantes (5, 10, 15, 20, 25, 30 e 35 °C) em presença ou ausência de luz. O Experimento III foi conduzido em casa de vegetação, no qual as sementes foram alocadas a diferentes profundidades no solo (0,0, 1,0, 2,0, 3,0, 4,0, e 5,0 cm) sob presença ou ausência de cobertura vegetal com palha de azevém (Lolium multiforum L.). Em geral, os tratamentos pré-germinativos utilizando NP e AG aplicados de forma sequencial são favoráveis para a superação da dormência, permitindo máxima expressão do vigor e germinação das sementes, possibilitando gerar plântulas com estruturas primárias normais. As sementes de E. plantagineum podem ser classificadas como fotoblásticas neutras, possuindo a temperatura de 20 °C como ótima para germinação, variável de 10 a 30 °C. Quando as sementes foram submetidas a profundidades no solo, ocorreu diminuição acentuada da emergência com o aumento da profundidade, sendo que as sementes localizadas na superfície apresentaram maior emergência, ocorrendo influência positiva da cobertura do solo com palha.
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Leeks, C. R. F. "Determining seed vigour in selected Brassica species." Lincoln University, 2006. http://hdl.handle.net/10182/1274.
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Variables for the accelerated ageing (AA) test, methods for reducing fungal contamination during the AA test, using the conductivity test as a vigour test, the effect of seed size on seed vigour and the relationship between laboratory test results and field perfonnance in selected Brassica spp were investigated. In the first experiment, three seed lots of turnip rape hybrid (B. rapa x campestris), turnip (B. campestris) and forage rape (B. napus); and seven seed lots of Asian rape (B. napus), six seed lots of Asian kale (B. oleraceae var. alboglabra L.) and five seed lots of choisum (B. rapa var. pekinensis) with germinations above 90% were aged at two different temperatures (41 and 42°C ± 0.3°C) and three ageing times (24, 48 and 72 ± 15 minutes). The second experiment was divided into three sections. In the first, the same seed lots and species were aged at one temperature (41°C) and time (72 h), but either 40 ml of saturated salts; KCl (83%RH), NaCl (76%RH), NaBr (55%RH); or distilled water (96%RH) were used as the ageing solutions. In the second, one turnip rape hyprid seed lot was aged at three temperatures (41, 42 and 45°C) and two times (72 and 96h), again using the three saturated salts and distilled water as ageing solutions. In the third, three turnip rape hybrid seed lots and three Asian kale seed lots were surface sterilised (1 % sodium hypochlorite) prior to ageing at one temperature (41°C) and time (72 h). In the third experiment, the same species and seed lots used in experiment one at their original seed moisture content (SMC) were tested for conductivity after soaking in deionised water for 4, 8, 12, 16, 20 and 24 h. They were then re-tested after the SMC had been adjusted to 8.5%. In the fourth experiment, three seed lots of forage rape and three seed lots of Asian kale were graded into three seed size categories; large (retained on a 2.0 mm screen), medium (retained on a 1.7 mm screen) and small (passed through a 1.7 mm screen). Graded seeds were then tested for standard germination, AA (41°C/48 h) and conductivity (measured at 16 and 24 h). In the final experiment, the relationships between laboratory tests for the six species (each consisting of three seed lots), field emergence from three sowings, and cold room emergence were evaluated. Both time and temperature influenced post-AA germination. Increasing the ageing period from 48 to 72 hours at 41°C, and 24 to 48 hours at 42°C resulted in decreased mean germination percentage for all species but not always clear separation of seed lots. While there were sometimes few differences between ageing at 41°C and 42°C, the former is preferred because it is already the temperature used for other species. For Asian rape, choisum and turnip, the previously recommended testing conditions of 41°C/72 h provided good seed lot separation, but for Asian kale and turnip rape hybrid, AA testing at 41°C/48 h provided better results. Seed moisture content after ageing ranged from 29-37% depending on species. Fungal growth on seeds during the ageing period appeared to reduce post-ageing germination in some seed lots . Substituting saturated salts for distilled water did not stress seed lots in the AA test, due to the lowered RH%, the exception being seed lots 1210 and 1296. For forage and Asian species, seed lot germination mostly remained above 90% when aged for 72 h at lowered RH%. Increasing the ageing duration from 72 to 96 hours resulted in some decreases in post-AA germination but no clear separation of seed lots. Surface sterilising the seeds prior to the AA test resulted in a lower incidence of contaminant fungi which was associated with a lower percentage of abnormal seedlings. The conductivity test was mostly able to identify vigour differences among forage and Asian vegetable brassica seed lots. Differences in conductivity readings were observed among seed lots in all species. Increasing the period of imbibition resulted in increased conductivity from most seed lots but radicle emergence occurred after 16-20 h of imbibition. Variation was observed in the time to reach 95% maximum of the imbibition curve for most species. Conductivity readings at 16 h would avoid possible influences of radicle emergence on results. Adjusting the SMC to 8.5% resulted in reduced variation in conductivity among replicates of seed lots, due to a reduction in imbibition damage. Seed size had a significant effect on both post-AA germination and conductivity results. In forage rape, large size seeds had higher post-AA germination cf. medium cf. small size seeds. In Asian kale, large size seeds had higher post-AA germination compared with small size seeds. For both forage rape and Asian kale, large size seeds had lower conductivity readings cf. small size seeds. The correlation analyses demonstrated significant relationships between AA testing and field emergence parameters (percentage emergence, emergence index and emergence rate). Significant relationships were also observed between conductivity testing and these field emergence parameters. Based on the correlation analysis, AA testing at 41°C/48 hand/or 42°C/48 h could be recommended to be used as an AA test for turnip and Asian rape; and 41°C/48 hand/or 41°C/72 h for Asian kale and choisum. Based on the correlation analysis, conductivity testing at 16 h can be used to predict the field emergence potential of forage and Asian vegetable seed lots. Vigour tests were consistently able to provide better indicators of field perfonnance than the standard germination test, although these relationships did vary with the different field sowings.
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Vithanage, Krishanthi D. "ECOPHYSIOLOGY OF SEEDLING EMERGENCE AND DEVELOPMENT OF SEEDLING EMERGENCE MODELS (SEM) FOR CUT AND PEEL CARROTS (Daucus carota var Sativus L.)." Thesis, 2013. http://hdl.handle.net/10222/35305.
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Effect of soil moisture potential (?), temperature (T), genotype, seeding depth (SD) and rate (SR) on seedling emergence (SE), emergence velocity (EV), root yield and grades of cut and peel carrots were studied.
SE was reduced at –120 kPa and totally inhibited at -156 kPa. EV was the lowest at – 5 kPa and – 90 kPa. SE was delayed by 33 d at 5°C, reduced at 30°C and totally inhibited at 35 and 40 °C. Heat units 99.75 and 159.60°Cd were the lowest to initiate and complete SE respectively while the optimum was 300 – 350 °Cd. There was no interaction effect between ? and T on SE. Honey snax at 85 seeds/ 30 cm showed the best SE whereas, Triton recorded the highest total yield at 2.54 cm SD and Fancy yield at 85 seeds/ 30 cm implying certain crop ecological and management factors can influence SE, root yield and quality.
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Fessehazion, M. K. (Melake Kessete). "Predicting and improving seedling emergence of three vegetable crops." Diss., 2005. http://hdl.handle.net/2263/27620.
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The predictive values of standard and non-standard germination temperatures, standard accelerated ageing (AA) and saturated salt accelerated ageing (SSAA) tests were investigated. Germination tests were performed at standard and non-standard temperatures of 10°, 20°, 20°/30° and 30°C for cabbage and tomato, and 10°, 15°, 20° and 30°C for onion. The AA and SSAA tests were conducted using four relative humidities: standard AA (RH100), NaCl (RH75), Ca(NO3)2 (RH43) and MgCl2 (RH32). Emergence trials were also conducted at a range of temperatures (winter, 15°/25° and 30°C) and media (Hygromix and soil) using seedling trays. Correlations were calculated to evaluate the relationship between laboratory and emergence test results. Three onion seed lots that have different vigour levels were primed with PEG or NaCl and were germinated and planted under varying temperatures and levels of salinity. There were vigour differences among different seed lots of cabbage, onion and tomato seeds used in this study. Using the different laboratory tests, seed lots were distinguished as high, medium and low vigour seed lots. The low temperature germination test (10°C) for cabbage and onion; and 20°C for tomato were found to be effective for separation of seed lots according to their vigour levels. All SSAA vigour tests were also useful in differentiating seed lots based on their physiological stage of deterioration. Using the standard AA (RH100) the seed moisture content was high (29 to 45%), resulting in fungal growth. However, in the SSAA test the moisture content was below 14% and no fungal growth was observed. Ageing of seed lots using NaCl and MgCl2 resulted in a low narrow range of moisture contents, but using Ca (NO3)2 the range of the moisture content between seed lots was higher. For all crop seeds, there was no significant difference in the percentage emergence between the two growth media but larger seedlings were observed from the commercial growth medium (Hygromix). For cabbage, highly significant correlations were obtained between germination percentage at 10°C and RH32 and all emergence trials. In onion, the correlations were not consistent; highly significant correlations were observed from germination capacity (GC), 15°C, 20°C, 30°C, RH75 and RH32; and emergence parameters at specific conditions. However, the germination percentage from 30°C correlated significantly with the final emergence percentage and seedling vigour index. Germination of tomato seeds at 20°C and all SSAA had highly significant correlation with all emergence parameters. The germination rate parameters: MGT (mean germination time) and GI (germination index) were valuable in categorising seed lots with moderate vigour levels, however, except GE in cabbage and onion, all other germination rate characters failed to correlate with any emergence parameters. The radicle percentage germination (viability or GC) and final emergence percentage (FEP) were not enhanced by priming in all seed lots in the germination and emergence trials at all temperatures. The percentage of normal seedling was increased due to priming when seeds were subjected to low temperature and higher salinity levels. Priming was effective in improving the rate, uniformity of germination/emergence; and increased the seedling dry mass of onion seeds when grown under relatively cold environmental conditions. Priming was more beneficial for low vigour seed lots (seed lot A) than for high vigour seed lots (B, C). Priming also improved germination rate and uniformity at all salinity levels, but faster rate of emergence, more uniform and higher seedling dry mass were only observed when seeds were watered with low salinity levels (25 mM of NaCl). No significant difference was observed using NaCl or PEG as priming agent. Onion seeds are tolerant to salinity during germination and the effect of priming was more beneficial at emergence.<br>Dissertation (MSc (Agric) Horticulture)--University of Pretoria, 2007.<br>Plant Production and Soil Science<br>unrestricted
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Lin, Tsu-Chi, and 林祖祺. "Functional Study of Tocochromanols in Rice Grain during Seedling Emergence." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/49056351718846826193.
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碩士<br>國立臺灣大學<br>農業化學研究所<br>103<br>Tocopherols (Toc) and tocotrienols (T3), collectively known as tocochromanols, are lipid-soluble antioxidants that belong to the group of vitamin E compounds, and possess good physiological activities in human body. Because T3 only present in seeds and fruits of a limited number of plant species, and their functions in plants remain unclear, hence it is necessary to have an insight understanding of their roles. This study aimed to examine the functions of tocochromanols in two rice varieties, namely Tainung 71 (TN71) and Kaoshiung 139 (KS139). Samplings were conducted at 0, 3, 6, 9, 12, 15 and 18 days after imbibition (DAI). The rice grain samples were examined for oxidation stress markers, antioxidative enzyme activities and antioxidant contents, in view of understanding the relationship between the roles of tocochromanols and antioxidant network, and the reason for their T3 present in seeds. The results showed that during seedling emergence, the oxidative markers concentration, antioxidative enzyme activities and antioxidant concentration in late stage (12 to 18 DAI) were higher than early stage. In terms of content, H2O2 and MDA contents were not significantly change in rice seeds. The ascorbate (AsA) content changed in different trends in TN71 and KS139. The Toc content decreased in the early stage but increased significantly in mid-late stage; this situation could be resulted from the expense of alpha-Toc in the early stage and the large accumulation of gamma-Toc after 9 DAI. Unlike Toc, the change of T3 content was not obvious during the seedling emergence. Nevertheless, alpha-T3 and gamma-T3 appeared to increase in contents at 0 to 12 DAI and decrease at 15 to 18 DAI. The gamma-oryzanol content increased in the early stage and maintained of a high level in the late stage. This study indicates that the antioxidative enzymes and contents of ASA and tocochromanols play an important role in the axtioxidant system network, and coordinating with each other to maintain the redox homeostasis during seedling emergence. The rice seeds may enter a different growing phase in the mid-late stage of seedling emergence that may need potent anioxidative enzyme activities and high amount of antioxidant, as well as the different forms of tocochromanols for fulfilling the requirement of different metabolisms, suggesting that tocochromanols have different functions in plants. As for tocotrienols, they may involve in seedling emergence through functioning as antioxidants or providing other functions in assisting the growth of seedlings.
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Mohamed, Ahmed Mahmoud. "Emergence, seedling vigor, and stand establishment of pearl millet as affected by mesocotyl elongation and other seed and seedling traits." 1985. http://hdl.handle.net/2097/27505.
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Donahue, Candice. "Restoring a prairie: Testing effectiveness of Chinese tallow tree (Sapium sebiferum) mulch to reduce seedling emergence." Thesis, 2004. http://hdl.handle.net/1911/17668.
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The invasive Chinese tallow tree (Sapium sebiferum) is difficult to control because of its large seed bank and ability to resprout from cut stumps. I performed laboratory and field experiments to evaluate the effectiveness of mulching live trees for restoring invaded prairies. Herbicide use was limited to manual application to cut stumps. I manipulated mulch depths and types in the field and measured soil temperatures beneath them. At depths of as little as 5 cm, Sapium mulch damped soil temperature fluctuations and reduced seedling emergence. Reduced seedling emergence was not the result of allelopathic compounds in Sapium mulch because other mulch types suppressed emergence similarly. Substantial regrowth of native vegetation occurred through the mulch. Independent manipulations of mulch depth and temperature fluctuations in a lab experiment confirmed that mulch suppressed seed germination indirectly via soil temperature effects. This prairie site can now be managed by mowing or burning.
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"ROLE OF FIRE AND PLANT-DERIVED SMOKE IN SEED GERMINATION AND SEEDLING EMERGENCE IN FESCUE PRAIRIE." Thesis, 2015. http://hdl.handle.net/10388/ETD-2015-12-2331.
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Fire, a natural disturbance, regulates species composition in Fescue Prairie. However, little is known about the contribution of different regeneration strategies in altering species composition after burning in Fescue Prairie. The present study was conducted to determine if and how fire and associated fire cues regulate species composition in Fescue Prairie through their effects on seedling recruitment. The effects of fire and various fire cues, including smoke, ash, and smoke plus ash on seedlings emerging in the field and/or from litter, 0-1 cm, and 1-5 cm layers of the soil seed banks were therefore examined. These studies were complimented by a study of testing effects of smoke originated from different plant materials on seed germination and seedling growth of species from Fescue Prairie. Chemical analyses were also conducted to determine whether different active compounds existed in smoke made from different materials, which in turn affect germination and seedling growth differently. Burning increased densities, richness, and diversity of seedlings emerging in the field. This was possibly attributed to direct fire cues of burning. Seedling densities of native forbs and non-native graminoids emerging from the soil seed bank were increased and decreased by burning, respectively. Ash and smoke plus ash increased density of forbs emerging from the soil seed bank. Species composition of seedlings emerging in the field and from the soil seed bank was altered by burning. Complex responses were observed for the effects of smoke on seedling establishment, which depended on the type and dilution of smoke solutions, as well as germination conditions. Smoke solutions partly substituted light requirement for germination of Artemisia ludoviciana. Germination of Cirsium arvense and Conyza canadensis only responded to smoke solutions at 25/15°C, but not at 10/0 °C. Diluted smoke solutions increased radical length of Artemisia ludoviciana. Karrikinolide (KAR1) was in the smoke made from prairie hay and wheat straw, but not in that made from alfalfa. This is the first report that different active compounds existed in smoke made from different materials. Highly concentrated smoke solutions made from alfalfa increased germination and radical length of Conyza canadensis, while the same concentrated smoke solutions made from prairie hay and wheat straw reduced germination of Conyza canadensis at 25/15 °C in darkness. Priming in KAR1 solutions and active fractions obtained from prairie hay and/or wheat straw increased germination of Artemisia frigida, Artemisia ludoviciana, and Conyza canadensis at certain germination conditions. In summary, fire and direct fire cues, smoke and ash specifically, stimulated recruitment of some species, especially early seral species and native forbs, contributing to potential changes in species composition of the Fescue Prairie. Different compounds existed in smoke solutions made from alfalfa as compared with those from prairie hay and wheat straw, showing different effects on seed germination and seedling growth. KAR1, the most important active compound discovered in smoke, was present in the smoke made from prairie hay and wheat straw, but was not in that made from alfalfa.