Vegetable soybean, also known as edamame, has become increasingly popular in the United States due to its excellent nutrition and health benefits. This rising demand has sparked the interest of local farmers in growing edamame. However, a significant problem in edamame production is the poor seedling emergence. This dissertation focuses on three key objectives: 1) exploring the physiological traits linked to the low emergence of edamame seeds; 2) enhancing edamame seedling emergence by identifying genotypes with high vigor and resistance to soil-borne diseases; and 3) determining the optimal temperature for edamame seedling emergence. The study includes newly developed edamame breeding lines from the soybean breeding programs at Virginia Tech and the University of Arkansas, and major edamame cultivars commonly used in the Mid-Atlantic region. The results have identified several genotypes that exhibit high seeding vigor, aging tolerance, and consistently achieve a plant stand of over 80% in both laboratory and field conditions. It is also clarified that edamame's larger seed size leads to lower germination rates and slower emergence, although this is not correlated to total emergence. Moreover, environmental factors, pathogens and temperature, impact emergence. The study highlights that current edamame genotypes are commonly affected by soilborne pathogens, including Rhizoctonia solani, Athelia rolfsii, and Pythium irregulare, leading to seed rot and seedling damping off. However, the research has successfully identified partially resistant varieties characterized by significantly low disease indexes (p<0.05). Furthermore, the optimal temperature range for edamame seedling emergence (25-32°C) was found to be lower than that of other types of soybeans such as grain-type soybeans (29-36°C). This research provides a scientific foundation to improve edamame production practices. / Doctor of Philosophy / Vegetable soybean, also known as edamame, commonly consumed as a healthy snack, is steadily gaining popularity in the United States. However, there are significant challenges in achieving successful edamame plant growth from seeds. This research focuses on three primary objectives: first, understanding the underlying factors contributing to poor seedling emergence in edamame; second, identifying edamame genotypes with exceptional vigor and resistance to soil-borne diseases; and third, determining the ideal temperature conditions for optimal edamame seedling development. To accomplish these goals, a comprehensive study was conducted, encompassing various edamame varieties, including those developed by Virginia Tech and the University of Arkansas. The research identified some edamame genotypes that exhibited exceptional seed vigor, aging tolerance, and consistently achieved plant stands of over 80% under both laboratory and field conditions. Additionally, we also learned that bigger edamame seeds take longer time to grow, but the seed size does not affect the total emergence. Furthermore, we found that some diseases in the soil can hurt edamame seedlings, but we identified a few genotypes that are more resistant to these diseases. Lastly, in terms of temperature, we found that edamame seedlings grow the best between 25-32°C, which is slightly lower than other types of soybeans. Overall, this research helps farmers grow better edamame and brings more delicious and healthy food to our tables.

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.

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.

With the rapid proliferation of carbon nanotube technologies and consumer products comes a need to research the toxicological and ecotoxicological effects of these materials. This research attempted to develop a baseline knowledge of the effects of bulk, unmodified multi-walled carbon nanotubes on commonly studied soil toxicology test organisms: earthworms, springtails, and agricultural plants. In order to minimize confounding factors in the study, a slurry composed of bulk multi-walled carbon nanotubes, silica sand, and water was used to amend test soil without the use of surfactants or functionalization. Analysis of data produced by these experiments showed no significant trends resulting from the exposure of the test organisms to artificial soil amended by the multi- walled carbon nanotube slurry. It was observed, however that carbon nanotubes accumulated in the gut of the earthworm Eisenia andrei and were expelled as castings in the test soil.

With the rapid proliferation of carbon nanotube technologies and consumer products comes a need to research the toxicological and ecotoxicological effects of these materials. This research attempted to develop a baseline knowledge of the effects of bulk, unmodified multi-walled carbon nanotubes on commonly studied soil toxicology test organisms: earthworms, springtails, and agricultural plants. In order to minimize confounding factors in the study, a slurry composed of bulk multi-walled carbon nanotubes, silica sand, and water was used to amend test soil without the use of surfactants or functionalization. Analysis of data produced by these experiments showed no significant trends resulting from the exposure of the test organisms to artificial soil amended by the multi- walled carbon nanotube slurry. It was observed, however that carbon nanotubes accumulated in the gut of the earthworm Eisenia andrei and were expelled as castings in the test soil.

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.

No description available.

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.

Made available in DSpace on 2014-06-11T19:33:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-03-27Bitstream added on 2014-06-13T18:45:35Z : No. of bitstreams: 1 silva_jb_dr_jabo.pdf: 199072 bytes, checksum: 14fd74baadfa1ee3eebbb79f63e6a4fa (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) / 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. / 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.

Orientador: Roberval Daiton Vieira / Banca: Teresinha de Jesus Deléo Rodrigues / Banca: Arthur Bernardes Cecílio Filho / Banca: Júlio Marcos Filho / Banca: Ana Dionisia da Luz Coelho Novembre / 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. / 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. / Doutor