Symbiotic interactions among various organisms are often necessary for one or both individual's survival. These symbiotic relationships must be considered in restoration projects to allow for the successful establishment of the species. Rhizobia are nitrogen-fixing bacteria found in symbiotic relations with legumes. By utilizing this relationship, restoration practitioners can establish native legume species more successfully while repopulating soil microorganisms into degraded soils. Despite the potential benefits a rhizobium inoculant can have on restoration efforts, minimal research has been done to understand the impacts this treatment has on specific species and the systems they are employed within. Our research goal was to assess the efficacy of applying a commercial rhizobium product (EXCEED ®) and indigenous rhizobium strains on two lupine species (Lupinus argenteus Pursh and Lupinus sericeus Pursh), commonly used for rangeland seedings in the Great Basin region of the western United States. We conducted laboratory and field trials to meet this research goal, with the results of the laboratory experiments shared in chapter 1 and findings from the field reported in chapter 2. In chapter 1, we evaluated in the laboratory whether indigenous rhizobia strains could be isolated, cultured, and applied as a liquid inoculant or a seed coating to induce root nodulation and increase plant growth. The performance of these inoculums was compared against the commercial rhizobium product. Additionally, we tested in a trial if compost could be applied within the seed coating to improve the efficacy of the rhizobium treatment. Our research demonstrated that the commercial inoculum induced root nodulation, and in one of three trials, this treatment improved plant growth. We also found indigenous strains effectively formed nodules on the plant roots when applied through a liquid culture or a seed coating. However, the number of root nodules and the presence of a pink color (indicating nitrogen fixation) were typically higher in the commercial product than in the indigenous strains when applied through a seed coating. These short-term laboratory studies generally provided minimal evidence that rhizobia impacted plant growth. However, data indicated that having compost in the coating alone improved shoot biomass by 33% (P = 0.025). In chapter 2, research assessed the performance of the same rhizobia inoculums tested in the laboratory trials on a mine in northern Utah at two waste-rock sites, one comprised of crushed waste rock and the other made of waste rock amended with topsoil. One year after seeding, we had high plant recruitment at both study sites, and there were more plants, which were more vigorous, in the amended site (P<0.001). These results demonstrate that reclamation efforts on mineland overburden can be improved when topsoil is incorporated into the growing medium. At this stage in the study, there was no difference in plant establishment and vigor between any seed treatments, but future research is planned to assess these metrics in the next growing season. The lack of improvement in plant growth from a rhizobia treatment in some of our laboratory and field trials may be due to the short period of these studies. Nodules that form on mature root systems provide more nitrogen-fixing benefits than those formed on immature roots. Hence, future research should consider conducting trials for more extended periods to understand how the treatments influence the growth of mature plants. Because we found in the laboratory that the rhizobia inoculums were successful in nodulating the test species, we anticipate that future studies will find that these treatments can improve plant performance and subsequently restoration success.

O tratamento de sementes pode ser uma importante técnica para o fornecimento de micronutrientes na cultura do milho (Zea mays L.), sendo capaz de promover um melhor estabelecimento da cultura no campo. Solos contendo níveis insuficientes de zinco e de cobre para as plantas são frequentes em grande parte das regiões agrícolas do Brasil e do mundo. Deste modo, o fornecimento destes elementos via sementes pode ser uma alternativa viável e eficaz para produtores de milho. Este trabalho teve como objetivo avaliar diferentes tratamentos de sementes de milho contendo Zn e Cu, considerando aspectos relacionados à qualidade fisiológica das sementes e à eficiência nutricional. Para tal, foram utilizados quatro lotes do híbrido 2B688Hx, apresentando diferenças quanto ao tamanho e vigor das sementes. Os tratamentos foram compostos por diferentes dosagens e combinações de suspensões líquidas contendo óxido de Zn e carbonato de Cu, fornecidos juntos ou separadamente. Os lotes foram avaliados pelo teor de água das sementes, germinação e teste de frio em cinco épocas: 0, 30, 60, 180 e 360 dias. Nas três primeiras épocas, também foram realizados os testes de emergência de plântulas, velocidade de emergência de plântulas e análises do crescimento de raiz por meio do software SVIS®. O desenvolvimento inicial das plantas foi avaliado pela altura, área foliar e massa seca de raiz e de parte aérea. Os dados de massa seca associados aos teores de Zn e de Cu nos tecidos permitiram calcular as eficiências de absorção, transporte e utilização dos mesmos. A qualidade fisiológica de sementes de milho tratadas com Zn e Cu, isoladamente ou associados, não é afetada ao longo de doze meses de armazenamento; por outro lado, o Cu utilizado isoladamente causa fitotoxicidade quando a avaliação é realizada tendo o papel como substrato, afetando principalmente o desenvolvimento radicular das plântulas. O tratamento de sementes com zinco e cobre se constitui em alternativa viável e eficaz para o fornecimento destes elementos para as plantas de milho. / Seed treatment is a potential tool for supplying micronutrients on maize crop (Zea mays L.), enabling a better plant stand establishment in the field. Soils presenting insufficient levels of zinc and copper to plants are common in various agricultural regions throughout Brazil and the world. Thus, the supply of such elements via seeds can be viable and effective for maize crop. This study aimed to evaluate different maize seed treatments containing Zn and Cu, related to the effects on seeds physiological quality and nutritional efficiency. Thus, four seeds lots of the corn hybrid 2B688Hx, differing in size and vigor, were used for this study. The treatments were composed of liquid suspensions containing Zn oxide and Cu carbonate, applied together or separately at different dosages. The lots were evaluated by seed moisture, germination and cold test in five periods: 0, 30, 60, 180 and 360 days. Seedling emergence, seedling emergence speed and image analysis of root growth (software SVIS®) were also performed in the first three periods. The plants development was assessed by height, leaf area and dry weight of roots and shoots. The efficiencies of absorption, transport and utilization were calculated with the data of seedlings dry weight and tissues content of Zn and Cu. The physiological quality of maize seeds is not affected by the treatments containing Zn and Cu, together or separated, during the twelve-month storage period; on the other hand, the treatments containing only Cu caused phytotoxicity on paper-based tests, affecting mainly the seedlings root development. Seed treatment with zinc and copper is a viable and effective approach for supplying these elements to maize plants.

The primary impacts of mining on the environment include the deterioration of soil properties and the loss of vegetation cover and density, often leading to increased erosion. In order to encumber further degeneration of such ecosystems and all subsequent other negative environmental impacts, active rehabilitation practices are often implemented. Active rehabilitation involves the introduction of species by different re–seeding (re–vegetation) methodologies. A higher vegetation cover and density is needed to increase soil quality, combat erosion and contribute to species richness, diversity and ground cover. Several Acts regarding environmental legislation and the conservation of the natural resource in South Africa are used to ensure that sustainable development, rehabilitation and effective environmental management of disturbed areas are enforced. Legislation therefore provides a measure to prevent pollution and ecological degradation, promotes conservation, secure ecologically sustainable development and the use of natural resources, while promoting justifiable economic and social development. Legislation also enforces and regulates the remediation of disturbed ecosystems, such as the rehabilitation of mine tailing areas. Some of this legislation mentioned above is described in the thesis. Species selected for the compilation of seed mixtures for re–seeding and re–vegetation purposes should comply with the standards determined by the regional biodiversity framework where the disturbed area is situated. Only seed of species with non–invasive potential, that are adapted to the specific environmental conditions and have specific genetic traits, should be included in the seed mixture for rehabilitation. Since seed from local ecotype species are often not available, seed companies use seed from especially grass species that might be adapted to the environmental conditions and type of disturbance or degradation to help remediate the poor soil conditions and improve the vegetation cover. The problem is that if the morphological and physiological aspects of the seed type have not been researched properly, it may lead to poor germination and establishment results when used for the rehabilitation of certain degraded and disturbed areas, such as rangelands or mine tailings. Advance Seed Company tries to enhance seed by adding a coating around the caryopsis (grass seed) for better germination and establishment rates. Such seeds are then referred to as “enhanced” or “coated” seed. The term “seed” will be used throughout the dissertation to describe the whole, intact caryopsis (e.g. Anthephora pubescens). The coatings normally refer to the physical enhancements of the seeds by the application of a water–soluble lime–based coating, which may contain nutrients, fungicides, pesticides and other polymers. This study focused on the evaluation of the germination– and establishment rates in four soil types (growth mediums), as well as the activity of three growth enzymes on coated seed of three grass species, namely Anthephora pubescens, Cynodon dactylon and Panicum maximum. Advanced Seed Company provided the seeds for the three selected grass species that were coated with their newly developed certified formulae. Experimental trails were carried out in the laboratory and greenhouses (controlled conditions) at the North West University and in the field (uncontrolled conditions) at the four locations representing the different soil types, namely the clayey and sandy soils at Taaibosbult near Potchefstroom and the platinum (alkaline growth medium) and gold mine tailings (acidic growth medium) near Rustenburg and Stilfontein respectively. Detailed soil analysis was carried out by certified soil laboratories in Potchefstroom and seed purity, viability and quality determined by the Plant Protection Institute in Pretoria. The results from the greenhouse and the field trials differed significantly for all seed types (coated and uncoated) of the three grass species in the four soil types. The germination and establishment rates in both the greenhouse (controlled conditions) and field (uncontrolled conditions) trials were overall very low. The latter can also be ascribed to the competition with other weed species that were present in the soil seed bank before re–seeding, as well as the predation by ants and guinea fowls in especially the field trials of the sandy and clayey soils. Due to the absence of competition in the field trials on the mine tailings, the germination and establishment rates were higher for most grass species. The quality of the seed batches as supplied by Advance Seed Company was not very good. Although the purity was high, many dead seeds were found, especially for Panicum maximum. The germination and establishment rates of Antephora pubescens of the uncoated seed was higher in the sandy, platinum and gold mine tailings soil types in both the uncontrolled field and controlled greenhouse trials and low for both seed types (coated and uncoated) in the clayey soils. Cynodon dactylon had higher germination and establishment rates for especially the gold mine tailings soil in the field trials for both seed types, as well as the sandy soils under controlled conditions in the greenhouse. Both rates were lower in the sand– and clayey soils field trials. The germination rates for Panicum maximum for both seed types were similar for the clay and sandy soil types, but very low in the soils from the mine tailings, especially under controlled conditions in the greenhouse trials. The germination and establishment rates for both seed types of this species were however much higher in the field trials at both the gold and platinum mine tailings, mainly due to the absence of competition. No results for Panicum maximum were obtained from the field trials on the clay soils due to management and maintenance problems. The peroxidise enzyme activity was higher in the coated seed of Antephora pubescens, but lower in both seed types of Cynodon dactylon and Panicum maximum. The alpha amylase enzyme activity was high in the coated seed of Antephora pubescens and both seed types of Panicum maximum, but low in both seed types of Cynodon dactylon. The activity of the lipoxygenase enzyme was higher in all the coated seed of all three grass species that were used in this study. It also appears as if the storage period played a significant role in the germination of the species, especially after and during the seed coating process, as it had a negative effect on the physiology of the seed. In all species, a higher rate of gaseous exchange was observed in the uncoated seed types. However, the water content of the seed types differed between the seed types. Depending on the size and the genetic characteristics of the species, the longevity of the enzyme proteins differed. This is especially observed in the enzyme activity of three enzymes tested, i.e. lipoxygenase, peroxidase and alpha–amylase. The germination rate only improved shortly after being coated and then declined steadily. The germination capacity therefore depends on the length of the storage period. The genetic adaptation of the different species coincided with the four soil types. It is therefore recommended that only species that are adapted to a certain soil type is used in rehabilitation and if the seed is coated, it should be sown shortly after the coating process and not be stored for long periods. It is also recommended to first treat the area with herbicide before any re–seeding takes place, especially if low concentrations of seeds are used. / Thesis (M.Sc. (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.

The primary impacts of mining on the environment include the deterioration of soil properties and the loss of vegetation cover and density, often leading to increased erosion. In order to encumber further degeneration of such ecosystems and all subsequent other negative environmental impacts, active rehabilitation practices are often implemented. Active rehabilitation involves the introduction of species by different re–seeding (re–vegetation) methodologies. A higher vegetation cover and density is needed to increase soil quality, combat erosion and contribute to species richness, diversity and ground cover. Several Acts regarding environmental legislation and the conservation of the natural resource in South Africa are used to ensure that sustainable development, rehabilitation and effective environmental management of disturbed areas are enforced. Legislation therefore provides a measure to prevent pollution and ecological degradation, promotes conservation, secure ecologically sustainable development and the use of natural resources, while promoting justifiable economic and social development. Legislation also enforces and regulates the remediation of disturbed ecosystems, such as the rehabilitation of mine tailing areas. Some of this legislation mentioned above is described in the thesis. Species selected for the compilation of seed mixtures for re–seeding and re–vegetation purposes should comply with the standards determined by the regional biodiversity framework where the disturbed area is situated. Only seed of species with non–invasive potential, that are adapted to the specific environmental conditions and have specific genetic traits, should be included in the seed mixture for rehabilitation. Since seed from local ecotype species are often not available, seed companies use seed from especially grass species that might be adapted to the environmental conditions and type of disturbance or degradation to help remediate the poor soil conditions and improve the vegetation cover. The problem is that if the morphological and physiological aspects of the seed type have not been researched properly, it may lead to poor germination and establishment results when used for the rehabilitation of certain degraded and disturbed areas, such as rangelands or mine tailings. Advance Seed Company tries to enhance seed by adding a coating around the caryopsis (grass seed) for better germination and establishment rates. Such seeds are then referred to as “enhanced” or “coated” seed. The term “seed” will be used throughout the dissertation to describe the whole, intact caryopsis (e.g. Anthephora pubescens). The coatings normally refer to the physical enhancements of the seeds by the application of a water–soluble lime–based coating, which may contain nutrients, fungicides, pesticides and other polymers. This study focused on the evaluation of the germination– and establishment rates in four soil types (growth mediums), as well as the activity of three growth enzymes on coated seed of three grass species, namely Anthephora pubescens, Cynodon dactylon and Panicum maximum. Advanced Seed Company provided the seeds for the three selected grass species that were coated with their newly developed certified formulae. Experimental trails were carried out in the laboratory and greenhouses (controlled conditions) at the North West University and in the field (uncontrolled conditions) at the four locations representing the different soil types, namely the clayey and sandy soils at Taaibosbult near Potchefstroom and the platinum (alkaline growth medium) and gold mine tailings (acidic growth medium) near Rustenburg and Stilfontein respectively. Detailed soil analysis was carried out by certified soil laboratories in Potchefstroom and seed purity, viability and quality determined by the Plant Protection Institute in Pretoria. The results from the greenhouse and the field trials differed significantly for all seed types (coated and uncoated) of the three grass species in the four soil types. The germination and establishment rates in both the greenhouse (controlled conditions) and field (uncontrolled conditions) trials were overall very low. The latter can also be ascribed to the competition with other weed species that were present in the soil seed bank before re–seeding, as well as the predation by ants and guinea fowls in especially the field trials of the sandy and clayey soils. Due to the absence of competition in the field trials on the mine tailings, the germination and establishment rates were higher for most grass species. The quality of the seed batches as supplied by Advance Seed Company was not very good. Although the purity was high, many dead seeds were found, especially for Panicum maximum. The germination and establishment rates of Antephora pubescens of the uncoated seed was higher in the sandy, platinum and gold mine tailings soil types in both the uncontrolled field and controlled greenhouse trials and low for both seed types (coated and uncoated) in the clayey soils. Cynodon dactylon had higher germination and establishment rates for especially the gold mine tailings soil in the field trials for both seed types, as well as the sandy soils under controlled conditions in the greenhouse. Both rates were lower in the sand– and clayey soils field trials. The germination rates for Panicum maximum for both seed types were similar for the clay and sandy soil types, but very low in the soils from the mine tailings, especially under controlled conditions in the greenhouse trials. The germination and establishment rates for both seed types of this species were however much higher in the field trials at both the gold and platinum mine tailings, mainly due to the absence of competition. No results for Panicum maximum were obtained from the field trials on the clay soils due to management and maintenance problems. The peroxidise enzyme activity was higher in the coated seed of Antephora pubescens, but lower in both seed types of Cynodon dactylon and Panicum maximum. The alpha amylase enzyme activity was high in the coated seed of Antephora pubescens and both seed types of Panicum maximum, but low in both seed types of Cynodon dactylon. The activity of the lipoxygenase enzyme was higher in all the coated seed of all three grass species that were used in this study. It also appears as if the storage period played a significant role in the germination of the species, especially after and during the seed coating process, as it had a negative effect on the physiology of the seed. In all species, a higher rate of gaseous exchange was observed in the uncoated seed types. However, the water content of the seed types differed between the seed types. Depending on the size and the genetic characteristics of the species, the longevity of the enzyme proteins differed. This is especially observed in the enzyme activity of three enzymes tested, i.e. lipoxygenase, peroxidase and alpha–amylase. The germination rate only improved shortly after being coated and then declined steadily. The germination capacity therefore depends on the length of the storage period. The genetic adaptation of the different species coincided with the four soil types. It is therefore recommended that only species that are adapted to a certain soil type is used in rehabilitation and if the seed is coated, it should be sown shortly after the coating process and not be stored for long periods. It is also recommended to first treat the area with herbicide before any re–seeding takes place, especially if low concentrations of seeds are used. / Thesis (M.Sc. (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Cucumis melo is one of the most important horticultural species representing the family Cucurbitaceae, moreover, it is the leader fruit concerning value and volume of exportation in Brazil. As in other cultures, both physiological and health quality of seeds used in the crop establishment are critical to ensure an appropriate population of plants and with high quality and productivity. Treatment of seeds is employed in order to protect them against pathogens, as well as, to accelerate and uniform their germination. Thus, this study aims to evaluate the physiological and health quality of melon seeds, cv. Gaúcho Redondo‟, treated with chemical fungicides, biocontrol agents, micronutrients and polymer. Application rates followed recommendations described by manufacturers. Evaluation of physiological traits was undertaken by means of germination, seedlings length, cold storage, germination at low temperatures, greenhouse emergence and emergence speed index tests. Health quality tests, by the other hand, were determined by Blotter test , transmission and pathogenicity of Fusarium spp. isolated from melon seeds. Treatments with micronutrients, purely or combined with polymer coating, incremented in seed germination, as well as, the emergence and the emergence speed index. Trichoderma spp. also provided a significant increase in the first count and germination. The fungicide Captan® acted efficiently on Fusarium spp. present in the seeds, though it had not been totally eradicated. This pathogen associated with melon seeds did not affect the germination process of them. / Cucumis melo é uma das principais hortaliças representantes da família Cucurbitaceae, além disso, é a fruta líder em valor e volume de exportação no Brasil. Como em todas as culturas, a qualidade fisiológica e sanitária das sementes utilizadas na implantação da lavoura é fundamental para garantir uma população adequada de plantas e com elevada qualidade e produtividade. O tratamento de sementes é utilizado para promover a proteção das sementes contra patógenos causadores de doenças e proporcionar uma germinação mais rápida e uniforme. Dessa forma, o presente trabalho teve como objetivo avaliar a qualidade fisiológica e sanitária das sementes de melão, cultivar Gaúcho Redondo, após tratamento das mesmas com fungicidas químicos, agentes de biocontrole, micronutrientes e polímero. As doses de aplicação dos produtos seguiram as recomendações dos fabricantes e as avaliações da qualidade fisiológica das sementes foram realizadas através do teste de germinação, comprimento de plântulas, teste de frio, germinação a baixas temperaturas, emergência em casa de vegetação e índice de velocidade de emergência. Já a qualidade sanitária foi determinada pelo teste de sanidade, transmissão e patogenicidade de isolados de Fusarium spp. obtidos das sementes de melão. Os tratamentos com micronutrientes, isolados ou com recobrimento de polímero, promoveram incremento na germinação das sementes, assim como na emergência e no índice de velocidade de emergência. Trichoderma spp. também proporcionou aumento significativo na primeira contagem e na germinação. O fungicida Captan® atuou de forma eficiente no controle de Fusarium spp. presente nas sementes, embora não tenha erradicado totalmente. Este patógeno, associado às sementes de melão, não interferiu no processo germinativo das mesmas.

O tratamento de sementes pode ser uma importante técnica para o fornecimento de micronutrientes na cultura do milho (Zea mays L.), sendo capaz de promover um melhor estabelecimento da cultura no campo. Solos contendo níveis insuficientes de zinco e de cobre para as plantas são frequentes em grande parte das regiões agrícolas do Brasil e do mundo. Deste modo, o fornecimento destes elementos via sementes pode ser uma alternativa viável e eficaz para produtores de milho. Este trabalho teve como objetivo avaliar diferentes tratamentos de sementes de milho contendo Zn e Cu, considerando aspectos relacionados à qualidade fisiológica das sementes e à eficiência nutricional. Para tal, foram utilizados quatro lotes do híbrido 2B688Hx, apresentando diferenças quanto ao tamanho e vigor das sementes. Os tratamentos foram compostos por diferentes dosagens e combinações de suspensões líquidas contendo óxido de Zn e carbonato de Cu, fornecidos juntos ou separadamente. Os lotes foram avaliados pelo teor de água das sementes, germinação e teste de frio em cinco épocas: 0, 30, 60, 180 e 360 dias. Nas três primeiras épocas, também foram realizados os testes de emergência de plântulas, velocidade de emergência de plântulas e análises do crescimento de raiz por meio do software SVIS®. O desenvolvimento inicial das plantas foi avaliado pela altura, área foliar e massa seca de raiz e de parte aérea. Os dados de massa seca associados aos teores de Zn e de Cu nos tecidos permitiram calcular as eficiências de absorção, transporte e utilização dos mesmos. A qualidade fisiológica de sementes de milho tratadas com Zn e Cu, isoladamente ou associados, não é afetada ao longo de doze meses de armazenamento; por outro lado, o Cu utilizado isoladamente causa fitotoxicidade quando a avaliação é realizada tendo o papel como substrato, afetando principalmente o desenvolvimento radicular das plântulas. O tratamento de sementes com zinco e cobre se constitui em alternativa viável e eficaz para o fornecimento destes elementos para as plantas de milho. / Seed treatment is a potential tool for supplying micronutrients on maize crop (Zea mays L.), enabling a better plant stand establishment in the field. Soils presenting insufficient levels of zinc and copper to plants are common in various agricultural regions throughout Brazil and the world. Thus, the supply of such elements via seeds can be viable and effective for maize crop. This study aimed to evaluate different maize seed treatments containing Zn and Cu, related to the effects on seeds physiological quality and nutritional efficiency. Thus, four seeds lots of the corn hybrid 2B688Hx, differing in size and vigor, were used for this study. The treatments were composed of liquid suspensions containing Zn oxide and Cu carbonate, applied together or separately at different dosages. The lots were evaluated by seed moisture, germination and cold test in five periods: 0, 30, 60, 180 and 360 days. Seedling emergence, seedling emergence speed and image analysis of root growth (software SVIS®) were also performed in the first three periods. The plants development was assessed by height, leaf area and dry weight of roots and shoots. The efficiencies of absorption, transport and utilization were calculated with the data of seedlings dry weight and tissues content of Zn and Cu. The physiological quality of maize seeds is not affected by the treatments containing Zn and Cu, together or separated, during the twelve-month storage period; on the other hand, the treatments containing only Cu caused phytotoxicity on paper-based tests, affecting mainly the seedlings root development. Seed treatment with zinc and copper is a viable and effective approach for supplying these elements to maize plants.

Seeds sown in the fall to restore sagebrush (Artemisia spp.) steppe plant communities could experience high mortality when they germinate and seedlings freeze during the winter. Delaying germination until the risk of frost is past could increase seedling survival. We evaluated the use of abscisic acid (ABA) to delay germination of Elymus elymoides, Pseudoroegneria spicata, and Linum perenne. The following treatments were applied: uncoated seed, seed coated with ABA at 2.2, 4.4, 8.8, 13.2, and 17.6 g of active ingredient kg-1 of seed, and seed coated with no ABA. The influence of seed treatments on germination were tested at five different incubation temperatures (5-25°C). The lowest application rate of ABA had no significant influence on germination percentage but higher application rates showed a decline. All concentrations of ABA tested delayed germination, especially at low incubation temperatures. For example, the time required for 50% of the seeds to germinate at 5°C was increased with the use of the lowest ABA application rate by 56, 61, and 14 days, for E. elymoides, P. spicata, and L. perenne, respectively. Quadratic thermal accumulation regression models were developed for each species and treatment to predict progress toward germination. For the two grasses, models had sufficient accuracy (R2 = 0.61- 0.97) to predict germination timing using field seedbed temperatures. Equations for L. perenne were less accurate (R2 = 0.03-0.70). Use of these models will allow testing whether ABA will delay germination sufficiently to avoid winter frost periods and provide the basis for future field tests.

Planting native species after a major disturbance is a critical tool land managers use to stabilize soils, restore ecosystem processes, and prevent weed invasion. However, within the sagebrush steppe and other arid and semi-arid environments the percentage of sown seeds that produce an adult plant is remarkably low. Applying fertilizers at the time of planting may improve native plant establishment by increasing the ability of the seedlings to cope with environmental stresses. However, traditional fertilizer applications are often economically infeasible and may be counterproductive by encouraging weed invasion. Seed coating technology allows for the efficient application of fertilizers within the microsite of the seeded species. The objective of our research was to determine the optimal rate of fertilizer to apply to the seed to improve seedling emergence and plant growth. We applied a phosphorus (P) rich fertilizer (0.13 g P g-1) to bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) Á. Löve) seeds in a rotary coater at rates ranging from 0 to 50 g of fertilizer 100 g-1 seed. Three separate studies were conducted to test germination, biomass, relative growth rate, and tissue nutrient uptake. Study one showed decreasing root and shoot biomass and increasing time to 50% germination as fertilizer rates increased. Study two showed no difference in relative growth rate between the controls and fertilizer treatments. Study three showed no difference in root and shoot biomass or nutrient concentration between treatments except in the lowest fertilizer treatment (10 g fertilizer 100 g-1 seed), which was significantly lower in root and shoot biomass than all other treatments but had higher P tissue concentrations than all other treatments. Collectively these results showed no evidence that a P fertilizer coating could aid in bluebunch wheatgrass seedling establishment. Because bluebunch wheatgrass and similar late-seral plants have evolved with low nutrient requirements they may not be physiologically capable of handling increased nutrient supply, which may explain the results of our studies. Continued studies and fieldwork need to be performed to evaluate the potential of fertilizer seed coatings in restoration efforts.

Public land management agencies, conservation organizations, and landowners are interested in expanding the diversity of plant species used in rangeland restoration seedings. While the restoration of native grasses and shrubs in the Great Basin has become increasingly successful, restoration of native forbs continues to be problematic. In the Great Basin, soil water availability and soil fungal pathogens are thought to limit to restoration success. During the course of two years, we conducted two field experiments at three sites in the Great Basin that spanned a latitudinal gradient encompassing different precipitation and temperature patterns. In the first experiment, we evaluated two treatments for enhancing native forb restoration – snow fences and N-sulate fabric. In addition, we tested whether multiple fungicide and hydrophobic seed coatings could reduce seed and seedling mortality from soil fungal pathogens. To quantify the effectiveness of treatments, we tracked the fate of sown seeds over four life stages: germination, seedling emergence, establishment, and second-year survival. We found that snow fences and N-sulate fabric had varying degrees of success for increasing seedling emergence or establishment but ultimately did not increase second-year survival. Seed coatings increased seedling emergence but did not increase establishment or second-year survival. In the second experiment, we replicated the first experiment and also measured soil water availability to better understand how snow fences and N-sulate fabric alter soil water availability, and if differences in soil water availability can explain restoration outcomes. While we found that our treatments can increase soil water availability, increased soil water did not consistently result in better restoration outcomes. Snow fences did not benefit any life stage at any site while N-sulate fabric had positive and negative effects on forb restoration depending on the site. Seed coatings increased seedling emergence and establishment at all sites, warranting further research with other forb species. Results from both experiments provide insights for developing new treatments and techniques that can improve native forb restoration in the Great Basin and similar semiarid systems.

Made available in DSpace on 2014-08-20T13:44:36Z (GMT). No. of bitstreams: 1 tese_juliana_simoes_nobre_gama.pdf: 1507852 bytes, checksum: 5e0a4c29059c50c485c1e2ea802a1945 (MD5) Previous issue date: 2014-03-11 / This research aimed to evaluate the effect of silicon on cotton, through variables agronomic, physiological, yield and fiber quality and seeds produced. The experiments were conducted in 2012 and 2013. In the first year of cultivation, were evaluated five levels of Si: 0, 1000, 2000, 3000 and 4000 kg Si ha-1, applied to soil, 0, 45, 60, 135 and 180 kg Si ha-1 foliar, and 0, 100, 200, 300 and 400 g kg seed-1, applied through seed coating. In the second year, were evaluated five levels: 0, 45, 60, 135 and 180 kg Si ha-1 and 0, 2000, 4000, 6000 and 8000 kg Si ha-1, applied via foliar and soil, respectively. The silicon source used is aluminum silicate. Evaluations were performed at 25, 50, 75 and 100 days from emergence (DAE). The results of the experiments allow to conclude that aluminum silicate applied by seed coating does not interfere in the physiological characteristics of cotton. However, when applied by foliar and soil, increases the chlorophyll index and reduces the diameter of the stem of cotton plants. In relation to yield, the number of seeds per fruit and number of fruit and seeds per plant were negatively affected with the increase of Si foliar applied. The silicon improves some physical characteristics of the fiber such as reflectance, short fiber index, degree of yellowing and micronaire index. Regarding the quality of seeds produced, increases the length of roots and shoots of seedlings, positively influences the weight of a thousand seeds by seed coating and soil and can increase productivity. / Esta pesquisa teve a finalidade de avaliar o efeito do silício no algodoeiro, por meio das variáveis agronômicas, fisiológicas, rendimento e qualidade da fibra e sementes produzidas. Os experimentos foram realizados em 2012 e 2013. No primeiro ano de cultivo, avaliaram-se cinco doses de Si: 0, 1000, 2000, 3000 e 4000 Kg de Si ha-1, aplicadas via solo; 0, 45, 60, 135 e 180 Kg de Si ha-1, via foliar; e 0, 100, 200, 300 e 400 g Kg de sementes-1, aplicadas via recobrimento de sementes. No segundo ano, avaliaram-se cinco doses: 0, 45, 60, 135 e 180 Kg de Si ha-1 e 0, 2000, 4000, 6000 e 8000 Kg de Si ha-1, aplicadas via foliar e solo, respectivamente. A fonte de silício utilizada foi o silicato de alumínio. As avaliações foram realizadas aos 25, 50, 75 e 100 dias após a emergência (DAE). Os resultados obtidos dos experimentos permitem concluir que, o silicato de alumínio aplicado via recobrimento de sementes, não interfere nas características fisiológicas do algodoeiro. Porém, quando aplicado via foliar e no solo, aumenta o índice de clorofila e reduz o diâmetro do caule de plantas de algodão. Em relação ao rendimento, o número de sementes por capulho e o número de capulhos e sementes por planta, foram afetados, negativamente, com o aumento das doses de Si aplicadas via foliar. As doses de silício melhoram algumas características físicas da fibra como a reflectância, índice de fibras curtas, grau de amarelamento e índice micronaire. Em relação à qualidade das sementes produzidas, aumenta o comprimento da raiz e parte aérea de plântulas, influencia positivamente o peso de mil sementes, via recobrimento de sementes e solo, podendo incrementar a produtividade.