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Sustainable rehabilitation can be compromised by the inability of vegetation to survive in hostile mine wastes on a long-term basis. The adverse chemical and physical properties of mine wastes, together with extreme pH conditions and lack of nutrients, provide poor growth conditions for vegetation during seed development and germination. This raises concern for the long-term survival of vegetation through means of seed production when under stress from the punitive properties of mine wastes. Seed vigour is a function of a variety of factors to which the parent plant is subjected during seed formation and maturation. Environmental conditions experienced by the maternal plant during the growth season plays a significant role in determining subsequent germination rates in seeds. Traits of offspring seed depend on the abiotic environment attributed by the growth medium during seed development and maturation The general aim of this study was to determine the viability of seed produced by a previous generation of grass species established in eight different mine wastes and two soils (namely: gypsum wastes; gold tailings with low pyrite content; gold tailings with high pyrite content; platinum tailings; kimberlite mine waste; fluorspar mine waste; andalusite mine waste; coal discard; red soil; and vertic soil) in order to identify suitable species for specific mine wastes to ensure long-term survival through means of seed production. The species selected included: Eragrostis curvula; Eragrostis tef; Cenchrus ciliaris; Eragrostis curvula; Digitaria eriantha; Cynodon dactylon; Chloris gayana; Hyparrhenia hirta; and Sorghum bicolor. The progeny seed‟s viability and ability to germinate were determined through a pot trial study and additional germination testing at the laboratory of Advance Seed (Pty) Ltd. (AS). The germination results were correlated with the growth media analyses by statistical non-parametric correlations which indicated several significant correlations among the growth media properties themselves, and with the germination of the progeny seed. C. gayana (Rhodes grass) seed had poor germination percentages, especially seed harvested from Rhodes grass grown in acidic wastes. Seed harvested from each of the E. curvula grasses grown in various mine wastes, had excellent germination percentages. According to the Repeated Measures ANOVA statistical analysis, there was a significant influence of the growth media in which the parent grass were grown as a variable on the germination of the progeny seed batches from S. bicolor, C. ciliaris, C. gayana, and D. eriantha, indicating that the environmental factors as attributed by the growth media, i.e. the eight different mine waste materials and two soils, and experienced by the maternal plant, did indeed influence the germination of progeny seed. However, it was found that significant correlations between the properties of the growth media and the germination of the progeny seed, was species dependent. The second general aim for this study was to evaluate above-ground re-growth of parent plants after cutting in the mine waste materials and soil types mentioned above. The ability of established grasses to re-grow after a cutting event was determined by cutting the above-ground biomass of the parent grasses, after which it was scored according observable above-ground growth in the following growth season. The measurement of re-growth was subjectively done by scoring the grasses according to observable above-ground biomass. Re-growth was observed for all the perennial grass species. This can be ascribed to the grasses showing resilience to stress factors attributed by the growth media; or new grasses which emerged from seed that collected in the pots, being mistaken for re-growth; or new emerging grasses from the nodes of stolons and/or rhizomes being mistaken for re-growth. However, the emergence of new grasses was an indicator of good health, as biomass allocation to rhizomes and stolons is reduced under low nutrient availability and stress conditions. Therefore the emergence of new grasses is indicative that the plant is either tolerant to stress conditions or that the plant adapted to the restriction of growth due to the roots being bound to the size of the pot. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

Sustainable rehabilitation can be compromised by the inability of vegetation to survive in hostile mine wastes on a long-term basis. The adverse chemical and physical properties of mine wastes, together with extreme pH conditions and lack of nutrients, provide poor growth conditions for vegetation during seed development and germination. This raises concern for the long-term survival of vegetation through means of seed production when under stress from the punitive properties of mine wastes. Seed vigour is a function of a variety of factors to which the parent plant is subjected during seed formation and maturation. Environmental conditions experienced by the maternal plant during the growth season plays a significant role in determining subsequent germination rates in seeds. Traits of offspring seed depend on the abiotic environment attributed by the growth medium during seed development and maturation The general aim of this study was to determine the viability of seed produced by a previous generation of grass species established in eight different mine wastes and two soils (namely: gypsum wastes; gold tailings with low pyrite content; gold tailings with high pyrite content; platinum tailings; kimberlite mine waste; fluorspar mine waste; andalusite mine waste; coal discard; red soil; and vertic soil) in order to identify suitable species for specific mine wastes to ensure long-term survival through means of seed production. The species selected included: Eragrostis curvula; Eragrostis tef; Cenchrus ciliaris; Eragrostis curvula; Digitaria eriantha; Cynodon dactylon; Chloris gayana; Hyparrhenia hirta; and Sorghum bicolor. The progeny seed‟s viability and ability to germinate were determined through a pot trial study and additional germination testing at the laboratory of Advance Seed (Pty) Ltd. (AS). The germination results were correlated with the growth media analyses by statistical non-parametric correlations which indicated several significant correlations among the growth media properties themselves, and with the germination of the progeny seed. C. gayana (Rhodes grass) seed had poor germination percentages, especially seed harvested from Rhodes grass grown in acidic wastes. Seed harvested from each of the E. curvula grasses grown in various mine wastes, had excellent germination percentages. According to the Repeated Measures ANOVA statistical analysis, there was a significant influence of the growth media in which the parent grass were grown as a variable on the germination of the progeny seed batches from S. bicolor, C. ciliaris, C. gayana, and D. eriantha, indicating that the environmental factors as attributed by the growth media, i.e. the eight different mine waste materials and two soils, and experienced by the maternal plant, did indeed influence the germination of progeny seed. However, it was found that significant correlations between the properties of the growth media and the germination of the progeny seed, was species dependent. The second general aim for this study was to evaluate above-ground re-growth of parent plants after cutting in the mine waste materials and soil types mentioned above. The ability of established grasses to re-grow after a cutting event was determined by cutting the above-ground biomass of the parent grasses, after which it was scored according observable above-ground growth in the following growth season. The measurement of re-growth was subjectively done by scoring the grasses according to observable above-ground biomass. Re-growth was observed for all the perennial grass species. This can be ascribed to the grasses showing resilience to stress factors attributed by the growth media; or new grasses which emerged from seed that collected in the pots, being mistaken for re-growth; or new emerging grasses from the nodes of stolons and/or rhizomes being mistaken for re-growth. However, the emergence of new grasses was an indicator of good health, as biomass allocation to rhizomes and stolons is reduced under low nutrient availability and stress conditions. Therefore the emergence of new grasses is indicative that the plant is either tolerant to stress conditions or that the plant adapted to the restriction of growth due to the roots being bound to the size of the pot. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

Small burnet (Sanguisorba minor scop.) Is a hardy, relatively long lived evergreen forb native to Eurasia that has potential to improve grazinglands and extend grazing into late fall and winter. Trials evaluating small burnet tolerance to spring and fall postemergence herbicide applications were conducted at the Utah State University Evans farm in Millville, UT. Two small burnet genotypes were grown in a randomized complete block design with a split-plot arrangement. Twelve treatments, clethodim, clopyralid, imazamox, 2,4DB, metribuzin, aminopyralid, pendimethalin, dimethenamid-P, bromoxynil, dicamba, quinclorac, and an untreated were applied at moderate field use rates either spring or fall of the establishment year. Plots were rated for visual injury on a 0 to 100 scale where 0 = no injury and 100 = complete mortality. Ratings were done 7, 14, 60 days after treatment (DAT) and the spring following treatment. Seed yield, seed viability, and dry matter yield (DMY) were determined. Fall treatments of aminopyralid reduced seed yield 65%, seed germination 43%, and DMY 67%. Fall applied imazamox treatments reduced DMY by 36%, and seed yield by 33%, but did not impact germination. Visual injury was greatest from spring and fall applied aminopyralid treatments with ratings of 24% and 79%. Spring applied treatments did not impact seed yield or seed germination. Results suggest that clethodim, metribuzin, quinclorac, clopyralid, dimethenamid-P, bromoxynil, and pendimethalin cause little or no injury to small burnet.

Nessa pesquisa foi avaliada a utilização do sal de tetrazólio para determinar a maturidade fisiológica das sementes de milho. As sementes utilizadas foram dos híbridos Pioneer 4285 e Dow 2B587, semeadas em 03/10/2014 e 05/12/2014 respectivamente, e colhidas a partir dos 40 dias após o florescimento (DAF), com intervalos de 4 dias até os 68 DAF. As sementes colhidas foram avaliadas quanto à viabilidade e ao vigor (testes de germinação, de emergência da plântula, de condutividade elétrica, de envelhecimento acelerado e determinações do comprimento da plântula). Os parâmetros utilizados para determinar o ponto de maturidade fisiológica das sementes foram a camada preta, a linha de leite, a massa de matéria seca, o teor de água e a avaliação dos tecidos da semente utilizando o sal de tetrazólio, utilizando o método descrito para avaliar a viabilidade, complementado pela avaliação da atividade das células da chalaza e da zona de transferência do endosperma para o embrião. Para as sementes de milho dos dois híbridos a germinação foi superior a 95% e não houve diferença entre as épocas de colheita, somente nas últimas colheitas das sementes do híbrido Dow 2B587 houve redução da germinação e do vigor. O ponto de maturidade fisiológica (PM) foi identificado aos 56 DAF para as sementes de milho do híbrido P4285 e aos 48 DAF para as do híbrido Dow 2B587 e correspondeu ao estádio 4 da linha de leite e ao máximo de acúmulo da matéria seca. O máximo de vigor foi detectado por meio do resultado do teste de envelhecimento acelerado oito dias antes do (PM) para os dois híbridos. A atividade das células do endosperma está relacionada com os demais indicadores do PM (linha de leite, camada preta, massa de matéria seca e teor de água). O transporte de fotoassimilados da planta mãe para a semente cessa no ponto de maturidade fisiológica da semente, desativando o transporte no qual atuam as células da chalaza e da região basal do endosperma. A utilização do sal de tetrazólio possibilita identificar a morte das células da região basal do endosperma, uma vez que a partir desse momento não há mais a reação dessas células com o sal de tetrazólio, indicando que não têm atividade celular. Dessa forma, é possível caracterizar o ponto de maturidade fisiológica da semente de milho, por meio da atividade do sal de tetrazólio; essa caracterização é confirmada pela expressão das enzimas CAT e MDH. / In this study were evaluated the use of the tetrazolium salt to determine corn seed physiological maturity. The seeds used were the hybrids 4285 Pioneer and Dow 2B587, planted on 10.03.2014 and 05.12.2014 respectively, and harvested after 40 days after flowering (DAF), with 4-day intervals until 68 DAF. The harvested seeds were evaluated for viability and vigor (germination test, seedling emergence, electrical conductivity test, accelerated aging test and seedling length). The parameters used to determine the seeds physiological maturity were the black layer, the milk line, the seed dry matter, seed water content and the evaluation of seed tissues using the tetrazolium salt, method to assess seed viability associated to the evaluation of chalaza cells the endosperm cells. The seeds corn germination, both hybrids, was greater than 95% and there is no difference between harvest times. Corn seed physiological maturity (PM) was identified at 56 DAF for both hybrids, P4285 and 48 DAF for hybrid Dow 2B587 and corresponded to stage 4 of the milk line and the accumulation of maximum dry matter. The maximum vigor was detected by accelerated aging test eight days before PM, for the two seed hybrids. The activity of endosperm cells is related to the other PM indicators (milk line, black layer, dry matter and water content). The transport of the nutrients from plant to the seed ceases at the seed physiological maturity, disabling the transport through chalaza cells and basal area. The use of the tetrazolium salt allows identifying the cell death of basal region, since from that time no further reaction of these cells as the tetrazolium salt indicating that these do not already have cell activity. This parameter corresponds to the others evaluated, thus demonstrating that the tetrazolium salt is effective for corn seed physiological maturity characterization.

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.

Made available in DSpace on 2015-03-26T13:40:01Z (GMT). No. of bitstreams: 1 texto completo.pdf: 490123 bytes, checksum: 9f147e7cd146787e2a64f9385999148f (MD5) Previous issue date: 2013-09-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Macaw palm, Acrocomia aculeatea, native palm tree from the cerrado, savannas and open forest in America tropical, is found widely distribuited in the states of Mato Grosso do Sul, Rio de Janeiro, São Paulo, Pará and Minas Gerais. Among the oleaginous species, macaw palm stands for being a palm tree highly productive and native from semi-arid regions. This way, in the first chapter the objective was to adequate methodologies to evaluate the vigor and viability of the macaw palm seeds. The germination tests, germination speed index (GSI), electrical conductivity, accelerate aging and tetrazolium were analyzed. In this experiment four seed lots were used, being Lot 1 (Montes Claros) that showed the best results for all of the tests applied. Among the applied tests the GSI and the electrical conductivity were efficient in the physiological quality evaluation of the seeds. The accelerate aging and the tetrazolium tests require more studies to adequate and posterior utilization to evaluate the macaw palm seeds. The second chapter had as an objective to develop a method for conditioning macaw palm seeds guarantying the conservation of the physiological quality. Two assays were performed: first assay, the seeds were stored under three moisture ranges 4,0 ≤ 6,0%; 6,0 ≤ 8,0% and 8,0 ≤ 10,0% in impermeable containers under environment temperature and 10oC. At 0, 4, 8 and 12 months of storing the seeds were submitted to following evaluations: water content and germination test. Second assay, the seeds were stored in three different kinds of containers: a) permeable (Kraft type paper), b) semi-permeable (rigid polyethylene) and c) impermeable (Flexible sheet of aluminium). Three storing conditions were compared: a) environment temperature in laboratory conditions (condition 1); b) 45% of UR and temperature of 15oC (condition 2); and c) 55% of UR and temperature of 20oC (condition 3). Water content, germination rate and germination speed index (GSI) were evaluated; at 0, 4, 8 and 12 months of storing. In the first assay the best germination results were obtained with the moisture range 6,0 ≤ 8,0%. However, the seeds stored at temperature 10oC, independently from the humidity content didn t survive when they were evaluated at 4 months of storing. In the second assay, the stored seeds with 5,86% water content and the storing environment 15oC/45%UR and 20oC/55%UR independently from the type of container showed the best results. / A macaúba, Acrocomia aculeata, palmeira nativa dos cerrados, savanas e florestas abertas da América Tropical, encontra-se amplamente distribuída nos estados de Mato Grosso do Sul, Rio de Janeiro, São Paulo, Pará e Minas Gerais. Entre as espécies oleaginosas, a macaúba se destaca por ser uma palmeira altamente produtiva e nativa de regiões semi-áridas. Desse modo, no primeiro capítulo objetivou-se adequar metodologias para a avaliação do vigor e viabilidade das sementes. Os testes de germinação, índice de velocidade de germinação (IVG), condutividade elétrica, envelhecimento acelerado e tetrazólio foram analisados. Nesse experimento utilizaram- se quatro lotes de sementes, sendo que o lote 1 (Montes Claros) apresentou os melhores resultados para todos os testes aplicados. Dentre os testes aplicados o IVG e condutividade elétrica mostraram-se eficientes na avaliação da qualidade fisiológica das sementes. A utilização dos testes de envelhecimento acelerado e tetrazólio necessitam de maior aperfeiçoamento para serem empregados de forma segura para a avaliação das sementes de macaúba. O segundo capítulo teve como objetivo desenvolver um método de acondicionamento das sementes de macaúba garantindo a conservação da qualidade da fisiológica das mesmas. Foram realizados dois ensaios: no primeiro, as sementes foram armazenadas sob três faixas de umidade 4,0 ≤ 6,0%; 6,0 ≤ 8,0% e 8,0 ≤ 10,0% em embalagens impermeáveis em temperatura ambiente e 10°C. Aos 0, 4, 8, e 12 meses de armazenamento as sementes foram submetidas as seguintes avaliações: teor de água e teste de germinação. No segundo ensaio, as sementes foram armazenadas em três tipos de embalagem: a) permeável (papel tipo Kraft), b) semipermeável (polietileno rígido) e c) impermeável (folha flexível de alumínio). Foram comparadas três condições de armazenamento: a) temperatura ambiente em condição de laboratório (condição 1); b) 45% de UR e temperatura de 15oC (Condição 2); e c) 55% de UR e temperatura de 20oC (Condição 3). Avaliou-se o teor de água, a taxa de germinação e índice de velocidade de germinação (IVG); aos 0, 4, 8, 12 meses de armazenamento. No primeiro ensaio os melhores resultados de germinação foram obtidos com a faixa de umidade de 6,0 ≤ 8,0%. No entanto, as sementes armazenadas em temperatura de 10°C, independente dos teores de umidades não sobreviveram quando avaliadas aos quatro meses de armazenamento. No segundo ensaio as sementes armazenadas com 5,86% de teor de água e os ambientes de armazenamento de 15°C/45%UR e 20°C/55%UR independente do tipo de embalagem apresentaram os melhores resultados.

Nessa pesquisa foi avaliada a utilização do sal de tetrazólio para determinar a maturidade fisiológica das sementes de milho. As sementes utilizadas foram dos híbridos Pioneer 4285 e Dow 2B587, semeadas em 03/10/2014 e 05/12/2014 respectivamente, e colhidas a partir dos 40 dias após o florescimento (DAF), com intervalos de 4 dias até os 68 DAF. As sementes colhidas foram avaliadas quanto à viabilidade e ao vigor (testes de germinação, de emergência da plântula, de condutividade elétrica, de envelhecimento acelerado e determinações do comprimento da plântula). Os parâmetros utilizados para determinar o ponto de maturidade fisiológica das sementes foram a camada preta, a linha de leite, a massa de matéria seca, o teor de água e a avaliação dos tecidos da semente utilizando o sal de tetrazólio, utilizando o método descrito para avaliar a viabilidade, complementado pela avaliação da atividade das células da chalaza e da zona de transferência do endosperma para o embrião. Para as sementes de milho dos dois híbridos a germinação foi superior a 95% e não houve diferença entre as épocas de colheita, somente nas últimas colheitas das sementes do híbrido Dow 2B587 houve redução da germinação e do vigor. O ponto de maturidade fisiológica (PM) foi identificado aos 56 DAF para as sementes de milho do híbrido P4285 e aos 48 DAF para as do híbrido Dow 2B587 e correspondeu ao estádio 4 da linha de leite e ao máximo de acúmulo da matéria seca. O máximo de vigor foi detectado por meio do resultado do teste de envelhecimento acelerado oito dias antes do (PM) para os dois híbridos. A atividade das células do endosperma está relacionada com os demais indicadores do PM (linha de leite, camada preta, massa de matéria seca e teor de água). O transporte de fotoassimilados da planta mãe para a semente cessa no ponto de maturidade fisiológica da semente, desativando o transporte no qual atuam as células da chalaza e da região basal do endosperma. A utilização do sal de tetrazólio possibilita identificar a morte das células da região basal do endosperma, uma vez que a partir desse momento não há mais a reação dessas células com o sal de tetrazólio, indicando que não têm atividade celular. Dessa forma, é possível caracterizar o ponto de maturidade fisiológica da semente de milho, por meio da atividade do sal de tetrazólio; essa caracterização é confirmada pela expressão das enzimas CAT e MDH. / In this study were evaluated the use of the tetrazolium salt to determine corn seed physiological maturity. The seeds used were the hybrids 4285 Pioneer and Dow 2B587, planted on 10.03.2014 and 05.12.2014 respectively, and harvested after 40 days after flowering (DAF), with 4-day intervals until 68 DAF. The harvested seeds were evaluated for viability and vigor (germination test, seedling emergence, electrical conductivity test, accelerated aging test and seedling length). The parameters used to determine the seeds physiological maturity were the black layer, the milk line, the seed dry matter, seed water content and the evaluation of seed tissues using the tetrazolium salt, method to assess seed viability associated to the evaluation of chalaza cells the endosperm cells. The seeds corn germination, both hybrids, was greater than 95% and there is no difference between harvest times. Corn seed physiological maturity (PM) was identified at 56 DAF for both hybrids, P4285 and 48 DAF for hybrid Dow 2B587 and corresponded to stage 4 of the milk line and the accumulation of maximum dry matter. The maximum vigor was detected by accelerated aging test eight days before PM, for the two seed hybrids. The activity of endosperm cells is related to the other PM indicators (milk line, black layer, dry matter and water content). The transport of the nutrients from plant to the seed ceases at the seed physiological maturity, disabling the transport through chalaza cells and basal area. The use of the tetrazolium salt allows identifying the cell death of basal region, since from that time no further reaction of these cells as the tetrazolium salt indicating that these do not already have cell activity. This parameter corresponds to the others evaluated, thus demonstrating that the tetrazolium salt is effective for corn seed physiological maturity characterization.

<p>  </p> <p>Annual bluegrass (<em>Poa annua</em> L.) is the most troublesome weed in turfgrass systems and the second most troublesome weed across all grass crops. Controlling annual bluegrass is exceptionally complicated due to its high genetic adaptability to new environments. Additionally, prolific seed production allowed the rapid development of herbicide resistance to 12 herbicide modes of action. Experiments were initiated with the goal to better understand annual bluegrass ecology and resistance to ethofumesate. A dose-response experiment was initiated in 2022 to determine the potential level of ethofumesate resistance in annual bluegrass collected from seed production systems. Seed from 55 annual bluegrass populations was obtained from three sources: seed production fields (31 populations), seed cleaning process (6 populations), and seed testing prior to retail distribution (18 populations). </p> <p>Individual seedlings (2–3 tillers) were treated with ten doses of ethofumesate: 0, 0.6, 1.1, 2.8, 5.6, 8.4, 11.2, 16.8, 22.4, and 44.8 kg ai ha−1; with 1.1 to 2.2 kg ha−1 as the label application rates for perennial ryegrass (<em>Lolium perenne</em> L.). The resistance to susceptible ratio of populations across all sources ranged from 0.48 to 5.48. The most resistant populations from production fields, removed during the seed cleaning process, or found in seed testing lots had ED50 values of 12.1, 13.1, and 9.4 kg ai ha−1, respectively. Further, 68% of the populations found in production fields had ED50 higher than 6 kg ai ha−1, which indicates that annual bluegrass resistance is common in grass seed production. A garden study was initiated in November 2020 to assess the development, reproduction, and survival of ten annual bluegrass populations in Indiana. Annual bluegrass plants were maintained in the absence of turf competition and not subjected to typical turfgrass management practices including irrigation, mowing and fertilization. Data collected in included growth rate, biomass production, ground cover, morphology, flowering time, seed production and morphology, and both winter survival and subsequent summer survival of plants. Principal component analysis indicated that certain populations grouped together based on their development, morphology, stress tolerance, and seed production. Plants from the cooler climates (OR, PA, and IN) were characterized by higher growth rates and biomass compared to southern ecotypes. These three populations survived the longest during the summer, with the PA population averaging the highest ground cover of 276 cm2 on 23 July 2021. Plants from warm climates (AL, FL, NC, SC, TN, TX) had poor summer survival. Additionally, the FL population had the highest winterkill of 68%, followed by TX at 45%. The NJ population was distinct from other populations, and plants had robust aboveground biomass and high seed production. The results indicate that the development, reproduction, and survival of different annual bluegrass biotypes are dependent on the climate of origin. A third experiment was designed to understand patterns of germination and seed longevity in populations from five climates across the U.S. at two depths of burial. Seed was retrieved in 6-month intervals up to 24 months. Seed viability by depth (surface vs. 5-cm deep) of burial differed only 18 months after the initiation of the study. However, seed viability did differ among populations on each date of seed retrieval. Viability was low ranging from 0.21 to 0.91%, and populations originating from cool climates (New Jersey, Pennsylvania, and Oregon) generally had higher viability than populations originating from warmer climates. Annual bluegrass seed tested in this study typically had low levels of survival (<0.5%); however, all populations retained some level of viability 24 months after burial, which would allow future reproduction of this troublesome weed. Overall, this research determined that herbicides alone will likely be ineffective at controlling annual bluegrass and that knowledge of the development, reproduction, and survival of local annual bluegrass populations should be factored into an integrated weed management strategies created for each site. </p> <p>  </p>