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Morfoanatomia, perfil químico e propagação de Smilax fluminensis Steud. (Smilacaceae) / Morph-anatomy, chemical profile and propagation of Smilax fluminensis Steud. (Smilacaceae)Anielca Nascimento Soares 25 August 2010 (has links)
As espécies do gênero Smilax L., conhecidas popularmente como salsaparrilha, são empregadas na medicina popular desde o século XVI, porém essas plantas ainda são exploradas de maneira extrativista. Com o aumento da comercialização de plantas medicinais cresce a necessidade de trabalhos que certifiquem a qualidade da matéria prima. A caracterização anatômica e o perfil químico certamente fornecem uma base mais segura nessa certificação. Visando auxiliar no atendimento da demanda e apontar propostas do manejo sustentável em áreas de ocorrência natural de Smilax fluminensis Steud. os objetivos do presente estudo foram: a) analisar a morfoanatomia dos órgãos vegetativos e indicar as características de valor diagnóstico para essa espécie; b) analisar o perfil químico de S. fluminensis através da Cromatografia Líquida de Alta Eficiência acoplada com Detector de Arranjo de Diodos utilizando-se extratos metanólicos (EMeOH) de raízes, rizóforos e ramos aéreos; c) realizar estudos de germinação de sementes e de propagação vegetativa por estacas de ramos aéreos e subterrâneos e, d) acompanhar ao longo de um ano a capacidade de rebrotamento das plantas no campo. As análises ao microscópio de luz foram realizadas utilizando-se as técnicas usuais para o preparo de lâminas semipermamentes e permanentes. Para as análises no microscópio eletrônico de varredura, amostras de folhas foram fixadas em Karnovsky, desidratadas em série etílica e submetidas ao método do ponto crítico de CO2, montadas sobre suportes de alumínio e metalizadas. As sementes foram submetidas a diferentes temperaturas, sob fotoperíodo diário de oito horas e na ausência de luz. Para o enraizamento de estacas, foram utilizados ramos aéreos e subterrâneos com aproximadamente 20 cm, com duas regiões nodais submetidas ao tratamento com ácido indolbutírico a 100 ppm ou apenas em água destilada. Dentre os caracteres anatômicos que permitiram a delimitação da espécie destacam-se: estômatos anisocíticos e paracíticos presentes na epiderme da face abaxial; cera epicuticular na forma de grânulos globosos; mesofilo homogêneo com ampla câmara subestomática; presença da bainha amilífera nos primeiros entrenós do caule aéreo; presença de endoderme com reforço em U; ausência de meristema de espessamento no rizóforo adulto; presença de exoderme com estrias de Caspary nas raízes brancas e ausência de córtex interno nas raízes marrons. Em relação ao perfil químico, os extratos obtidos apresentaram picos correspondentes às substâncias: ácido clorogênico, ácido cafeico, rutina, ácido p-cumárico, ácido ferúlico e ácido trans-cinâmico. As melhores porcentagens de germinação foram 80% em 20-30º C no claro e 85% a 30ºC no escuro. Apenas as estacas de ramos subterrâneos enraizaram. Ao final de um ano de acompanhamento das plantas no campo, todas apresentaram em média 4.05 novos brotamentos. As espécies cujas partes utilizadas para o preparo dos medicamentos são as raízes correm maior risco de extinção como é o caso de S. fluminensis. Portanto, a capacidade de propagação por sementes, por estacas e de regeneração de ramos aéreos após a remoção de parte das estruturas subterrâneas aliada ao perfil químico confirma o seu potencial para a exploração econômica de maneira sustentável, sendo uma alternativa para reduzir o extrativismo predatório dessa espécie nativa. / The Smilax L. species, popularly known as salsaparrilha, have been used in folk medicine since the sixteenth century; however, these plants have still been handled in extractive way. With the increasing commercialization of medicinal plants, there is need to study to certify the raw material quality. Anatomical analyses and chemical profile characterization certainly provides a more secure basis to this certification. Aiming to meet the demand and to point proposals for sustainable management of natural occurrence of Smilax fluminensis Steud., the objectives of this study were: a) to analyze the morph-anatomy of vegetative organs and indicate the features of diagnostic value for this species, b) to examine the chemical profile of S. fluminensis by High Performance Liquid Chromatography Coupled with Diode Array Detector using methanol extracts (EMeOH) of roots, rhizophore and stems c) to conduct studies of seed germination and vegetative propagation on cuttings of aerial and subterranean stems and d) to monitor, over a year, the resprouting ability of plants in the field. We carried out the analyses under a light microscopy using the usual techniques for preparing semi-permanent and permanent slides. To perform the analyses under a scanning electron microscopy, leaf samples were fixed in Karnovsky, dehydrated in ethanol series and subjected to critical point method of CO2, mounted on aluminum supports and coated with gold. Seeds were exposed to different temperatures under a daily photoperiod of eight hours and in the absence of light. To analyze the sprouting, aerial and subterranean stems were used with about 20 cm of length, with two nodal regions subjected to treatment with IBA at 100 ppm or in distilled water. Among the anatomical features that enable delimitation of the species are: anisocytic and paracytic stomata in the epidermis of the abaxial surface, epicuticular wax in the form of granules globules, homogeneous mesophyll with large substomatal chambers, presence of starch sheath in the first internodes of the aerial stem, the presence of endoderm-reinforced U and the absence of primary thickening meristem in the adult rhizophore, exodermis with Casparian strips in roots, and the absence of inner cortex in brown roots. Regarding the chemical profile, extracts showed peaks corresponding to the following substances: chlorogenic acid, caffeic acid, rutin, p-coumaric acid, ferulic acid and trans-Cinnamic acid. The best germination was 80% at 20-30ºC under light and 85% at 30ºC in the dark. Only roots sprouted. After one year of monitoring the plants in the field, all had an average of 4.05 new aerial shoots. The species whose roots are used for the preparation of medicines face a greater risk of extinction as is the case of S. fluminensis. Therefore, the ability to spread by seeds, cuttings and shoots regeneration after removal of aerial stems combined with the chemical profile confirms its potential for economic use in a sustainable manner, and an alternative to reduce the predatory extraction of native species.
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PROPAGAÇÃO IN VITRO E EX VITRO DE Symplocos uniflora (POHL.) BENTH. (SYMPLOCACEAE) / PROPAGATION IN VITRO AND EX VITRO OF Symplocos uniflora (POHL.) BENTH. (SYMPLOCACEAE)Lucho, Simone Ribeiro 10 March 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Symplocos uniflora species is a native tree that reaches up to 10m tall, belonging to the Symplocaceae family. It is popularly known as pau-de-canga, maria-mole-do-banhado and sete-sangria. Virtually, there is no information in the literature on reproduction, growth and development of this species, whose studies of forms of propagation is essential. Thus, the present study intended to examine the sexual and vegetative propagation of the species S. uniflora through protocols for seed germination and micropropagation. Fruit and vegetative material of adult plants from the Botanical Garden of UFSM were collected. The fruits without pulp, containing the seeds were used to evaluate the effect of temperature, storage time, light, collection time, the application of chemical and mechanical scarification, besides the use of gibberellic acid on seed germination of S. uniflora. Plants grown in a greenhouse were used as donor explants (nodal and apical segment) in order to obtain the direct organogenesis. In the study, MS medium and different combinations of auxin naphthaleneacetic acid (NAA) and cytokinin 6-benzylaminopurine (BAP) were used. The presence of light is essential for the germination of Symplocos uniflora, being classified as positive photoblastic preferred. The use of pre-germination treatment with concentrated sulfuric acid is favorable for overcoming seed dormancy. Of the substrates analyzed, the filter paper showed the best germination percentages and speed of germination. Plantmax® substrate offered the highest length of air shoots. In micropropagation, the average percentage of air shoots was 29% with no occurrence of root formation. / Symplocos uniflora (Symplocaceae) é uma árvore que atinge até 10 m de altura, nativa e conhecida popularmente como pau-de-canga, maria-mole-do-banhado e sete-sangria. O trabalho visou estudar a propagação sexuada e vegetativa da espécie, através de protocolos para a germinação de sementes e micropropagação. Endocarpos concrescidos com as sementes (diásporos) foram utilizados para estudos da germinação das sementes avaliando temperatura de armazenamento (10 e 25ºC), temperaturas de incubação (15, 20, 25 e 30ºC), regimes de luz (fotoperíodo de 16 horas e escuro contínuo), época de coleta dos frutos (janeiro e março de 2013), escarificação química (ácido sulfúrico concentrado por 10 minutos), escarificação mecânica (desponte do endocarpo) e ácido giberélico (GA3), 1,5 m L-1. Plantas cultivadas em casa de vegetação, com 18 meses de idade, foram utilizadas como doadoras de explantes (segmento nodal e apical), visando à obtenção da organogênese direta. No estudo foi utilizado o meio MS e diferentes combinações (tratamentos) de ácido naftalenoacético (ANA) e 6-benzilaminopurina (BAP), em mg L-1: 0,0; 0,1; 0,2 e 0,4 e 0,0; 1,0; 2,0 e 4,0, respectivamente. A temperatura de 25ºC promoveu a maior porcentagem de germinação das sementes (24%). Frutos maduros apresentaram as melhores porcentagens de germinação (30%) e índice de velocidade de germinação (1,19). A presença de luz favoreceu à germinação das sementes, sendo classificadas como fotoblásticas positivas preferenciais. O tratamento pré-germinativo com ácido sulfúrico concentrado por 10 minutos promoveu a superação da dormência das sementes. Na germinação in vitro o uso de GA3 no meio de cultura propiciou os melhores índices de velocidade de germinação (0,18), não influenciando na porcentagem da mesma. No cultivo in vitro, a maior porcentagem de explantes com brotações aéreas (29%) ocorreu na combinação de 0,2 mg L-1 de ANA e 2,0 mg L-1 de BAP, sem ocorrência de formação de raízes. Os explantes utilizados e brotações obtidas in vitro apresentaram taxas de oxidação variando de 10 a 70%.
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Response of fever tea (Lippia Javanica)to fertigation frequency, growth medium and propagation methodMpati, Kwena Winnie 20 February 2007 (has links)
Fever tea is one of the important medicinal plants belonging to the family Verbenaceae. The leaves of the plant are used as a remedy to treat malaria, stomach pains, colds and fever. There are different clones of Lippia species available with different medicinal value. Therefore, the purpose of this study was to determine protocols for propagation of fever tea so as to multiply an ideal clone. Vegetative propagation of this plant species by stem cuttings, requirements for seed germination and response of fertigation frequencies and growing medium to growth, yield and quality has not been studied. In this study, factors influencing effective propagation of fever tea were studied. Those factors were: cutting position (apical vs. basal), media (pine bark vs. sand), hormone (seradix No. 2 vs. no hormone) light and temperature requirement for fever tea seed germination and effect of fertigation frequencies (0.4 L/day, 1L/day, 2L/day, 2L/2nd day and 2L/week) and growing media (pine bark vs. sand) on growth, oil yield and oil quality. In vegetative propagation by stem cuttings, measurements made were number of roots per rooted cutting, fresh mass, stem circumference and number of leaves and the rate of rooting during four consecutive sampling dates (5, 10, 15 and 20 days after planting). Apical cuttings rooted earlier by 5 days than basal cuttings at 10 days but at 15-20 days after establishment, both cuttings had good rooting. Fresh mass was not affected by cutting position and rooting media, but cuttings performed slightly better when propagated in pine bark medium than sand medium. Basal cuttings resulted in thicker stems and more leaves as compared to apical cuttings. Seradix No.2 (0.3% IBA) hormone increased the fresh mass, stem circumferences, root number and leaf numbers on both apical and basal cuttings. For the establishment of fever tea stem cuttings, both apical and basal cuttings can be used but pine bark is the ideal medium. The cuttings can be ready for transplanting in 15-20 days after establishment and Seradix No. 2 (0.3% IBA) promotes rooting of fever tea cuttings. The ideal combination of light and temperature for seed germination of fever tea was investigated. Germination was tested at constant temperature regimes (15, 20, 25 and 30¨¬C with continuous light or dark period and alternating temperatures of 20:30 and 16L: 8D (light: dark) combinations respectively. Seeds started to germinate after 8 days from incubation and the last germination was observed at 30 days from incubation. Germination percentages increased at 20-30 constant temperatures and 20/30 alternating temperatures but the difference amongst them was not significant. Higher germination of 86% were achieved when seeds were exposed to continuous light than alternating light and dark. Seeds failed to germinate in continuous darkness. Fever tea seeds were positively photoblastic. The effect of fertigation frequency and growing medium on the growth, yield and quality of fever tea were investigated in a tunnel. Treatments used were five fertigation frequencies (0.5L/day, 1L/day, 2L/day, 2L/2nd day, and 2L/week) and two growing media (pine bark and sand). Measurements made were plant height, stem circumference and number of branches at 8, 16 and 32 weeks after planting. At 8 weeks after planting all fertigation frequencies improved fever tea growth except fertigation frequency of 2L/week. All the fertigation frequencies were ideal to sustain the growth and development of fever tea plants except 2L/week. At 16 weeks after planting there were interactive effects between fertigation frequencies and the growing medium for the plant height of fever tea. Plants fertigated with 2L/day grown in sand media grew taller than all the other fertigation frequencies. At 32 weeks after planting there was a significant effect on the plant height from the main effects of fertigation frequency and growing medium. Plants fertigated with 2L/day were significantly the tallest followed by plants fertigated with 0.5L/day, 1L/day, 2L/2nd day and 2L/week. When plants were younger better plant growth was obtained in pine bark media. Stem circumference and number of branches of fever tea were significantly affected by fertigation frequency and growth medium. At 16 and 32 weeks after planting, plants grown in sand media had thicker stems and more branches as compared to plants grown in pine bark media. The essential oil of fever tea was extracted using hydro-distillation. Fertigation frequency did not affect oil yield. Plants grown in pine bark media yielded more oil than plants grown in sand medium. Microscopical studies using scanning electron microscope were investigated to determine the development of oil glands and trichomes on the abaxial (upper) and adaxial (lower) surfaces of the leaves as affected by fertigation frequency and the growing medium. There were no significant effects on the number of oil glands and trichomes developed on both surfaces of the leaves. Pine bark medium resulted in larger oil glands than sand medium regardless of the treatments, and pine bark also yielded more oil percentages than sand medium. Based on this investigations for commercial production of fever tea essential oil pine bark media is recommended. Chemical compounds of fever tea oil were also not affected by fertigation frequency or growth medium. In this study the chemical compounds detected from essential oils of fever tea were monoterpenes (i.e. ¥á-pinene, sebinen, 1.8 cinede, myrcene, ipsenone and ipsedienone) and the sesquiterpenes (i.e. ¥â-caryophyllene and germacrene-D). Compounds that gave the smallest chemical percentages and the shortest time to be detected were ¥á-pinene, sebinen, 1.8 cinede, myrcene, ipsenone and ipsedienone. Compounds found with the highest chemical percentages with highest peaks were ¥â-caryophyllene and germacrene-D. / Dissertation (MSc (Horticulture))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted
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Seed germination, tree growth and flowering responses of Moringa Oleifera lam. (horseradish tree) to temperatureMuhl, Quintin Ernst 07 October 2010 (has links)
Moringa oleifera Lam. is a tree with great potential as it is fast growing and drought tolerant. Amongst the tree’s multitude of benefits, it can also be used to produce a biodiesel fuel. However, prior to the establishment of commercial plantations, all cultivation aspects of this promising tree have to be understood. Temperature is a significant climatic factor influencing both geographical plant distribution and growth, and since M. oleifera trees are naturally found in tropical climates around the world, the extent of their adaptability to cooler climates was the main objective of this study. Trees were cultivated from seed and germinated in a controlled greenhouse environment at the Experimental Farm of the University of Pretoria. After germination, 50% of the seedlings were hardened-off by placing them outside under ambient growing temperatures, while the rest remained inside the greenhouse. With trial commencement, 132 of both the hardened and non-hardened seedlings were planted into 10 ℓ plastic bags and randomly placed into three temperature-controlled greenhouses, each with a different fluctuating night/day temperature regime namely; 10/20°C ± 2°C, 15/25°C ± 2°C and 20/30°C ± 2°C. In addition, half the trees within each temperature regime were treated with the growth regulator paclobutrazol to determine its effect on growth/flowering at different temperatures. During the 224-day trial period, biweekly measurements of tree height, stem diameter and leaf area estimates of each individual tree within all three temperature regimes were taken. Despite germination percentages being slightly higher at the low 10/20°C regime, the MGT, germination rate, uniformity and seedling growth were superior at the higher 20/30°C regime. The temperature induced seed dormancy at the 20/30°C regime, could be overcome by an incubation period at lower temperatures, as fewer instances of seed dormancy were observed at the 10/20°C regime. The increase in temperature resulted in significant (P≤0.05) growth rate increases of over 650% between the 10/20°C and 20/30°C and 250% between the 10/20°C and 15/25°C night/day temperature regimes. In addition, the 20/30°C temperature treatment, although fluctuative, consistently had the highest leaf area over the entire trial period. Hardening-off of trees during the seedling stage, significantly (P≤0.05) increased the final tree height by 3.09X, 1.44X and 1.23X, compared to their non hardened-off counterparts under the 10/20°C, 15/25°C and 20/30°C temperature regimes respectively. Leaf thickness decreased by a significant (P≤0.05) 43.1% with increase in temperature between the 10/20°C and 20/30°C regime, mostly due to a thinner mesophyll layer. The efficacy of paclobutrazol on M. oleifera growth was found to be temperature dependant, reducing growth at 10/20°C, while increasing growth at both the higher 15/25°C and 20/30°C regimes. Flowering however remained unaffected by paclobutrazol. The highest instances of flowering and pollen viability were observed at the 15/25°C regime. The absence of inflorescence induction at the 20/30°C regime was responsible for the reduced flowering, signifying the necessity of vernalization prior to flowering. Even though all the results confirm the preference of M. oleifera trees towards a tropical climate, satisfactory growth with possibly improved flowering during the hot summer months in certain sub-tropical climates is achievable. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2010. / Plant Production and Soil Science / unrestricted
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Inheritance of seed quality traits, seed germination and seed longevity in three doubled haploid populations of oilseed rapeWidiarsih, Sasanti 14 November 2017 (has links)
No description available.
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N-Acylethanolamine Metabolism During Seed Germination: Molecular Identification of a Functional N-Acylethanolamine AmidohydrolaseShrestha, Rhidaya 08 1900 (has links)
N-Acylethanolamines (NAEs) are endogenous lipid metabolites that occur in a variety of dry seeds, and their levels decline rapidly during the first few hours of imbibition (Chapman et al., 1999, Plant Physiol., 120:1157-1164). Biochemical studies supported the existence of an NAE amidohydrolase activity in seeds and seedlings, and efforts were directed toward identification of DNA sequences encoding this enzyme. Mammalian tissues metabolize NAEs via an amidase enzyme designated fatty acid amide hydrolase (FAAH). Based on the characteristic amidase signature sequence in mammalian FAAH, a candidate Arabidopsis cDNA was identified and isolated by reverse transcriptase-PCR. The Arabidopsis cDNA was expressed in E. coli and the recombinant protein indeed hydrolyzed a range of NAEs to free fatty acids and ethanolamine. Kinetic parameters for the recombinant protein were consistent with those properties of the rat FAAH, supporting identification of this Arabidopsis cDNA as a FAAH homologue. Two T-DNA insertional mutant lines with disruptions in the Arabidopsis NAE amidohydrolase gene (At5g64440) were identified. The homozygous mutant seedlings were more sensitive than the wild type to exogenously applied NAE 12:0. Transgenic seedlings overexpressing the NAE amidohydrolase enzyme showed noticeably greater tolerance to NAE 12:0 than wild type seedlings. These results together provide evidence in vitro and in vivo for the molecular identification of Arabidopsis NAE amidohydrolase. Moreover, the plants with altered NAE amidohydrolase expression may provide new tools for improved understanding of the role of NAEs in germination and seedling growth.
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Development of clonal propagation protocols for Uapaca kirkiana and Pappea capensis, two southern African trees with economic potentialMngomba, Simon Alfred 30 July 2008 (has links)
Experiments were carried out with the objectives of developing propagation protocols for Uapaca kirkiana and Pappea capensis tree species of southern Africa, and evaluating the graft compatibility within U. Kirkiana tree clones, provenances and species. Reverse phase high performance liquid chromatography (RP-HPLC), Folin-Ciocalteau reagent, fluorescence microscopy and callus fusion methodologies were used to diagnose graft compatibility. Results indicated that U. Kirkiana culture asepsis was achieved with 0.1% w/v mercuric chloride HgCl2) and using pre-conditioned grafted trees. Sodium hypochlorite (NaOCl) improved P. Capensis seed asepsis and germination, and discarding floating seeds improved germination. Murashige and Skoog (MS) medium with 2.0 mg l-1 benzylaminopurine (BAP) and 0.3 mg l-1 casein hydrolysate (CH) was superior in shoot multiplication and 0.5 mg l-1 indole-3-butyric acid (IBA) for rooting of P. Capensis microshoots. For somatic embryogenesis, three quarter strength MS medium with 0.05 mg l-1 thidiazuron (TDZ) and 0.3 mg l-1 CH, or 0.2 mg l-1 BAP with 0.3 mg l-1 CH, were effective in germination of P. Capensis somatic embryos. For U. Kirkiana lateral shoot explants, shoot multiplication was superior on three quarter strength MS medium with 0.1 mg l-1 BAP and 0.3 mg l-1 CH. Rooting of micro-cuttings (36%) was achieved on ½ MS with 2.5 mg l-1 IBA. RP-HPLC, fluorescence microscopy and callus fusion studies showed that phenolic compounds play a major role in U. Kirkiana graft incompatibility. Less graft compatible combinations showed an increase in phenol deposits above the union and graft incompatibility was more pronounced above the union than below the union. Proliferation of parenchymatous tissues was better below the union than above the union. Fluorescence microscopy showed presence of flavonoids and polymers above the union of less graft compatible combinations. The chromatograms showed that ferulic acid was abundant and responsible for wood discolouration. The chromatograms also isolated ρara-coumaric acids which were predominant above the union of the less compatible combinations. Therefore, ρara-coumaric acids, flavonoids and polymers were implicated in graft incompatibility of U. kirkiana trees. Copyright / Thesis (PhD)--University of Pretoria, 2008. / Plant Production and Soil Science / unrestricted
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Urbanization Increases Seed Dispersal Interaction Diversity but Decreases Dispersal Success in Toxicodendron RadicansStanley, Amber, Arceo-Gómez, Gerardo 01 June 2020 (has links)
Urbanization is increasing at a rapid pace with negative consequences for native biodiversity. While it is well-known that urbanization can lead to biotic homogenization (dominance of a few competitive species), effects of urbanization on ecological functions that rely on the frequency and efficiency of species interactions are less understood. Seed dispersal success depends on seed disperser feeding rate and diversity, which can affect the probability of fruit removal (i.e. seed dispersal) and germination rates. However, how these factors are affected by urbanization is unknown. In this study, we evaluate the effects of urbanization on factors that contribute to seed dispersal success (seed disperser diversity, frequency, probability of fruit removal and germination rate using Toxicodendron radicans and its seed disperser community as a model system. We found that urban sites had three times more disperser species and two times higher feeding rate compared to natural sites. However, the probability of individual fruit removal did not differ between natural and urban sites. Moreover, germination rate after dispersal was 20% lower in urban sites, leading to overall negative effects of urbanization on T. radicans seed dispersal. We propose differences in seed germination rate are driven by changes in seed disperser species composition and their differences in seed gut transit time. This in turn affects disperser species’ ability to successfully scarify seeds. Overall, our results highlight the need to evaluate urbanization's effects on functional ecological processes, in addition to biotic homogenization effects, in order better understand and mitigate its negative impacts on biodiversity.
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Switchgrass (Panicum virgatum L.) intraspecific variation and temperature tolerance classification using in vitro seed germination assaySeepaul, Ramdeo 01 May 2010 (has links)
An experiment was conducted to determine temperature effects on switchgrass seed germination, a native species with feedstock potential for the biofuel industry. Stratified seeds were germinated at constant temperatures, 15 to 45°C with 5°C interval. Maximum seed germination (MSG) and germination rate (GR), estimated by fitting sigmoid function to germination-time series data, varied among genotypes. Quadratic and bilinear models best described the MSG and GR responses to temperature, respectively. The mean cardinal temperatures, minimum, optimum and maximum, were 8.1, 26.6 and 45.1ºC for MSG and 11.1, 33.1 and 46.0ºC for GR, respectively, varied among genotypes. Genotypes were classified for temperature tolerance based on cumulative temperature response index: ‘Summer’ and ‘Expresso’ were identified as the most heat- and cold-tolerant genotypes, respectively. The functional algorithms and identified tolerant genotypes may be used to improve switchgrass models for field applications and breeding programs to develop new genotypes with enhanced tolerance for niche environments.
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The effect of scarification, temperature and light conditions on seed germination of Artemisia afra jacq. Ex willd.Letsoalo, Mmakoma Mendy January 2022 (has links)
Thesis (M.A. Agricultural Management (Plant Production)) -- University of Limpopo, 2022 / Artemisia afra Jacq. ex Willd is a common medicinal plant in Africa belonging to the
Asteraceae plant family. It has been used for decades as a treatment for cold related
illnesses and a variety of other ailments such as asthma, malaria and kidney disorders.
As such this has led to its high demand and it is faced with threats of overharvesting. As
the plant is naturally occurring and not widely cultivated, it’s seed biology and germination
properties are not documented. The optimum requirements (temperature and
photoperiod) for seed germination as well as the effects of Moringa based biostimulant
and different scarification methods were investigated on A. afra seeds in this study. The
seeds were exposed to different scarification methods including physical scarification
(rubbing using sandpaper), hot water soaking, cold water soaking, acid treatment (H2SO4)
and fermentation (using effective microorganisms) while the untreated seeds served as
the control under all conditions.
Moringa based biostimulant was also used as a seed priming agent at 0, 0.5, 1 and 3%
levels. The seeds were then placed under a variety of photoperiods including constant
light, alternating light (16/8 hours) and continuous darkness at different temperatures
(15°C, 25°C and 35°C). Germination percentages and mean germination time (MGT)
were calculated from the results and Statistix 10.0 software was used at the probability
level of 5%, to compare the mean values. It was observed that under the different
temperatures without any other treatments, the highest germination rate (70%) was
achieved at a 25°C. No germination (0%) was obtained at both 15°C and 35°C in all the
experiments including scarification methods and photoperiods.
Under the scarification treatments, soaking in hot and cold water scarification improved
germination with final germination of 70%, compared to the other scarification methods
(Physical at 20%, acid treatment at 20% and control at 10%). There was no germination
observed (0%) for the fermented seeds in all the experiments. On the photoperiod
treatments, the highest germination percentage of 70% was observed under alternating
light condition. However, when mean germination time was calculated, continuous
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darkness resulted in shortest MGT of 11 days compared to 13 days for both alternating
light and for continuous light in this set of experiment. Seed priming with Moringa based
biostimulant under alternating light conditions and at 25°C resulted in improved MGT.
Under the investigated treatments, the use of 3% biostimulant exerted the highest
improvement on germination with germination percentage of 62% and the shortest MGT
of 7 days compared to the other treatments.
Generally the final germination (%) and time of A. afra seeds were affected by
scarification, temperature, light and priming using Moringa based biostimulant. The
information generated from this study is important because it will contribute in bridging
the scientific gap on the information that has never been documented on optimum
requirements for effective propagation of A. afra through seeds. As such this information
will be useful for small scale farmers and medicinal plant growers who are willing to
recover the lost populations of A. afra through seed propagation thus improving their supply and income / National Research Foundation (NRF)
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