It is becoming increasingly important to improve the yield of seed crops to feed an expanding population and, more recently, to cope with additional strains on food-oriented agriculture posed by biofuel production and global climate change. One strategy to increase yield is to increase seed size. However in nature, due to the limited resources of the mother plant, an enlarged seed size is often associated with a concomitant reduction in seed number. Using the model plant Arabidopsis thaliana, a biotechnological approach to increase seed size through the modification of the triploid endosperm or the ovule integuments was shown to be a viable strategy to improve seed yield. Targeted over-expression of the ANT transcription factor specifically within the endosperm significantly increased seed size without negative effects on fertility. Overcoming compromised fertility in arf2 mutants established that ARF2 and the integuments are important factors in determining seed size and yield. To ensure agronomic relevance, both the gross yield and the harvest index (HI, ratio of seed yield to biological yield) were used to assess the impact of traits, such as increased integument size, introduced into Arabidopsis. To uncover novel regulators of seed size and further develop the current understanding of seed development, second-site mutations were induced in the auxin response factor 2 (arf2) mutant, which produces large seeds due to extra cell division in the ovule integuments. The ARABIDOPSIS CRINKLY 4 (ACR4) gene was identified as a suppressor of the arf2 seed phenotype. In arf2-8 acr4 double mutants, an additive effect on cell proliferation was observed, indicating that ACR4 affects the seed coat through a developmental pathway independent of ARF2. Natural variation present in Arabidopsis was used to study seed yield and its components. Considerable variation in seed size, yield and HI was revealed. Significantly, high seed weight was not associated with high yield or high HI. In contrast, high seed number and reduced plant stature were revealed as important components of high yield and yield efficiency. Additionally, ERECTA was identified as a potential ‘Green Revolution’ gene. Seed size in Arabidopsis was shown to be an extremely plastic trait in response to alterations in the post-flowering source-sink ratio, increasing by 35.0 – 66.2% in the ecotypes tested. Furthermore, a difference in seed weight between restricted (high source-sink ratio) and unrestricted (low source-sink ratio) pollinations was first observed remarkably early in seed development. However, reducing seed number by restricting pollination did not substantially alter integument or endosperm development in order to facilitate increased nutrient uptake.

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.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2017-03-08T13:00:25Z No. of bitstreams: 1 Priscila Cordeiro Souto.pdf: 850577 bytes, checksum: 3e11dedd8f9c5e3025499ee8500e675b (MD5) / Made available in DSpace on 2017-03-08T13:00:25Z (GMT). No. of bitstreams: 1 Priscila Cordeiro Souto.pdf: 850577 bytes, checksum: 3e11dedd8f9c5e3025499ee8500e675b (MD5) Previous issue date: 2016-07-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The Caesalpinia ferrea is a native of Brazil that despite having great economic importance, medicinal, landscaping and restoration of degraded areas, currently is endangered. The demand for high quality seeds is increasing continuously and seed technology has been seeking to improve the existing tests to ensure the achievement of results that are consistent and that express the real physiological quality of a seed lot. Among the vigor tests, stand the test of electrical conductivity, potassium leaching test and exudate pH test - phenolphthalein. The experiments were carried out at the Seed Analysis Laboratory at the Federal Rural University of Pernambuco / Academic Unit of Garanhuns (UFRPE / UAG) in order to verify the efficiency of rapid vigour test to evaluate the physiological potential of two batches of C. ferrea seeds. The fruits were harvested in the states of Paraíba (lot 1) and Pernambuco (lot 2) and after harvest benefited for extracting the seeds, which were chemically scarified with sulfuric acid and determined: water content, weight of thousand seeds, germination test, first count test; germination speed index; shoot length and root seedlings; shoot dry mass, root and cotyledons of seedlings, electrical conductivity, potassium leaching test and exudate pH test - phenolphthalein by individual method. The electrical conductivity were tested volumes of water (50, 75, and 100 mL) quantities of seeds (25, 50 and 100) and soaking periods (2, 4, 6, 8, 10 and 24 hours) at constant temperature 30°C. Potassium leaching test was carried out with a water volume (50, 75, and 100 mL) and seed numbers (25, 50, and 100 seeds) for 24 hours at 30°C. In the pH test exudate - phenolphthalein, seeds were imbibed for 30, 60, 90, 120 and 150 minutes for the temperatures of 25 and 30°C. Rapid electrical conductivity, potassium leaching and pH of exudate - phenolphthalein show promise and effective in determining the physiological potential of the seeds of C. ferrea. / A Caesalpinia ferrea é uma espécie nativa do Brasil que apesar de possuir grande importância econômica, medicinal, paisagismo e recomposição de áreas degradadas, atualmente encontra-se ameaçada de extinção. A demanda por sementes de alta qualidade vem aumentando continuamente e a tecnologia de sementes vem procurando aperfeiçoar os testes de vigor para garantir a obtenção de resultados que sejam consistentes e que expressem a real qualidade fisiológica de um lote de sementes. Dentre os testes de vigor,destacam-se o teste da condutividade elétrica, o teste de lixiviação de potássio e o teste do pH do exsudato – fenolftaleína. Os experimentos foram desenvolvidos no Laboratório de Análise de Sementes na Universidade Federal Rural de Pernambuco/Unidade Acadêmica de Garanhuns (UFRPE/UAG) com o objetivo de verificar a eficiência dos testes rápidos de vigor visando avaliar o potencial fisiológico de dois lotes de sementes de C. ferrea. Os frutos foram colhidos nos estados da Paraíba (lote 1) e Pernambuco (lote 2) e após a colheita foram beneficiados para a extração das sementes, as quais foram escarificadas quimicamente com ácido sulfúrico e determinados: o teor de água, peso de mil sementes, teste de germinação, teste de primeira contagem; índice de velocidade de germinação; comprimento da parte aérea e raiz de plântulas; massa seca da parte aérea, raiz e cotilédones de plântulas, condutividade elétrica, teste de lixiviação de potássio e o teste do pH do exsudato – fenolftaleína pelo método individual. Para a condutividade elétrica foram testados volumes de água (50, 75 e 100 mL), quantidades de sementes (25, 50 e 100) e períodos de embebição (2, 4, 6, 8, 10 e 24 horas) na temperatura constante de 30°C. O teste de lixiviação de potássio foi conduzido com volumes de água (50, 75 e 100 mL) e números de sementes (25, 50 e 100 sementes) por 24 horas a temperatura de 30°C. No teste do pH do exsudato – fenolftaleína as sementes foram embebidas por 30, 60, 90, 120 e 150 minutos nas temperaturas de 25 e 30°C. Os testes rápidos de condutividade elétrica, lixiviação de potássio e pH do exsudato – fenolftaleína mostram-se promissores e eficazes na determinação do potencial fisiológico das sementes de C. ferrea.

O presente trabalho foi realizado visando estabelecer metodologia para o teste de germinação e verificar a possibilidade de uso do teste de raios-X para avaliar a qualidade de sementes de aroeira-branca. Foram utilizados quatro lotes de sementes colhidas em áreas da região sul de Minas Gerais, no ano de 2001. As condições de execução do teste de germinação foram determinadas com base nas percentagem e velocidade de germinação das sementes sob nove faixas de temperatura em um gradiente linear entre 15 e 35 °C e sobre os substratos papel mata-borrão, areia e vermiculita. Para o teste de raios-X, as sementes foram radiografadas e classificadas em função do estádio de desenvolvimento e da morfologia, normal e anormal, dos embriões; após o teste de germinação, procedeu-se a comparação da anatomia das sementes com as respectivas plântulas/sementes resultantes. Os resultados permitiram concluir que: (1) o teste de germinação deve ser conduzido a 27 °C, sobre substrato vermiculita e as contagens efetuadas aos 20 e 45 dias após sua instalação; (2) o teste de raios-X é eficiente na detecção de danos e anormalidades nos embriões prejudiciais à germinação. / The present work was carried out with the objective to establish a methodology for the germination test and to verify the possibility to use the X-rays in the evaluation of 'aroeira-branca' seed quality. Four seed lots collected in different places in the south region of the State of Minas Gerais in 2001 were used. The conditions for performing the germination test were determinated basing on the percentage and on the rate of seed germination under nine ranges of temperature in a linear gradient between 15 and 35°C and on substrates of blotters, sand and vermiculite. For the X-ray test, radiography of seeds were made as well as classification in relation to stage of development and morphology, normal and abnormal, of embryo; the germination test was run aiming to detect possible relationship between seedlings/seeds and the respective anatomy as revealed by radiographic pictures. It was concluded that the germination test for 'aroeira-branca' seeds may be run at 27 °C on vermiculite substrate; records have to be made on twenty and forty-five days after the begining of the test. The X-ray test was seen to be able to detect successfully damages and abnormalities in embryos of 'aroeira-branca' seeds.

A pesquisa teve como objetivo estudar procedimentos para a condução dos testes de deterioração controlada, envelhecimento acelerado, condutividade elétrica e lixiviação de potássio, procurando-se verificar sua eficiência para identificação de diferentes níveis de vigor de lotes de sementes de melão (Cucumis melo L.). Para tanto, o estudo foi conduzido em duas etapas, utilizando-se cinco lotes de sementes dos híbridos AF-646 e AF-682. Na primeira foram realizados os testes de germinação, primeira contagem de germinação, Método Agroflora, emergência de plântulas em casa de vegetação e estudos específicos para os testes de deterioração controlada (graus de umidade de 18%, 21% e 24%, a 45ºC, durante 24 e 48 horas), de envelhecimento acelerado, com e sem solução salina (períodos 48, 72 e 96 horas, a 38ºC ou 41ºC), de condutividade elétrica (temperaturas de 20ºC, 25ºC e 30ºC, volumes de 50 e 75mL de água, 25 e 50 sementes e períodos de 1, 2, 4, 8, 12, 16, 20 e 24 horas) e de lixiviação de potássio (25 e 50 sementes, 50 e 75mL de água, a 25ºC e 30ºC, durante 30, 60, e 90 minutos, 2h, 2h e 30 minutos, 3, 4 e 5 horas). Os procedimentos considerados mais promissores para cada teste, nesta primeira fase, foram comparados na segunda etapa, que também incluiu os testes de germinação, primeira contagem de germinação, Método Agroflora e emergência de plântulas em casa de vegetação. Diante dos resultados obtidos, concluiu-se que os testes de deterioração controlada (24%/45ºC/24h) e de envelhecimento acelerado (procedimento tradicional e com solução salina), utilizando a combinação 41ºC/72h, apresentam sensibilidade suficiente para avaliação do potencial fisiológico de sementes de melão. O teste de condutividade elétrica não constitui em opção eficiente para avaliação do vigor das sementes, enquanto o teste de lixiviação de potássio necessita de estudos adicionais para adequar sua metodologia e viabilizar a sua utilização para sementes de melão, considerando-se, inclusive, os prováveis efeitos do genótipo. / This research was conducted to study and select procedures for the controlled deterioration, accelerate aging, electrical conductivity and potassium lixiviation tests, to verify their sensitivity to identify different vigor levels of melon (Cucumis melo L.) seed lots. Five seed lots each from the hybrids AF-646 and AF-682 were used. In the first experimental stage, the following tests were performed: germination, germination first count, Agroflora Method and seedling emergence. Specific studies were also conducted to the following tests: controlled deterioration (seed moisture content of 18%, 21% and 24%, at 45ºC, for 24 and 48 hours), traditional accelerated aging, saturated salt accelerated aging (for 48, 72 and 96 hours, at 38 o C or 41 o C), electrical conductivity (25 or 50 seeds imbibed in 50mL or 75mL water, 20 o C, 25 o C and 30 o C, for 1, 2, 4, 8, 12, 16 and 20 hours) and potassium leachate (25 or 50 seeds, imbibed in 50mL and 75mL, at 25 o C and 30 o C, for 30, 60, 90, 120, 150, 180, 240 and 300 minutes). The procedures considered the most promising for each test in the first stage were compared, in the second stage. The later stage also included germination, germination first count, Agroflora Method and seedling emergence tests. From the results, it was concluded that controlled deterioration (24%/45 o C/24h) and accelerate aging (traditional procedure and salt saturated) tests, using the 41 o C/72h combination, showed to be sufficiently sensitive for the evaluation of the physiological potential of melon seeds. The electrical conductivity test does not constitute an efficient option for the vigor evaluation, while the potassium lixiviation test needs further studies in order to adjust its methodology and enable its use for melon seeds, also considering the probable genotype effects.

O tratamento industrial de sementes é utilizado para, aproximadamente, 100% das sementes híbridas de milho comercializadas no Brasil. Assim, é essencial verificar se a aplicação de produtos químicos nas sementes de milho interfere nos resultados das análises destas sementes. Portanto, nesta pesquisa foi comparada a germinação das sementes híbridas de milho de três cultivares classificadas em peneiras de crivo circular e oblongo, em função da aplicação de produtos químicos (fungicida, inseticida, nematicida e polímero) em relação às sementes sem tratamento químico (Controle). Para complementar a determinação da qualidade das sementes foram avaliados o teor de água das sementes, o comprimento médio da raiz da plântula, a emergência da plântula e o vigor. As análises foram realizadas no Departamento de Produção Vegetal da Escola Superior de Agricultura \"Luiz de Queiroz\", Universidade de São Paulo. O teor de água foi determinado pelo método da estufa a 105 ± 3 °C, por 24 horas. Para o teste de germinação foram utilizados o substrato papel (RP), quatro repetições de 50 sementes ou oito repetições de 25 sementes e as avaliações entre o 3º e o 7º dia após a instalação do teste. Os tratamentos com fungicida, inseticida e nematicida não interferiram no teor de água das sementes de milho, independentemente do genótipo e da forma das sementes. Os resultados do teste de germinação das sementes de milho foram analisados, estatisticamente e utilizando as Tabelas de Tolerância das Regras para Análise de Sementes, e é possível verificar que o tratamento industrial das sementes não interfere nos resultados do teste de germinação, conforme proposto nas atuais Regras para Análise de Sementes. No teste de germinação, é possível avaliar a germinação das sementes de milho no 3º dia após a instalação do teste, para antecipar a obtenção dos resultados. A colocação de 25 sementes de milho no substrato papel (RP) favorece a avaliação do desenvolvimento da plântula no teste de germinação, em comparação à utilização de 50 sementes. / The seed industrial treatment is used to approximately 100% of the maize hybrids seeds marketed in Brazil. Thus, it is essential to verify if the application of chemical products in maize seeds interferes in the analysis results of these seeds. Therefore, in this research was compared maize seeds germination of three cultivars classified in circular and oblong screen sieves, depending on the application of chemical products (fungicide, insecticide, nematicide and polymer) in relation to the seeds without chemical treatment (Control). In order to complement the determination of seed quality, seed water content, seedling root mean length, seedling emergence and vigor were evaluated. The analysis were carried out in the Plant Production Department of the Luiz de Queiroz College of Agriculture, University of São Paulo. The water content was determined by the oven method at 105 ± 3 °C for 24 hours. In the germination test, the paper substrate (RP), four replicates of 50 seeds or eight replicates of 25 seeds were used and the evaluations between the 3rd and the 7th day after of the test installation. The treatments with fungicide, insecticide and nematicide did not interfere in the water content of the maize seeds, independently of the genotype and the seeds shape. The results of the maize seeds germination test were statistically analyzed and using the Tolerance Tables of the Rules for Seed Testing and it is possible to verify that the seed industrial treatment does not interfere in the results of the germination test, as proposed in the current Rules for Seed Testing. In the germination test, it is possible to evaluate the maize seeds germination on the 3rd day after the test installation, in order to anticipate the results. The placement of 25 maize seeds on the paper substrate (RP) favors the evaluation of the seedling development in the germination test, compared to the use of 50 seeds.

Triacylglycerols (TAGs) are stored in variable amounts (1-90 % by dry weight) in seed and non-seed tissues of various plant species. We analyzed the deep transcriptional profiling data obtained for eight species (brassica, castor, nasturtium, euonymus, oil palm, date palm, and avocado), to gain insights into tissue- and species-specific regulation and biosynthesis of TAG in plants. In all tissues analyzed, an increased expression was noted for genes mostly associated with fatty acid biosynthesis in plastid, but much less increase in those for TAG assembly in the endoplasmic reticulum. In most oil-rich tissues, transcripts associated with hexose metabolism in plastid also showed higher expression, relative to cytosol; this is likely associated with the need for high pyruvate flux directed toward plastid fatty acid synthesis. Additionally, expression of WRINKLED1 transcription factor, a regulatory element associated with oil biosynthesis in seed and non-seed tissues of monocot and dicot plants, was observed in most oil-rich tissues. Transcripts for other regulatory factors that are candidates associated with TAG synthesis in seed and non-seed tissues are also identified. In summary, our studies point to distinctive modes of regulation of fatty acid biosynthesis and TAG assembly that are conserved in both seed and non-seed oil-rich plants.

The objectives of this research were to investigate the ecological importance of soil seed reserves and seed rain on regeneration of a good condition sagebrush- grass range vegetation after a wildfire and draw conclusions leading to better understanding and management of such ecosystems. Investigations were conducted for two successive years on a community where major plants were neither rhizomatous nor sprouting. In such cases soil seed reserves and seed rain have to be the main source of regeneration. In addition to monitoring soil seed reserves and seed rain, vegetation changes during the past two years and the historical conditions of the study area were examined. Study of germinable soil seed reserve dynamics showed that fire can have a destructive effect on this portion of the community. Cheatgrass soil seed reserves were high even in good condition sagebrush-grass vegetation. Although fire reduced the Bromus tectorum seed bank by half, the cover of this grass increased to almost twice the level observed on the control (unburned) plots a year later. This shows the enormous reproductive capacity of this highly competitive weed species following a wildfire. Even though the pre-burn vegetation contained a high proportion of native perennial plants, soil seed reserves and seed rain had very small proportions of their germinable seeds. Timing of the fire is likely important in controlling undesirable range plants and their seeds. Had the fire occurred earlier when more seeds were attached to the culms, greater reduction in cheatgrass probably would have been obtained. Timing of the fire was just right to control sagebrush, because it occurred before their seed set and complete destruction of this species was achieved. Mormon tea was the only shrub to reestablish its cover relatively rapidly. This was related to its strong ability to sprout from root crowns. Greater germinable soil seed reserves were found under shrub canopies than in the inter spaces. This is probably related to the semi-logarithmic dispersal of seed where seed fall is greatest closest to mother plants (Harper 1977). Since flammable fuel follows the same pattern, it was found that fire has a serious impact on soil seed reserves at "hot" points, but temperatures were apparently not hot enough to cause much damage on seed banks at "cold" points in the former interspaces. Since soil seed reserves accumulate in significantly higher proportions in the surface 0-2 cm, fire has a more serious impact on the seeds in surface soil than those lower lower down. Variance of the germinable seed rain was so high that none of the grand totals, life forms totals and species values were statistically significant at alpha

Thesis (M.S. in plant pathology)--Washington State University, December 2007. / Includes bibliographical references.

A trade-off between seed size and seed number is central in seed ecology, and has been suggested to be related to a trade-off between competition and colonization, as well as to a trade-off between stress tolerance and fecundity. Large seeds endure hazards during establishment, such as shading, drought, litter coverage and competition from other plants, better than do small seeds, due to a larger amount of stored resources in the seed. Small seeds, however, are numerous and small-seeded species are therefore more fecund. Moreover, a pattern with small-seeded species being associated with open habitats and large-seeded species being associated with closed habitats has been reported in the literature. In this thesis I assess effects of seed size on recruitment, and how relationships between seed size and recruitment may relate to habitat conditions. Seed sowing experiments were performed in the field to assess inter- and intra-specific relationships between seed size and recruitment in open and closed habitats (Paper I and II). Seed removal experiments were performed in the field to assess what effects seed predation may have on a relationship between seed size and recruitment (Paper III). A garden experiment was performed based on contests between larger-seeded and smaller-seeded species, in order to examine different models on co-existence of multiple seed size strategies. The results showed that there was a weak positive relationship between seed size and recruitment in the field, and that this relationship was only weakly and inconclusively related to habitat (Paper I and II). Seed removal was negatively related to seed size in closed habitats and unrelated to seed size in open habitats (Paper III). This indicates that any positive relationship between seed size and recruitment may be an effect of higher seed removal in small-seeded species. However, when grown under controlled conditions in a garden experiment, there was a clear advantage of larger-seeded species over smaller-seeded species (Paper IV). This advantage was unaffected by seed density, indicating that there was no competitive advantage of the larger-seeded species. Instead, indirect evidence suggests that larger-seeded species exhibit higher tolerance to stress. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted.</p><p> </p>