Seeds are very complex and diverse plant organs. Seed germination is the most sensitive stage of plant life and is influenced by various environmental signals including phytohormones, salt, light, temperature and water potential. Seeds have an innate mechanism called dormancy that blocks germination, and plants have developed several dormancy-inducing strategies to optimise the timing of germination. Seed germination vigour is an important factor in crop yield. Seedling vigour is defined as the sum of the seed properties which determine the level of activity and performance during germination and seedling emergence. A poor seed lot can be improved by post-harvest treatment such as hydro-priming as it is used in the seed industry, but the biological mechanism is unknown. The aim of this study is to understand the mechanism(s) of hydro-priming in order to improve seed vigour and seed germination. I set seeds at different temperatures to produce variation in seed vigour and it showed that germination of seeds with low vigour can be improved by hydro-priming. Using LC-IT-ToF/MS I characterised compounds that leach from seeds during hydro-priming, and showed that some of these are putative germination inhibitors. Adding these compounds to the water during hydro-priming showed that the inhibitory effect of these compounds is not the main mechanism that regulates germination. Also, transcriptomic analysis showed that genes involved in OPDA pathway are expressed during hydro-priming as well as during endosperm weakening cap associated genes. I concluded that hydro-priming improves the speed of germination of low temperature set and its efficiency is dependent of activation of metabolic activity.

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Made available in DSpace on 2014-06-11T19:33:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-02-13Bitstream added on 2014-06-13T19:23:48Z : No. of bitstreams: 1 mendonca_eaf_dr_jabo.pdf: 430450 bytes, checksum: 749d37129a1b1e5e271af946d67074a0 (MD5) / A semente de milho doce, em virtude do baixo conteúdo de amido, é normalmente leve e rugosa. A rugosidade torna difícil a classificação das sementes quanto à forma e ao tamanho e isso, dificulta a semeadura. Uma solução para sanar esse problema seria a utilização da técnica de revestimento. Diante do exposto, este trabalho teve por objetivo avaliar diferentes materiais de revestimento, adesivos e corantes na peletização de sementes de milho superdoce e verificar quais combinações de materiais seriam eficientes na manutenção da qualidade fisiológica das sementes durante o armazenamento e que permitiriam vazão e distribuição uniformes durante a semeadura. Para tanto, foram testados doze materiais de revestimento (calcários 1 e 2, caulim, carvão vegetal ativado, areia, vermiculita, fubá de milho, farinha de trigo, polvilho de mandioca, amido de milho, celite e terra diatomáceas) e dois adesivos (goma arábica e cascorez extra). As avaliações da qualidade física e fisiológica das sementes revestidas e nuas foram efetuadas através dos testes: teor de água, fragmentação, peso de mil sementes, volume aparente e plantabilidade, germinação em papel toalha e em areia, primeira contagem da germinação em papel e areia, comprimento e massa seca de plântulas, porcentagem e velocidade de emergência das plântulas em campo. O revestimento de sementes de milho superdoce é possivel, pois proporciona homogeneidade de forma e tamanho às sementes, melhora a vazão e a distribuição dos péletes na semeadura. O revestimento propiciou um aumento na porcentagem e velocidade de emergência das plântulas em campo após quatro meses de armazenamento. / Sweet corn seeds, due to their low starch content, are usually light and irregularly shaped in comparison to common corn seeds thus making very difficult and low in precision the conditioning operations to classify them as to size and shape. On the other hand, this causes serious difficulties for the sowing operation. A solution for this problem would be the peletization of the seeds. The objective of this research work was thus to experiment with several different materials so as to find the best combination of filling and cementing materials with which to cover the seeds. The final objective would be to obtain more uniform seed-containing-particles (pelets) which would allow better sowing procedures. The tested materials were: lime 1 and 2, caulim, activated charcoal, finely granulated sand, finely granulated vermiculite, wheat flour, finely ground cassava flour, corn starch, celite, and diatomaceous earth as filling materials and two cementing materials: arabic glue and cascorez extra. Seed quality was then evaluated by means of the water content test, fragmentation test, one thousand seeds weight, apparent volume and sowing easiness, seed germination test in paper towel and in sand, seedling dry weight and length, total and speed of emergence in the field. The filling, cementing and coloring tested materials yielded good results. The peleting of the seeds caused them to have higher total emergence and speed of emergence in the field after the 4 month storage period.

Made available in DSpace on 2014-06-11T19:34:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-04-11Bitstream added on 2014-06-13T18:45:48Z : No. of bitstreams: 1 silva_avc_dr_jabo.pdf: 1547135 bytes, checksum: b0b11a2e0aab9f1987f1a287a67503e9 (MD5) / A videira é uma frutífera de grande importância mundial e, atualmente, a ausência de sementes tem sido uma característica bastante exigida pelos consumidores de uvas de mesa. O objetivo do presente trabalho foi a identificação de marcas moleculares associadas à ausência de sementes, utilizando as técnicas RAPD e fAFLP. O material vegetal foi oriundo dos bancos de germoplasma da EMBRAPA (CPATSA e CNPUV), totalizando 19 cultivares, umas com sementes, outras sem sementes e ainda, três porta-enxertos. Para a análise RAPD foram utilizados 213, onde apenas 30 possibilitaram amplificação de todas as amostras, sendo estes os usados para a obtenção dos dendrogramas. Esses primers produziram um total de 337 bandas polimórficas, tendo sido possível encontrar uma marca específica para a ausência de sementes, utilizando o primer UBC 443, que poderá futuramente ser utilizada para o desenvolvimento de marcadores SCAR, possibilitando a criação de um kit de identificação rápida e precoce de apirenia em videira. A análise fAFLP proporcionou a visualização de um dendrograma onde verificou-se que as cultivares foram agrupadas especificamente, ou seja, separados em cultivares com sementes, sem sementes e os porta enxertos. Foi possível identificar uma marca molecular específica para a característica de ausência de sementes, utilizando o marcador RAPD e, com o fAFLP, obteve-se um melhor agrupamento das cultivares estudadas. / The grapevine is one of the most important fruit world-wide and, actually, the absence of seeds has been a desirable feature by table grapes consumers. This research had as an objective, the identification of molecular marks associated to the absence of seeds, using RAPD and fAFLP techniques. The vegetal material used were proceeding from the germoplasm banks of EMBRAPA (CPATSA and CNPUV). It was used 19 cultivars, with and without seeds, and three different rootstocks. For RAPD analysis it was used 30 primers, producing a total of 337 polymorphics bands, it was also possible to find a specific mark for the absence of seeds, using primer UBC 443, that it could be used in the future for the development of SCAR markers, making possible the creation of a kit of fast and precocious identification of absence of seeds in grapevine. The fAFLP analysis provided a visualization of a dendrogram where it was verified that the cultivars were arranged in specific groups, separated in three different cultivars: with seeds, without seeds and the rootstocks. It was possible to identify a specific molecular mark for the feature of absence of seeds, using RAPD marker and, with fAFLP, to obtain a better arrangement of these cultivars.

Made available in DSpace on 2014-06-11T19:28:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-02-22Bitstream added on 2014-06-13T20:58:22Z : No. of bitstreams: 1 iossi_e_me_jabo.pdf: 445691 bytes, checksum: 3b74424d05bb4320fcd1e85fceffe915 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Phoenix roebelenii é uma palmeira com pequeno porte, com desenvolvimento a pleno sol e boa adaptabilidade às condições climáticas brasileiras, fatores que a tornam muito procurada. É uma espécie originária das regiões do norte do Laos e do Vietnã, e do sudoeste da China. Sementes de frutos recém colhidos e secas durante um dia foram utilizadas para o levantamento dos dados biométricos e semeadas em bandejas contendo Sphagnum sp. Algumas plântulas foram fotografadas e esquematizadas, representando as etapas do processo germinativo. A germinação de sementes de P. roebelenii é do tipo remota tubular. Para estudo da germinação e qualidade fisiológica foram desenvolvidos dois experimentos, nos quais foram utilizadas quatro repetições de 25 sementes. No primeiro experimento, avaliou-se o efeito de quatro substratos (esfagno, serragem, areia e vermiculita) associados a cinco temperaturas (20°C, 25°C, 30°C, 35°C e 40°C), conduzido com 8 horas de luz e 16 horas de escuro, em caixas gerbox. Foi utilizado o delineamento inteiramente casualizado, em esquema fatorial 5X4. Na porcentagem de germinação os melhores resultados foram obtidos sob temperatura de 25°C e 30°C em todos os substratos. Para o IVG, os melhores tratamentos foram sob a temperatura de 30°C, utilizando-se esfagno ou areia. No segundo experimento, estudou-se o efeito dos quatro substratos sobre a germinação das sementes, o peso da massa seca e o comprimento das plântulas. Os melhores substratos para a porcentagem de germinação das sementes foram serragem, areia e esfagno, sendo que este último apresentou os melhores resultados para a maioria das características das plântulas avaliadas. / Phoenix roebelenii is a pigmy palm tree, with development to full sun and good adaptability to brazilian climatic conditions, factors that turn it very sought. It's a native of the north of Laos and Vietnam, and in the Southwest of China. Seeds of freshly fruits were dried during one day to obtain the biometric data and seeded in trays containing Sphagnum sp. Some seedlings were photographed and schematized, representing the stages of the germinative process. The seed germination of P. roebelenii is of the tubular remote kind. To study the germination and physiological quality, two experiments were developed with four replications of 25 seeds each one. In the first experiment, the effect of four substratas were evaluated. (Sphagnum sp., sawdust, sand and vermiculite) associated to five temperatures (20°C, 25°C, 30°C, 35°c e 40°C), with 8 hours of light and 16 hours of darkness, in boxes (gerbox). The experimental design used was the complete randomized in a fatorial scheme 5x4. The best results of germination percentage were obtained at 25°C and 30°C in all the substratas. For speed of germination index , the best treatments were obtained at 30°C, being used Sphagnum sp. or sand. In the second experiment, was studied the effect of the same four substratas used before, in the seed germination and seedlings length and dry weight, at environmental condition. For the germination percentage, the best result was obtained with Sphagnum sp., sawdust or sand. However, the best treatments for the most of the seedlings characteristics were obtained using the Sphagnum sp.

Resumo: As características dos frutos como morfologia e química têm sido tradicionalmente explicadas como resultado da seleção dos dispersores de sementes. Mas a importância dos frugívoros em moldar as características dos frutos tem sido recentemente questionada sob diferentes perspectivas. Alguns estudos sugerem que outras interações podem simultaneamente atuar sobre a evolução das características dos frutos. Muitos organismos atuam como predadores de sementes e seus efeitos precisam ser considerados. Desta maneira, as plantas enfrentam um dilema evolutivo entre atração aos legítimos dispersores de sementes e defesa contra predadores e patógenos. Neste estudo, primeiramente nós avaliamos as características dos frutos relacionadas com atração e defesa em uma ampla amostra de frutos da Mata Atlântica, da Ilha do Cardoso, São Paulo, Brasil. Posteriormente, nós testamos como algumas características específicas influenciam o consumo pelas aves frugívoras. Nós observamos que as características morfológicas e químicas dos frutos apresentam sinal filogenético e em geral padrões independentes de co-variação. Ao contrário, as cores e os contrates dos frutos não apresentam sinal filogenético e frutos mais saturados são ricos em lipídeos e energia mas pobres em carboidratos. Portanto, nós sugerimos que o grau de saturação da cor pode indicar a qualidade nutricional dos frutos. As aves detectaram consistentemente frutos com maior contraste cromático do que o contraste acromático. Além disso, as aves frugívoras selecionam frutos ricos em lipídeos e energia e pobres em compostos secundários. Nós concluímos que a preferência das aves por determinadas características dos frutos não afeta necessariamente a evolução das mesmas, uma vez que, para isso ocorrer é necessário que as aves selecionem entre indivíduos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Fruit characteristics such as morphology and chemistry have traditionally been explained as the result of adaptations to their seed dispersers. But the importance of frugivores in shaping fruit traits has now been questioned from a number of perspectives. Some studies suggested that other interactions simultaneously shape the evolution of fruit traits. Many organisms act as seed predators and their effects must be taken into account. Therefore, plants are faced with an evolutionary dilemma between attraction to legitimate seed dispersers and defense against seed predators and pathogens. In this study we focused on fruit traits related to attractiveness and defense. We first evaluated how fruit characteristics interact in a broad sample of Atlantic rainforest species, at Cardoso Island, São Paulo, Brazil, after accounting for phylogeny. We then evaluated specific fruit characteristics to test whether they influence consumption by birds. We found that morphological and nutritional traits showed phylogenetic signal and in general independent patterns of covariation. On the contrary, fruit color and contrast did not present phylogenetic signal and saturated fruits are rich in energy and lipids, and poor in carbohydrates. Thus we suggest that saturated fruits may indicate fruit quality. Birds consistently detected fruits with higher chromatic contrasts rather than achromatic ones. Frugivorous birds also selected lipid and energyrich fruits and fruits low defended by secondary compounds. We conclude that in spite of bird's preferences these processes do not operate on the evolution of fruit traits, since this requires birds to differentiate between plant individual of the same and not different species. Therefore, in our study we observed that fruit traits are in general weak associate, with the exception of fruit color, that may indicate fruit adaptation to frugivores. / Orientador: Mauro Galetti / Coorientador: Marco Aurélio Pizo Ferreira / Banca: Pedro Jordano / Banca: Wesley Rodrigues Silva / Banca: Marco Aurélio Ribeiro de Mello / Banca: Silvana Buzato / Doutor

The primary aim of this study was to investigate the effects of seed inoculation with the biocontrol agent Pseudomonas fluorescens strain F113 (producing the antibiotic DAPG) and its modified derivative strain F113G22 (with DAPG production disrupted) on the uptake of nitrogen by pea and wheat plants. Uptake of N by the two plant species was investigated in soil microcosms amended with 15N-labelled fertilisers (urea or ammonium nitrate) or 15N-labelled plant residues. Uptake of fertiliser-N was unaffected by inoculation. However, uptake of N derived from organic residues was enhanced in pea inoculated with either strain. In contrast, uptake of N by wheat was reduced in the presence of either strain F113 or F113G22, suggesting that the effects of these microbial inocula on N-mineralisation in the rhizosphere were dependent on plant species. It was subsequently found that microfaunal populations, especially soil nematodes in the rhizosphere of inoculated pea were significantly larger than those associated with the rhizosphere of non-inoculated controls. In wheat, however, microfaunal populations in the rhizosphere of inoculated plants were lower than those associated with noninoculated controls. These trends were repeated using simple sand microcosms into which soil bacteria and the bacterial-feeding nematode Caenorhabditis elegans were introduced. This suggested that effects on N-mineralisation were mediated by changes in populations of microbial-feeding microfauna. As a possible explanation for the increased nematode populations in the rhizosphere of inoculated pea plants, the nematicidal effects of pea seed exudates on C. elegans were investigated in small-scale sand systems. It was found that exposure to non-inoculated pea seeds reduced the short-term survival of C. elegans as compared to unamended sand, and that survival was greater in the presence of pea seeds inoculated with either strain than non-inoculated seeds, suggesting that nematicidal compounds released by germinating pea seeds were utilised by the P.fluorescens strains. No such effects were observed for wheat.

Master of Science / Department of Biological & Agricultural Engineering / Ajay Sharda / In recent years, the technology employed on precision row-crop planters has rapidly advanced. These new technologies include automatic downforce control systems and electronic drive singulation seed meters. These new technologies offer producers higher productivity through high speed planting and increased yield potentials through accurate seed spacing and placement. To begin to understand the benefits and performance of these new technologies, research must be conducted that specifically targets these new systems. With this research, producers would be able to better select equipment for their operation and have a deeper understanding of proper system operation and settings. A test stand, of a scissor-lift type design, was developed to evaluate row crop planter automatic downforce systems. Evaluation of a planter’s automatic downforce system is important for understanding the planter’s capability of maintaining target seeding depth throughout varying field conditions. The test stand consists of a horizontal platform that can raise and lower to simulate terrain changes as well as a mechanism to load the planter row unit’s opening discs to simulate varying soil texture. The vertical height of the test stand and the disc load can be varied in real-time based on utilizing real-world scenarios under simulated conditions to evaluate downforce system response. The stand incorporated several sensors to obtain the overall applied downforce, applied disc load, applied gauge wheel load, and hydraulic pressure. The test stand’s capabilities were evaluated and found to be satisfactory for planter downforce system testing. The test stand was then used to evaluate a commercial automatic downforce system when operating under simulated field conditions. Field data was used to create simulations representing soil type changes, planter operating speed changes, and extreme conditions such as a hard, packed clay or rocky soil type. It was found that the evaluated downforce system was able to maintain target gauge wheel load to within ±223 N for at least 94% of the time during all simulations. This would suggest that the planter would be able to maintain target seeding depth for at least 94% of field operations. Another key aspect for precision agricultural planters is to achieve accurate seed spacing at varying speeds. An electronic drive singulation seed metering system was evaluated to gather the meter’s effectiveness for high speed planting during straight and contour farming mode using simulated field conditions. The simulated conditions were used to gather the meter’s response when encountering high planting speeds, accelerations, decelerations, point-rows, and contours. These meters were found to be highly accurate, with less than 1.5% error in target seed meter speed during all simulated conditions. The meters were also found to have a response time that was always 0.34 seconds or less for all simulated conditions.

Seven plants native to the moist habitats of the pine savannas, woodlands, and Hillside Bog natural area at the Crosby Arboretum, Picayune, MS, were evaluated under laboratory and nursery conditions to determine seed germination percentage, optimal germination temperature, and the effect of substrates on germination. These native plants include: titi (Cyrilla racemiflora L.), buckwheat tree (Cliftonia monophylla Britt.), flameflower (Macranthera flammea (Bartr.) Pennell), deertongue (Carphephorus odoratissimus (Gmel.) Herb. var. odoratissimus), pink coreopsis (Coreopsis nudata Nutt.), tall ironweed (Vernonia angustifolia Michx.), and swamp bay (Persea palustris (Raf.) Sarg.). Laboratory experimentation concluded with germination and determination of optimal temperature regimes. Tall ironweed had the highest rate of success in the nursery. Black Kow compost had suboptimal performance compared to Sunshine Mix 1 and pine bark / sand under nursery conditions. Several of the species tested had minimal germination and require further research to optimize germination and nursery growth.

No description available.