Stage of maturity at harvest and relative seed size can affect seed vigor. Greenhouse and field studies were conducted to determine the effect of seed maturity on seed vigor, storability, and subsequent plant growth of four cultivars of snap bean (Topcrop, Provider Black, Provider White, and Cherokee Wax). Seeds harvested between physiological maturity (PM) and harvest maturity (HM) showed the highest seed vigor and storability. At PM, seed moisture content was about 55%. A drop in seed fresh weight and a pod color change from green to yellow appear to signal the stage of PM. Delaying harvest past HM reduced seed vigor. The three cultivars with colored seed coats showed higher seed vigor than Provider White. Climatic and weathering effects on maturity, vigor, and yield of Topcrop and Cherokee Wax seed were evaluated at three locations (L-I, L-2, and L-3) in Sri Lanka having different agro-climatic conditions. Seeds that developed and matured under cooler conditions (L-l) produced higher yields and had larger size, better color, and higher vigor. Seeds developed and matured faster under warmer conditions (L-3); however, seed vigor and yields were lower and seed vigor dropped prior to HM. Cherokee Wax was the most tolerant to field weathering. Seeds of Topcrop and Cherokee Wax were separated by weight into three seed sizes (small, medium, and large) and evaluated for crop performance in two plantings (12/90 and 3/91). Field emergence was higher from larger seeds in the second planting, where the soil conditions were more stressful. Seedlings and plants at the flowering stage were larger and pod yields higher from larger seeds. The cultivar x seed size interaction was significant for pod yield per plant. Topcrop showed no differences, while with Cherokee Wax, pod yield per plant increased with increase in seed size during both plantings. Seeds produced from small seeds were similar or higher in vigor, indicating that small seeds could be used for seed production purposes. The data from these experiments indicate that vigor in snap bean seeds can be optimized by harvesting at an early stage after PM and by grading to remove small seeds. / Ph. D.

Respiration rates of developing muskmelon (Cucumis melo L.) seeds were determined polarographically using a Clark-type O₂ electrode (Hansatech LD2). Seeds were obtained from fruits harvested 20, 30, 40, and 50 days after anthesis (DAA). Respiration (O₂ uptake) was measured for fresh intact seeds and fresh dissected seeds. The respiration rate of intact seeds declined from a maximum of 2.28 μmol O₂/min/g DWT at 20 DAA to a minimum of 0.16 μmol O₂/min/g DWT at 50 DAA. Dissecting intact seeds into embryo, testae, and perisperm tissues increased the respiration rate of 20 DAA seeds to 3.12 μmol O₂/min/g DWT but had no effect on more mature seeds. Respiration rate was highly correlated with seed relative growth rate and water content. Respiration rate was not consistently changed after incubation in water. This indicates that respiration rate is not directly controlled by subtle variations in water content. Rather, seed respiration rate is directly linked with turgor-driven, expansive growth and relative growth rate. Fifty-DAA seeds from dry storage were imbibed on water saturated blotters, and respiration rates of whole seeds, decoated seeds, and embryos were compared. Respiration during imbibition was not significantly inhibited by the testae or perisperm tissue. In addition, 50-DAA dried, imbibed seeds were subjected to reduced O₂ concentrations ranging from 3.5 kPa partial pressure O₂ (pO₂) to 21 kPa pO₂. Respiration was not limited by O₂ until pO₂ was reduced to approximately 5 kPa, indicating a high affinity for O₂. Gas chromatography revealed that pO₂ in the seed cavity of muskmelon fruits ranged from 12.5 to 8 kPa. Fifty-DAA seeds from dry storage were imbibed on polyethylene glycol (PEG), mannitol, or NaCl ranging from -0.5 to -2.5 MPa water-potential or on abscisic acid (ABA) solutions ranging in concentration from 10 to 50 μM. Respiration and solution water-potential were measured at 10-hr intervals. At 10 hr of imbibition, each type of osmoticum and ABA stimulated respiration to values greater than for seeds imbibed in pure water. Beyond 10 hr, respiration rates were variable. / Master of Science

no abstract provided by author / Master of Science

no abstract provided by author / Master of Science

Yes / This study used sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis and a jar test apparatus to investigate the molecular weight (MW) and turbidity removal potential of Hibiscus seeds. Three Hibiscus species were assessed: okra crude extract (OCE), sabdariffa crude extract (SCE), and kenaf crude extract (KCE). Furthermore, purified versions of each [i.e., purified okra protein (POP), purified sabdariffa protein (PSP), and purified kenaf protein (PKP)] obtained from anionic exchange were evaluated. The results show that whereas the crude extracts had multiple proteins with MW sizes between 11 and 82 kDa, the purified samples consisted of a single coagulant protein band around 39 kDa. In each case, significant turbidity removal was recorded with the purified proteins; POP, PSP and PKP achieved approximately 98%, 94%, and 90% removal, respectively, at a reduced dosage of ≤0.6  mg/L. However, OCE and SCE achieved lower turbidity removal of 86% and 85% using 40-mg/L doses, respectively, whereas KCE recorded only 73% turbidity removal with a 60-mg/L dose. Sludge generation by crude and purified proteins was approximately 25% of sludge produced by aluminum sulfate and had the additional benefit of being biodegradable. Therefore, the coagulant protein in Hibiscus plant seeds has potential applications for improvements to accessing clean water in developing countries.

Most seed storage proteins accumulate in protein bodies which are derived from the vacuole. Zeins, the major corn storage proteins, however, are retained in the endoplasmic reticulum (ER) and their protein bodies are derived from the ER. There are circumstantial and preliminary data indicating that 27K zein, the proline-rich zein, may span the ER membrane. This potential transmembrane feature is considered very significant to understand the mechanism for zeins' ER retention. The transmembrane feature may retain the 27K zein in the ER where it could serve as an anchor for other classes of zein through specific protein interactions. In this study, a heterologous system (<i>Xenopus laevis</i> oocytes) was used to investigate the potential transmembrane domain of 27K zein. This study utilized physical assays of proteolytic digestion (proteinase K) and chemical modification (biotinylation) on isolated protein vesicles from <i>Xenopus</i> oocytes injected with <i>in vitro</i> transcribed 27K zein mRNA. In addition, the transmembrane features were analyzed by monitoring the protein's mobility in the lumen of the ER by pulse-chase experiments. The results showed that the possibility of 27K zein as a transmembrane protein was consistently refuted in this study. The 27K zein protein was not affected by the proteinase K treatment or biotinylation. Moreover, 27K zein and total zeins moved freely in the lumen of the ER similar to a secretory protein (ovalbumin), totally different from an ER membrane protein (a mutant transmembrane hemagglutinin envelope protein). The free movement, within the ER lumen, of total zeins under conditions where zein aggregates should form necessitates a reevaluation of the mechanisms responsible for zein polypeptides' ER retention and protein body formation. This study, therefore, concludes that 27K zein is not a protein body nucleating factor by virtue of an ER transmerrlbrane feature or association with the ER membrane and that the significance of zein solubility should be reconsidered to explain the zeins' ER retention leading to protein body formation in the ER. / Ph. D.

In this study we assayed the extent of genetic variation for five microsatellites in 94 accessions of wild (Glycine soja) and cultivated soybean (G. max). F₂ segregation analysis indicated that all five of the microsatellites were independently inherited and four loci were located in four independent linkage groups. The number of alleles per microsatellite locus ranged from five to 21. Overall, 43 more microsatellite alleles were detected in wild than in cultivated soybean. Allelic diversity for microsatellite loci was significantly higher in wild than in cultivated soybean. In a second study, molecular markers were used to identify and characterize quantitative trait loci (QTL) controlling seed weight in soybean, and to extend reports of orthologous seed weight genes in the genus Vigna to the genus Glycine by "comparative QTL mapping". DNA samples from 150 F₂ individuals from an interspecific soybean cross were analyzed with 91 genetic markers. Three and five markers were significantly associated with seed weight variation (P<0.01) in the F₂ and F_2:3 generations, respectively. Two-way ANOVA tests for digenic interactions identified three significant epistatic interactions in both generations. In a combined analysis, the significant marker loci and epistatic interactions explained 50 and 60% of the total variation for seed weight in the F₂ and F_2:3 generations, respectively. Comparison of our results in Glycine with those reported in Vigna indicated that both genera share orthologous seed weight genes. Moreover, a significant epistatic interaction between seed weight QTLs was conserved in both genera. The objective of the third study was to use molecular markers and interval mapping techniques to position and characterize quantitative trait loci controlling seed protein, oil, sucrose, and calcium content as well as seed weight in soybean. Two QTLs were detected for protein and calcium content, five for oil content and seed weight and six for sucrose content, respectively. Percent phenotypic variation explained by these individual QTLs ranged from 6.6 to 34.0%. The total phenotypic variation explained by all QTLs for specific traits were 42.5%, 36.7%, 49.0%, 53.1%, and 42.6% for seed weight, protein, oil, sucrose, and calcium, respectively. Of the 11 genomic intervals identified in this study, six were associated with more than one seed quality trait. These results suggest that the genetic correlations observed between seed quality traits may be due to a pleiotropic effect of a single QTL or that QTLs controlling different seed quality traits were inherited in clusters as tightly linked loci. / Ph. D.

Made available in DSpace on 2017-07-21T20:42:37Z (GMT). No. of bitstreams: 1 Raphael Euclides Prestes Salem.pdf: 3931677 bytes, checksum: c378168a7c789517c20cf8c142c060f0 (MD5) Previous issue date: 2012-08-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Alumina is a ceramic material of great technological importance, due to its mechanical, electrical, thermal and optical properties. At industrial scale, alumina is obtained from bauxite, by the Bayer process. By this process, α phase, the most stable one, is obtained at temperatures above 1200°C, through a reconstructive transformation of its precedent transition phase, followed by nucleation and growth of particles. With the advance of technology, chemical methods for synthesis of powdered materials have been much studied, due to the need to obtain materials with improved properties. Pechini method was a method developed in the decade of 1960 in order to obtain ceramic oxides through simple procedures and using relatively low temperatures, allowing the production of materials with smaller particle size, controllable properties and high purity. This work aims to synthesize α-alumina powders by Pechini method with addition of α-alumina seeds, thus promoting the formation of α-phase in lower temperature than in the traditional methods. Also, the objective is to study the influence of an oxygen flow in the calcination process and in the elimination of organic matter from the precursor resin. After the synthesis and the formation of precursor resins, the obtained samples with and without the addition of seeds were calcined at temperatures between 500°C a nd 1100°C. The precursor resins were characterized by infrared spectroscopy and differential thermal analysis associated with thermogravimetry, and the calcined powders were characterized by differential thermal analysis associated with thermogravimetry, X-ray diffraction, infrared spectroscopy and scanning electron microscopy. The seeding process promoted a significant reduction in the temperature of formation of α-phase, consequently allowing to form particles with smaller crystallite size, although as strong agglomerates irregularly shaped. The incidence of an oxygen flow on the calcination process contributed in a less significant way to eliminate the residual organic matter, present in the calcined samples even at high temperatures. It is observed that seeding the reaction medium is a simple method to favor the phase transformation of alumina through a mechanism of diffusional nucleation, promoting the formation of α-phase at lower temperatures. / A alumina é um material cerâmico de grande importância tecnológica, devido às suas propriedades mecânicas, elétricas, térmicas e ópticas. Em escala industrial, a alumina é obtida a partir da bauxita, através do processo Bayer. A fase α, a mais estável da alumina, é obtida a temperaturas acima de 1200°C pelos processo tradicionais, através de uma transformação reconstrutiva de sua fase de transição precedente, seguida de nucleação e crescimento das partículas. Com o avanço da tecnologia, métodos químicos de síntese de materiais particulados têm sido muito estudados, devido à necessidade de se obterem materiais com propriedades melhoradas. O método Pechini foi um método desenvolvido na década de 1960 para a obtenção de óxidos cerâmicos através de procedimentos simples e com temperaturas relativamente baixas, permitindo a produção de materiais com tamanho de partícula cada vez menor, propriedades controláveis e elevada pureza. Este trabalho tem como objetivo sintetizar pós de α-alumina através do método Pechini com a adição de seeds (ou germens de cristalização) de α-alumina, assim promovendo a formação da fase α em temperatura mais baixa do que os métodos tradicionais. Também se tem como objetivo estudar a influência de um fluxo de oxigênio no processo de calcinação e na eliminação de matéria orgânica da resina precursora. Após o processo de síntese e a formação da resina precursora, as amostras obtidas sem e com adição de seeds foram calcinadas a 500°C, 600°C, 900°C, 1000°C e 1100°C. As resinas precursoras fora m caracterizadas por espectroscopia no infravermelho e análise térmica diferencial associada a termogravimetria, e os pós calcinados foram caracterizados por análise térmica diferencial associada a termogravimetria, difração de raios X, espectroscopia no infravermelho e microscopia eletrônica de varredura. A adição dos seeds na síntese promoveu uma redução significativa na temperatura de formação da fase , consequentemente permitindo a formação de partículas com menor tamanho de cristalito, porém em forma de aglomerados fortes com formato irregular. Além disso, a incidência de um fluxo de oxigênio no processo de calcinação contribuiu de forma pouco significativa para a eliminação de matéria orgânica residual, presente nas amostras calcinadas ao ar em maior quantidade mesmo após tratamento a altas temperaturas. Observa-se que a adição de seeds no meio reacional é um método simples de favorecer a transformação da célula unitária da alumina através de um mecanismo de nucleação difusional, promovendo a formação da fase a temperaturas mais baixas.

Prime Hard wheat, a high protein hard wheat classification of the Australian Wheat Board, has traditionally been grown in Queensland and the northern areas of New South Wales. Recently there have been moves to extend this area into the more southern regions of the wheat belt, to expand production of this grain and for greater reliability of supply. The emphasis of this thesis is on the opportunities and constraints to Prime Hard wheat production in South Australia. The environmental factors affecting wheat crops in South Australia are different to those in the traditional Prime Hard producing areas, with heat and moisture stress likely to be the most important climatic influences. Management practices such as the recent trends towards higher seeding densities could also be important (influencing main stem and tiller ratios). An experiment using controlled temperature and moisture conditions showed that main stems and tillers differed in their responses to post-anthesis heat and drought. A field experiment with moisture stress as the only treatment also showed differences in harvest parameters and grain quality between main stems and tillers. Grain produced from field plots at different plant densities showed significant differences in a number of quality measurements, the most important being 1000-grain weight and flour colour. Less screenings and higher 1000-grain weights were obtained from plots with higher seeding rates. However, flour from plots with higher seeding rates had slightly more yellow colour. When main stems and tillers from these plots were tested separately, using small-scale equipment, grain weight and flour colour also differed between main stems and tillers. Main stems produced larger grains than tillers, as expected, and tillers produced grains with yellower flour. The smaller grain size and yellower flour of the tillers is attributed to the higher degree of stress likely to be experienced by tillers, as they have later anthesis dates and are more likely to experience moisture, and/or heat stress at a critical stage of grain filling. Plants with more tillers, such as those grown in a low-density crop, have a later average anthesis date than an equivalent crop of higher seeding density, with more main stems. Therefore it is likely that increasing seeding density will give a shorter crop ripening period and a more uniform seed quality. However, care must be taken not to exceed the optimum plant population density. In conclusion, the experiments showed that tillers are more sensitive to conditions of moisture or heat stress than main stems, and that they make a measurable contribution to the quality of a wheat crop. Increasing the crop density decreased the proportion of tillers present, leading to a more uniform crop and less screenings at harvest. Increased competition in high-density crops may result in slightly more yellow flour, but dough and loaf quality were not affected. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2004.

Thesis (M.S.)--University of Pretoria, 2004. / Title from PDF t.p. (viewed Mar. 11 2005). Includes bibliographical references (p. 99-107).