Seed priming is a controlled hydration process, followed by dehydration, that allows pregerminative metabolic activity to proceed without germination. The objective of this research was to investigate the effects of priming on intrinsic characteristics of seed germination including temperature, water, and development, in order to understand how priming affects the germination of broccoli (<i>Brassica oleracea var. italica</i> Plenck) seeds. Priming of broccoli seeds consistently improved germination and emergence rate in the laboratory and field and was related to the accumulation of a specific level of hydropriming units expressed in MPa*h. Priming reduced the sensitivity of seed germination to temperature and increased the temperature range of germination but did not lower the minimum temperature for germination. Primed seeds leaked less electrolytes at supraoptimal temperatures (≥ 35°C) compared to nonprimed seeds. In the field, primed seeds produced a greater plant stand and yield under stressful emergence conditions. Under optimal conditions in the field for stand establishment, the advancement in emergence of primed seeds did not carry over to earlier, greater yields. Matric priming, using calcium silicate as the carrier in the ratio 1.0:0.8:1.8 (seed:carrier:water; by weight) for 7 d at 20°C, was superior to osmotic priming using polyethylene glycol (pEG 8000) at -1.2 :MPa in nearly all variables examined. This may be attributed to reduced respiration during priming of seeds in PEG or nutrient uptake by seeds in calcium silicate. The testa was observed to be a barrier to broccoli seed germination. Priming-induced changes to the physical characteristics of broccoli seeds included increased volume (32%) and an irreversibly expanded, and weakened testa with some minute cracking near the area where the radicle emerges. Primed seeds germinated faster, in part by maintaining a lower hydrotime constant, and thus exhibited a greater progression towards germination per unit water potential at a constant temperature compared with nonprimed seeds. It was hypothesized that, since the testa threshold was reduced after priming by expansion and formation of free spaces, the reversibly expanded embryo of primed seeds does not become immediately appressed to the testa upon rehydration. Thus the yield threshold component controlling the rate of germination of primed seeds is lower by the amount of the testa threshold. The priming effect is more than just reducing the yield threshold as indicated by a significant invigoration of seeds with split testae. Despite the increased volume as a result of the formation of free spaces, primed broccoli seeds did not imbibe more water or have a greater turgor at full hydration. Priming did not lower the minimum water potential allowing germination, and primed seeds did not plateau in water uptake but, instead, moved immediately from imbibition to expansive growth. Priming improved the germination rate of broccoli seeds at all stages of maturity with the most significant effects at stages before attainment of maximum dry weight. Dry storage of broccoli seeds at harvest able maturity (≥ 56 days after pollination) did not improve germination, indicating a lack of post harvest dormancy. / Ph. D.

Orientador: Carlos Raimundo Ferreira Grosso / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T19:13:13Z (GMT). No. of bitstreams: 1 Batista_JulianaAlves_M.pdf: 801759 bytes, checksum: ce425cfeb38d557f43487020978dd9ff (MD5) Previous issue date: 2004 / Resumo: O desenvolvimento e a aplicação de filmes ou coberturas biodegradáveis são técnicas praticadas há vários anos que visam promover melhoria na qualidade do produto embalado ou revestido. O objetivo do presente trabalho foi desenvolver e caracterizar filmes a base de pectina e ácidos graxos e da mistura pectina/gelatina, adicionados ou não de ácidos graxos, e verificar sua eficiência como cobertura para bananas e sementes de brócolos. Os filmes foram caracterizados quanto às propriedades de barreira à água e ao oxigênio, solubilidade em água, propriedades mecânicas, opacidade e microscopia eletrônica de varredura (MEV). A adição crescente dos ácidos láurico, palmítico e esteárico e da mistura (blenda) desses ácidos (1:1:1) em todos os filmes elaborados promoveu um aumento da permeabilidade ao vapor de água, verificando-se através da MEV que não houve incorporação desse material lipídico na matriz filmogênica. Filmes compostos de pectina/gelatina apresentaram aumento da permeabilidade ao vapor de água e da opacidade, diminuição da resistência à tração e aumento da elongação, quando a blenda de ácidos graxos foi adicionada. Os filmes compostos com maior proporção de gelatina apresentaram a menor solubilidade em água. Todos os filmes caracterizados quanto à permeabilidade ao oxigênio apresentaram resultados semelhantes. A partir dos filmes obtidos com menor permeabilidade ao vapor de água e alta resistência à tração, as soluções filmogênicas foram elaboradas e aplicadas como cobertura para banana 'Nanica¿ e para sementes de brócolos 'Ramoso¿. Durante o armazenamento das bananas foram realizadas análises de cor, perda de massa e textura a cada dois dias. A contagem e observação de sementes germinadas foi realizada em média a cada três dias e ao final do experimento as plantas foram submetidas a quantificação do teor de matérias fresca e seca. As bananas com aplicação de cobertura apresentaram menor perda de massa e menor índice de dureza em relação ao controle. A aplicação tornou-se inviável devido a perda acentuada da dureza da fruta. No caso das sementes de brócolos, as coberturas filmogênicas não afetaram a emergência das plantas / Abstract: The development and application of edible films and coatings have been studied for a long time in order to improve the quality of a packed or coated product. The objective of this work was the development and characterization of pectin-based edible films with fatty acids and pectin/gelatin blend films with the addition of fatty acids or not and the application as coatings for bananas and broccoli seeds. Water vapor and oxygen permeability, solubility in water, mechanical properties, opacity and surface morfology were measured for the films. The addition of increasing concentrations of lauric, palmitic and stearic acid and their blend (1:1:1 v/v/v) increased water vapor permeability that was verified by the scanning electron microscopy that showed no incorporation of these lipids into the film matrix. Films with gelatin/pectin blend showed higher water vapor permeability, opacity and elongation and lower tensile strength when the fatty acids blend was additioned. Films with higher concentration of gelatin had lower solubility in water. There was no significant difference in oxygen permeability between all the films. Films with lower water vapor permeability and higher tensile strength were used as coatings for the application on 'Nanica¿ bananas and 'Ramoso¿ broccoli seeds. Weight loss, firmness retention and color were analyzed in each 2 days during the storage of bananas. For the seeds, counting and visual observation of the germinated seeds were effected in each 3 days, and the fresh and dried weight of the plants were determined in the end of the experiment. The coated bananas showed lower weight loss and also firmness retention than the control. The coating application is unfeasible due to the high loss of texture. The coated seeds showed no negative effect of the coating to the growing of the plants / Mestrado / Mestre em Alimentos e Nutrição

Organic agriculture is an important and growing sector of U.S. and world food production. Consumers are increasingly aware of and interested in the production practices and impacts associated with agriculture and as such, are showing a preference for sustainably produced, raised, and harvested foods. In order to continue to meet the growing demand for organic produce, organic growers need cultivars that are optimally adapted to organic and low input conditions. Quality seed is the foundation of any functional and stable farming system. Unfortunately the lack of organically bred and produced seed is hindering the continued growth and success of organic farming. Meeting the needs of the organic sector has been a challenge for the seed industry; it is an industry that often doesn't understand the specific and unique requirements associated with the diversity of environmental and market demands of organic systems. However, organic farmers and the organic food systems they supply, require a robust organic seed system that is appropriately adapted to regional agronomic challenges and market needs, meets standards and regulations, and encompasses the social and ecological values of organic agriculture. One plausible approach to meeting the cultivar and seed needs of organic and low input production systems is through the use of participatory plant breeding (PPB). PPB is a collaborative approach for identifying and developing genetically diverse plant material and varieties involving partnerships among formal sector breeders and researchers, farmers, extension agents, educators, and end users. Participatory plant breeding fundamentally changes the way that formal breeding programs and farmers manage germplasm and plant genetic resources. Typically, formal breeding programs restrict access to germplasm and breeding materials and only supply farmers with finished varieties. In PPB, farmers are involved in the early stages of creation and evaluation of germplasm and breeding material, and stay engaged with the breeding process until new varieties are created. PPB is an excellent model for breeding specifically for organic systems because organic systems in developed countries have many similarities to low-input agricultural systems in the developing world. Some of these parallels include heterogeneous growing environments, a wide range of end uses and marketing strategies, lack of suitably adapted and/or derived varieties, lack of attention from the formal seed sector, and a reduced reliance on synthetic inputs (compared to conventional systems). Breeding for organic systems is a relatively young field and breeders in the formal sector do not have a good handle on what traits are important for robust production under organic conditions. Thus the opportunity to meld farmers' experience and knowledge with breeders' expertise is an effective way to breed for organic production systems. The purpose of this project was to investigate and explore the opportunities and challenges of organic plant breeding using participatory research methods. This research had three goals: 1) to develop an open pollinated broccoli with contemporary quality traits for organic production systems using participatory strategies; 2) to compare broccoli selections made by formally trained plant breeders and farmer breeders; and 3) to capture the stories and experiences of the formal breeders and farmer breeders involved with this broccoli material in order to contribute to the growing wealth of knowledge on collaborative and organic breeding work. The Oregon State University Vegetable Breeding Program made significant progress towards decreasing the variability of the broccoli project material through three successive years of modified half-sibling selections. Evaluations and selections were based more strongly on quality traits rather than soley on production traits such as yield. Although progress was incremental and statistically verified in only three out of the fifteen quality traits, we observed trends in the data indicating progress towards an increasingly uniform, stable, and reliable open pollinated broccoli with specific adaptation for organic production systems. There were very few differences between broccoli materials developed by formally trained plant breeders and farmer breeders. This was especially true for the three cultivars developed in the Pacific Northwest (PNW) (one in Washington and two in Oregon). The 'East Coast' population, which had been collaboratively selected by formal and farmer breeders in New York, expressed significantly distinct differences from the PNW materials. When the farmer breeder and formal breeder materials were pooled together and compared to pooled check cultivars they expressed significant differences for nearly all traits across all years. This demonstrated that all of the collaboratively developed open pollinated materials are distinctly different from the F1 hybrids currently available. Our work has demonstrated a few of the myriad of positive outcomes achievable with the use of participatory plant breeding for organic production systems. The participatory nature of this project resulted in increased confidence and feelings of empowerment for all involved. Both farmers and breeders felt their involvement was socially beneficial and widened their networking and seed community circles. The farmer-bred cultivar 'Solstice' is now available as a result of Jonathan Spero's work, and a cultivar tentatively named 'Benton' is about to be released for sale through Oregon State University. Our results agree with previous study findings that formal and farmer breeder selections are often not distinctly different; thus providing evidence for continuing to support the involvement and education of farmers in plant breeding, especially in reference to organic production systems. This study demonstrates the potential of collaboratively developed and farmer-bred cultivars to become viable and vibrant open pollinated alternatives to the current open pollinated cultivars on the market today. / Graduation date: 2013