Made available in DSpace on 2014-06-11T19:24:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-10Bitstream added on 2014-06-13T20:31:56Z : No. of bitstreams: 1 oliva_ace_me_botfca.pdf: 1453048 bytes, checksum: f648ec027fadbe4bdfc9c0fa76f8a8e5 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O crambe (Crambe abyssinica Hochst) é uma planta da família Brassicaceae cujas sementes possuem elevado teor de óleo, sendo destinado no Brasil, principalmente, para a produção de biodiesel. É uma cultura que apresenta baixo custo de produção, seu cultivo é totalmente mecanizado com semedura no inverno e favorece a rotação com outras culturas de verão. No Brasil, a produção e a comercialização de sementes de crambe iniciaram-se há poucos anos, por isso estudos na área de tecnologia de produção são essenciais para obtenção de sementes de boa qualidade. Dentre os fatores que afetam a qualidade das sementes está o processo de secagem. A diminuição do teor de água das sementes em níveis adequados permite preservar as sementes por um período prolongado, possibilitando menor perda de vigor e germinação ao longo do armazenamento. O objetivo deste estudo foi avaliar o efeito de diferentes métodos de secagem sobre a qualidade de sementes de crambe no decorrer do armazenamento. O campo de produção de sementes de crambe foi instalado na Fazenda Experimental Lageado e os tratamentos experimentais foram conduzidos no Laboratório de Processamento de Produtos Agrícolas, pertencente ao Departamento de Engenharia Rural, e na Fazenda Experimental Lageado. As avaliações de qualidade foram realizadas no Laboratório de Análise de Sementes pertencente ao Departamento de Produção Vegetal – Setor Agricultura... / Crambe (Crambe abyssinica Hochst) is a member of the Brassicaceae family. Its seeds have high oil contents and its growth in Brazil aims to produce bio diesel. It is a low cost production and its cultivation is totally mechanized. It is also sowed at winter time, which favors crop rotation with other summer crops. In Brazil, Crambe seeds production and commercialization began a few years ago. The research in technology production is essential to obtain high quality seeds. Among the factors that affect seed quality there is the drying process. Seed water content decreased to an appropriate level allowing for a prolonged preservation time and enabling less vigor and germination loss during storage. The aim of this study was to evaluate the effect of different drying methods on Crambe seeds quality during storage. The seeds were produced in Fazenda Lageado, Faculdade de Ciências Agronômicas, UNESP, Botucatu / SP. Experimental treatments were conducted at Laboratório de Processamento de Produtos Agrícolas, Departamento de Engenharia Rural, and Fazenda Experimental Lageado. Evaluations on seed quality were conducted at Laboratório de Análise de Sementes, Departamento de Produção Vegetal – Setor Agricultura. Seeds were submitted to the following drying methods: a) seed drying in the shade with natural ventilation; b) artificial drying method using heated air; c) artificial drying method using unheated air; d) drying on ceramic patio; e) drying on the mother plant. Seeds were stored in laboratory conditions with bimonthly monitoring of their quality during a 8 month period. The following testes were performed: seed moisture content, standard germination test, first count of germination test, seedling emergence,emergence speed index and electrical conductivity. The accelerated ageing and seedling growth tests were performed on the 8th month of storage. The data obtained in each storage... (Complete abstract click electronic access below)

O tratamento de sementes pode ser uma importante técnica para o fornecimento de micronutrientes na cultura do milho (Zea mays L.), sendo capaz de promover um melhor estabelecimento da cultura no campo. Solos contendo níveis insuficientes de zinco e de cobre para as plantas são frequentes em grande parte das regiões agrícolas do Brasil e do mundo. Deste modo, o fornecimento destes elementos via sementes pode ser uma alternativa viável e eficaz para produtores de milho. Este trabalho teve como objetivo avaliar diferentes tratamentos de sementes de milho contendo Zn e Cu, considerando aspectos relacionados à qualidade fisiológica das sementes e à eficiência nutricional. Para tal, foram utilizados quatro lotes do híbrido 2B688Hx, apresentando diferenças quanto ao tamanho e vigor das sementes. Os tratamentos foram compostos por diferentes dosagens e combinações de suspensões líquidas contendo óxido de Zn e carbonato de Cu, fornecidos juntos ou separadamente. Os lotes foram avaliados pelo teor de água das sementes, germinação e teste de frio em cinco épocas: 0, 30, 60, 180 e 360 dias. Nas três primeiras épocas, também foram realizados os testes de emergência de plântulas, velocidade de emergência de plântulas e análises do crescimento de raiz por meio do software SVIS®. O desenvolvimento inicial das plantas foi avaliado pela altura, área foliar e massa seca de raiz e de parte aérea. Os dados de massa seca associados aos teores de Zn e de Cu nos tecidos permitiram calcular as eficiências de absorção, transporte e utilização dos mesmos. A qualidade fisiológica de sementes de milho tratadas com Zn e Cu, isoladamente ou associados, não é afetada ao longo de doze meses de armazenamento; por outro lado, o Cu utilizado isoladamente causa fitotoxicidade quando a avaliação é realizada tendo o papel como substrato, afetando principalmente o desenvolvimento radicular das plântulas. O tratamento de sementes com zinco e cobre se constitui em alternativa viável e eficaz para o fornecimento destes elementos para as plantas de milho. / Seed treatment is a potential tool for supplying micronutrients on maize crop (Zea mays L.), enabling a better plant stand establishment in the field. Soils presenting insufficient levels of zinc and copper to plants are common in various agricultural regions throughout Brazil and the world. Thus, the supply of such elements via seeds can be viable and effective for maize crop. This study aimed to evaluate different maize seed treatments containing Zn and Cu, related to the effects on seeds physiological quality and nutritional efficiency. Thus, four seeds lots of the corn hybrid 2B688Hx, differing in size and vigor, were used for this study. The treatments were composed of liquid suspensions containing Zn oxide and Cu carbonate, applied together or separately at different dosages. The lots were evaluated by seed moisture, germination and cold test in five periods: 0, 30, 60, 180 and 360 days. Seedling emergence, seedling emergence speed and image analysis of root growth (software SVIS®) were also performed in the first three periods. The plants development was assessed by height, leaf area and dry weight of roots and shoots. The efficiencies of absorption, transport and utilization were calculated with the data of seedlings dry weight and tissues content of Zn and Cu. The physiological quality of maize seeds is not affected by the treatments containing Zn and Cu, together or separated, during the twelve-month storage period; on the other hand, the treatments containing only Cu caused phytotoxicity on paper-based tests, affecting mainly the seedlings root development. Seed treatment with zinc and copper is a viable and effective approach for supplying these elements to maize plants.

No description available.

Plants depend on a wide variety of vectors, both biotic and abiotic, to move their seeds to locations away from parent plants. The stages between seed production and seedling establishment in the plant life cycle are under the influence of a complex set of ecological and evolutionary factors (Wang and Smith 2002). In ecological time scales, seed dispersal has been shown to influence both plant population and community dynamics (Howe and Miriti 2004, Seidler and Plotkin 2006). The evolutionary effects are seen in the way these interactions influence the fruiting season, fruit crop size, fruit size, nutritive value of fruit or seed and other strategies adopted by the plant to ensure effective dispersal of their seeds (Howe and Smallwood 1982, Schupp 1993). Most seed dispersal research has focussed on arboreal frugivores such as birds, primates and bats. In comparison, terrestrial frugivores such as ruminants, elephants and rodents are poorly researched. Large-bodied terrestrial frugivores are key to the dispersal of several large-seeded plants and are also capable of dispersing seeds to long distances (> 1 km). Given that large mammals have witnessed tremendous declines in their abundances and ranges in historical times, plants that depend upon them for long distance dispersal might have limited ability to move across fragmented landscapes under changing climates. However, very little is understood about seed dispersal by large mammals or about seed dispersal characteristics of tropical dry forests which support among the highest biomass of large terrestrial mammals. Tropical dry forests are among the most endangered tropical ecosystems (Janzen 1988). It has also been forecast that tropical dry forests in the Indian subcontinent will witness significant changes in temperature and rainfall regimes in the coming decades (Ravindranath et al. 2006). However, compared to tropical moist forests which have received most of the scientific interest, theory, methodology and base line information about seed dispersal in dry forests is poorly developed. To address some of these lacunae, I examined seed dispersal at both population and community-scales in the tropical dry forests of Mudumalai Wildlife Sanctuary from 2005 -2007. Mudumlai is located within a relatively large contiguous stretch of tropical dry forests in southern India and has an intact and abundant frugivore assemblage. In addition, the Mudumalai Forest Dynamics Plot (MFDP), a large 50 hectare plot has been monitored for recruitment, mortality and diameter growth of woody plants for the last twenty years. The plot is an invaluable resource for seed dispersal studies since it provides us an opportunity to link seed dispersal with plant population and community dynamics. In the first part of the thesis (Chapters 3 and 4), I focus on evaluating the effectiveness of ruminants as seed dispersers and then examine factors that influence frugivory by ruminants. This work was carried out at the population level, for the tree Phyllanthus emblica. The fruits of P. emblica are important non-timber forest produce from Asian dry tropics and understanding the quantity of fruit consumed by frugivores has implications for sustainable harvest practices of this resource (Shahabuddin and Prasad 2004). In the second part of the thesis (Chapters 5 and 6), I characterized seed dispersal at the community-scale for woody plants on the MFDP. Community-wide characterization of seed dispersal at sites harboring an intact faunal assemblage is critical to identify plants dependent on endangered dispersers. The second half of the thesis focuses on examining the associations between dispersal mode and fruit characteristics, and also between dispersal mode and spatial patterning of woody plants. Evaluating the effectiveness of ruminants as seed dispersers: Disperser effectiveness is defined as the contribution a disperser makes to the future reproduction of a plant. Evaluating disperser effectiveness involves addressing both quantitative aspects such as frequency of visits, quantity of fruit consumed, diversity of species dispersed, and, qualitative components such as the treatment given in mouth and gut and the suitability of seed deposition sites for germination (Schupp 1993, Dennis and Westcott 2006). Information on quantity and quality of seed dispersal services provided by ruminants is very limited. This is because techniques such as tree watches or fruit traps adapted from avian frugivore studies are ill suited to study terrestrial frugivores, and conventional camera traps provide little quantitative information on the quantity of fruit consumed by frugivores. The quantity of dispersal services provided by ruminants for P. emblica was assessed using a novel camera trap technique. Time-delay was programmed into the camera trap units (4 pictures taken 2 minutes apart) to tell apart frugivores from visitors (by comparing number of fruit remaining in the time-delay picture sequence). During a two year study using this technique, six terrestrial mammals were identified as frugivores of P. emblica. Additionally, seven mammals and one bird species visited fruiting trees but did not consume fallen fruit. Two ruminants, the Indian chevrotain Moschiola indica and chital Axis axis, were the most frequent frugivores of P. emblica and these ruminants accounted for over 95% of fruit removal, while murid rodents accounted for less than 1%. The quality of dispersal services provided by ruminants was examined using a combination of feeding trials (with captive animals) and germination experiments for large-seeded species dispersed by ruminants in tropical dry forests, including P. emblica. Ruminants regurgitated well-protected seeds larger than 5 mm, after retaining them in the rumen for 2–50 h. Though germination success was lowered after rumen retention, it was not too low (> 15%), and would still ensure dispersal if suitable micro-habitats could be found. Given the daily home-range of chital (14–20 ha in tropical dry forests (Mishra 1982)), and their seed retention times (2–50 h), movement of chital during the 1–2 d period when seeds remain in the rumen can potentially disperse seeds to distances over 1 km. Thus, our research shows that ruminants account for most of the fruit removal and are the principal primary dispersers of P. emblica. Factors influencing frugivory by ruminants: Fruit removal, the quantity of fruits consumed by frugivores, is highly variable within plant populations. Understanding factors influencing this selection operated by frugivores helps link frugivore behavior with plant demography. The outcome of such selection operated by frugivores has been examined mostly for interactions involving avian frugivores. The extension of this theory to terrestrial frugivores, which are presented with fruit on the ground, is not well understood. In addition, factors influencing fruit removal have been examined mostly with respect to changing spatial contexts such as crop size and fruiting neighborhoods. The influence of varying temporal contexts on frugivore choice, and their possible demographic and evolutionary consequences is poorly understood. We examined if temporal variation in fruit availability across a hierarchy of nested temporal levels (interannual, intraseasonal, 120 h, 24 h) altered fruit removal of P. emblica on the MFDP. The interactions between P. emblica and its primary disperser (ruminants) was mediated by another frugivore (a primate, langur), which made large quantities of fruit available on the ground to ruminants. The direction and strength of crop size and neighborhood effects on this interaction varied with changing temporal contexts. Fruit availability was higher in the first of the two study years, and at the start of the season in both years. Fruit persistence on trees, determined by primate foraging, was influenced by crop size and conspecific neighborhood densities only in the high fruit availability year. Fruit removal by ruminants was influenced by crop size in both years and neighborhood densities only in the high availability year. In both years, these effects were stronger at the start of the season. Intraseasonal reduction in fruit availability diminished inequalities in fruit removal by ruminants and the influence of crop size and fruiting neighborhoods. Temporal asymmetry in frugivore-mediated selection could reduce the potential for co-evolution between frugivores and plants by diluting selective pressures. Langurs determined the length of time fruit persisted on individual trees, and, also influenced the quantity and duration of fruit availability for the primary dispersers, ruminants. Such inter-dependencies formed between disparate animal consumers add additional levels of complexity to plant–frugivore mutualistic networks and can have potential reproductive consequences for specific individuals within populations. Seed dispersal within a tropical dry forest community: Megafauna are considered to be important seed dispersers, but their contribution has mostly been examined in isolation, with limited reference to other frugivores within communities. Community-wide characterization of seed dispersal at sites harboring an intact fauna is essential to evaluate the role of megafauna in dispersal, examine dispersal syndromes and assess the vulnerability of plant communities to disperser declines and climate change. Dispersal modes were inventoried for 92% of species and fruit traits for 84% of the woody plant community on the MFDP. Fruit–frugivore interactions were identified using a combination of camera traps, tree watches and opportunistic observations. Though 60% of the species were animal-dispersed, mechanically-dispersed species were more dominant and constituted nearly 70% of the stand. Bird-dispersed species were very rare and constituted less than 10% of the stand cumulatively. In comparison, bird-dispersed species account for ~ 50% of the stand in moist forests of tropical Asia. Three broad dispersal modes were identified – mechanical, mammal and bird-mammal, and these displayed strong associations with fruit traits. Among the 11 frequently-observed frugivore groups, the three largest frugivores, deer, bear and elephant, together dispersed 40% of the community. There was low overlap in fruit diets between these three megafaunal groups, though diets of deer and bear overlapped with different groups of small and medium-sized frugivores. Deer and bear displayed significant associations with fruit traits, while elephant did not. Among the fleshy fruits, large fruits and large-seeded fruits had fewer dispersers compared to smaller, multi-seeded fruits. Although the largest fleshy fruits and seeds were often dispersed by megafauna, few were exclusively dependent on megafauna. The three megafaunal groups were the only potential long distance dispersers for 25% of the community. For a better understanding of the impacts of megafaunal extinctions, even rare events of dispersal by megafauna should be considered since these could prove important for plants lacking other long distance dispersers. Given that these megafauna and several medium-sized frugivores are rare in degraded areas of tropical Asia (Corlett 2007, Karanth et al. 2010), one fourth of the plant community at Mudumalai could have limited ability to disperse across fragmented landscapes in response to changing climates. Seed dispersal and spatial patterns in tropical dry forests: To address the relevance of seed dispersal to plant community structure, the linkages between dispersal mode and spatial aggregation of trees were examined for the woody plant community on the MFDP. For plants, seed arrival patterns vary depending upon their dispersal mode and form the primary matrix upon which further forces shape spatial patterns. Spatial patterns were examined via the pair correlation function (statistic) and statistics derived from cluster models (Matern process). Considering only trees that had 10 individuals (48 species), it was found that tropical dry forest trees exhibited extensive spatial aggregation. The degree of spatial aggregation at Mudumalai was remarkably similar to wet forests in tropical Asia. Species with limited-dispersal (mechanically-dispersed species) were more aggregated than those with more frequent long-distance dispersal (animal-dispersed species) at smaller spatial scales (< 50 m). Animal-dispersed species had larger cluster radius, with bird-dispersed species having the largest radii. These results are in concordance with Siedler & Plotkin (2006) and Li et al. (2009) who find that mechanically-dispersed species are more aggregated than animal-dispersed species. These results demonstrate that seed dispersal has a strong influence on the spatial patterning of plant communities. Conclusion: At the population level, our results imply that P. emblica is mainly dependent on ruminants for seed dispersal. In tropical dry forest sites such as Mudumalai, up to 15% of the species are dispersed by ruminants, with langurs mediating the ruminant-plant interaction similar to P. emblica. The observed fruit removal patterns for P. emblica reiterate the fact that all fruiting individuals in a population are not equally attractive to frugivores, especially when fruits are abundant. Alterations of such complex fruit-frugivore interactions through human-mediated changes of fruit or frugivore densities (through fruit harvests or hunting of large mammalian frugivores such as ruminants), can feed back into the seed dispersal loop and affect several downstream ecological and evolutionary processes. At the community-scale, the dispersal profile of woody plants in Mudumalai’s tropical dry forests differed considerably from tropical moist sites, with a greater representation of mammal and mechanically-dispersed species. However, the linkages between seed dispersal and spatial patterns of trees at Mudumalai are similar to tropical moist forests. Extensions of the models developed from this site harbouring an intact faunal assemblage to other tropical dry forests would enable rapid characterization of dispersal profiles and identification of plant species dependent on endangered fauna for seed dispersal that should be prioritized for restoration programs.

Astragalus ampullarioides and A. holmgreniorum are two rare endemics of southwestern Utah. Over two consecutive field seasons (2009-2010) we examined pre-emergent reproductive success, based on F/F and S/O ratios, from populations of both Astragalus ampullarioides and A. holmgreniorum, estimated the density of the soil seed bank of A. holmgreniorum as a measure of potential post-emergent reproductive success, and estimated seed persistence within the soil seed bank. Fruit/flower (F/F) ratios and seed/ovule (S/O) ratios varied significantly between populations and among years in both species, and showed low reproductive output in both taxa. In Astragalus ampullarioides F/F and S/O were 0.06±0.01 and 0.16±0.02, respectively (2009), and 0.14±0.01 and 0.41±0.02, respectively (2010). For Astragalus holmgreniorum F/F and S/O ratios were 0.11±0.01 and 0.38±0.02, respectively (2009), and 0.23±0.01 and 0.66±0.02, respectively (2010). Although Astragalus holmgreniorum exhibited a low soil seed bank density (4.3 seeds m-2), seed persistence data showed low a low percentage of seeds germinated during the first year in the soil seed bank. Seeds remaining in the seed bank maintained high percent viability. Soil seed persistence of Astragalus ampullarioides differed from A. holmgreniorum in that a high percentage of seeds germinated during the first year in the soil seed bank. A high percentage of viability in ungerminated seeds was also maintained in A. ampullarioides. Although these species differ in life histories and dependence on soil seed banks, an understanding of the strategies unique to each species will prove useful in management plans.

Thesis (MScAgric (Agronomy))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Little is known about the nutrient requirements of broccoli grown for seed production. During 2006 and 2007 broccoli were grown for seed production in sand bags in a net structure, using a drain to waste hydroponic system. The experimental design was a randomized complete block with seven treatments replicated in four blocks. In 2006 seven nutrient solution treatments were tested. The Standard solution based on Steiner’s universal solution was compared with different levels of N, S, K and Ca with regard to the effect on total biomass, nutrient concentration, nutrient assimilation, seed yield and quality. No significant differences in total biomass produced were found. Total dry mass increased by 225% from the mature head stage until harvest of seed. Nutrient concentration in plant samples were not influenced by treatments except where low levels of K and S in nutrient solutions led to significantly lower levels of K and S concentrations. The total assimilation of elements were calculated to determine the effect of the much longer growth period needed for seed production in comparison to normal head production on nutrient requirements. Major elements assimilated ha-1 was: N 173.0 kg, P 35.5 kg, K 348.4 kg, Ca 114.7 kg, Mg 30.5 kg, S 42.2 kg. The seven treatments used during 2007 included three of the treatments which were used in 2006 as well as treatments with foliar sprays containing Ammonium Nitrate and Calcium Metalosate. The standard solution treatment was also used in 2007 to compare results with 2006. Plant analysis done on plants from the standard solution (2006 & 2007) showed similar trends. As the plants developed towards maturity there was a relative increase in concentration in the top plant parts (pods, flowers and stems) for Ca, Mg and S. Contrary, N and P concentration declined. The minor elements, Fe, Mn and B also increased in concentration in the top plant parts at harvest indicating a strong relative flow of these elements to the top plant parts towards maturation. Concentration values of major elements in plant samples were generally different when the two years were compared. Element concentrations in the seed pods were in general higher than in the rest of the plant indicating the pods as a strong sink on the plants. During both years the two best nutrient solutions for yield were the same, namely the Standard solution and Standard - K which contain low levels of K. During 2006 no significant differences in seed quality were found. During 2007 no significant differences were found for seed quality measurements, except for size (of the cotyledons). The results indicate that no special adjustments need to be made to the Standard solution in order to produce good broccoli seed yield of good quality. As substantial differences in nutrient solution composition did not significantly affect the quality of broccoli seed produced. Seed yield was however significantly affected by nutrient solution composition. Key words: Brassica seed, broccoli seed, seed production, broccoli nutrition, hydroponic production, broccoli production, nutrient assimilation. / AFRIKAANSE OPSOMMING: Min inligting is bekend rakende die voedingsbehoeftes van brokkoli wat gekweek word vir saadproduksie. Gedurende 2006 en 2007 is brokkoli gekweek vir saadproduksie in sakke sand in ‘n net struktuur met ‘n oop hidroponiese besproeiingstelsel. Die proefontwerp was ‘n ewekanisige geheel blok met sewe behandelings wat ewekansig binne bloke toegeken is en herhaal is in vier blokke. Sewe voedingsmengsel behandelings is gedurende 2006 toegepas. Die Standaard mengsel is geskoei op Steiner se universele mengsel en dit is vergelyk met verskillende vlakke van N, S, K en Ca t.o.v. die invloed daarvan op biomassa produksie, voedingselement konsentrasie, voedingselement assimilasie, saad opbrengs en saad kwaliteit. Biomassa geproduseer het nie wesenlik verskil nie. Totale droë massa het met 225% toegeneem vanaf die volwasse kop tot die oes stadium. Die konsentrasie van voedings elemente in plant monsters is nie beïnvloed deur behandelings nie behalwe in gevalle waar lae konsentrasies van K en S in die voedingsmengsels gelei het tot lae konsentrasies van K en S in plantontledings. Die totale opname van voedingselemente is bereken om die effek van die veel langer groeiperiode wat benodig word vir saadproduksie in vergelyking met normale kop produksie te bepaal t.o.v. voedingselement behoefte. Makro element opname per hektaar was as volg: N 173.0 kg, P 35.5 kg, K 348.4 kg, Ca 114.7 kg, Mg 30.5 kg, S 42.2 kg. Die sewe behandelings van 2007 het drie behandelings van 2006 ingesluit asook behandelings van blaarbespuitings met Ammonium Nitraat en Kalsium Metalosaat. Die Standaard voedingsmengsel is weer gebruik ten einde die resultate van 2006 en 2007 te vergelyk. Voedingselement ontledings op plante van die Standaard mengsel (2006 & 2007) is vergelyk en het soortgelyke tendense aangedui. Soos wat plante ontwikkel het na volwassenheid was daar ‘n relatiewe toename in konsentrasie in die boonste plant dele (peule, blomme en stele) van Ca, Mg en S. In teenstelling hiermee het die konsentrasies van N en P afgeneem. Die mikro elemente Fe, Mn en B het ook in konsentrasie toegeneem in die boonste plant dele teen oes wat daarop dui dat daar ‘n sterk relatiewe vloei van hiedie elemente na die boonste plant dele plaasvind met volwasse wording. Die konsentrasie vlakke van makro elemente in plantontledings het in die algemeen wesenlik verskil tussen die twee jare. Die voedingselement konsentrasies was in die algemeen hoër in die saad peule as in die res van die plant wat daarop dui dat die peule as ‘n sterk sink op die plant funksioneer. In beide jare was die hoogste opbrengs afkomstig van die Standaard voedingsmengsel en die Standaard – K mengsel wat lae vlakke van K bevat het. Gedurende 2006 is geen wesenlike verskille in saadkwaliteitsnorme gevind nie. Soortgelyke resultate is gevind in 2007 behalwe vir grootte van die kiemblare. Die resultate dui daarop dat dit nie nodig is om die Standaard voedingsmengsel samestelling te verander ten einde goeie opbrengs saad van goeie gehalte te produseer nie. Wesenlike verskille in voedingsmengsels het geen invloed op die kwaliteit van brokkoli saad gehad nie. Saad opbrengs is egter wesenlik beïnvloed deur die samestelling van die voedingsmengsels. Sleutel woorde: brassica saad, brokkoli saad, saad produksie, brokkoli voeding, hidroponiese produksie, brokkoli produksie, voedingstof assimilasie.

Os objetivos dessa pesquisa foram avaliar as alterações de natureza física, fisiológica e bioquímica durante a formação das sementes de soja, produzidas nos anos 2009 e 2010, em Piracicaba, São Paulo. Foram utilizadas sementes de dois cultivares de soja, CD - 202 e CD - 224, e os tratamentos foram compostos pelos momentos de colheita, ao longo do processo de formação das sementes, e pela utilização ou não da secagem artificial. Para as avaliações foram determinados os número de dias para a emergência da plântula, para a floração, para a floração plena, para a colheita, os parâmetros físicos (produtividade, teor de água das sementes e massa de mil sementes) fisiológicos (viabilidade e vigor) e bioquímicos (teores de óleo, de proteína, de clorofila, carotenoides, de lignina e de carboidratos). O delineamento experimental utilizado foi em blocos ao acaso, em que cada bloco continha uma unidade experimental de cada cultivar, distribuída de forma casualizada, em esquema fatorial de onze (momentos de colheita) x dois (sem secagem e com secagem), com quatro repetições e as análises estatísticas foram realizadas com o software R. Foi possível concluir que na maturidade fisiológica das sementes de soja, estádio R7, independentemente do cultivar e da avaliação das sementes úmidas ou secas, a produtividade, a viabilidade e os teores de lignina são máximos; No momento de colheita das sementes de soja, estádio R9, independentemente do cultivar e da avaliação de sementes úmidas ou secas, o acúmulo de massa é máximo, há a redução do teor de água, da viabilidade e do vigor e a semente tem mais óleo e proteína; O vigor das sementes é máximo no estádio R7 para as sementes avaliadas secas e no estádio R8 para as avaliadas úmidas, independentemente do cultivar; Há a degradação completa da clorofila nos estádios R7, para as sementes do cultivar CD - 202, e R8, para as sementes do cultivar CD - 224; Há carotenoides em todos os estádios de desenvolvimento da semente de soja, porém há mais carotenoides no início do processo de formação das sementes; Há variação da quantidade de carboidratos em função da avaliação das sementes úmidas ou secas. / This experiment aimed at the evaluation of the physical, physiological and biochemical changes during formation of soy seeds, produced in 2009 and 2010, in Piracicaba, São Paulo. Seeds of two cultivars of soy were used, namely CD - 202 and CD - 224, and treatments were composed by the moment of harvest, along the process of formation of seeds, and by the use or non-use of artificial drying. For the evaluations, we determined the number of days for seedling emergency, flowering, full flowering, harvest, physical parameters (productivity, rate of water in the seeds and mass of a thousand seeds) physiological parameters (viability and vigor) and biochemical parameters (rate of oil, of protein, of chlorophyll, of lignin and carbohydrates). The experimental delineation in use was in random blocks, in which each block contained one experimental unit of each cultivar, distributed at random, in a factorial scheme of eleven (harvesting periods), x two (dried and not dried), at four repetitions, and the statistical analysis were performed with software R. It was possible to conclude that at physiological maturity of soy seeds, stage R7, independently of the cultivar and of the evaluation of dry or humid seeds, the productivity, viability and rates of lignin are at their maximum; In the moment of harvest of soy seeds, stage R9, independently of the cultivar and evaluation of humid or dry seeds, the accumulation of mass is at its maximum, there is a drop in the level of water, of the viability and vigor, and the seed contains more oil and protein; The vigor of the seeds is at its maximum at stage R7 for the seeds which were evaluated dry and at stage R8 for the ones evaluated as humid, independently of the cultivar; There is the complete deterioration of the chlorophyll at stages R7, for the seeds of cultivar CD - 202 and R8, for the seeds of cultivar CD - 224; There are carotenoids in all stages of development of soy seed, however there are more of them in the beginning of the process of formation of seeds. There is variation of quantity of carbohydrates according to the evaluation of humid or dry seeds.

Thesis (M. A. Agricultural Management (Agricultural Extension)) -- University of Limpopo, 2019 / Smallholder farmers’ need for regular supply of adequate, quality and affordable seed led to the establishments of Community-Based Maize Seed Production Schemes (CBSPSs) in most developing countries, including South Africa. In view of the important influence of perception on the adoption and continued use of an innovation, this study was undertaken to evaluate farmers’ perceptions of CBSPSs in Polokwane and Lepelle-Nkumpi Local Municipalities of Limpopo province. The conceptualization of perception used in this study was based on the Düvel (1991) framework. The evaluation focused on whether planting the scheme’s main product, improved Open-Pollinated Varieties (improved OPV maize) seed meets farmers’ needs based on their perceptions and the extent of farmers’ planting of improved OPV maize. A census approach was used in view of the small numbers of seed producers in the schemes; all scheme members (50) were, therefore, interviewed between 27 March and 21 April 2017. To allow for comparison, an equal number of farmers (50) who were not members of the scheme were also interviewed. Data was collected from farmers using a semi-structured questionnaire. Descriptive and inferential statistics were applied to analyze the data using SPSS software. A binary logistic model was used to analyze factors that influence farmer perceptions on OPV benefits. The study findings showed that there is a significant relationship between awareness knowledge of improved OPV maize and planting of improved OPV maize. Furthermore, the results showed that farmers perceptions of the advantages and disadvantages of improved OPV maize seed were not different among scheme and non-scheme members as they were all in agreement that improved OPV maize have more benefits than their own previously recycled seeds. Finally, findings showed that respondents municipality and scheme membership had a significant, effect on the positive perception of planting improved OPV maize seeds. Other explanatory variables such as sex, farming experience, years of viii schooling, farm size, income and age of participants had no significant effect on farmer perceptions. It is therefore recommended that improved OPV maize be made widely available and promoted based on its advantages to enhance its adoption. Future studies on these seed schemes could look into the production and financial analysis of CBSPSs to ascertain their profitability and sustainability. / Agricultural Research Council (ARC)

The release of genetically modified, herbicide tolerant canola (<I>Brassica napus</i> L.) genotypes in western Canada has increased interest in the persistence of volunteer canola. <i>B. napus</i> seed may be induced into secondary dormancy in the laboratory, however, little is known of the seedbank ecology and the role of secondary dormancy as a persistence mechanism in this species in the region. The objectives of this research were i) to determine seedbank additions at the time of harvest, ii) determine the role of secondary seed dormancy in seedbank persistence under different management systems, iii) determine the relative importance of factors contributing to secondary dormancy potential and iv) evaluate the role of abscisic acid (ABA) during secondary dormancy induction in <I>B. napus</i>. On farms, average seedbank additions during harvest were approximately 20 times the normal seeding rate of canola. High secondary seed dormancy potential prolonged seedbank persistence in fields, irrespective of tillage system. <I>B. napus</i> exhibited seedling recruitment of a typical summer annual weed where seedling recruitment was only observed in the spring. Seasonal seedling recruitment was the result of two fates: seed death in the shallow seedbank, irrespective of dormancy potential, and increased ungerminability in buried seeds which was related to secondary seed dormancy potential. Among the factors that contribute to secondary seed dormancy potential, genotype was of greatest significance. Seed size was of lesser importance, while the contributions of pre-harvest factors including seed maturity, year, and location were negligible in comparison. Differences in ABA synthesis and the response to ABA application were related to secondary seed dormancy potential and correlated well previous reports linking ABA to seed dormancy. Conclusions that emerge from this research are i) that on some farms, seedbank additions may be lowered by more diligent harvest practices, ii) seedbank persistence of <I>B. napus</i> may be reduced by growing low dormancy genotypes and avoiding seed burial for one year after seedbank establishment and iii) ABA + ABA-glucose ester (ABA-GE) and the ability of seeds to respond to ABA application after seed dormancy induction may potentially be used to identify seed dormancy potential in this species.

The release of genetically modified, herbicide tolerant canola (<I>Brassica napus</i> L.) genotypes in western Canada has increased interest in the persistence of volunteer canola. <i>B. napus</i> seed may be induced into secondary dormancy in the laboratory, however, little is known of the seedbank ecology and the role of secondary dormancy as a persistence mechanism in this species in the region. The objectives of this research were i) to determine seedbank additions at the time of harvest, ii) determine the role of secondary seed dormancy in seedbank persistence under different management systems, iii) determine the relative importance of factors contributing to secondary dormancy potential and iv) evaluate the role of abscisic acid (ABA) during secondary dormancy induction in <I>B. napus</i>. On farms, average seedbank additions during harvest were approximately 20 times the normal seeding rate of canola. High secondary seed dormancy potential prolonged seedbank persistence in fields, irrespective of tillage system. <I>B. napus</i> exhibited seedling recruitment of a typical summer annual weed where seedling recruitment was only observed in the spring. Seasonal seedling recruitment was the result of two fates: seed death in the shallow seedbank, irrespective of dormancy potential, and increased ungerminability in buried seeds which was related to secondary seed dormancy potential. Among the factors that contribute to secondary seed dormancy potential, genotype was of greatest significance. Seed size was of lesser importance, while the contributions of pre-harvest factors including seed maturity, year, and location were negligible in comparison. Differences in ABA synthesis and the response to ABA application were related to secondary seed dormancy potential and correlated well previous reports linking ABA to seed dormancy. Conclusions that emerge from this research are i) that on some farms, seedbank additions may be lowered by more diligent harvest practices, ii) seedbank persistence of <I>B. napus</i> may be reduced by growing low dormancy genotypes and avoiding seed burial for one year after seedbank establishment and iii) ABA + ABA-glucose ester (ABA-GE) and the ability of seeds to respond to ABA application after seed dormancy induction may potentially be used to identify seed dormancy potential in this species.