The effect of drying corn, rice and wheat seed in two stages was studied, using germinability as a measure of quality. For the first stage, fluidised bed dryer (FBD) and spouted bed dryer (SBD) were used to dry seed from 20-25%wb to 18%wb while in-store dryer (ISO) was used in the second stage for drying from 18%wb to below 14%wb. The drying air temperature range of 40-80??C was studied for the first stage while 18-30??C and relative humidity 60-70% were for the second stage. It was found that dryer type, drying temperature, initial moisture content of seeds and drying time had significant effects on the seed germination. From the result, the drying air temperature of 40??C was safe for corn and rice in FBD while 60??C was acceptable for wheat. In SBD, the 40??C was the maximum drying temperature for rice and wheat without quality deterioration. Meanwhile the second stage drying in an ISD under all specified conditions was safe. In this work, the thin-layer drying models were developed. The results showed that the modified Page's model and modified two-compartment model were the best-fitted models with the root mean square (RMS) of the differences between the predicted moisture ratio and the measured values below 0.03. Besides, the existing ISD simulation program provided the RMS of 0.3, 1.1, and 0.9%wb for corn, rice and wheat respectively. The germination models for FBD and SBD were also developed. As a result, the modified Giner's models 1&2 were the best-fitted models for FBD with the RMS of the differences between predicted and measured germination percentages of 7.9, 4.2 and 3.4% for corn, rice and wheat while the modified Giner's models 2&3 were for SBD with the RMS of 5.5 and 6.1% for rice and wheat respectively. The comparison between FBD and SBD revealed that FBD had faster drying rate while SBD consumed less energy. Ultimately, the energy cost analysis showed that single-stage drying in a fixed bed dryer using ambient condition consumed less energy than two-stage drying using a FBD and ISD but lower energy cost must be weighed against the faster drying rate, flexibility, portable design, and product uniformity of FBD.

The effect of drying corn, rice and wheat seed in two stages was studied, using germinability as a measure of quality. For the first stage, fluidised bed dryer (FBD) and spouted bed dryer (SBD) were used to dry seed from 20-25%wb to 18%wb while in-store dryer (ISO) was used in the second stage for drying from 18%wb to below 14%wb. The drying air temperature range of 40-80??C was studied for the first stage while 18-30??C and relative humidity 60-70% were for the second stage. It was found that dryer type, drying temperature, initial moisture content of seeds and drying time had significant effects on the seed germination. From the result, the drying air temperature of 40??C was safe for corn and rice in FBD while 60??C was acceptable for wheat. In SBD, the 40??C was the maximum drying temperature for rice and wheat without quality deterioration. Meanwhile the second stage drying in an ISD under all specified conditions was safe. In this work, the thin-layer drying models were developed. The results showed that the modified Page's model and modified two-compartment model were the best-fitted models with the root mean square (RMS) of the differences between the predicted moisture ratio and the measured values below 0.03. Besides, the existing ISD simulation program provided the RMS of 0.3, 1.1, and 0.9%wb for corn, rice and wheat respectively. The germination models for FBD and SBD were also developed. As a result, the modified Giner's models 1&2 were the best-fitted models for FBD with the RMS of the differences between predicted and measured germination percentages of 7.9, 4.2 and 3.4% for corn, rice and wheat while the modified Giner's models 2&3 were for SBD with the RMS of 5.5 and 6.1% for rice and wheat respectively. The comparison between FBD and SBD revealed that FBD had faster drying rate while SBD consumed less energy. Ultimately, the energy cost analysis showed that single-stage drying in a fixed bed dryer using ambient condition consumed less energy than two-stage drying using a FBD and ISD but lower energy cost must be weighed against the faster drying rate, flexibility, portable design, and product uniformity of FBD.

Made available in DSpace on 2014-06-11T19:28:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-09Bitstream added on 2014-06-13T19:37:06Z : No. of bitstreams: 1 ferreira_ac_me_jabo.pdf: 206579 bytes, checksum: ae1661430b2626c1ec623bac6a3fbb05 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As sementes de milho-doce apresentam a espessura reduzida do pericarpo e maior quantidade de açúcares no endosperma e estas características tornam-nas mais suscetíveis aos danos mecânicos, à entrada e proliferação de patógenos e à deterioração, quando comparadas às de milho comum. Assim, as sementes de milho-doce apresentam menor longevidade no armazenamento e baixo desempenho em campo. O condicionamento fisiológico de sementes e o uso de fitorreguladores podem ser utilizados como técnicas para melhorar o desempenho de sementes. Este trabalho teve como objetivo avaliar os efeitos do condicionamento fisiológico, de fitorreguladores e do armazenamento no desempenho de sementes de milho-doce. Os seguintes tratamentos foram aplicados às sementes: tratamento 1 – sem condicionamento fisiológico; tratamento 2 – com condicionamento fisiológico; tratamento 3 – com condicionamento fisiológico + auxina (50 ppm); tratamento 4 – com condicionamento fisiológico + ácido giberélico (50 ppm) e tratamento 5 – com condicionamento fisiológico + auxina (50 ppm) + ácido giberélico (50 ppm). As sementes foram armazenadas em câmara fria com temperatura de 10 ºC ±1 ºC e umidade relativa do ar de 50% ±5% durante quatro meses. Imediatamente após o condicionamento fisiológico e após quatro meses, foram utilizados os testes de teor de água, teste de germinação, teste de envelhecimento acelerado, teste de frio com solo, teste de condutividade elétrica e teste de emergência de plântulas para avaliar o ensaio. O condicionamento fisiológico com e sem fitorreguladores não teve efeito sobre a germinação e o vigor de sementes de milho-doce, permitindo concluir que estas técnicas não tiveram efeitos positivos na qualidade das sementes de milho-doce nas condições do ensaio / The seeds of sweet corn have reduced the thickness of the pericarp and higher amount of sugars in the endosperm and these characteristics make them more susceptible to mechanical damage at the entrance and proliferation of pathogens and the deterioration when compared to normal corn. Thus the seeds of sweet corn in storage have reduced longevity and poor performance on the field. Priming and the growth regulators can be used as techniques to improve the performance of seeds. This study aimed to evaluate the effects of priming, growth regulators and storage on sweet corn performance. The following treatments were applied to seeds: treatment 1 - no priming; treatment 2 - priming; treatment 3 - priming + auxin (50 ppm); treatment 4 - priming + gibberellic acid (50 ppm) and treatment 5 - priming + auxin (50 ppm) + gibberellic acid (50 ppm). The seeds were stored in cold chamber with temperature of 10 ºC ± 1 ºC and relative humidity of 50% ± 5% for four months. Immediately after the priming and after four months, were used the water content test, germination test, accelerated aging, cold test with soil, electrical conductivity test and seedling emergency test to evaluate the assay. The priming with and without growth regulators had no effect on germination and seed vigor of sweet corn, the report concludes that these techniques did not have positive effects on quality of sweet corn seeds in the assay conditions

Orientador: Roberval Daiton Vieira / Banca: Ana Dionisia da Luz Coelho Novembre / Banca: Claudio Cavariani / Resumo: As sementes de milho-doce apresentam a espessura reduzida do pericarpo e maior quantidade de açúcares no endosperma e estas características tornam-nas mais suscetíveis aos danos mecânicos, à entrada e proliferação de patógenos e à deterioração, quando comparadas às de milho comum. Assim, as sementes de milho-doce apresentam menor longevidade no armazenamento e baixo desempenho em campo. O condicionamento fisiológico de sementes e o uso de fitorreguladores podem ser utilizados como técnicas para melhorar o desempenho de sementes. Este trabalho teve como objetivo avaliar os efeitos do condicionamento fisiológico, de fitorreguladores e do armazenamento no desempenho de sementes de milho-doce. Os seguintes tratamentos foram aplicados às sementes: tratamento 1 - sem condicionamento fisiológico; tratamento 2 - com condicionamento fisiológico; tratamento 3 - com condicionamento fisiológico + auxina (50 ppm); tratamento 4 - com condicionamento fisiológico + ácido giberélico (50 ppm) e tratamento 5 - com condicionamento fisiológico + auxina (50 ppm) + ácido giberélico (50 ppm). As sementes foram armazenadas em câmara fria com temperatura de 10 ºC ±1 ºC e umidade relativa do ar de 50% ±5% durante quatro meses. Imediatamente após o condicionamento fisiológico e após quatro meses, foram utilizados os testes de teor de água, teste de germinação, teste de envelhecimento acelerado, teste de frio com solo, teste de condutividade elétrica e teste de emergência de plântulas para avaliar o ensaio. O condicionamento fisiológico com e sem fitorreguladores não teve efeito sobre a germinação e o vigor de sementes de milho-doce, permitindo concluir que estas técnicas não tiveram efeitos positivos na qualidade das sementes de milho-doce nas condições do ensaio / Abstract: The seeds of sweet corn have reduced the thickness of the pericarp and higher amount of sugars in the endosperm and these characteristics make them more susceptible to mechanical damage at the entrance and proliferation of pathogens and the deterioration when compared to normal corn. Thus the seeds of sweet corn in storage have reduced longevity and poor performance on the field. Priming and the growth regulators can be used as techniques to improve the performance of seeds. This study aimed to evaluate the effects of priming, growth regulators and storage on sweet corn performance. The following treatments were applied to seeds: treatment 1 - no priming; treatment 2 - priming; treatment 3 - priming + auxin (50 ppm); treatment 4 - priming + gibberellic acid (50 ppm) and treatment 5 - priming + auxin (50 ppm) + gibberellic acid (50 ppm). The seeds were stored in cold chamber with temperature of 10 ºC ± 1 ºC and relative humidity of 50% ± 5% for four months. Immediately after the priming and after four months, were used the water content test, germination test, accelerated aging, cold test with soil, electrical conductivity test and seedling emergency test to evaluate the assay. The priming with and without growth regulators had no effect on germination and seed vigor of sweet corn, the report concludes that these techniques did not have positive effects on quality of sweet corn seeds in the assay conditions / Mestre

The pattern and sequence of zein degradation in the endosperm of germinating maize seeds were investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting. The proteases involved in the degradation of various zein components (α, ß and γ) were extracted with three buffer systems and partially characterized with respect to their ability to degrade various zein components. They were also investigated in vivo by germinating the seeds in the presence of protease inhibitors used singly and in combination. Of the various zein components, γ-zein (27-kD) was the first to be degraded and its degradation was complete by the third day after germination (DAG). Beta-zeins (17- and 18-kD) began to be degraded on the second DAG, degradation being complete by the seventh day for the l7-kD polypeptide, and the fourth day for the 18-kD polypeptide. The degradation of 10-kD- zein began on the fourth DAG and was complete by the eighth day. The α-zein fraction (22-and 24-kD) was degraded beginning on the faith day and continued gradually until after the tenth day. From the results of these studies, the arrangement of various zein fractions within the protein bodies can be deduced and this was consistent with the immunocytochemical data published by others. Gamma-zein is situated in the peripheral region of the protein bodies and could be a structural component of the protein body membrane or it may be directly anchored in the membrane. Beta-zeins are internal to γ-zein with the l0-kD in the interface between the 17-kD and γ-zein. The 10- kD zein is located between the 17-kD and α-zein or interlacing with α-zein in the protein body core. Finally, a-zeins are in the protein body core. Based on these observations the proteolysis of the protein in protein bodies of maize would start from the periphery and proceed towards their core. The proteases involved in degradation of various zein components were synthesized de novo. The mRNAs pre-existing in dry seeds appeared to direct the synthesis of active proteases required for zein degradation at least during the initial stages of germination. Serine protease was responsible for the degradation of a- and ß-zeins while aspartic (acid) protease may play some role in ß-zein degradation. Serine and cysteine (thiol) proteases worked synergistically in γ-zein degradation. Enzymes extractable from the endosperm of germinating seeds with 0.2 M acetate buffer (pH 3.8) were able to degrade the α-, ß-, and γ-zeins in an in vito assay. / Ph. D.

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)

Thesis (M. A. Agricultural Science (Agricultural Economics)) -- University of Limpopo, 2021 / Maize seeds differ according to varieties. The traditional maize varieties(also referred to as (Landraces)are maize varieties that have been cultivated and subjected to selection by farmers for generations. They retain a distinct identity and lack formal crop improvement. Improved maize varieties, on the other hand, are bred with characteristics such as drought and disease tolerance. This research was conducted to determine the attributes preferred by farmers when making a maize varietal choice. To be specific, the study aimed to achieve the following objectives:(i) Identify and describe socio economic characteristics of smallholder maizefarmers’ in Mogalakwena Municipality;(ii) Analyse socioeconomic characteristics of smallholder maize farmers in Mogalakwena Municipality;(iii)Identify different maize varieties grown by smallholder farmers in Mogalakwena Municipality, and (iv) determine and analyse factors influencing farmers’ choice of a maize variety. Descriptive statistics and the Multinomial Logistic Regression Mode lwere used for data analysis. The results of the study revealed that 64% of the respondents had formal education. This meant that they have the capability to grasp more information, if provided witht rainings. It was found that 75% of the farmers did not have access to extension service which is supposed to play a significant role in agricultural information dissemination. The most grown maize variety was landrace varieties which constituted 59.5%. This percentage was said to be resultant from limited access to the seed market. Infact, 80% of the farmers had to travel an average o f42 kilomteres to access the market which also had a limited number of varieties. The Multinomial Logistic Regression Model revealed that only 5variables (Educational level, farm size, yield, extension contact and knowledge of maize varieties) were significant at 1%, 5%,1 %,1% and1%, respectively. The majority of farmers were old people with little access to extension service andaninad equate farming knowledge which lead to a high percentage of farmers continuing to grow landrace varieties. Based on thef indings, this study recommend further research on attributes that influence farmers varietal choice and Government intervention in provision for resources and development of existing and new infracstrcture to encourage extension service delivery Keywords: Landrace, improve maize variety, smallholder farmer

Carrots (Daucus carota L. cv. Royal Chantenay) and sweet corn vi (Zea mays L. cv. Iochief) were grown rm the Utah State University's Greenville farm in 1969 and 1970. The soil was fumigated with Telone (a mixture of 1, 3-dichloropropene and other chlorinated hydrocarbons) at the rates of 10, 20, and 30 gal/acre and Nemagon (1, 2-dibromo-3-chloropropane) at the rates of 1, 2, and 3 gal/acre one week before planting. Samples of uniformly mature carrot roots were taken for the studies of total carotenes, β-carotene, total and reducing sugars, respiration, and ultrastructural changes; and those of sweet corn seeds for the studies of total carotenoids , starch, total sugar, and total nitrogen changes. Compared to the controls, carrots grown on fumigated soil had a significantly higher content of total carotenes, β-carotene, and total sugars, and a lower rate of respiration. The electron microscopic study indicated that the carrots from Telone (30 gal/acre) and Nemagon (3 gal/acre) fumigated soil had larger chromoplasts that contained more globuli and crystals than those of the controls. The soil fumigations with Telone and Nemagon also brought about the increase in total carotenoid content in sweet corn seeds.

Made available in DSpace on 2016-06-02T19:51:21Z (GMT). No. of bitstreams: 1 DissRARJ.pdf: 1930702 bytes, checksum: a1b0d68f6f193815099874af8118a5e1 (MD5) Previous issue date: 2006-05-23 / The production of corn seeds involves a complex agro-industrial production chain whose main agents must offer products of high quality and low price to stay competitive. Efficient tools to coordinate this chain are thus essential to fulfill these conditions. This work proposes a linear programming model for the strategic planning of production, storing and transportation, designed to minimize production, transportation and tax costs. The model is a function of crop planning, capacity and client demand restrictions. Although relevant to the product s final cost, taxes are not traditionally considered by the planning methods currently used by the seed industry. The raw material is generally sent to the industrial unit closest to the farm; proximity to the end consumer is of secondary importance. The main productive processes and features of the seed industry described here are based on literature and visits to plants that produce corn seeds. The mathematical model detailed in this work is implemented using the GAMS programming language and the resulting system of equations solved with CPLEX. The model was validated by using different scenarios with real-world data collected during the visits to the plants; the results were consistent with those expected. Next, the results given by the model of a case study with data for an entire season were compared against those obtained by one of the companies employing the traditional method of shortest distance between farm and industrial unit. The proposed model showed a substantial decrease in total cost when compared to the traditional method. This study also confirmed the importance of integrating taxes with production and transportation planning at the logistics level. / A produção de sementes de milho envolve uma cadeia de produção agroindustrial complexa cujos agentes devem primar por oferecer produtos de alta qualidade a um baixo custo para se manterem competitivos no mercado. Instrumentos eficientes para a coordenação dessa cadeia são fundamentais para atender a esta exigência, orientando seus agentes para o cumprimento dos objetivos comuns. Neste trabalho um modelo de programação linear é proposto para realizar o planejamento tático da produção, estocagem e de transportes de forma a minimizar custos de produção, transportes e fiscais, atendendo ao mesmo tempo às restrições de programação da colheita, de capacidade e de demanda. Tradicionalmente, não são considerados nos métodos de planejamento do setor custos fiscais, como o de ICMS, que se mostram relevantes no custo unitário do produto final. A matéria-prima, em geral, é enviada para a unidade mais próxima ao campo de produção agrícola, deixandose para um segundo plano a proximidade da demanda. As principais características do processo produtivo e do setor são descritas de acordo com a literatura e visitas a empresas produtoras de sementes. Utilizou-se a linguagem GAMS e o solver CPLEX para resolver o modelo matemático. O modelo foi implementado e testado com dados realistas das empresas visitadas em diferentes cenários, verificando-se coerência nas respostas obtidas. Realizou-se um estudo de caso em uma das empresas estudadas utilizando-se os dados completos de uma safra e os resultados obtidos com o modelo proposto foram comparados com o método empregado na empresa, que considerava apenas a menor distância entre a região agrícola e a unidade industrial. Os resultados dessa comparação foram bastante satisfatórios, proporcionando uma redução significativa dos custos considerados. Além disso, foi confirmada, também para este caso, a importância de incorporar os custos fiscais na disciplina de logística integrando planejamento tributário com o de produção e dos transportes.