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The use of mutagenic agents to increase the protein content and improve the amino acid composition of sweet potato (Ipomea batatas Lam.) /Sedijani Prapti. January 1997 (has links)
Thesis (M. Sc.) (Hons.) -- University of Western Sydney, Hawkesbury, 1997. / Thesis submitted for the degree of Master of Science (Honours), School of Horticulture, University of Western Sydney, Hawkesbury, 1997. In Chapter 1, figures 1.1 and 1.2 are not reproduced in the text. Bibliography : leaves 112-135.
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Biology of sweet cherry powdery mildew /Calabro, Jill M. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.
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Variáveis relacionadas ao processamento de minitomates inteiros desidratados em secador convectivo adiabático e liofilizados / Variables related to processing of dehydrated whole cherry tomatoes in adiabatic and lyophilized convective dryerAngela de Fátima Kanesaki Corrêia 28 August 2015 (has links)
Os produtos com umidade reduzida têm-se evidenciados como proposta alternativa para disponibilizar produtos de origem vegetal caracterizados pelo alto teor de umidade e vida útil curta, proporcionando, assim, um produto diferenciado, estável, com maior tempo de vida útil, além de possibilitar diversificação no consumo e aplicações. Este trabalho teve como objetivo a desidratação de minitomates inteiros do híbrido Sweet Grape, pelo processo de secagem convectiva adiabática e as interferências do pré-tratamento osmótico e adição de antioxidante, além da comparação do produto desidratado e liofilizado. O tratamento osmótico consistiu de cinco combinações de soluções osmóticas compostas por açúcar invertido, sacarose e cloreto de sódio. A desidratação adiabática foi caracterizada por duplo estágio a 80°C/ 2h em seguida a diferentes temperaturas: 50, 60, 70 e 80°C, até atingir umidade do produto de aproximadamente 30%. Foram aplicados antioxidantes e acidulante (ácido ascórbico, metabissulfito de sódio e ácido cítrico), no intuito de minimizar as alterações durante a desidratação. Em seguida, foi realizado um comparativo entre minitomates desidratados e liofilizados, acondicionados em embalagem laminada e mantidos a 5°C por 120 dias. O tratamento osmótico composto por açúcar invertido (60°Brix), sacarose (15%) e NaCl (5%) a 25°C por 50 min foi o processo mais eficaz, que apresentou menor incorporação de sólidos, maior perda de massa e menor atividade de água, associado à aplicação de 750mg.L-1 de ácido ascórbico, 50mg.L-1 de metabissulfito de sódio e 3g.L-1 de ácido cítrico. Os minitomates desidratados em duplo estágio a 80°C/2h e 70°C/11h apresentaram melhor aceitação quando comparados aos liofilizados, visto que a liofilização promoveu redução acentuada da cor e umidade, tornando o produto mais rígido. As características dos produtos desidratados e liofilizados foram mantidas estáveis por um período de 90 dias, aproximadamente, e o tratamento osmótico promoveu maior estabilidade aos produtos durante o armazenamento. / Products with low humidity have been considered an alternative for vegetable products characterized by high humidity content and short shelf life. Thus low-humidity products provide stable with longer shelf life products, enabling diversity for consumption and applications. This study investigated dehydration of whole cherry tomatoes of the Sweet Grape variety by the process of adiabatic convective drying and interference of osmotic pretreatment and antioxidant addition, comparing to dehydrated and lyophilized tomatoes. The treatment consisted of five combinations of osmotic solutions composed by inverted sugar, saccharose and sodium chloride. Adiabatic dehydration was characterized by double stage at 80°C/2 h followed by different temperatures: 50, 60, 70 and 80°C until the product reached moisture of 30%. Antioxidants and acidulants were applied (ascorbic acid, sodium metabisulphite and citric acid) to minimize changes during dehydration. Afterward, we compared dehydrated and lyophilized cherry tomatoes, packed in laminated packaging and kept at 5°C for 120 days. The osmotic treatment with inverted sugar (60° Brix), sucrose (15%) and sodium chloride (5%) at 25°C for 50 min was the most effective process. This process showed lower incorporation of solids, greater weight loss and lower water activity, associated with the application 750 mg.L-1 of ascorbic acid, 50 mg.L-1 of sodium metabisulphite and 3 g.L-1 of citric acid. The cherry tomatoes dehydrated in a double stage at 80°C/2 h and 70°C/11 h showed better acceptance when compared to lyophilized ones as freeze-drying caused greater color and moisture reduction, making the product more rigid. Characteristics of dehydrated and lyophilized products were kept stable for roughly 90 days and the osmotic treatment on the products promoted greater stability during storage.
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Manipulation of the chilling requirement of sweet cherry treesKapp, Cornelius Johannes 03 1900 (has links)
Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2008. / Commercial production of sweet cherries has recently increased in South Africa, with more than 400 ha planted by 2006. Cherry, a high chilling fruit variety, is however not suited for the mild winter climate of South Africa. This was recognizable through common observed symptoms of delayed foliation and poor fruit set. In addition, cherry is exposed to long and hot summers in the postharvest period. The objective of this study was to evaluate cherry cultural practices that can manipulate (reduce) the trees chilling requirement under South African conditions. Cultural practices where aimed at increasing reserves (nitrogen, cytokinin and carbohydrates) in the tree. In addition, bud dormancy progression of cherry buds was quantified to determine the bud dormancy progression pattern under mild winter conditions. This was achieved through sampling of cherry shoots from different cherry production areas which was then forced in the growth cabinets. A model was developed to identify possible factors and groupings that can explain the cherry bud dormancy pattern.
A model, comprising two joined straight lines, was fitted in order to characterize bud dormancy behaviour for sweet cherry cultivars under mild winter conditions. All cherry cultivars followed the expected pattern of entrance and exit from dormancy. Factor analysis showed that factors related to the entrance into dormancy primarily characterize bud dormancy behaviour. Bud dormancy patterns were also a function of environmental conditions within a year as shown by cluster analysis. In addition, buds entered dormancy in mid-summer and remained dormant until chilling accumulation commenced. Bud dormancy release was generally extended over a three to five-month period for all cultivars. Prior to spring budburst exit of both lateral and terminal buds occurred rapidly. Data indicate that there is no ecodormant phase for cherry under the prevalent climatic conditions in South Africa.
Further experimentation was aimed at increasing reserves within the trees through cultural practices. In the nitrogen trials, fertilization in the postharvest period had no significant effect on field budburst or bud dormancy progression in one-year-old shoots. Time of flowering was advanced in N treatments during 2007 only. Yield was not significantly increased. Therefore, in this trial, N fertilization in the postharvest period did not significantly reduce the chilling requirement of mature sweet cherry trees under mild winter conditions. Application of particle films (Surround® and Raynox®) or ethylene inhibitors (Retain®) in the summer did not reduce the heat stress the trees experienced. Treatments had no significant effect on carbon assimilation, stomatal conductance, leaf surface temperature, fluorescence, bud dormancy, budburst, flowering and fruit set.
Cytokinins sprays (benzyladenine) in autumn did not affect bud dormancy progression, spring budburst or flowering.
Hydrogen cyanamide application in spring significantly advanced budburst, time to full bloom and increased yield. Promalin® and Retain®, however, had no significant effect on budburst, flowering or yield.
It is therefore evident that cherry, due to its unexpected bud dormancy behaviour and its inability to be significantly influenced by several cultural practices, adapts poorly to South African climatic conditions through not reducing its chilling requirement significantly.
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A study of Myzus persicae (Sulzer) (Aphididae, Homoptera) with special reference to sweet potatoesKring, James Burton. January 1948 (has links)
Call number: LD2668 .T4 1948 K7 / Master of Science
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Management of biofuel sorghums in KansasDooley, Scott J. January 1900 (has links)
Master of Science / Department of Agronomy / Scott A. Staggenborg / Current demand for ethanol production is stressing feedstock production. Previous
research has shown sweet sorghum and photoperiod sensitive sorghum [Sorghum bicolor (L.)
Moench] as viable feedstocks which may supplement or replace current feedstocks. Studies
were conducted at two dryland locations in north central and northeast Kansas in 2008 and 2009
to determine the effects of cultivar, nitrogen fertilizer rate, plant density, and harvest date on
sweet sorghum juice and biomass yields. The cultivar study indicated the cultivar ‘M81E’
generally had the greatest yield. Other cultivars were not well suited for this region. No
significant results were found in the nitrogen rate trial, indicating sweet sorghum may be
insensitive to nitrogen fertilizer applications. The plant density trial results indicated that sweet
sorghum possess a great ability to compensate for plant spacing. No differences were found in
juice yields across densities, and the only difference found in total dry biomass was at the highest
plant density. Results from the harvest date study indicate that sweet sorghum harvest should be
delayed until at least the grain soft dough stage and can be continued for at least 10 days after a
killing freeze without a yield penalty. Delaying harvest allowed for an increase in total dry
matter and fermentable carbohydrates without a decrease in juice yield. Two studies were
conducted at two dryland locations in northcentral and northeast Kansas in 2008 and 2009 to
determine the effects of plant density on photoperiod sensitive sorghum yields, with an
additional study to determine the effects of winter weathering. Photoperiod sensitive sorghum
was found to be similarly insensitive to plant density, with few differences found in total dry
biomass yield. Yields were found to decrease significantly due to winter weathering. A final
study was conducted to examine a variety of sorghums as biofuel feedstocks. Photoperiod
sensitive sorghum yielded the greatest in 2008 while sweet sorghum yielded less. In 2009, sweet
and photoperiod sensitive sorghum yielded less than the cultivar TAMUXH08001. Sweet
sorghum yields are generally the greatest with ‘M81E’ and when harvested after soft dough.
Yields of both sorghums are occasionally influenced by plant density.
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Efficient extraction method to collect sugar from sweet sorghumJia, Fei, Chawhuaymak, Jeerwan, Riley, Mark, Zimmt, Werner, Ogden, Kimberly January 2013 (has links)
BACKGROUND:Sweet sorghum is a domesticated grass containing a sugar-rich juice that can be readily utilized for ethanol production. Most of the sugar is stored inside the cells of the stalk tissue and can be difficult to release, a necessary step before conventional fermentation. While this crop holds much promise as an arid land sugar source for biofuel production, a number of challenges must be overcome. One lies in the inherent labile nature of the sugars in the stalks leading to a short usable storage time. Also, collection of sugars from the sweet sorghum stalks is usually accomplished by mechanical squeezing, but generally does not collect all of the available sugars.RESULTS:In this paper, we present two methods that address these challenges for utilization of sweet sorghum for biofuel production. The first method demonstrates a means to store sweet sorghum stalks in the field under semi-arid conditions. The second provides an efficient water extraction method that can collect as much of the available sugar as feasible. Operating parameters investigated include temperature, stalk size, and solid-liquid ratio that impact both the rate of sugar release and the maximal amount recovered with a goal of low water use. The most desirable conditions include 30degreesC, 0.6 ratio of solid to liquid (w/w), which collects 90 % of the available sugar. Variations in extraction methods did not alter the efficiency of the eventual ethanol fermentation.CONCLUSIONS:The water extraction method has the potential to be used for sugar extraction from both fresh sweet sorghum stalks and dried ones. When combined with current sugar extraction methods, the overall ethanol production efficiency would increase compared to current field practices.
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Effects of photo-selective netting on sweet pepper (capsicum annuum l.) plant growth and fruit quality at harvest.Mashabela, Ngwatshipane Madonna. January 2014 (has links)
M.Tech. Agriculture / Sweet peppers (Capsicum annuum L.) are also known as bell peppers or capsicum belonging to the family Solanaceae. The sweet pepper contains various bioactive compounds along with significant amounts of beta-carotene (provitamin-A) and other similar compounds. This technological study was carried out to investigate the influence of photo-selective nets (ChromatiNet™) (red, pearl and yellow), with 40% shading effect, on the morphological parameters (plant height, leaf chlorophyll, stem diameter, leaf area, number of leaves, number of flowers, number of fruit, fruit weight, marketable yield, and pest and disease incidence, the fruit quality parameters (fruit mass, firmness, colour, soluble solids content and titratable acidity) and health promoting compounds (ascorbic acid, lycopene content, β-carotene, total phenols and flavonoids, and antioxidant scavenging activity) of three selected sweet pepper cultivars at harvest maturity stage. The commercially used black net (25% shading) was also included for comparison measures (control). The photosynthetically active radiation, air temperature and relative humidity were monitored throughout the growing period.
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Peroxidase and lipoxygenase activities and their effect on the stability of polyunsaturated fatty acids in two different varieties of sweet corn (Zea mays L.), Jubilee and GH 2684, during frozen storageRodriguez-Saona, Luis Enrique 01 October 1993 (has links)
The effect of different blanching treatments and
packaging materials on the enzymatic (lipoxygenase and
peroxidase) activity and fatty acid stability of two
different varieties of sweet corn on the cob (Jubilee and GH
2684) was evaluated during nine months of frozen storage at
-23.3°C.
The initial moisture content in the kernels of the two
sweet corn varieties averaged 72.5%. After nine months of
frozen storage the moisture content in the kernels of corn
depended greatly on the packaging material used. The ears
stored in Cryovac B and E bags showed the best moisture
retention (72.2% final moisture content), followed by the
polyethylene bags (71.4%) while the ears stored without
packaging material showed severe dehydration (70.1%).
The peroxidase and lipoxygenase activities were
determined using spectrophotometric assays on a crude
extract obtained from liquid nitrogen powdered corn. Both
unblanched varieties of sweet corn showed similar initial
peroxidase specific activity and general behavior during the
nine months of frozen storage. The presence of lipoxygenase
isozymes with different thermal stabilities in both
varieties was suggested by the higher lipoxygenase specific
activity found in Jubilee after freezing and nine months of
frozen storage (0.135 units/mg protein) compared with the GH
2684 variety (0.115 units/mg protein).
Complete inactivation of lipoxygenase was obtained
after 9 minutes steam blanching at 100°C. Peroxidase was
more heat resistant showing some remaining specific activity
after 9 minutes steam blanching with a complete inactivation
after 15 minutes steam blanching. No regeneration of either
enzyme was observed during the nine months of frozen storage
suggesting a permanent disruption of the active site of both
enzymes.
Relative fatty acid content was determined by gas
chromatographic analysis of fatty acids methyl esters. The
major fatty acids present in both varieties were palmitic
(14.93%), stearic (2.79%), oleic (31.54%), linoleic
(46.87%) and linolenic (1.89%) acids. Good stability of
the polyunsaturated fatty acids was observed during the nine
months storage at -23.3°C, with autoxidation as the main
mechanism responsible for the decrease in the relative percent of polyunsaturated fatty acids. Some enzymatic
oxidation also occurred, decreasing the linolenic acid
content.
The control of the degradation of polyunsaturated fatty
acids depended mostly on the frozen storage temperature
(-23.3°C) and not on the oxygen permeability of the different
packaging materials.
The results obtained in our study suggested that
blanching of the ears of sweet corn had an important effect
on reducing the enzyme activity but little effect on the
polyunsaturated fatty acid degradation after 9 months of
storage at -23.3°C. / Graduation date: 1994
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Crop model review and sweet sorghum crop model parameter developmentPerkins, Seth A. January 1900 (has links)
Master of Science / Department of Biological and Agricultural Engineering / Kyle Douglas-Mankin / Opportunities for alternative biofuel feedstocks are widespread for a number of reasons: increased environmental and economic concerns over corn production and processing, limitations in the use of corn-based ethanol to 57 billion L (15 billion gal) by the Energy Independence and Security Act (US Congress, 2007), and target requirements of 136 billion L (36 billion gal) of renewable fuel production by 2022. The objective of this study was to select the most promising among currently available crop models that have the potential to model sweet sorghum biomass production in the central US, specifically Kansas, Oklahoma, and Texas, and to develop and test sweet sorghum crop parameters for this model.
Five crop models were selected (CropSyst, CERE-Sorghum, APSIM, ALMANAC, and SORKAM), and the models were compared based on ease of use, model support, and availability of inputs and outputs from sweet sorghum biomass data and literature. After reviewing the five models, ALMANAC was selected as the best suited for the development and testing of sweet sorghum crop parameters. The results of the model comparison show that more data are needed about sweet sorghum physiological development stages and specific growth/development factors before the other models reviewed in this study can be readily used for sweet sorghum crop modeling.
This study used a unique method to calibrate the sweet sorghum crop parameter development site. Ten years of crop performance data (Corn and Grain Sorghum) for Kansas Counties (Riley and Ellis) were used to select an optimum soil water (SW) estimation method (Saxton and Rawls, Ritchie et al., and a method that added 0.01 m m [superscript]-1 to the minimum SW value given in the SSURGO soil database) and evapotranspiration (ET) method (Penman-Montieth, Priestley-Taylor, and Hargraeves and Samani) combination for use in the sweet sorghum parameter development. ALMANAC general parameters for corn and grain sorghum were used for the calibration/selection of the SW/ET combination. Variations in the harvest indexes were used to simulate variations in geo-climate region grain yield. A step through comparison method was utilized to select the appropriate SW/ET combination. Once the SW/ET combination was selected the combination was used to develop the sweet sorghum crop parameters.
Two main conclusions can be drawn from the sweet sorghum crop parameter development study. First, the combination of Saxton and Rawls (2006) and Priestley-Taylor (1972) (SR-PT) methods has the potential for wide applicability in the US Central Plains for simulating grain yields using ALMANAC. Secondly, from the development of the sweet sorghum crop model parameters, ALMANAC modeled biomass yields with reasonable accuracy; differences from observed biomass values ranged from 0.89 to 1.76 Mg ha [superscript]-1 (2.8 to 9.8%) in Kansas (Riley County), Oklahoma (Texas County), and Texas (Hale County). Future research for sweet sorghum physiology, Radiation Use Efficiency/Vapor Pressure Deficit relationships, and weather data integration would be useful in improving sweet sorghum biomass modeling.
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