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Call number: LD2668 .T4 1957 K31 / Master of Science

Call number: LD2668 .T4 1958 D89 / Master of Science

The challenge of food security requires that agricultural production is no longer based on a narrow genetic material present in conventional crops. Whereas conventional crops have been genetically improved to suit management practices of the modern farmer, the future farmer requires that there be access to a wide variety of genetic material for economic exploitation and to respond to the challenges of climate change in a sustainable fashion. This study was designed to learn about production of wild water melon [Citrullus lanatus (Thunb.) Matsumura and Nakai] from seed germination, seedling establishment and field crop production. The specific objectives of the study were (a) to determine the effect of water stress on three landraces of watermelon differing in seed colour and provenance during seedling establishment, (b) to determine the effect of planting date on crop growth and yield under field conditions, and (c) to relate proline accumulation to water stress in wild watermelon. Three seedlots, ‘B’, ‘DB’ and ‘VDB” were derived from seeds collected from subsistence farming communities of the Eastern Cape, and KwaZulu-Natal. Following one season of seed production in Pietermaritzburg, KwaZulu-Natal, seeds were tested for germination capacity, before seedlot response to water stress was determined in three substrates made of pine bark, a 1:1 mixture of fine sand and pine bark and fine sand only. The substrates were kept at 75% FC, 50% F.C and 25% F.C., to create varying levels of water regimes during 12 weeks of seedling growth in a glasshouse (16/21oC (day/night) and 60% RH). Leaf proline content was determined at seedling harvest. Crop production under field conditions occurred at one site with three planting dates late September 2008, November 2008 and January 2009, respectively. There were significant differences among seedlots with respect to seed quality and seedling yield, which consistently showed that B > VDB > DB. The differences in seedlots continued in the same order even in response to field conditions. Wild watermelon was responsive to water stress during seedling growth, but high water regimes compromised water use efficiency. Proline accumulation correlated with water stress. The best plant growth and yield under field conditions was obtained when planting occurred in September, followed by November and January plantings, respectively. Early planting was also associated with high crop growth rate and larger fruit size. It is concluded that despite being a desert crop, wild watermelon responds to water deficits during seedling growth. Results of field studies cannot be conclusively used to determine crop response to water stress, although they gave a good indication of crop response to different conditions of rainfall and temperature at the study site from September to March. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Thesis (MTech (Food Technology))--Cape Peninsula University of Technology, 2018. / The use of egusi melon in soup has been domesticated and egusi has predominantly been regarded as a secondary crop. The aim of this study was to evaluate the functional characteristics of egusi seed (Citrullus lanatus subsp mucosospermus) hydrocolloid and oil in instant egusi soup. An instant production of egusi soup by adding boiling water to an instant soup mix will promote the availability of this nutritious seed as a healthy meal option. Egusi oil was successfully extracted from egusi seed using supercritical carbon dioxide method. The percentage oil yield which measures the amount of oil derivable from egusi seed ranged from 46-53% w/w. There was a significant difference in the oil yield as pressure and temperature are increased at a constant CO2 flow rate of 30 g/h. The proximate composition of egusi oil was determined using standard AOAC method. The moisture contents were 1.3, 2.0 and 1.9% w/w, respectively for EO1 (60oC and 450 bar), EO2 (55oC and 600 bar) and EO3 (75oC and 600 bar). EO1 was significantly (p ≤ 0.05) lower in moisture content compared to EO2 and EO3. The fat content was 99.1% w/w (EO1), 98.3% w/w (EO2) and 98.9% w/w (EO3), with no significant difference in the three oil samples. The fatty acid composition was analyzed using gas chromatography. The fatty acid content of egusi oil was high in polyunsaturated and monounsaturated fatty acids, which was identified as linoleic (62%) and oleic (15%) acids. The saturated fatty acid (undecylic, myristic, palmitic and stearic) composition of egusi oil differed significantly (p ≤ 0.05) with EO1, having the lowest compared to EO2 and EO3. The index of atherogenicity (IA %) were significantly low 0.35, 0.38 and 0.38% w/w for EO1, EO2, and EO3, respectively. The thrombogenicity index (IT %) were 0.08, 0.09 and 0.09% w/w for EO1, EO2, and EO3, respectively with no significant difference. Peroxide Value (PV) measured using auto titrate Titrino plus, ranging from 11.60 for EO1 milliequivalents peroxide/kg to 12.60 for EO2 and 11.89 milliequivalents peroxide/kg for EO3. The oxidative stability index (OSI) was measured using Methrohm Rancimat at 120°C, expressed as the induction time of oxidation was 10.2, 11.5 and 5.3 h for EO1, EO2, and EO3, respectively, with E03 significantly higher than EO1 and EO2 (p ≤ 0.05). The iodine number, determined by AOAC direct titration method was high and ranged from 95 g/100 g for EO1 to 129 g/100 g for EO3, with EO3 being significantly high (p ≤ 0.05). The nutritional and functional properties of defatted egusi flour and hydrocolloid extracted using supercritical carbon dioxide extraction was also successfully achieved. Proximate analysis of defatted egusi (DEF) flour after supercritical extraction was carried out according to standard AOAC procedures. The moisture content of DEF ranged from 5.3 to 10.1% w/w, crude protein 48.3 to 60.4% w/w, crude fibre 3.4 to 4.5% w/w) and ash 5.3 to 6.8 % w/w). The protein content of defatted egusi flour differed significantly (p ≤ 0.05) between samples. The amino acid compositions of DEF showed glutamic acid had the highest concentration of 12.9, 11.8 and 9.8 mg/100 g for DEF1, DEF2, and DEF3, respectively with a significant difference (p ≤ 0.05) across the samples. In functionality, the water absorption and solubility index at a low temperature of 50oC ranged between 52.5 to 57.6% w/w and 68.0 to 73.3% w/w respectively for DEF1 to DEF3, which significantly differed between samples. The final viscosity of defatted egusi flour ranged from 126.7 to 126.3 cP, which differed significantly (p ≤ 0.05) between samples. Egusi flour is high in protein 60% w/w and carbohydrate 25% w/w was treated with hot water to extract its hydrocolloid. Functional properties of egusi hydrocolloid for the three defatted flour shows a stable emulsifier as the breakdown viscosity remained constant at (8.00 cP). Breakdown viscosity of egusi hydrocolloid confirmed its stability.

Thesis (Ph.D. (Plant Protection)) --University of Limpopo, 2012 / Global withdrawal of synthetic fumigant nematicides like methyl bromide due to their eco-unfriendliness resulted in serious consequences in production of crops which do not have genotypes that are resistant to plant-parasitic nematodes. Watermelon (Citrullus lanatus) is one such crop, where infection by highly aggressive root-knot nematodes (Meloidogyne species) invariably results into as high as 50% yield loss, with occasional total crop failures. Initial screening for nematode resistance in Cucumis species indigenous to South Africa suggested the possibility of the existence of nematode resistance, with the probability of these species being compatible with Citrullus species in inter-generic grafting technology. Uses of indigenous genera in Cucurbitaceae family as nematode-resistant seedling rootstocks in watermelon production could promote the South African watermelon industry as outlined in ISO 9001 certification guidelines to have competitive advantage in lucrative watermelon export markets. The objectives of this study were to determine the: (1) host-status and host-sensitivity of C. africanus and C. myriocarpus seedlings using a series of inoculation levels of M. incognita race 2 under various conditions, (2) host-status and host-sensitivity of C. africanus and C. myriocarpus seedlings using a series of inoculation levels of M. incognita race 4 and M. javanica, including the resistance form in these plant species, at least, under selected environmental conditions, (3) host-status and host-sensitivity of C. africanus and C. myriocarpus seedlings using a series of inoculation levels of M. incognita race 2 with multi-nematode xxviii infestations in order to establish whether the observed nematode resistance was sustainable when the plant was attacked by various pests at the root system level, (4) compatibility of inter-generic grafting of Citrullus and Cucumis seedlings in order to establish the potential uses of Cucumis species in olericulture, and (5) influence of the greenhouse whitefly (Trialeurode vaporariorum) infection on resistance of C. africanus to Meloidogyne species in order to establish whether the observed nematode resistance was sustainable when the plant was attacked by pests on complimentary organs. Reliability of measured variables was ensured by using statistical levels of significance (P ≤ 0.05) and coefficient of determination (R2), with validity being ensured by conducting experiments at the same location over two seasons or conducting one experiment during one season at two different locations, viz. the University of Limpopo and the Agricultural Research Council – Institute for Industrial Crops, and/or by setting up factorial treatments. Results consistently demonstrated that C. africanus and C. myriocarpus were non-hosts to M. incognita races 2 and 4 and M. javanica, without the test nematodes inflicting any damage to plants, which in plant-parasitic nematodes is described as nematode resistance. Quadratic relationships between RF values and log10(Pi + 1) transformations, in addition to confirming the density-dependent growth patterns of plant-parasitic nematodes, also suggested that chemical compounds responsible for suppression of nematodes in the two Cucumis species were different. The two Cucumis species were resistant to M. incognita races 2 and 4 and M. javanica, regardless of the environment under which the experiments were conducted. In field studies, the xxix two Cucumis species supported the ring nematodes (Criconema mutabile) and the spiral nematodes (Helicotylenchus dihystera), without these exo-parasitic nematodes inflicting any damage to plants, which in plant-parasitic nematodes is described as tolerance. Interactions among Meloidogyne species, C. mutabile and H. dihystera were either stimulatory or inhibitory, depending on whether Meloidogyne species were in the soil or inside the roots. Mechanisms of nematode resistance in the two Cucumis species were different, with C. africanus and C. myriocarpus depicting pre-infectional and post-infectional forms of resistance, respectively, without any sign of hypersensitivity in roots. When, seeds of Citrullus species were primed in water to hasten germination. Using the developed technology, survival of grafts improved from 36% to 100%, translating to relative improvement of 178%, with nematode-resistant rootstocks retaining their nematode resistant capabilities, while watermelon scions flowered earlier, with relatively higher fruit yield, without any deleterious effect on accumulation abilities of essential nutrient elements in leaves. Resistance of C. africanus to M. javanica was invariably broken by the greenhouse whitefly infection at high population levels, possibly through loss of non-structural carbohydrates, which are essential in synthetic pathways of secondary metabolites. Cucumis africanus and C. myriocarpus contain cucurbitacin B (C32H48O8) and cucurbitacin A [cucumin (C27H40O9), leptodermin (C27H38O8)], respectively, which have high demand for carbon and energy. Consequently, the efficacy of indigenous Cucumis species as nematode-resistant rootstocks in suppression of Meloidogyne species would be dependent upon the management of the xxx greenhouse whitefly population densities. In conclusion, C. africanus and C. myriocarpus have the potential for use as nematode-resistant rootstocks in the production of watermelon cultivars ‘Congo’ and ‘Charleston Gray’ in South Africa, where nematode population densities of M. incognita races 2 and 4 and M. javanica are widely distributed and are highly injurious to watermelons. Although nematode resistance in the two Cucumis species had attributes of sustainability, populations of the greenhouse whitefly broke the resistance. Proposed future research areas included influence of cucurbitacins in fruit quality of watermelons and protocols for mass culturing the nematode-resistant Cucumis rootstocks using tissue culture technology. / the National Research Foundation,the Agricultural Research Council (ARC) and the Landbank Chair of Agriculture-University of Limpopo

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1943. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliographies: leaves 60-89, 126-135.

Orientador: Marcelo Agenor Pavan / Banca: Rumy Goto / Banca: Rômulo Fujito Kobori / Resumo: A melancia (Citrullus lanatus (Thunb.) Mansf.) é uma das hortaliças mais produzidas no mundo. Uma das principais doenças que ocorrem na cultura é o crestamento gomoso do caule, causado pelo fungo Didymella bryoniae. O controle da doença tem sido realizado por meio de pulverizações com fungicidas, no entanto, o uso de cultivares resistentes deve ser pensado como uma alternativa viável e de efetivo controle no manejo da doença. O trabalho teve como objetivo estudar a herança da resistência ao crestamento gomoso do caule no acesso de melancia Ojakkyo. Para o estudo da herança, as gerações F1, F2 e retrocruzamentos de Ojakkyo com um parental resistente(AU - Pruducer) e um suscetível (Crimson Sweet) foram avaliados em ambiente protegido. Foi considerado também nesse estudo a combinação com a população de AU-Producer. Para comparar as razões de segregação obtidas no estudo da herança da resistência, adotou-se o teste do Quiquadrado (X²). Com base nas segregações obtidas no estudo da herança e nas análises de agressividade realizadas, concluiu-se que a resistência de Ojakkyo ao crestamento gomoso do caule é devida a mais de um gene / Abstract: The watermelon (Citrullus lanatus (Thunb.) Mansf.) is the most produced oleraceous in the world. One of the main diseases that occur in the culture is the gummy stem blight, caused for Didymella bryoniae. The control of the disease has been carried through by means of sprayings with fungicides, however, the use to cultivars resistants must be one of the viable alternative and of effective control about the handling of the disease. The work objectified to elucidate the inheritance of the resistance to gummy stem blight in access of watermelon Ojakkyo. For the study of the inheritance, the F1, F2, generations and backcrosses generations of Ojakkyo with two susceptible populations had been evaluated in protected environment and artificial inoculation. To compare the gotten reasons of segregation in the study of the inheritance of the resistance, the test of Quisquare (X²) was adopted. On the basis of the segregations gotten in the study of the inheritance, were concluded that the resistance of Ojakkyo to the gummy stem blight is due to more than one gene / Mestre

Made available in DSpace on 2014-06-11T19:26:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-10-17Bitstream added on 2014-06-13T19:13:50Z : No. of bitstreams: 1 000752743.pdf: 457953 bytes, checksum: 76498d2749d134ffb27c125ada94eda0 (MD5) / A melancia (Citrullus lanatus (Thunb.) Mansf.) é uma das hortaliças mais produzidas no mundo. Uma das principais doenças que ocorrem na cultura é o crestamento gomoso do caule, causado pelo fungo Didymella bryoniae. O controle da doença tem sido realizado por meio de pulverizações com fungicidas, no entanto, o uso de cultivares resistentes deve ser pensado como uma alternativa viável e de efetivo controle no manejo da doença. O trabalho teve como objetivo estudar a herança da resistência ao crestamento gomoso do caule no acesso de melancia Ojakkyo. Para o estudo da herança, as gerações F1, F2 e retrocruzamentos de Ojakkyo com um parental resistente(AU – Pruducer) e um suscetível (Crimson Sweet) foram avaliados em ambiente protegido. Foi considerado também nesse estudo a combinação com a população de AU-Producer. Para comparar as razões de segregação obtidas no estudo da herança da resistência, adotou-se o teste do Quiquadrado (X²). Com base nas segregações obtidas no estudo da herança e nas análises de agressividade realizadas, concluiu-se que a resistência de Ojakkyo ao crestamento gomoso do caule é devida a mais de um gene / The watermelon (Citrullus lanatus (Thunb.) Mansf.) is the most produced oleraceous in the world. One of the main diseases that occur in the culture is the gummy stem blight, caused for Didymella bryoniae. The control of the disease has been carried through by means of sprayings with fungicides, however, the use to cultivars resistants must be one of the viable alternative and of effective control about the handling of the disease. The work objectified to elucidate the inheritance of the resistance to gummy stem blight in access of watermelon Ojakkyo. For the study of the inheritance, the F1, F2, generations and backcrosses generations of Ojakkyo with two susceptible populations had been evaluated in protected environment and artificial inoculation. To compare the gotten reasons of segregation in the study of the inheritance of the resistance, the test of Quisquare (X²) was adopted. On the basis of the segregations gotten in the study of the inheritance, were concluded that the resistance of Ojakkyo to the gummy stem blight is due to more than one gene