Thesis (Ph. D.)--Colorado State University, 2004. / Includes bibliographical references.

No description available.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references.

Triploid and tetraploid watermelon seed are visually indistinguishable, increasing costs to growers, who cannot market the low-quality 4N melons. Efforts were made to separate 3N and 4N seeds by thickness and weight. Means in both cases were not separable. Successful seed 'priming' would be beneficial to seedless watermelon growers. Seeds from the open-pollinated 4N x 2N cross were primed in solutions of distilled water, polyethylene glycol '8000' (PEG), and potassium nitrate (KNO₃), or left untreated; treated seeds were subsequently dried for either 1 or 7 days. Seeds were scored for germination or emergence in the lab and for emergence under field conditions. Water was better than KNO₃ or PEG, but not always better than the control. One day in treatment was superior to 3 or 6 days; length of drying time was insignificant. In the field trial, treatments did not differ in emergence.

No description available.

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 89-95).

Thesis (MSc)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: Various researchers have determined that salinity causes several kinds of damage to plants such as germination inhibition, metabolic disturbances, yield reduction and quality losses. However, the severity of salt damage has been found to be dependent on the cultivar, level of salinity, period of exposure to salinity, and the growth stage of the plant. An understanding of the severity of salinity and its potential negative impacts on crops is essential to optimise production. Knowledge of seed vigour, expressed as germination percentage and germination rate at the optimum temperature for germination, would provide growers with valuable information to measure and compare the viability of seed lots. A study was done where fresh and aged seeds of two watermelon cultivars were investigated in germination tests under laboratory conditions at four salinity levels and five temperature regimes. The best germination was achieved at 4 mS cm-1 for both cultivars, Odem and Paladin. At 8 mS cm-I, the germination percentage for Paladin was 31% better than for Odem. The germination time for aged Odem seeds was significantly delayed at this EC 8 level but ageing of Paladin seeds had no detrimental effect at this EC level. Paladin germinated significantly better than Odem at the relatively low temperature range of I5-20°C, indicating that it is well-adapted for early planting. A new plant growing system, using vertical training of two shoots was tested in a greenhouse, aiming to optimise the growth regulating capabilities of this crop environment. Traditional watermelons are open-field planted in rows at low densities. Even with this plant spacing, by harvesting time the vines are spread in such a way that the foliage laterally covers the inter-row spacing, making cultivation practices such as spraying, weeding and harvesting difficult and almost impossible. The production of greenhouse crops is advantageous, but involves a number of cultural inputs and techniques for optimum yields. The effects of plant pruning systems and salinity levels on watermelon cultivars (Odem and Paladin) in a low-cost greenhouse were studied using a drain-to-waste fertigation system. Changing the nutrient solution from a low salinity level (EC 4 mS cm1) during vegetative growth to EC 4 mS cm-I after pollination, did not reduce fruit mass, but significantly increased the sugar yield of Odem, the icebox-type cultivar. Excessive pruning (less leaves per shoot) was more efficient with low salinity levels than at a high salinity level. Moderate pruning (more leaves per shoot) represented a good system, producing fruits of lesser weight and acceptable quality. / AFRIKAANSE OPSOMMING: Verskeie navorsers het reeds die skadelike gevolge van brak toestande op ontkieming, plant metabolisme, opbrengs en kwaliteit van gewas plante ondersoek. Die omvang van die skade kan deur kultivars, die konsentrasie soute, die periode van blootstelling asook plante se groeistadium bepaal word. 'n Goeie begrip van die potensiële skadelikheid van hoë sout konsentrasies op gewasse is nodig om produksie te optimaliseer. Inligting oor die kiemkragtigheid van saad, uitgedruk as die persentasie ontkieming asook die ontkiemingstempo, is vir kwekers nodig ten einde te verseker dat goeie saad gebruik kan word. 'n Ondersoek is gedoen waar vars asook verouderde saad van twee waatlemoen kultivars onder laboratorium toestande by vier sout peile en vyf temperature ontkiem is. Die beste ontkieming vir beide kultivars, Odem en Paladin, is gevind waar die elektriese geleiding (Eï,') 4 mS cm-1 was. Teen 8 mS cm-1 was die persentasie ontkieming vir Paladin 31% beter as vir Odem. Veroudering van Odem saad het 'n betekenisvol swakker ontkiemingstempo met'n Ee van 8 mS cm-1 getoon terwyl verouderde Paladin saad nie by hierdie Ee swakker vertoon het nie. Paladin het by die relatief lae temperatuur sone van 15-20oe betekenisvol beter as Odem saad ontkiem wat daarop dui dat dit vir vroeë aanplantings geskik is. 'n Nuwe produksiestelsel, waar twee lote per plant vertikaal in 'n V-vorm opgelei is, is in 'n kweekhuis getoets in 'n poging om die groeiregulerende potensiaal van so 'n omgewing te optimaliseer. Waatlemoene word tradisioneel in rye teen 'n lae plantdigtheid in veldaanplantings verbou. Met so 'n praktyk ontwikkel daar soveel ranke tussen die rye dat praktyke soos onkruid beheer, plaagbeheer en oes bemoeilik word. Die produksie van gewasse in kweekhuise hou voordele in maar 'n aantal insette en spesiale tegnieke is nodig vir optimum opbrengs. Die invloed van snoeipraktyke en soutpeile is met twee waatlemoen kultivars (Odem en Paladin) in 'n lae-koste kweekhuis ondersoek deur 'n sisteem te gebruik waar voedingsoplossings in vry dreinerende sakke met saagsels gedrup is. Waar die Ee van die voedingsoplossing voor vrugset 2 mS cm-1 was en toe vir die periode van vrugontwikkeling tot 4 mS cm-1 verhoog is, het geen vrugverkleining by Odem gevolg nie terwyl die suikeropbrengs wel verhoog het. Oormatige verwydering van blare was minder skadelik met 'n lae EC as waar die EC hoog was. 'n Matige snoeiproses met meer blare per loot, het 'n goeie produksie van aanvaarbare vruggrootte en 'n goeie kwaliteit verseker.

The wild watermelon, Citrullus lanatus L. was among the most important foodstuffs to a number of African communities, until the colonists introduced their own foodstuffs in a process that was highly supported by the laws of the time. However, there is now a growing realization by government and other stakeholders of the importance of indigenous crops (including the wild watermelon) as substitute food stuff to improve food security. Wild watermelon is an adaptable crop, which can contribute to food security as it has a potential for commercialization. However, there are no records on the production of wild watermelon with reference to optimum planting density and the effects of mulch on the growth and development of the crop. To investigate this issue, which the smallholder farmers are faced with, a study that designed to (a) determine the effects of population density on growth and yield of wild watermelon and (b) investigate the effects of mulching on growth and yield of wild watermelon under field conditions. The study was undertaken over two seasons during which two different types of propagules, namely seed and seedlings, were used. A field study of wild watermelon establishment and yield using seeds and seedlings to compare the effects of different population densities (3000, 6000, 9000 and 12000 plants/ha) and mulching rates (0, 2.5 and 5 t/ha) based on the availability of grass on soil water, temperature, vine length (height), number of branches and leaves per plant, fruit number, total yields, fruit size and weed distribution was conducted at Dohne Agricultural Development Institute (Lat-32.52521; Long – 27.46119, alt. 907 m above sea-level) over a two year period ( 2009 – 2011 growing season). Results on data collection and analysis of growth and yield parameters are that: When seed was used as means of propagation, there were significant effects (p 0.05) of mulching and population density, on soil temperature and volumetric water content. However, no significant differences were found with regards to vine length, number of branches and leaves per plant. Concerning yield, there were no significant differences recorded on any of the measured parameters in response to mulch. Yet, with population density, significant differences were noted on fruit number per hectare and total yield at p 0.05. The number of fruits and total yield per hectare increased as plant population increased, resulting in high yields to range from 9000 -12 000 plants per hectare with both seed and seedling propagules used during the study period with or without mulching. Seedling propagules were associated with differences in soil temperature and volumetric water content with regards to mulching and population density (p 0.05). Results obtained from this study in both years, revealed that yield is more influenced by plant population density than by mulching. Mulching has been found to be ineffective as far as growth and yield are concerned, but it was found to influence soil temperature and volumetric water content. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

LD2668 .T4 1965 W916 / Master of Science