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.

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.

MSCFST / Department of Food Science and Technology / Watermelon (Citrullus lanatus) juice is rich in phytochemicals that possess antioxidant properties which are known to have a positive contribution to human health. Colour, pH, total soluble solids, lycopene, β-carotene, ascorbic acid, total polyphenolic content and antioxidants activity are quality properties that characterise watermelon juice. However, these quality properties undergo some chemical changes throughout the stages of maturity of the fruit as well as during thermal processing. The aim of this study was to investigate the effects of maturity and filtration on the physicochemical properties (colour, pH, total soluble solids) and the phytochemicals (lycopene, β-carotene, ascorbic acid, total polyphenolic content and antioxidants activity) of fresh watermelon juice. It further investigated thermosonication effects on these quality properties using response surface methodology (RSM). RSM considering temperature (25 – 52ºC), time (2 – 10 min) and amplitude level (24.1 – 60 μm) at a constant frequency of 20 kHz were the independent variables while colour variables (L*, a* and b*, C* and h*), pH, total soluble solids, lycopene, β-carotene, ascorbic acid, total polyphenolic content and antioxidants activity were the dependent variables. Results showed that colour, pH, total soluble solids, lycopene, β-carotene, ascorbic acid, total polyphenolic content and antioxidants activity of watermelon fruit juice are maturity dependent. All the physicochemical and phytochemical properties increased with maturity. The combination of the CIELAB parameters (L*, a*, b*) was clearly explained by the Chroma (C*) and hue (hº). The (C*) and hº values of the watermelon fruit juice were significantly (p < 0.05) affected by the stages of maturity. The red colour was observed to be more saturated in the fully - ripe sample as indicated by the highest Chroma (7.35) values. The half - ripe sample which was observed to be pink - red had a C* of 5.88 while the lowest (4.32) value was observed from the unripe sample. The highest hº value was obtained from unripe sample (83.89), while lower value was observed from the fully - ripe (76.03) sample because of the saturation of the red colour in the fully - ripe sample. The total soluble solids also increased with stages of maturity 6.66 to 6.60 at half - ripe while at fully - ripe redness changed from 9.3 to 8.99 and TSS 8.37 to 8.02. Filtration has shown a significant (p < 0.05) on the C* and hº values. There was a higher retention of all dependent variables at lower thermosonication treatment (25ºC; 24.4 μm), especially the lycopene which increased by 127%. Model predictions for the colour properties and phytochemicals were closely correlated to the experimental results obtained. Prediction models were found to be significant (p < 0.05) with low standard errors and high coefficients of determination (R2). / NRF