http://hdl.handle.net/10386/71 2026-04-05T17:46:16Z 2026-04-05T17:46:16Z Lutombo, Mulalo http://hdl.handle.net/10386/4918 2025-03-07T01:00:27Z 2023-01-01T00:00:00Z

A comparative study on water deficit stress tolerance between the cowpea (Vigna Unguiculata [L.] walp) and soybean (Glycine max [L.] merrill) Lutombo, Mulalo The world has lately suffered prominent natural disasters, most with potential to extirpate all form of life. Drought comes in second to hurricanes in regards to causing severe economic impacts worldwide. Drought is a prolonged period of not enough rainfall or below average precipitation that results in shortage of water in the soil. Water shortage crisis and its effects can be easily observed in the agricultural sector. Each year, the agricultural sector and the food supply chains suffer a loss worth R100s trillions of the total average yield of agro-economic crop due to drought stress. Soybean production in sub-Saharan Africa is still low as is anywhere in Africa. The production could be much higher but local farmers suffer harsh environmental conditions such as pest, diseases and drought. Conventionally cowpea is considered the trunnion of small farmers in Central and West African regions. This is because it is well adapted to areas with lower rainfall. The aim of this study was to investigate the similarities and dissimilarities between soybean and cowpea’s response and tolerance to water deficit stress. Three genotypes where used for each plant, Red, Blonde and white (cowpea) and TGx 1937-f, PAN 1664R and LS 678 (soybean). Polyethylene glycerol 8000 was used to induce drought stress at five different levels of osmotic potential (of 0.00, -0.02, -0.27, -1.27, and -1.80 MPa) for evaluation of water deficit tolerance during germination. To assess both vegetative and reproductive growth plants were subjected to three drought stress levels; control- watered daily (no water stress), moderate (watered once in 5 days) and severe (watered once in seven days). Morphological parameters (number leaves, length of stem, root length, mass of the nodules, number of flowers, number of pods, seeds per pod, mean seed number per pod and mass of 100 seeds) were directly counted or measured on the plants. Samples were collected for physiological analyses including determination of proline content, determination of leaf relative water content, determination of malondialdyde content and determination of chlorophyll content. Lastly, an experiment to assess the ability of cowpea and soybean to recover from. Plants were subjected to drought for 14 days followed by re-watering for two weeks and the samples were collected for physiological analyses mentioned above. The control set was watered daily. The results showed that the seed germination percentage and mean daily germination declined with the increase in water stress severity reaching lower than 10% germination at the lowest osmotic potential treatment (-1.80 MPa) for both cowpea and soybean. Germination results showed no significant differences between cowpea and soybean for all parameter. However, cowpea was significantly different from soybean with regard to vi seedling growth parameters. Morphological results showed that soybean nodule weight significantly decreased as the stress severity increased. Cowpea nodule weight, number of stomata on both surfaces, and root length showed no significant difference between treatments and also between the genotypes. White genotype cowpea had a significantly lower root length and nodule weight and a slightly lower number of stomata but not significantly different from the other genotypes. Drought stress decreased the leaf relative water content of both cowpea and soybean under moderate and severe stress. However, cowpea performed distinctly superior to soybean. Cowpea with its lower nodule weight maintained no significant difference between all treatments. Water deficit stress affected leaf development. The highest number of leaves 1st count were 24.60 and 16.50 (control) and the lowest count was 19.33 and 14.50 (severe) for cowpea and soybean, respectively. The 1st count of the number of leaves of soybean genotypes showed a significant difference between genotypes for all water stress treatments with the exception of TGx 1937-f and PAN 1664R under severe stress, 20.16 and 20.83, respectively. With regards to water stress metabolites, the proline content and malondialdehyde content of both beans were significantly increased comparing control with stressed treatments. However, malondialdehyde content and proline content of soybean was significantly higher than cowpea for both control and stressed plants. The same trend was observed for stressed-rewatered experiment. The recovery response of cowpea was excellent and better than soybean which failed to recover. Considering morphological and physiological parameter during vegetative growth, the results suggested that cowpea response better to water stress than soybean. In conclusion, cowpea response and tolerate water deficit stress better than soybean. In future, it is necessary to genetically compare the two legume plants, to trace the genes that are responsible for such tolerance in cowpea. Thesis (M.Sc. (Botany))-- University of Limpopo, 2023

2023-01-01T00:00:00Z Molwantoa, Enosencia http://hdl.handle.net/10386/4912 2025-03-07T01:00:18Z 2023-01-01T00:00:00Z

Crossbreeding of indigenous watermelon for high oil content Molwantoa, Enosencia Watermelon (Citrullus lanatus) is an annual plant which survives better under warm temperatures, and is believed to have originated in southern Africa. The plant is now distributed across the world and grown because of the juicy appetising flesh of its fruit. There are more than 12000 varieties of watermelons across the world. Looking at the rate at which population size is rapidly increasing, it is not surprising that it is expected to reach about 8.1 billion by 2040. This puts a great pressure on available resources. Oil is one of the essential resources that human need. It is used in the production of lots of our daily needs like medicine and cosmetics. Watermelon is one of the crops that produces seeds that are rich in oil. However, their seeds are not enough to harvest and extract adequate oil for industrial purposes. Each variety has got its superior and inferior seed production traits. The aim of the study was to crossbreed different types of indigenous watermelons in an attempt to produce a hybrid or hybrids with high oil content. As a result, Bitter and Weedy watermelon varieties were planted in the nursery on the grounds of the University of Limpopo, and cross-pollinated. The crossed seeds were then self-pollinated. Dried seeds from all watermelon types including Bitter, Weedy Cross and F1 generation were ground into powder and oil was extracted. Oil percentage together with some physiochemical properties of oils were determined and compared. This study found that there was an improvement in terms of seed production, oil quality and quantity for both cross and F1 generation. Cross fruits showed to have improved in terms of the total number of seeds (717); the seeds had the highest oil content (39.16%) with the highest saponification (118.67 mg KOH/g oil) and iodine (114.21 g of Iodine/100 g oil) values. The F1 generation which resulted from self-pollinated Cross plants had the highest mass of 100 seeds (13.51 g); mean geometric diameter (6.91 mm); and coming second (33.30%) after Cross seeds for oil content. On the other hand, Weedy produced oil with the highest specific gravity (0.91) and lowest moisture content (2.98%). It is concluded that the crossbreeding of Bitter and Weedy watermelons produces improved offspring which performs better after self-pollination. The physiochemical properties of the current investigated watermelon oils are mostly within the acceptable ranges of oils reported to be of good quality for soap production and consumption industrial purposes. In conclusion, Cross watermelons are the most superior ones because of their adequate intermediate amount of total seeds produced, highest oil yield and better physiochemical properties of oil. However, watermelon oil is still inadequately used industrially. This can be improved by further studying more physiochemical properties such as index viscosity, flash point and fatty acid composition of the current investigated watermelons Thesis (M.Sc. (Botany)) -- University of Limpopo, 2023

2023-01-01T00:00:00Z Mdaka, Blessing http://hdl.handle.net/10386/4843 2025-01-31T01:00:23Z 2017-01-01T00:00:00Z

The effect of Helinus integrifolius (Lam.) kutze crude leaf extract on ruminant gas production and fodder digestibility Mdaka, Blessing There have been numerous attempts to alleviate enteric methane emissions by ruminants in both commercial and subsistence farming. This is because methane is the most potent greenhouse gas responsible for atmospheric contamination leading to the greenhouse effect, global warming and climate change. Although, carbon dioxide emissions via the use of fossil fuels and in industrial production have had considerable attention, livestock production continues to contribute substantial amounts (80 Mt per year) of methane to the atmosphere. Ruminants are a source of meat and dairy products that mankind cannot do without. Eliminating them is definitely not a viable option hence strategies such as feed, feeding management and nutrition, rumen modifiers and animal genetic production and other management approaches have been proposed. Recently studies have focused on the use of plants with high content of secondary metabolites. Plant secondary metabolites possess numerous desirable biological activities which lead to their exploitation as nutraceuticals, pharmaceuticals/recreational drugs and supplements. Properties such as antifungal, antimicrobial and anti-inflammatory effects have prompted their use in attempts to reduce enteric fermentation’s major by-product i.e. methane. This study’s main objective was to investigate the effect of a methanolic crude saponin extract and leaf powder of Helinus integrifolius on in vitro ruminant total gas production and fodder digestibility. A methanolic crude extract was obtained by sequential extraction in Soxhlet apparatus starting with n-hexane and then methanol. Total gas production and feed digestibility were quantified using a ruminant gas production/digestion bioassay. The gas released was analysed with the aid of gas chromatography. The methanolic crude extract was found to contain 286.0±0.60 mg saponins/g of dry material by colorimetric spectrophotometry. In numerous studies the anti-methanogenic effect in ruminants is attributed to condensed tannin activity. However, no tannins were detected in the methanolic crude saponin extract when a tannin test was performed. The methanolic crude saponin extract showed substantial reduction of total gas release (99%) and increased fodder digestion (55%) compared to the control treatment. Leaf powder inclusion did not reduce total gas release. However, digestion was slightly improved but less than 50% of dry material was digested. It was evident that leaf powder inclusion had minimum effect on ruminant enteric microbial activity. The methanolic crude saponin extract imposed much vi greater effects in both total gas production and fodder digestibility compared to the leaf powder. These observations indicate that the Helinus integrifolius plant may be one of the ideal candidates with potential to reduce ruminant methane production. Furthermore, its methanolic crude saponin extract may contain the ideal phytochemicals to be investigated further as a ruminant feed additives/supplement. They may aid in the alleviation of enteric fermentation and increased feed utilisation efficiency while improving dairy and meat yield in livestock production. Thesis (M.Sc. (Botany)) -- University of Limpopo, 2017

2017-01-01T00:00:00Z Rasethe, Marula Triumph http://hdl.handle.net/10386/4804 2025-01-25T01:00:16Z 2017-01-01T00:00:00Z

The utilization and management of selected listed-threatened or protected species in the Limpopo Province, South Africa Rasethe, Marula Triumph In South Africa, the harvesting of indigenous plants has been taking place for centuries, and people in rural areas still rely on them to meet their primary health care needs. In the Limpopo Province, this traditional medicine is based on various plant resources, including those that are protected by legislation, such as the Threatened or Protected Species (TOPS) Regulations promulgated in terms of the National Environmental Management: Biodiversity Act (NEMBA) of 2004. Despite a number of ethnobotanical studies conducted in this province, which briefly highlighted the overutilization of some of the TOPS-listed plants, there has been no detailed study that focused on the use and management of these plant species. This study was conducted to document the different uses, threats, local management strategies and approaches to conserving these plant species. The study was conducted in the Capricorn, Sekhukhune, Mopani, Waterberg and Vhembe districts of the Limpopo Province. Six TOPS-listed species occurring in the Province were selected after a pilot study based on their occurrence in the Province, familiarity with participants and known vernacular name. These species included Alepidea amatymbica Eckl. & Zeyh, Brackenridgea zanguebarica Oliv, Dioscorea sylvatica Eckl, Drimia sanguinea (Schinz) Jessop, Siphonochilus aethiopicus (Schweinf.) B.L.Burtt and Warburgia salutaris (G.Bertol.) Chiov. Information was collected from 180 traditional healers, 110 community members, 26 traditional leaders and 15 conservation officers, using semi-structured questionnaires, supplemented with field observations. Results indicated that the selected species are used by traditional healers and community members exclusively for medicinal purposes. Preferences were predominantly for D. sanguinea, S. aethiopicus and W. salutaris. Remedies were most often prepared using the underground parts of the plants, which were chiefly purchased from muthi shops or markets trading both indigenous and exotic plant and animal materials used for witchcraft and/or healing. Just over 59% of respondents indicated that they purchase materials from muthi shops due to the scarcity and thus unavailability of some species in local communal lands (open access lands). In contrast nearly 40% of participants (traditional healers and community members) disclosed that they harvest materials from open access land. Only 1.49% of participants (traditional healers and community members) sourced from their homegardens; cultivating D. sanguinea and S. aethiopicus for both proximity (quick access) and easy harvesting. Generally, participants (82%) who did not cultivate these species, however, indicated an interest to cultivate if seed/seedlings were to be provided. An analysis of participants’ perceptions regarding factors threatening the survival of these species revealed that they (93%) viewed overharvesting for medicinal use as the most significant threat. During field visits, it was observed that the degree of impact due to harvesting on populations of these species was very high. This was exacerbated by destructive harvesting techniques by collectors, including uprooting of herbaceous species such as A. amatymbica, D. sylvatica, D. sanguinea and S. aethiopicus. Woody tree species, particularly W. salutaris, were sometimes felled for easy harvesting of stem bark. Most (65.86%) of the community members and traditional healers revealed that there was nobody managing plants on communal lands, and therefore no conservation strategies are in place. However, a minority of participants indicated that chiefs (16.55%), chiefs and indunas (senior officials appointed by the king or chief, who often act as a bridge between the people and the chief) (14.83%), government (2.07%) and indunas (0.69%) are responsible for the management of plants in their areas. Community members, traditional healers and traditional leaders mentioned that there are general community rules for conserving plants, but these mostly focused on trees used for fuelwood. Similarly, conservation officers indicated that in most cases they patrol in rural areas for fuelwood use monitoring rather than medicinal plants, because they were unable to identify medicinal plant use impact during their patrols. The study concludes that TOPS-listed plants are unsustainably harvested for medicinal purposes in the Limpopo Province, and without adequate control or management of the resource. This is due to a limited knowledge regarding conservation by harvesters, users, community leaders and elders, as well as unsustainable harvesting by collectors. Consequently, this study recommends that effective conservation measures are urgently needed to prevent further loss of most of these species in the natural environment. It is proposed that a workshop to educate harvesters, traditional leaders and conservation officers regarding the TOPS-listed species be held. An identification guide for conservation officers should also be compiled, to be used during field patrols. Furthermore, practical skill development should be provided to people who currently cultivate at home or have expressed interest in cultivating TOPS species. Institutions such as SANBI could play an enabling role in providing seed/seedlings for home cultivation. Traditional leaders should furthermore be encouraged to work with government agencies (e.g. SANBI, LEDET, DEAT) in implementing and strengthening traditional rules that apply to medicinal plants. Thesis (M.Sc. (Botany)) -- University of Limpopo, 2017

2017-01-01T00:00:00Z