Thesis (M.Sc. Agriculture (Plant Production)) -- University of Limpopo, 2014 / The management of root-knot nematodes (Meloidogyne spp.) has become a challenging task in tomato (Solanum lycorpesicum) production, due to the withdrawal of effective chemical nematicides. Currently, crude extracts of different plant species are being researched as alternative to chemical nematicides, with promising results. The objective of this study was to determine the effect of crude extracts of wild garlic (Tulbaghia violacea) on the growth of tomato under greenhouse conditions, and the suppression of M. incognita race 2 population densities. Treatments consisted of four levels of crude extracts viz. 0, 2, 4 and 8 g per pot, were arranged in a randomised complete block design with 10 replicates. Seedlings were inoculated with 1000 juveniles of M. incognita race 2 at transplanting and treated with crude extracts two days later. At 56 days, the crude extract of T. violacea increased plant height, stem diameter, number of cluster, flowers, fruits and leaves by 43-73%, 108-200%, 57-81%, 55-110%, 170-223% and 51-66%, respectively. It also increased the root mass and shoot mass by 95% and 96%, respectively. Crude extracts of T. violacea did not have any effect on soil pH and electrical conductivity (EC). Crude extracts of T. violacea consistently reduced population densities of M. incognita race 2 by 50, 64 and 73% in roots at 2, 4 and 8 g crude extracts, respectively and by 21, 30 and 58% in soil at similar levels, respectively. In conclusion, crude extracts of T. violacea have the potential to improve growth of tomato plants and suppress population densities of M. incognita race 2 and could be used as botanical nematicide in tomato production.

Studies have shown that the traditional healers have used Tulbaghia violacea (TV) (also known as ‘wild garlic’) for the treatment of a number of ailments including fever, tuberculosis, stomach problems, and oesophageal cancer. However, little is known with regards to the anticancer and antiproliferative properties of this plant. Therefore, this study investigated the effects of TV and domesticated garlic extracts on Jurkat cells, in order to determine whether or not these extracts possess anti-proliferative properties. Cultured Jurkat cells were treated with IC50 concentrations of garlic (14μg/ml), TV leaf (256μg/ml), TV bulb (225μg/ml) and TV stalk (216μg/ml) extracts as determined by the methylthiazol tetrazolium assay. Free radical production was measured using the thiobarbituric acid reactive substance (TBARS) and nitric oxide (NO) assays, while glutathione (GSH) concentration was measured using the GSH-Glo™ assay. The apoptosis inducing properties of each extract were measured using flow cytometry (Annexin V- Fluos and JC-1 assays) and luminometry (caspases 3/7, 8, 9 and ATP). Western blots were run to determine protein expression, while comet and DNA fragmentation assays were used to determine the level of DNA damage induced. Wild and domesticated garlic extracts induced a significant increase in malondialdehyde concentration ([MDA]), with TV bulb extract inducing the highest concentration (p<0.0001). A significant increase in NO concentration was observed in the bulb (p<0.0001) and stalk (p<0.001) extracts, and leaf (p<0.05) and stalk (p<0.05) TV extracts significantly increasing GSH concentration. The longest comet tails were observed in TV bulb extracts (p<0.0001) and comprised mainly of single strand breaks, while the comets induced following garlic exposure contained double strand breaks. All extracts, except TV leaf, increased the percentage of cells undergoing apoptosis. Tulbaghia violacea leaf induced a significant (p<0.0001) increase in percentage of cells undergoing necrosis, whereas TV bulb resulted in a significant (p<0.0001) decrease. All TV extracts induced caspase 3/7 and 9 activity, with the most significant increase in caspase 9 activity observed for TV leaf and bulb. No significant change in caspase 3/7 activity was evident for domesticated garlic. Cleavage of PARP and expression of NF B and HSP 70 occured for all extracts. However, HSP 70 was not differentially expressed. Exposure to wild and domesticated garlic extracts induced peroxidative lipid and DNA damage within the cells, indicating oxidative stress. This damage occurred in conjunction with increased percentage of cells undergoing apoptosis and expression of caspase 3/7. Therefore, these findings suggest that TV is inducing cell death through apoptosis in Jurkat cells using a number of mechanisms, including the induction of oxidative stress. This is of clinical significance, as cell death through apoptosis is the preferred method of action for anti-cancer drugs. / Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2012.