conservation measures and improves our understanding of the grass- land. Fire and mowing can be a very important management technique. There is no literature available on the effects of a mowing vs fire management strategy for managing biodiversity in the Woodbush Granite Grassland. Data was collected within the grassland with the following management strategies: Annual burn, 3 year burn, Mow only, Mow and burn, Mow irregularly and graze. Modified Braun-Blanquet data sheet were used to record estimated aerial cover of grass, forbs, and woody species per plot. The aerial cover of leaf litter, bare soil and rock was also recorded. The number of stems and height of woody species per plot was recorded. Difference in aerial cover between various veld management strategies was observed. Woody species establishment was observed to be an increasing phenomenon in three year burn sites. doi:10.1016/j.sajb.2017.01.137 Functional role of ammonium and nitrate in regulating transpiration for mass-flow acquisition of nutrients M. Naku, L. Kambizi, I. Matimati Department of Horticultural Sciences, Faculty of Applied Sciences, Cape Peninsula University of Technology, South Africa E-mail address: mcnaku@gmail.com (M. Naku) Transpiration functions in cooling the leaves, maintaining turgidity, driving root to shoot ascension of solutes via the xylem and powering the delivery of nutrients through the soil to the root surface via mass-flow. Nitrogen may regulate transpiration and possibly mass-flow acquisition of soil nutrients. Despite such knowledge on N regulation of transpiration, it remains unknown whether both inorganic N forms can regulate transpiration. The study investigates the hypothesis that both NO 3 - and NH 4 + indirectly signal for the increase in rates of transpiration, when N is limiting, for increasing mass-flow acquisition by roots. Phaseolus vulgaris was grown in troughs designed to create a N-availability gradient by restricting roots from intercepting a slow-release NO 3 - or NH 4 + , placed at one of six distances behind a 25-μm mesh from which nutrients could move by diffusion or mass-flow (dubbed ‘ mass-flow’ treatment). Control plants will have direct access to NO 3 - and NH 4 + in their root zone through interception, mass-flow and diffusion (dubbed ‘interception’ treatment). Transpiration (E), photosynthetic rate (A), stomatal conductance (g s ), intercellular [CO 2 ](Ci) and water use efficiency (WUE) were measured using an infra-red gas analyser (LiCor6400XT). To compare the amount of nutrient acquired through “mass-flow” and “interception”, root and shoot dry weight and nutrient analysis were perfomed. One-way analyses of variance (ANOVA) and post-hoc Tukey’s HSD tests were performed on the measured variables using Statistica (version 10 Statsoft Inc., Tulsa, USA). Linear models relating total biomass, E, g s , WUE, Ci, A and foliar elemental concentrations to distance from N were generated in R to describe the observed data. doi:10.1016/j.sajb.2017.01.138 Assessing species boundaries in the Tribulus zeyheri complex in Namibia L. Nanyeni a , E.G. Kwembeya b , F.M. Crawford a a National Herbarium of Namibia (WIND), National Botanical Research Institute, Private Bag 13184, Windhoek, Namibia b University of Namibia, Department of Biological Sciences, Private Bag 13301, Windhoek, Namibia E-mail address: NanyeniL@mawf.gov.na (L. Nanyeni) Tribulus L. first described by Carolus Linnaeus in 1753 is a genus which is represented by 25 species of which five occur naturally in Namibia. Between 1887 and 1934 different forms and variations have been observed which, have resulted in several synonyms. The constant variation and many forms make the delimitation of taxonomic groups difficult, thus the main aim of this study is to redefine T. zeyheri. This will be accomplished by identifying morphological characters to aid in distinguishing species in the genus Tribulus; comparing morphological characters on herbarium and field material and to explore morpholog- ical variation within the genus Tribulus by using the Numerical Taxonomy and Multivariate Statistical Analyses System (NTSYS). doi:10.1016/j.sajb.2017.01.139 The effect of enviromental stress on the phytochemistry and bioactivity responses of a South African medicinal bulbous plant Tulbaghia violacea W. Ncise, C.W. Daniels, F. Nchu Department of Horticultural Sciences, Faculty of Applied Sciences, Cape Peninsula University of Technology, PO Box 1906, Bellville 7535, South Africa E-mail address: wangancise@gmail.com (W. Ncise) Tulbaghia violacea is a South African medicinal, bulbous plant (family: Alliaceae) which is commonly utilized for the treatment of gastrointestinal ailments, asthma, fever, tuberculosis and cancer of the oesophagus. Scientific research on this species is ongoing because of its antioxidant, antifungal and antibacterial properties. The research will investigate the effect of drought and shade stresses, which are currently, experienced in the natural habitats on the antioxidant properties of this species. The plant material for the antioxidant studies will be grown under outdoor conditions where drought and shade stresses will be applied. Furthermore, this study will compare the antioxidant properties of natural populations with those obtained by cultivation to ascertain whether there are significant differences in both populations. A hydroponic cultivation study will be conducted to ascertain whether a change in the nutrient solution pH will affect the known antifungal properties of this species. Plant material for the hydroponic pH-stress experiment will be grown under greenhouse conditions with a temperature range of between 24°C and 27°C and a relative humidity maintained at 60%. Crude extracts of whole plants will be used to determine the in vitro antifungal properties against the fungus Candida albicans which can be pathogenic in humans. The results of this study could benefit pharmaceutical companies, traditional healers and the horticulture industry by the enhance- ment of the medicinal properties of T. violaceae. In addition, if successful, the general and hydroponic cultivation practices applied in this study could prevent over-exploitation as well as enhance general conservation of the species. doi:10.1016/j.sajb.2017.01.140 Heterogeneity expression of growth and physiology as a function of nitrogen form and ratio in Cyrtanthus guthrieae L. B. Ncube, J. Van Staden Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa E-mail address: ncubeb@ukzn.ac.za (B. Ncube) Abstracts 358