Bambara groundnut is a protein-rich legume, with food security potential in drought-prone regions. It has been grown for many centuries and has remained an important crop to most African subsistence farmers. However, despite its high nutritional status and yield advantages in poor soils, it remains one of the neglected crops by science. There have now been recent efforts to study underutilised crops, with the aim of promoting them as healthy alternatives for people facing resource and environmental challenges and to contribute to food security. In order to do this, there needs to be information that can be used to advise farmers on the agronomic aspects of producing the crop. The overall aim of the study was to evaluate the response of bambara groundnut landraces to drought under controlled environment and field conditions. Seeds were initially collected from subsistence farmers in Jozini, KwaZulu-Natal, and characterised into three seed lots distinguished by seed coat colour: red, white and brown. In the initial study (Chapter 2) seed quality of bambara groundnuts was evaluated. Seed lots were used for standard germination (SG) and cold test (CT). Seeds were germinated under two conditions, 25°C for 8 days (SG) and 4°C for 7 days followed by 8 days at 25°C (CT). Germination percentage, seedling size and mass were determined. Desiccation tolerance was evaluated by suspending 30 seeds of each seed lot over saturated salt solutions of NaCl, LiCl, KNO3 and H2O (control) for 0, 2, 4, 8, 24 and 48 hours. Five seeds were sampled at each interval and stored at -21°C for 7 days. Samples were ground and analysed for proline content. In addition, early establishment performance of bambara groundnut was evaluated under controlled environment conditions in seedling trays using two water regimes (Chapter 2). The experimental design had three factors: seed lot (colour), priming (NaCl, LiCl, KNO3, H2O and control) and water regimes [25% and 75% Field Capacity (F.C.)]. The experiment was replicated three times. Seedling emergence was determined daily for 21 days. Seedling height and leaf number were determined weekly for three weeks, thereafter, seedling leaf area, root and shoot mass (fresh and dry), root and shoot lengths and root to shoot ratio were also determined. Seedlings were later transplanted in 90 pots for a pot trial in order to evaluate growth responses of bambara groundnut to water stress; plant height, leaf number and yield components were determined (Chapter 3). Lastly, the use of planting date selection as a management strategy for managing the occurrence of water stress under field conditions was evaluated in field trials. The experimental design was a split-split-plot design with planting date as main factor (early, optimum and late), irrigation and rainfed as sub-main factor, and seed colour as sub-plots (brown, red and white) arranged in a randomised complete block design (RCBD), with three replications. There were three planting dates: 7 September (early planting), 24 November (optimum planting) and 19 January (late planting). Results from Chapter 2 showed that the brown seed lot had the highest germination across treatments, followed by red and white seeds, respectively. There were significant differences between seed lots (P < 0.05) and salt solutions (P < 0.05) with respect to proline content. Seed proline content increased from 0 to 8 hours and later declined; NaCl was associated with the highest proline accumulation. There were highly significant differences (P < 0.001) between seed colours, priming treatments and F.C., as well as their interaction, with respect to seedling emergence. White seeds had the highest emergence, followed by brown and red, respectively. Priming seeds improved their emergence compared to the control, with highest emergence being observed in seeds treated with LiCl. Priming also improved emergence under water stress; 25% F.C. had the highest emergence compared to 75% F.C. Results from Chapter 3 showed that, seeds primed with NaCl and KNO3 resulted in tallest plants with the highest number of leaves per plant. However, NaCl and KNO3 were also the most affected under water stress. Priming was shown to improve germination and early crop establishment of bambara groundnut landraces under water stress. However, yield per plant did not improve in response to either halo- or hydro-priming. Results from field trials showed that in terms of the measured plant growth parameters (plant height, leaf number and LAI), bambara groundnut landraces were sensitive water stress. Water stress decreased yield components, and hence yield. However, selection of planting dates was shown to be a useful management tool for managing water stress under water limited field conditions. Choice of planting date significantly affected both plant growth and yield. The optimum planting date resulted in the best crop growth for all measured plant growth parameters followed by late and early planting dates, respectively. Seed quality was shown to be associated with seed lot colour. Darker coloured (red and brown) seeds performed better than light (white) seeds with respect to germination. Priming was also shown to improve germination and early crop establishment of bambara groundnut landraces under water stress. However, yield per plant did not improve following priming. Growth of bambara groundnut landraces was shown to be sensitive to water stress. Water stress decreased yield components and hence yield under both controlled and field conditions. Choice of planting date significantly affected both plant growth and yield. The optimum planting date was shown to be the best performing planting date. The findings of this study suggest that bambara groundnut seed performance in terms of germination, stand establishment and productivity is associated with seed lot colour. Seed priming improves seed performance and enhances crop capacity to withstand water stress. If the optimum planting date for groundnuts (late spring to early summer) is missed, better crop performance and yield are obtained from late planting (late summer to early spring) compared with early planting (early spring). Bambara groundnut has a potential for production under water stress conditions in controlled and field environments. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

MSCFST / Department of Science and Technology / Heat-moisture treatment (HMT) is a physical modification that alters the physicochemical properties of starch without changing its molecular structure. The objective of the study was to investigate the influence of HMT on the functional, colour and thermal properties of bambara groundnut (BG) starch. A central composite rotatable design comprising two independent factors (temperature and time) was used for the study. The central composite rotatable design was generated using Design-Expert software version 8.0.1.0. Bambara starch extraction was done by milling BG into flour (5 Kg), suspension in 15 L, 0.3% sodium hydroxide and centrifugation followed by washing using distilled water. The starch was then HMT treated in an air oven at 80 - 120 °C for 30 - 90 min under 15 % moisture content (MC) (HMT 15), 25% MC (HMT 25) and 35% MC (HMT 35). The highest L* and WI values for HMT treated BG starch were observed at HMT 80 °C for 30 min under 15% MC; 100 °C for 60 min (25% MC); and 100 °C for 17.57 min (35% MC) while the lowest was observed in HMT 100 °C for 102.43 min (15% MC); 120 °C for 90 min (25% MC); and 120 °C for 90 min (35% MC). In HMT 15-BG starch, the gelatinisation parameters onset (To), peak (Tp) and concluding temperature (Tc) of the samples decreased as treatment time and temperature increased whereas gelatinisation enthalpy of BG starch increased with increase in HMT treatment temperature and time. In HMT 25-BG starch Tp, and gelatinisation enthalpy of the starch increased with increase in HMT treatment temperature and time. While in HMT 35-BG starch, To, Tp, Tc and gelatinisation enthalpy of the starches decreased with increase in HMT treatment temperature and time. In HMT 15-BG starch, the water absorption capacity (WAC), solubility and swelling power (SP) decreased as treatment time and temperature increased while oil absorption capacity (OAC) of the starch increased with increase in HMT treatment temperature and time. In terms of HMT 25-BG starch, the WAC and OAC increased as HMT treatment time and temperature increased while SP and solubility of the starch decreased with increase in HMT treatment temperature and time. In HMT 35-BG starch, OAC, solubility and SP decreased as treatment time and temperature increased while WAC of the starch increased with increase in HMT treatment temperature and time. The optimum HMT conditions for BG starch were found to be 80 °C for 30 min (HMT 15), 105.74 °C for 30 min (HMT 25), and 113.16 °C for 30 min (HMT 35). Desirability of the obtained optimum conditions were 0.63 (HMT 15), 0.56 (HMT 25) and 0.64 (HMT 35). Information obtained from scanning electron micrograph indicates oval and round shape for bambara starch granules, with varying sizes. The range of the granule size width was 4.2 – 4.7 mm and 10 μm for length. The modified starches showed some changes in granule morphology as they seem to disintegrate with application of HMT. Unmodified and HMT - BG starches showed characteristic FTIR bands linked with common starches. All the samples displayed complex vibrations in the region below 1000 cm-1 due to the skeletal vibrations of the glucose pyranose ring. Statistical analysis on colour, thermal and functional properties of HMT 15-BG, HMT 25-BG and HMT 35-BG starch showed that effects of temperature and treatment time had no significant (p ≥ 0.05) effect on these properties of HMT-BG starch. However, treatment time had a significant linear effect (p ≤ 0.05) on swelling power, for HMT 15-BG starch. In HMT 35-BG starch, WAC was significantly affected by quadratic effect of temperature and time while solubility was significantly affected by linear effect of time and quadratic effect of temperature. / NRF

MRDV / Institute for Rural Development / This study originated from the realisation that non-conventional crops such as Bambara nuts (Vigna subterranea) were becoming increasingly important in addressing food insecurity and malnutrition in the smallholder farming sector of countries in sub-Saharan Africa. Moreover, some of the smallholder crop farmers were observed to be continuing to rely on indigenous techniques to forecast rainfall and adapt agricultural activities in response to climate variability. However, it was not clear how climate change influenced the productivity of V. subterranea. Nor were the indigenous approaches that farmers used to forecast rainfall on this phenomenon well understood. Thus, a study was carried out to identify and document indigenous approaches that smallholder farmers used to forecast rainfall and adaptation practices relating to V. subterranea. The study was conducted in Xigalo and Lambani villages located in Collins Chabane Local Municipality of Vhembe District in Limpopo Province. The villages served as case study areas that helped to compare the native approaches that the Va-Tsonga and Vha-Venda used to forecast rainfall in the course of producing V. subterranea. A multi-case study research design, which was exploratory in nature was adopted. Convenience and snowball sampling techniques were used to identify and select respondents. The triangulation of participatory methods, techniques and tools guided the collection of qualitative data. Key informant interviews, learning circles, photovoice, one-on-one interviews and narrative inquiry techniques were applied during data collection. Smallholder farmers and the elderly members of communities were the respondents. Nine key informants in Xigalo and Lambani villages were interviewed. One retired and two currently serving government extension officers were also interviewed. Separate learning circles comprising mainly elderly men and women were also organised. Each learning circle was made up of 7-10 respondents. Atlas.ti version 7.5.7 software was used to analyse the qualitative data following the thematic content analysis approach. It was observed that the respondents were aware of climate variability events that affected V. subterranea. Some of the events were shifts in rainfall patterns, heavy rainfall, extreme temperatures, scarcity of summer rainfall, the disappearance of lunar signs and the seasonal cycle variations. Eighteen types of phenological signs used to predict rainfall were identified. The most common signs included the Milky Way Galaxy of stars, musical sounds of birds and frogs, moon shapes, cumulus and cumulonimbus cloud types. A close relationship between conservation of V. subterranea and adaptation strategies was said to exist. It was evident that most commonly used conservation strategies were rainmaking ceremonies, planting after the summer rains, hoeing weeds, soaking seeds before planting, hilling or earthing up around the base of the V. subterranea plant and storing the legumes in traditional vessels and sacks. The need for integrating western scientific knowledge with native forecasts to inform the production of V. subterranea was uncovered. In addition to this, the needs of Tsonga and Venda communities should inform local policy interventions. Lastly, adaptation strategies that address food insecurity with V. subterranea being part of the agro-ecosystem deserve attention in scientific investigation and policymaking. / NRF