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With the signing of the New Partnership Agreement (Cotonou Convention) between the European Union and the African, Caribbean, and Pacific States in June 2000, the trading relationship between Senegal and the European Union (EU) has taken a new direction. Under the new agreement, Senegal must decide by 2004 if it will enter into a Regional Economic Partnership Agreement (REPA) with the EU, similar to a free trade arrangement, or move to an enhanced form of the Generalized System of Preferences (GSP). Given the high percentage of Senegalese groundnut products that are exported to the European Union and the significance of the groundnut sector to the Senegalese economy, this study examines the economic impacts of both options on the Senegalese groundnut sector in conjunction with changes in development funding, infrastructural investments, and structural adjustment policies. Overall, the study finds that the REPA option is the more beneficial for the Senegalese groundnut sector. This result stems partially from the ability of increases in development funding to offset any adverse economic impacts caused by the REPA. Though overall more harmful than a REPA, moving to an enhanced GSP does have the benefit of increasing groundnut (in-shell and shelled) exports by a significant amount. Thus, the Senegalese government must weigh the benefit of a boost in the confectionery sector against the adverse impact on producers caused by the GSP. This study provides needed information for policy decisions by the Senegalese government, and a framework for future modeling efforts pertaining to the Senegalese groundnut sector. / Master of Science

One of the major problems facing aquaculture in Ghana is the non-availability of quality and affordable fish feeds. The present study investigated the nutritional suitability and cost-effectiveness of some Ghanaian oilseed by-products, soybean meal (Glycine spp), cottonseed meal (Gossypium spp), groundnut cake (Arachis hypogaea L.) and groundnut husk, as alternative protein sources to fishmeal (FM) in the diet of Nile tilapia (Oreochromis niloticus L.). The oilseed meals were used individually, as mixtures, as mixtures enriched with methionine and mixtures detoxified by heat processing (autoclaving) and/or addition of supplements (viz. phytase and ferrous sulphate) intended to reduce levels of the most important antinutritional factors (ANFs). Diets, containing the oilseed meals at inclusion levels from 25% to 75% dietary protein, were formulated to be isonitrogenous (320 g.kg-1), isolipidic (100 g.kg-1) and isoenergetic (18 KJ.g-1) and fed to juvenile Nile tilapia at 4-10% of their body weight for a period of eight weeks. Proximate analysis showed that soybean meal (SBM), cottonseed meal (CSM), groundnut cake (GNC) and groundnut husk (GNH) had 500.3, 441.4, 430.5 and 205.6 g.kg-1 crude protein, 38.2, 89.5, 12.8 and 89.2 g.kg-1 crude fibre and 20.19, 19.61, 23.17 and 22.18 kJ.g-1 gross energy respectively. Generally the oilseed meals had good essential amino acid (EAA) profiles with the exception of GNH. The EAA profile of SBM compared very well with FM but methionine and threonine were low (0.73 and 1.50 % of protein respectively) and the same was true for CSM and GNC with even lower levels. Analyzed ANFs in SBM, CSM, GNC and GNH were 17.54, 31.64, 14.86 and 3.99 g.kg-1 phytic acid, 14.09, 1.24 and 2.34 g.kg-1 trypsin inhibitors and 5.80, 6.50, 8.01 and 10.08 g.kg-1 saponin respectively and in CSM 5.6 g.kg-1 gossypol. Nutrient digestibility of these oilseed proteins suggested that Nile tilapia may be able to utilize SBM, CSM and GNC efficiently as dietary protein sources due to high apparent protein digestibility of 94.50%, 84.93% and 90.01% respectively. However, GNH may not be suitable because of very low apparent protein digestibility (27.67%). These protein sources when used individually were shown to cause depressed growth and feed efficiency when substituting more than 50% of the FM protein in diets. This may be attributed to high levels of ANFs, high fibre content and poor EAA profile. However, the use of mixtures of these meals was found to be marginally more effective than that of single sources. This may have been as a result of lower levels of ANFs and improvement in essential amino acid profile due to mixing. Supplementing the mixtures with methionine led to improvement in feed utilization but without significantly improving the nutritive value compared with FM. Heat processing was effective in reducing heat labile trypsin inhibitors in SBM, CSM and GNC by almost 80%, but not phytic acid and saponins, which remained virtually unaffected. Use of meals detoxified by heat processing with/without supplements at 50% inclusion improved growth and feed utilization compared to the unprocessed meals and performance was generally not significantly different from FM. Cost effectiveness analysis revealed that diets containing single feedstuffs or mixtures, particularly those containing equal proportions of oilseed meals and higher proportion of CSM replacing between 50% - 75% FM protein, were more profitable than FM diet. Similarly, the use of heat processed meals at 50% replacement of FM protein yielded greater profit than all other diets including the FM diet. However, essential amino acid supplementation of the meals was less profitable compared to the control. Generally, fish fed diets with oilseed meals would take longer to attain harvest size compared with FM and this could lead to an increase in production costs or a decrease in the number of production cycles which could be achieved within a year. It can be concluded that there is nutritional and economic justification for using SBM, CSM and GNC as partial replacement for FM in diets of Nile tilapia. Based on growth performance, nutrient utilization and economic benefits the diet with heat processed oilseed meal mixtures (containing equal proportions of 16.67% each) at 50% inclusion has the best prospects for replacing FM protein in diets of O. niloticus.

L’agriculture familiale s’affiche indéniablement comme un pilier de la sécurité alimentaire nationale. Elle représente près de 80% des exploitations en Afrique sub-saharienne et emploie 75% des actifs. Dans le Bassin arachidier, les exploitations agricoles familiales ont généralement une superficie moyenne comprise entre un et cinq hectares mais, elles font face aux divers défis de sécurité alimentaire, d’équité sociale et de durabilité environnementale. En outre, elles sont confrontées à des contraintes structurelles d’ordre organisationnel et économique dans un contexte d’incertitude climatique. Ainsi, cette thèse cherche à comprendre les stratégies mises en œuvre par les exploitations familiales face aux différents risques ainsi que les propositions alternatives des autres acteurs du développement du secteur. Il s’agit, à la fois, d’identifier les principales contraintes se posant aux exploitations et les stratégies qu’elles occasionnent pour proposer des stratégies complémentaires ou alternatives dans le cadre d’analyse de la gestion du risque. Pour une telle visée, nous avons appréhendé les concepts d’exploitation agricole familiale, de risque, de vulnérabilité et d’assurance agricole pour prendre en compte les dimensions de cet objet de recherche. Ce cadre théorique et conceptuel a été opérationnalisé sur le terrain au sein d’exploitations agricoles, en donnant la parole aux chefs d’exploitation. Plusieurs enquêtes ont été réalisées et ont porté sur les indicateurs sociodémographiques, structurels et techniques, sur les principaux risques et contraintes au niveau des exploitations, sur la perception de l’assurance agricole. Les principaux risques identifiés sont agricoles et climatiques. Les exploitations agricoles familiales considèrent l’accès aux intrants (engrais et semences) et au matériel agricole comme une contrainte structurelle, en plus du déficit pluviométrique. Aussi, il ressort une vulnérabilité importante dans ses trois composantes au niveau des exploitations agricoles du Bassin. Cette réflexion montre les limites des stratégies développées par les exploitations agricoles pour améliorer leur résilience dans le contexte pluvial du Bassin arachidier ; et justifie la nécessité d’aller vers de nouvelles stratégies complémentaires. L’une des pistes que nous avons explorée est l’assurance indicielle agricole. Son couplage au crédit, comme garantie pour les institutions financières et pour disposer de fonds de roulement, est positivement apprécié par les souscripteurs qui, à hauteur de 95%, sont prêts à prolonger l’utilisation des polices d’assurance. / Family farming undeniably appears as a pillar of national food security. It represents nearly 80% of farms in sub-Saharan Africa and employs 75% of assets. In the groundnut basin, family farms generally have an average size between one and five hectares, but they face the various challenges of food security, social equity and environmental sustainability. In addition, they face structural constraints of organizational and economic order in a context of climate uncertainty. Thus, this thesis seeks to understand the strategies used by family farms toward the various risks and alternative proposals from other actors in the sector's development. It is, at once, to identify the main constraints arising farms and strategies they cause to propose additional or alternative strategies in the analysis of the risk management framework. For such an aim, we arrested the concepts of family farm, risk, vulnerability and agricultural insurance to reflect the dimensions of this subject for research. This theoretical and conceptual framework was operationalized on the field within farms, giving a voice to farm managers. Several investigations have been conducted and focused on socio-demographic, structural and technical indicators, principal risks and constraints at the farm level, the perception of agricultural insurance. It appears from this study that the main risks identified are agriculture and climate. Family farms consider access to inputs (fertilizer and seed) and farm equipment as a structural constraint in the rainfall deficit. Also, it appears a significant vulnerability in its three components at farm level Basin. This reflection shows the limits of the strategies developed by the farms to improve their resilience in the context of rained groundnut basin; and justifies the need to go to new complementary strategies. One of the tracks that we have explored is the agricultural index insurance. Its coupling to credit, as collateral to financial institutions and to provide working capital is positively appreciated by the subscribers who, up to 95%, are willing to extend the use of insurance policies.

O amendoim (Arachis hypogaea) é a quarta oleaginosa mais consumida no mundo. O Brasil produziu, em 2002, aproximadamente 190 mil toneladas, sendo que 80% da área plantada situa-se no Estado de São Paulo. O principal problema da cultura neste Estado e no mundo são as doenças fúngicas de parte aérea. Diversas espécies do gênero Arachis são consideradas resistentes a várias pragas e doenças. Os objetivos dessa pesquisa foram: 1) identificar espécies silvestres pertencentes à Secção Arachis resistentes à mancha castanha (Cercospora arachidicola), mancha preta (Cercosporidium personatum) e ferrugem (Puccinia arachidis); 2) realizar cruzamentos entre espécies de genoma “A” e “B” resistentes a, pelo menos, uma doença fúngica; 3) duplicar os cromossomos dos híbridos estéreis; 4) realizar cruzamentos entre A. hypogaea e os anfidiplóides sintéticos; 5) obter a geração F1 que tivesse 50% do genoma do amendoim cultivado, 50% do genoma das espécies silvestres. Os experimentos foram conduzidos, em condições de telado, no Departamento de Genética da Escola Superior de Agricultura “Luiz de Queiroz”. Para a identificação de genótipos resistentes às doenças fúngicas, utilizou-se a técnica de folhas destacadas, em laboratório, com inoculação artificial, condições controladas de temperatura a 25°C e luz alternada (10h luz). Os cruzamentos entre espécies silvestres, de genoma “B” com as de genoma “A”, resistentes a pelo menos uma doença foram realizados em condições de telado, com emasculação realizada ao final da tarde e polinização na manhã do dia seguinte. A duplicação de cromossomos de células somáticas de híbridos com genoma “AB”, foi obtida mediante o tratamento de estacas com colchicina a 0,2%, por aproximadamente 12h, em condições de luz e com temperatura entre 25-30°C. Os cruzamentos entre A. hypogaea e os anfidiplóides sintéticos foram realizados em condições de telado, na Embrapa Recursos Genéticos e Biotecnologia. Observou-se que várias espécies silvestres foram altamente resistentes a, pelo menos, uma das três doenças estudadas. Foi possível selecionar, como genitores masculinos, 12 acessos de genoma “A” e, como femininos, seis acessos de genoma “B”. A partir de 26 cruzamentos distintos (3633 hibridações), foi possível obter 17 híbridos interespecíficos distintos com genoma “AB”. Após o tratamento com colchicina de todos os 17 tipos de híbridos, foram obtidas cinco combinações híbridas que produziram flores tetraplóides (A. hoehnei x A. helodes, A. ipaënsis x A. duranensis, A. hoehnei x A. cardenasii, A. aff. magna x A. villosa, A. aff. magna x A. aff. diogoi). Foram realizados 21 cruzamentos entre A. hypogaea e os anfidiplóides sintéticos. Foram obtidos 13 tipos de híbridos: A. hypogaea (cvs. IAC-Tatu-ST, Br-1, IAC-Caiapó, IAC-Runner) x [A. hoehnei x A. cardenasii]; A. hypogaea cv. Br-1 x [A. aff. magna x A. villosa] ; A. hypogaea (acessos V 12548, V 12549, Mdi 1560, Mdi 1538, cvs. BR-1, IAC-Tatu-ST, IAC-Caiapó, IAC-Runner) x [A. ipaënsis x A. duranensis]. Os resultados obtidos confirmam que é possível a introgressão de genes de resistência a partir de espécies silvestres no amendoim cultivado, via cruzamentos, expandindo-se a lista de espécies silvestres utilizadas e ampliando a variabilidade genética liberada para seleção nos programas de melhoramento de amendoim. / Groundnut (Arachis hypogaea) is one of the most important oil species in the world. In 2002, Brazil produced about 190 thousand tonelades, with 80 per cent of cultivated area concentrated in the State of São Paulo. The main problem in crop management in this State and in many other growing areas in the world is represented by fungal diseases. Several species of the genus Arachis are considered resistant to main pests and diseases. This research was developed to take advantage of the genetic variability present in the Arachis genus, and has the following objectives: 1) to identify accessions of wild species belonging to Section Arachis that are resistant to early leaf spot (Cercospora arachidicola), late leaf spot (Cercosporidium personatum) and rust (Puccinia arachidis); 2) to cross resistant species having B and A genomes; 3) to duplicate chromosomes of sterile hybrids; 4) to cross A. hypogaea with synthetic amphiploids; 5) to obtain an F1 generation with 50% of the cultivated groundnut genome and 50% of wild species genomes. Experiments were developed under greenhouse conditions, in the Department of Genetics, faculty of Agriculture "Luiz of Queiroz". Detached leaves technique was used, in laboratory conditions, with artificial inoculation, controlled temperature of 25°C and alternate light (10h light) for the identification of genotypes resistant to fungal diseases. Crosses among wild resistant species with B and A genome genotypes were carried out in greenhouse conditions. Emasculation were hand-made at the end of the afternoon and pollination was made in the following morning. Chromosome duplication of somatic cells in AB genome interspecific hybrids was obtained by treating cuttings with 0.2% colchicine for approximately 12h, in daylight conditions, maintaining the temperature in range of 25-30°C. Crosses between A. hypogaea and synthetic amphyploids were done in greenhouse conditions, at Embrapa Genetic Resources and Biotechnology. It was observed that several wild species were highly resistant to one or more of the studied diseases. Selection of 12 A genome accessions for use as male parents was possible as well as six B genome species as female parents. From 26 different combinations, it was possible to obtain 17 interspecific AB genome hybrids. After colchicine treatment of all 17 hybrid types, five hybrid combinations that produced tetraploid flowers were obtained (A. hoehnei x A. helodes, A. ipaënsis x A. duranensis, A. hoehnei x A. cardenasii, A. aff. magna x A. villosa, A. aff. magna x A. aff. diogoi). Twenty-one different crosses were done between A. hypogaea and synthetic amphyploids. Thirteen different hybrid types were obtained: A. hypogaea (cvs. IAC-Tatu-ST, Br-1, IAC-Caiapó, IAC-Runner) x [A. hoehnei x A. cardenasii]; A. hypogaea cv. BR-1 x [A. aff. magna x A. villosa]; A. hypogaea (accessions V 12548, V 12549, Mdi 1560, Mdi 1538, cvs. Br-1, IAC-Tatu-ST, IACCaiapó, IAC-Runner) x [A. ipaënsis x A. duranensis]. Results confirmed the possibility of introgression of resistance genes from wild species into cultivated groundnut, by manual crosses, increasing the number of wild species used, and thus to enhance the genetic variability released for applying selection in breeding groundnut programs.

O amendoim (Arachis hypogaea) é a quarta oleaginosa mais consumida no mundo. O Brasil produziu, em 2002, aproximadamente 190 mil toneladas, sendo que 80% da área plantada situa-se no Estado de São Paulo. O principal problema da cultura neste Estado e no mundo são as doenças fúngicas de parte aérea. Diversas espécies do gênero Arachis são consideradas resistentes a várias pragas e doenças. Os objetivos dessa pesquisa foram: 1) identificar espécies silvestres pertencentes à Secção Arachis resistentes à mancha castanha (Cercospora arachidicola), mancha preta (Cercosporidium personatum) e ferrugem (Puccinia arachidis); 2) realizar cruzamentos entre espécies de genoma "A" e "B" resistentes a, pelo menos, uma doença fúngica; 3) duplicar os cromossomos dos híbridos estéreis; 4) realizar cruzamentos entre A. hypogaea e os anfidiplóides sintéticos; 5) obter a geração F1 que tivesse 50% do genoma do amendoim cultivado, 50% do genoma das espécies silvestres. Os experimentos foram conduzidos, em condições de telado, no Departamento de Genética da Escola Superior de Agricultura "Luiz de Queiroz". Para a identificação de genótipos resistentes às doenças fúngicas, utilizou-se a técnica de folhas destacadas, em laboratório, com inoculação artificial, condições controladas de temperatura a 25°C e luz alternada (10h luz). Os cruzamentos entre espécies silvestres, de genoma "B" com as de genoma "A", resistentes a pelo menos uma doença foram realizados em condições de telado, com emasculação realizada ao final da tarde e polinização na manhã do dia seguinte. A duplicação de cromossomos de células somáticas de híbridos com genoma "AB", foi obtida mediante o tratamento de estacas com colchicina a 0,2%, por aproximadamente 12h, em condições de luz e com temperatura entre 25-30°C. Os cruzamentos entre A. hypogaea e os anfidiplóides sintéticos foram realizados em condições de telado, na Embrapa Recursos Genéticos e Biotecnologia. Observou-se que várias espécies silvestres foram altamente resistentes a, pelo menos, uma das três doenças estudadas. Foi possível selecionar, como genitores masculinos, 12 acessos de genoma "A" e, como femininos, seis acessos de genoma "B". A partir de 26 cruzamentos distintos (3633 hibridações), foi possível obter 17 híbridos interespecíficos distintos com genoma "AB". Após o tratamento com colchicina de todos os 17 tipos de híbridos, foram obtidas cinco combinações híbridas que produziram flores tetraplóides (A. hoehnei x A. helodes, A. ipaënsis x A. duranensis, A. hoehnei x A. cardenasii, A. aff. magna x A. villosa, A. aff. magna x A. aff. diogoi). Foram realizados 21 cruzamentos entre A. hypogaea e os anfidiplóides sintéticos. Foram obtidos 13 tipos de híbridos: A. hypogaea (cvs. IAC-Tatu-ST, Br-1, IAC-Caiapó, IAC-Runner) x [A. hoehnei x A. cardenasii]; A. hypogaea cv. Br-1 x [A. aff. magna x A. villosa] ; A. hypogaea (acessos V 12548, V 12549, Mdi 1560, Mdi 1538, cvs. BR-1, IAC-Tatu-ST, IAC-Caiapó, IAC-Runner) x [A. ipaënsis x A. duranensis]. Os resultados obtidos confirmam que é possível a introgressão de genes de resistência a partir de espécies silvestres no amendoim cultivado, via cruzamentos, expandindo-se a lista de espécies silvestres utilizadas e ampliando a variabilidade genética liberada para seleção nos programas de melhoramento de amendoim. / Groundnut (Arachis hypogaea) is one of the most important oil species in the world. In 2002, Brazil produced about 190 thousand tonelades, with 80 per cent of cultivated area concentrated in the State of São Paulo. The main problem in crop management in this State and in many other growing areas in the world is represented by fungal diseases. Several species of the genus Arachis are considered resistant to main pests and diseases. This research was developed to take advantage of the genetic variability present in the Arachis genus, and has the following objectives: 1) to identify accessions of wild species belonging to Section Arachis that are resistant to early leaf spot (Cercospora arachidicola), late leaf spot (Cercosporidium personatum) and rust (Puccinia arachidis); 2) to cross resistant species having B and A genomes; 3) to duplicate chromosomes of sterile hybrids; 4) to cross A. hypogaea with synthetic amphiploids; 5) to obtain an F1 generation with 50% of the cultivated groundnut genome and 50% of wild species genomes. Experiments were developed under greenhouse conditions, in the Department of Genetics, faculty of Agriculture "Luiz of Queiroz". Detached leaves technique was used, in laboratory conditions, with artificial inoculation, controlled temperature of 25°C and alternate light (10h light) for the identification of genotypes resistant to fungal diseases. Crosses among wild resistant species with B and A genome genotypes were carried out in greenhouse conditions. Emasculation were hand-made at the end of the afternoon and pollination was made in the following morning. Chromosome duplication of somatic cells in AB genome interspecific hybrids was obtained by treating cuttings with 0.2% colchicine for approximately 12h, in daylight conditions, maintaining the temperature in range of 25-30°C. Crosses between A. hypogaea and synthetic amphyploids were done in greenhouse conditions, at Embrapa Genetic Resources and Biotechnology. It was observed that several wild species were highly resistant to one or more of the studied diseases. Selection of 12 A genome accessions for use as male parents was possible as well as six B genome species as female parents. From 26 different combinations, it was possible to obtain 17 interspecific AB genome hybrids. After colchicine treatment of all 17 hybrid types, five hybrid combinations that produced tetraploid flowers were obtained (A. hoehnei x A. helodes, A. ipaënsis x A. duranensis, A. hoehnei x A. cardenasii, A. aff. magna x A. villosa, A. aff. magna x A. aff. diogoi). Twenty-one different crosses were done between A. hypogaea and synthetic amphyploids. Thirteen different hybrid types were obtained: A. hypogaea (cvs. IAC-Tatu-ST, Br-1, IAC-Caiapó, IAC-Runner) x [A. hoehnei x A. cardenasii]; A. hypogaea cv. BR-1 x [A. aff. magna x A. villosa]; A. hypogaea (accessions V 12548, V 12549, Mdi 1560, Mdi 1538, cvs. Br-1, IAC-Tatu-ST, IACCaiapó, IAC-Runner) x [A. ipaënsis x A. duranensis]. Results confirmed the possibility of introgression of resistance genes from wild species into cultivated groundnut, by manual crosses, increasing the number of wild species used, and thus to enhance the genetic variability released for applying selection in breeding groundnut programs.

Groundnut or peanut (Arachis hypogaea L.) is an important legume cultivated in several developing countries in the tropics and subtropics. It plays a significant role as a food crop in regions with alarming population growth rates. The disease “peanut clump”, which is caused by viruses in the genus Pecluvirus, has been reported from India and from several countries of West Africa. In India, the causal agent is the Indian peanut clump virus (IPCV), which is transmitted by a soil-borne root parasite, Polymyxa graminis. The virus is also transmitted by infected seed and so far no economical method of control has been found. Therefore efforts have been concentrated on understanding the epidemiology of peanut clump disease with the aim of devising cultural methods of control. The work addressed in this thesis describes how investigation in various aspects of clump disease epidemiology, including identification of alternative hosts of the virus and the vector, and of factors that contribute to survival and spread of inoculum, has led to formulation of simple cultural practices that could reduce disease incidence.

Groundnut or peanut (Arachis hypogaea L.) is an important legume cultivated in several developing countries in the tropics and subtropics. It plays a significant role as a food crop in regions with alarming population growth rates. The disease “peanut clump”, which is caused by viruses in the genus Pecluvirus, has been reported from India and from several countries of West Africa. In India, the causal agent is the Indian peanut clump virus (IPCV), which is transmitted by a soil-borne root parasite, Polymyxa graminis. The virus is also transmitted by infected seed and so far no economical method of control has been found. Therefore efforts have been concentrated on understanding the epidemiology of peanut clump disease with the aim of devising cultural methods of control. The work addressed in this thesis describes how investigation in various aspects of clump disease epidemiology, including identification of alternative hosts of the virus and the vector, and of factors that contribute to survival and spread of inoculum, has led to formulation of simple cultural practices that could reduce disease incidence.

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.

The Eastern Cape Province of South Africa has climatic conditions which differ from region to region. The groundnut (Arachis hypogaea L.) cultivars, as it is the case with other crops, do not always perform equally well in the varying conditions. Abiotic stresses such as drought, extreme temperatures, and high soil acidity restrict plant growth. Lack of studies on adaptability of commercial groundnut cultivars in the Eastern Cape necessitated this study. Abiotic and biotic factors are not the only limiting factors: calcium availability in the soil is also a limiting factor in groundnut production. The aim of the study was to identify best suited cultivars for climatic conditions of Mthatha and Lusikisiki regions of the Eastern Cape. Two similar field experiments were conducted in the two locations with different climatic conditions. The results showed significant differences (P<0.05) in genotypes with respect to seed yield in both locations. Kwarts produced higher seed yield of 1155 kg ha-1 in Mthatha, while the same genotype produced low seed yield of 630 kg ha-1 in Lusikisiki location. In Lusikisiki the highest seed yield was recorded in Anel (936 kg ha-1) which produced low yield of 692 kg ha-1 in Mthatha. The genotypes that performed well in Mthatha in 2010/11 season included Kwarts, Nyanda, ICGV-SM 95714 and Mwenje. These genotypes were further used to investigate their response to calcium supplementation at flowering stage under conditions of Mthatha in the 2011/12 season. The results were significantly different for calcium absorption (P<0.05). Nyanda, Kwarts and Mwenje responded positively to calcium application at flowering stage producing relatively high yield of 153, 150 and 110 kg ha-1, respectively. Oil content was significantly increased by calcium application at flowering in Nyanda with 27.28% compared to 20.7% without Ca.