Issues surrounding water scarcity will become topical in future as global fresh water resources become more limited thus threaten crop production. Predicted climate change and increasing population growth will place more pressure on agriculture to produce more food using less water. As such, efforts have now shifted to identifying previously neglected underutilised species (NUS) as possible crops that could be used to bridge the food gap in future. Taro (Colocasia esculenta L. Schott) and bambara groundnut (Vigna subterranea L. Verdc) currently occupy low levels of utilisation in South Africa. Both crops are cultivated using landraces with no improved varieties available. Information describing their agronomy and water–use is limited and remains a bottleneck to their promotion. The aim of this study was to determine the drought tolerance and water–use of selected landraces of taro and bambara groundnut from KwaZulu-Natal, South Africa. In order to meet the specific objectives for taro and bambara groundnut management, an approach involving conventional and modelling techniques was used. Three taro landraces [Dumbe Lomfula (DL), KwaNgwanase (KW) and Umbumbulu (UM)] were collected from the North Coast and midlands of KwaZulu-Natal, South Africa, in 2010. The UM landrace was classified as Eddoe type taro (C. esculenta var. antiquorum) characterised by a central corm and edible side cormels. The DL and KW landraces were classified as Dasheen (C. esculenta var. esculenta), characterised by a large edible main corm and smaller side cormels. A bambara groundnut landrace was collected from Jozini, KwaZulu- Natal, and characterised into three selections (‘Red’, ‘Light-brown’ and ‘Brown’) based on seed coat colour. Seed colour was hypothesised to have an effect on seed quality. Field and rainshelter experiments were conducted for both taro and bambara landraces at Roodeplaat in Pretoria and Ukulinga Research Farm in Pietermaritzburg, over two growing seasons (2010/11 and 2011/12). The objective of the field trials for taro and bambara groundnut was to determine mechanisms associated with drought tolerance in taro and bambara groundnut landraces. Experiments were laid out in a split-plot design where irrigation [fully irrigated (FI) and rainfed (RF)] was the main factor and landraces (3 landraces of either taro or bambara groundnut) were sub-factors. Treatments were arranged in a randomised complete block design (RCBD), replicated three times. Rainfed trials were established with irrigation to allow for maximum crop stand. Thereafter, irrigation was withdrawn. Whilst experimental designs and layouts for taro and bambara groundnut were similar, differences existed with regards to plot sizes and plant spacing. Trials were planted on a total land area of 500 m2 and 144 m2, for taro and bambara groundnut, respectively. Plant spacing was 1 m x 1 m for taro and 0.3 m x 0.3 m for bambara groundnut. Irrigation scheduling in the FI treatment was based on ETo and Kc and was applied using sprinkler irrigation system. Separate rainshelter experiments were conducted for taro and bambara groundnut landraces at Roodeplaat, to evaluate growth, yield and water-use of taro and bambara groundnut landraces under a range of water regimes. The experimental design was similar for both crops, a RCBD with two treatment factors: irrigation level [30, 60 and 100% crop water requirement (ETa)] and landrace (3 landraces), replicated three times. Irrigation water was applied using drip irrigation system based on ETo and Kc. Data collection in field and rainshelter trials included time to emergence, plant height, leaf number, leaf area index (LAI), stomatal conductance and chlorophyll content index (CCI). For taro field trials, vegetative growth index (VGI) was also determined. Yield and yield components (harvest index, biomass, corm number and mass) as well as water–use efficiency (WUE) were determined at harvest. Intercropping of taro and bambara groundnut was evaluated under dryland conditions using farmers’ fields at Umbumbulu, KwaZulu–Natal, South Africa. The experimental design was a RCBD replicated three times. Intercrop combinations included taro and bambara groundnut sole crops, a 1:1 (one row taro to one row bambara groundnut) and 1:2 intercrop combinations. The taro UM landrace and ‘Red’ bambara groundnut landrace selection were used in the intercropping study. Lastly, data collected from field and rainshelter experiments were used to develop crop parameters to calibrate and validate the FAO’s AquaCrop model for taro and bambara groundnut landraces. The UM landrace was used for taro while the ‘Red’ landrace selection was used for bambara groundnut. AquaCrop was calibrated using observed data from optimum (FI) experiments conducted during 2010/11. Model validation was done using observations from field and rainshelter experiments conducted during 2011/12 as well as independent data. Results showed that all taro landraces were slow to emerge (≈ 49 days after planting). Stomatal conductance declined under conditions of limited water availability (RF, 60% and 30% ETa). The UM landrace showed better stomatal regulation compared with KW and DL landraces under conditions of limited water availability. Plant growth (plant height, leaf number, LAI and CCI) of taro landraces was lower under conditions of limited water availability (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). The UM landrace showed moderate reductions in growth compared with the DL and KW landraces, suggesting greater adaptability to water limited conditions. The VGI showed a large reduction in growth under RF conditions and confirmed the UM landrace’s adaptability to limited water availability. Limited water availability (RF, 60% and 30% ETa) resulted in lower biomass, HI, and final yield in taro landraces relative to optimum conditions (FI and 100% ETa). For all trials, the DL landrace failed to produce any yield. WUE of taro landraces was consistent for the three irrigation levels (30, 60 and 100% ETa); however, on average, the UM landrace was shown to have a higher WUE than the KW landrace. Bambara groundnut landraces were slow to emerge (up to 35 days after planting). ‘Red’ and ‘Brown’ landrace selections emerged better than the ‘Light-brown’ landrace selection, confirming the effect of seed colour on early establishment performance. Plant growth (stomatal conductance, CCI, plant height, leaf number, LAI and biomass accumulation) was lower under conditions of limited water availability (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). The ‘Red’ landrace selection showed better adaptation to stress. Limited water availability resulted in early flowering and reduced flowering duration as well as early senescence and maturity of bambara groundnut landrace selections. The ‘Red’ landrace selection showed delayed leaf senescence under conditions of limited water availability. Yield reductions of up to 50% were observed under water limited conditions (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). Water use efficiency increased at 60% and 30% ETa, respectively, relative to 100% ETa, implying adaptability to limited water availability. The ‘Red’ landrace selection showed better yield stability and WUE compared with the ‘Brown’ and ‘Light-brown’ landrace selections suggesting that seed colour may be used as a selection criterion for drought tolerance in bambara groundnut landraces. The intercropping study showed that intercropping, as an alternative cropping system, had more potential than monocropping. Evaluation of growth parameters showed that taro plant height was generally unaffected by intercropping but lower leaf number was observed as compared with the sole crop. Bambara groundnut plants were taller and had more leaves under intercropping relative to the sole crop. Although not statistically significant, yield was generally lower in the intercrops compared with the sole crops. Evaluation of intercrop productivity using the land equivalent ratio (LER) showed that intercropping taro and bambara groundnut at a ratio of 1:1 was more productive (LER = 1.53) than intercropping at a ratio of 1:2 (LER = 1.23). The FAO’s AquaCrop model was then calibrated for the taro UM landrace and ‘Red’ bambara groundnut landrace selection. This was based on observations from previous experiments that suggested them to be drought tolerant and stable. Calibration results for taro and bambara groundnut landraces showed an excellent fit between predicted and observed parameters for canopy cover (CC), biomass and yield. Model validation for bambara groundnut showed good model performance under field (FI and RF) conditions. Model performance was satisfactory for rainshelters. Validation results for taro showed good model performance under all conditions (field and rainshelters), although the model over-estimated CC for the declining stage of canopy growth under RF conditions. Model verification using independent data for taro showed equally good model performance. In conclusion, the taro UM landrace and ‘Red’ bambara groundnut landrace selection were shown to be drought tolerant and adapted to low levels of water–use. The mechanisms responsible for drought tolerance in the taro UM landrace and ‘Red’ bambara groundnut landrace selection were described as drought avoidance and escape. The taro UM landrace and ‘Red’ bambara groundnut landraces avoided stress through stomatal regulation, energy dissipation (loss of chlorophyll) as well as reducing canopy size (plant height, leaf number and LAI), which translates to minimised transpirational water losses. This indicated landrace adaptability to low levels of water–use. The ‘Red’ bambara groundnut landrace selection showed phenological plasticity and escaped drought by flowering early, delaying leaf senescence, and maturing early under conditions of limited water availability. Performance of the ‘Red’ landrace selection lends credence to the use of seed coat colour as a possible selection criterion for drought tolerance in bambara groundnut, and possibly for other landraces with variegated seed. The taro UM landrace escaped drought by maturing early under conditions of limited water availability. The FAO’s AquaCrop model was successfully calibrated and validated for taro UM and ‘Red’ bambara groundnut landraces. The calibration and validation of AquaCrop for taro is the first such attempt and represents progress in the modelling of neglected underutilised crops. The calibration and validation of AquaCrop for taro requires further fine-tuning while that for bambara groundnut still needs to be tested for more diverse landraces. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Issues surrounding water scarcity will become topical in future as global fresh water resources become more limited thus threaten crop production. Predicted climate change and increasing population growth will place more pressure on agriculture to produce more food using less water. As such, efforts have now shifted to identifying previously neglected underutilised species (NUS) as possible crops that could be used to bridge the food gap in future. Taro (Colocasia esculenta L. Schott) and bambara groundnut (Vigna subterranea L. Verdc) currently occupy low levels of utilisation in South Africa. Both crops are cultivated using landraces with no improved varieties available. Information describing their agronomy and water–use is limited and remains a bottleneck to their promotion. The aim of this study was to determine the drought tolerance and water–use of selected landraces of taro and bambara groundnut from KwaZulu-Natal, South Africa. In order to meet the specific objectives for taro and bambara groundnut management, an approach involving conventional and modelling techniques was used. Three taro landraces [Dumbe Lomfula (DL), KwaNgwanase (KW) and Umbumbulu (UM)] were collected from the North Coast and midlands of KwaZulu-Natal, South Africa, in 2010. The UM landrace was classified as Eddoe type taro (C. esculenta var. antiquorum) characterised by a central corm and edible side cormels. The DL and KW landraces were classified as Dasheen (C. esculenta var. esculenta), characterised by a large edible main corm and smaller side cormels. A bambara groundnut landrace was collected from Jozini, KwaZulu- Natal, and characterised into three selections (‘Red’, ‘Light-brown’ and ‘Brown’) based on seed coat colour. Seed colour was hypothesised to have an effect on seed quality. Field and rainshelter experiments were conducted for both taro and bambara landraces at Roodeplaat in Pretoria and Ukulinga Research Farm in Pietermaritzburg, over two growing seasons (2010/11 and 2011/12). The objective of the field trials for taro and bambara groundnut was to determine mechanisms associated with drought tolerance in taro and bambara groundnut landraces. Experiments were laid out in a split-plot design where irrigation [fully irrigated (FI) and rainfed (RF)] was the main factor and landraces (3 landraces of either taro or bambara groundnut) were sub-factors. Treatments were arranged in a randomised complete block design (RCBD), replicated three times. Rainfed trials were established with irrigation to allow for maximum crop stand. Thereafter, irrigation was withdrawn. Whilst experimental designs and layouts for taro and bambara groundnut were similar, differences existed with regards to plot sizes and plant spacing. Trials were planted on a total land area of 500 m2 and 144 m2, for taro and bambara groundnut, respectively. Plant spacing was 1 m x 1 m for taro and 0.3 m x 0.3 m for bambara groundnut. Irrigation scheduling in the FI treatment was based on ETo and Kc and was applied using sprinkler irrigation system. Separate rainshelter experiments were conducted for taro and bambara groundnut landraces at Roodeplaat, to evaluate growth, yield and water-use of taro and bambara groundnut landraces under a range of water regimes. The experimental design was similar for both crops, a RCBD with two treatment factors: irrigation level [30, 60 and 100% crop water requirement (ETa)] and landrace (3 landraces), replicated three times. Irrigation water was applied using drip irrigation system based on ETo and Kc. Data collection in field and rainshelter trials included time to emergence, plant height, leaf number, leaf area index (LAI), stomatal conductance and chlorophyll content index (CCI). For taro field trials, vegetative growth index (VGI) was also determined. Yield and yield components (harvest index, biomass, corm number and mass) as well as water–use efficiency (WUE) were determined at harvest.Intercropping of taro and bambara groundnut was evaluated under dryland conditions using farmers’ fields at Umbumbulu, KwaZulu–Natal, South Africa. The experimental design was a RCBD replicated three times. Intercrop combinations included taro and bambara groundnut sole crops, a 1:1 (one row taro to one row bambara groundnut) and 1:2 intercrop combinations. The taro UM landrace and ‘Red’ bambara groundnut landrace selection were used in the intercropping study. Lastly, data collected from field and rainshelter experiments were used to develop crop parameters to calibrate and validate the FAO’s AquaCrop model for taro and bambara groundnut landraces. The UM landrace was used for taro while the ‘Red’ landrace selection was used for bambara groundnut. AquaCrop was calibrated using observed data from optimum (FI) experiments conducted during 2010/11. Model validation was done using observations from field and rainshelter experiments conducted during 2011/12 as well as independent data. Results showed that all taro landraces were slow to emerge (≈ 49 days after planting). Stomatal conductance declined under conditions of limited water availability (RF, 60% and 30% ETa). The UM landrace showed better stomatal regulation compared with KW and DL landraces under conditions of limited water availability. Plant growth (plant height, leaf number, LAI and CCI) of taro landraces was lower under conditions of limited water availability (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). The UM landrace showed moderate reductions in growth compared with the DL and KW landraces, suggesting greater adaptability to water limited conditions. The VGI showed a large reduction in growth under RF conditions and confirmed the UM landrace’s adaptability to limited water availability. Limited water availability (RF, 60% and 30% ETa) resulted in lower biomass, HI, and final yield in taro landraces relative to optimum conditions (FI and 100% ETa). For all trials, the DL landrace failed to produce any yield. WUE of taro landraces was consistent for the three irrigation levels (30, 60 and 100% ETa); however, on average, the UM landrace was shown to have a higher WUE than the KW landrace. Bambara groundnut landraces were slow to emerge (up to 35 days after planting). ‘Red’ and ‘Brown’ landrace selections emerged better than the ‘Light-brown’ landrace selection, confirming the effect of seed colour on early establishment performance. Plant growth (stomatal conductance, CCI, plant height, leaf number, LAI and biomass accumulation) was lower under conditions of limited water availability (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). The ‘Red’ landrace selection showed better adaptation to stress. Limited water availability resulted in early flowering and reduced flowering duration as well as early senescence and maturity of bambara groundnut landrace selections. The ‘Red’ landrace selection showed delayed leaf senescence under conditions of limited water availability. Yield reductions of up to 50% were observed under water limited conditions (RF, 60% and 30% ETa) relative to optimum conditions (FI and 100% ETa). Water use efficiency increased at 60% and 30% ETa, respectively, relative to 100% ETa, implying adaptabilityto limited water availability. The ‘Red’ landrace selection showed better yield stability and WUE compared with the ‘Brown’ and ‘Light-brown’ landrace selections suggesting that seed colour may be used as a selection criterion for drought tolerance in bambara groundnut landraces. The intercropping study showed that intercropping, as an alternative cropping system, had more potential than monocropping. Evaluation of growth parameters showed that taro plant height was generally unaffected by intercropping but lower leaf number was observed as compared with the sole crop. Bambara groundnut plants were taller and had more leaves under intercropping relative to the sole crop. Although not statistically significant, yield was generally lower in the intercrops compared with the sole crops. Evaluation of intercrop productivity using the land equivalent ratio (LER) showed that intercropping taro and bambara groundnut at a ratio of 1:1 was more productive (LER = 1.53) than intercropping at a ratio of 1:2 (LER = 1.23). The FAO’s AquaCrop model was then calibrated for the taro UM landrace and ‘Red’ bambara groundnut landrace selection. This was based on observations from previous experiments that suggested them to be drought tolerant and stable. Calibration results for taro and bambara groundnut landraces showed an excellent fit between predicted and observed parameters for canopy cover (CC), biomass and yield. Model validation for bambara groundnut showed good model performance under field (FI and RF) conditions. Model performance was satisfactory for rainshelters. Validation results for taro showed good model performance under all conditions (field and rainshelters), although the model over-estimated CC for the declining stage of canopy growth under RF conditions. Model verification using independent data for taro showed equally good model performance. In conclusion, the taro UM landrace and ‘Red’ bambara groundnut landrace selection were shown to be drought tolerant and adapted to low levels of water–use. The mechanisms responsible for drought tolerance in the taro UM landrace and ‘Red’ bambara groundnut landrace selection were described as drought avoidance and escape. The taro UM landrace and ‘Red’ bambara groundnut landraces avoided stress through stomatal regulation, energy dissipation (loss of chlorophyll) as well as reducing canopy size (plant height, leaf number and LAI), which translates to minimised transpirational water losses. This indicated landrace viii adaptability to low levels of water–use. The ‘Red’ bambara groundnut landrace selection showed phenological plasticity and escaped drought by flowering early, delaying leaf senescence, and maturing early under conditions of limited water availability. Performance of the ‘Red’ landrace selection lends credence to the use of seed coat colour as a possible selection criterion for drought tolerance in bambara groundnut, and possibly for other landraces with variegated seed. The taro UM landrace escaped drought by maturing early under conditions of limited water availability. The FAO’s AquaCrop model was successfully calibrated and validated for taro UM and ‘Red’ bambara groundnut landraces. The calibration and validation of AquaCrop for taro is the first such attempt and represents progress in the modelling of neglected underutilised crops. The calibration and validation of AquaCrop for taro requires further fine-tuning while that for bambara groundnut still needs to be tested for more diverse landraces. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, 2016. / Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2016-04-20T13:21:15Z No. of bitstreams: 1 2015_ CamilaCembrollaTelles.pdf: 2237224 bytes, checksum: cb343212b1a72f57a339b65e023e749b (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2016-04-22T21:21:50Z (GMT) No. of bitstreams: 1 2015_ CamilaCembrollaTelles.pdf: 2237224 bytes, checksum: cb343212b1a72f57a339b65e023e749b (MD5) / Made available in DSpace on 2016-04-22T21:21:50Z (GMT). No. of bitstreams: 1 2015_ CamilaCembrollaTelles.pdf: 2237224 bytes, checksum: cb343212b1a72f57a339b65e023e749b (MD5) / Este trabalho teve como objetivo avaliar a viabilidade técnica e econômica da consorciação de alface com bertalha e taro. O experimento foi conduzido no período de outubro de 2014 a junho de 2015. O delineamento experimental foi inteiramente casualizado, com sete tratamentos e quatro repetições, totalizando 28 parcelas. Os tratamentos foram os seguintes: monocultura de alface, monocultura de bertalha, monocultura de taro, consórcio duplo alface/bertalha, consórcio duplo alface/taro, consórcio duplo bertalha/taro e consórcio triplo alface/bertalha/taro. Durante o consórcio foram cultivados dois ciclos de alface, foram realizadas duas colheiras de bertalha e uma de taro. Os espaçamentos foram 0,25 x 0,25m para a alface, 1,0 x 0,6m para a bertalha e 1,0 x 0,3m para o taro. A maior produção de alface foi obtida no cultivo do seu primeiro ciclo, no arranjo em consórcio com bertalha e taro, com 270,5 gramas por planta. Para a bertalha o melhor desempenho foi observado em seu primeiro corte, no consórcio com alface (974,7 gramas por planta). A cultura do taro obteve maior produção no consórcio com a alface, com 7,6 quilogramas por planta. O índice de equivalência de área foi superior a 1,0 em todos os arranjos de consórcio. O índice de lucratividade foi superior a 85%, exceto para o cultivo da bertalha em monocultura. Os maiores valores de taxa de retorno foram observados no cultivo do taro em monocultura e em consórcio com alface, de 14,91 e 14,79, respectivamente. Os produtos obtidos apresentaram-se com qualidade comercial demanda pelo mercado. ________________________________________________________________________________________________ ABSTRACT / This study aimed to evaluate the effect of the intercropping in the performance of lettuce, bertalha and taro. They were observed productivity and economic aspect of the vegetables, and the economic viability of the system. The experiment was conducted from October 2014 to June 2015. The experimental design was completely randomized, with seven treatments and four replicates, totaling 28 plots. The treatments were: lettuce monoculture, bertalha monoculture, taro monoculture, double intercropping lettuce / bertalha, double intercropping lettuce / taro, double intercropping bertalha / taro and triple intercropping lettuce/ bertalha / taro. During taro crop cycle, there were two lettuce cycles and two bertalha harvest. The spacing were 0.25 x 0.25m for lettuce, 0.6 x 1.0m for bertalha and 0.3 x 1.0m for taro. The increased production of lettuce was obtained in the cultivation of its first cycle with bertalha and taro with 270.5 g per plant. For bertalha, the best performance was seen in its first cut, in intercropping with lettuce (974.7 grams per plant). The taro culture obtained higher production in intercropping with lettuce, with 7.6 kg per plant. The area equivalence index was greater than 1.0 in all intercropping arrangements. The profitability index was above 85%, except for the cultivation of bertalha in monoculture. The highest rate of return values were observed in taro cultivation in monoculture and intercropping with lettuce, 14.91 and 14.79, respectively. The products obtained were presented with commercial quality needed to market standards.

Orientador: Elisabeth Bauch Zimmermann / Dissertação (mestrado) - Universidade Estadual de Campionas, Instituto de Artes / Made available in DSpace on 2018-08-17T11:04:43Z (GMT). No. of bitstreams: 1 Aranha_RobertaHeinemanndeSouza_M.pdf: 6848970 bytes, checksum: 0e7cb8ad384b5c041add792031cf073b (MD5) Previous issue date: 2010 / Resumo: Este trabalho relaciona as imagens dos Arcanos Maiores do Tarô com o contexto imagético das Artes Visuais, em especial, evidencia a correlação entre a pintura da escola Simbolista e o Tarô. Também procura desvelar alguns aspectos arquetípicos encontrados através do diálogo simbólico entre essas duas manifestações criativas e artísticas, o que propicia um olhar subjetivo das transformações históricas do final do Século XIX / Abstract: This study relates the images of the Major Arcana of the Tarot imagery with the context of the Visual Arts, in particular, shows the correlation between the Symbolist school of painting and the Tarot. It also seeks to reveal some archetypal aspects found through symbolic dialogue between these two creative and artistic expressions, which provides a subjective look of the historic transformations of the late nineteenth century / Mestrado / Artes Visuais / Mestre em Artes

L’agrobiodiversité s'étudie au niveau génotypique mais également au niveau de l'expression chimique de ce génotype, le chimiotype. Les plantes à racines et tubercules tropicales (manioc, patate douce, ignames et taros) sont multipliées par voie asexuée et les bases génétiques sont bien souvent étroites chez les cultivars traditionnels. Malgré les faibles diversités génétiques révélées à l'aide de marqueurs ADN, les chimiotypes sont très variables et leur étude est riche d’informations. Ces cultures vivrières, plantes amylacées mais aussi sources de molécules intéressantes pour les industries alimentaire et pharmaceutique, tiennent un rôle déterminant dans la garantie de la sécurité alimentaire des pays du Sud. Dans cette optique, leur amélioration génétique par voie conventionnelle est une contribution majeure aux enjeux actuels. De nombreux efforts restent néanmoins à réaliser pour analyser, compiler et disséminer les informations liées à la diversité des compositions et teneurs de plantes qui restent sous-utilisées ou non appréciées à leur juste valeur. La biofortification qui vise une amélioration des propriétés nutritionnelles de ces plantes, présente de nombreux avantages dont le principal est de ne pas modifier les comportements alimentaires tout en permettant une meilleure adaptation environnementale des nouveaux génotypes. Leur amélioration passe par une sélection des parents basée sur leurs valeurs propres et le criblage de grands nombres d'individus hybrides. Le processus est long et fastidieux. L’élaboration de nouveaux outils permettant une optimisation de cette tâche est donc nécessaire. L'analyse d'échantillons représentatifs de la variabilité chimiotypique des collections du Vanouatou, un archipel Mélanésien abritant une riche agrobiodiversité, a permis d'étudier les relations entre composés majeurs, métabolites secondaire et préférences alimentaires locales. Les corrélations mises en évidence permettent d'apporter des éléments utiles à la compréhension du processus de sélection traditionnelle. L’identification des préférences visées par ce processus aident à comprendre les goûts et les attentes des consommateurs, et donc à mieux définir les idéotypes ciblés par les programmes d'amélioration. Ce travail a permis un premier criblage chimiotypique d'un grand nombre de cultivars appartenant aux deux espèces majeures, le taro (Colocasia esculenta) et la grande igname (Dioscorea alata). L'étude des caroténoïdes et des anthocyanes a permis d’identifier un certain nombre de cultivars comme parents potentiellement intéressants pour la biofortification mais aussi pour l'exploitation commerciale directe des clones. La caractérisation des hybrides, obtenus par panmixie et pollinisations libres au cours de cycles de sélection récurrente, indique que des gains importants sont obtenus pour des composés et métabolites essentiels. Les avancées réalisées dans le cadre de ce travail, et leurs conséquences pour les programmes d'amélioration génétique en cours, sont discutées. Les perspectives de mise au point de nouveaux outils de criblage et de nouvelles méthodes de caractérisation qui permettront in fine une meilleure approche de la biofortification de ces cultures vivrières, sont aussi envisagées / Agronomic selection generates and maintains agrobiodiversity which can be regarded as an essential resource. To describe phenotypic diversity, genotypes as well as their chemical expression, chemotypes, have been widely used. Tropical root and tuber crops are vegetatively propagated and their genetic bases are often narrow. Therefore, unveiling the impressive phenotypic diversity is still rather difficult through genotyping alone, whereas chemotype studies are very informative. Tropical root crops are staples and represent a good source of compounds related to health benefits and used in food and pharmaceutical industries. Those crops have key-roles to play in food security for developing countries and so plant breeding cannot be neglected. Biofortification is effective and does not imply change of dietary behaviours. Analysing, computing and compiling data bases for chemical data on diversity of neglected crops are still needed. Biofortification involving mass selection and profiling of numerous accessions is, however, time-consuming. Thus, efficient protocols and tools facilitating this process are required. Chemotypic variability within Vanuatu germplasm was characterised through core samples from different species and relationships between primary compounds, secondary metetabolites and local preferences have been studied. Useful correlations were shown, thus clarifying traditional selection process. This process has permitted the definition of ideotypes that will be interesting for the management of breeding programmes. At least for the two most important species in Vanuatu - taro Colocasia esculenta and the greater yam - Dioscorea alata -our work is the first broad screening of germplasm. The study of carotenoid and anthocyanin content indicates that some cultivars show potential for commercial exploitation. With the aim of improving staple foods by plant breeding, we identified accessions to be selected as parents for future crosses

Treize ans après le sommet de la Terre, cette thèse souligne les contradictions entre diversité culturelle et diversité biologique lorsqu'il s'agit de conserver un patrimoine de plantes cultivées. La présentation du contexte conceptuel de recherche, des sites d'étude au Vanuatu (principalement Vêtuboso sur Vanua Lava) et des espèces (le cocotier et le taro), ainsi que les méthodes s'appuyant sur des outils de l'agronomie, de l'anthropologie, de la génétique et de la géographie, ont été regroupées dans une première partie. La deuxième partie apporte des éléments de réponses aux trois questions principales de la thèse : 1. Quel est le statut social des deux espèces étudiées ? 2. De quelle agrobiodiversité parle-t-on ? et 3. Comment s'élabore-t-elle et se diffuse-t-elle ? La biologie de la plante mais aussi son histoire dans la communauté conditionnent son statut social et ainsi les modalités de sa gestion. Qualifié de « plante des Blancs » bien que présent avant l'arrivée des premiers colons, le cocotier, a quitté le statut d'arbre fruitier pour celui de culture de rente pérenne malgré ses nombreux usages et les mythes fondateurs qui lui sont associés. Son espace de culture, la cocoteraie, rappelle le temps du colonialisme, du travail forcé, et évoque la pénibilité de la production du coprah. Elle est accusée de « voler » l'espace de la forêt où vivent les esprits. La base génétique du cocotier est large même si l'on relève peu de catégories nommées. Le taro, une plante annuelle de subsistance identifiée localement par de nombreux noms correspondant à des morphotypes distincts, est socialement valorisé en tant que porteur de mémoire des ancêtres et vitrine des savoir-faire individuels. Cependant sa base génétique est étroite, et malgré l'attention que lui portent des horticulteurs passionnés, il ne pourra survivre à l'introduction de la maladie attendant aux portes du Vanuatu (TLB). Ainsi, la valorisation de la biodiversité, aussi bien du point de vue des représentations locales que des sciences, dépend des formes de socialisation des plantes comme des finalités recherchées : protéger la mémoire d'un lieu par les liens aux ancêtres, une diversité culturelle, une variabilité phénotypique ou un potentiel d'évolution. De plus, du point de vue de la conservation de la biodiversité, une même communauté peut être considérée, en raison de sa gestion des taros, comme une société qui possède de véritables « savoirs naturalistes locaux », et dans sa gestion des cocotiers, comme une société ayant préféré s'investir dans une économie de marché prônant l'intensification. L'intégration des diversités biologique et culturelle au sein du concept de biodiversité peut constituer une liaison dangereuse, si les savoirs, réduits au rang de recettes, sont abstraits de leur cadre cognitif et socioculturel. En s'appuyant sur les résultats précédents, la troisième partie passe en revue les sources d'érosion de l'agrobiodiversité au Vanuatu et s'intéresse aux politiques de sa conservation telles que la conservation in situ et la sélection participative. Sachant que les principales raisons pour lesquelles les agriculteurs conservent un matériel ancestral dépendent de sa relation aux ancêtres, le scientifique ou le développeur a peu d'influence sur l'évolution des pratiques locales garantissant une agrobiodiversité dynamique. Finalement ce serait en protégeant une espèce végétale « sociale » quitte à la « moderniser » en améliorant son potentiel d'adaptation, que l'on conserverait la diversité culturelle. La sélection participative serait alors un moyen d'allier conservation et amélioration, soit conservation et sécurité alimentaire, et de ce fait, conservation et développement. Dans ce cadre, une approche interdisciplinaire s'impose afin d'optimiser l'efficacité des programmes de conservation et de développement auprès des populations, parce qu'elle permet d'établir les bases d'une coopération avec les communautés locales qui les laisse libres de décider du sens et des modalités de leur inscription dans les processus de globalisation auxquelles elles sont désormais confrontées.

Involvement in agricultural activities has generally been the main livelihood strategy for rural people. This was also the case with KwaMbonambi and Sokhulu farmers, especially amadumbe producers. The research was therefore undertaken to explore the marketing opportunities for amadumbe in the Mbonambi Municipality under which KwaMbonambi and Sokhulu tribal areas fall. A research team was formed by five staff members from the Department of Agriculture including the researcher. Five research tools were used to collect data and these were questionnaires for formal retail shops, focus groups for processing centres, a transect walk to assess the land availability, sustainable livelihoods and force field analyses for amadumbe producers, From the findings, the formal retail shops and processing centres did not have a direct link with local amadumbe producers of KwaMbonambi and Sokhulu. Their produce came via agents from Durban and Johannesburg. Amadumbe producers on the other hand were producing amadumbe for their own consumption or to sell either to local communities (from the garden gate) or to hawkers in nearby towns. A recommendation was made that an amadumbe marketing forum be constituted in order to close the gap between formal retail shops, the processing centres and the amadumbe producers of KwaMbonambi and Sokhulu. Farmers felt that they could produce amadumbe of the quantity and quality required by the formal outlets if they improved their production amounts and marketing strategies. / Thesis (M.Soc.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

En esta Tesis Doctoral se hace un estudio pormenorizado de la producción fotográfica de Gerda Taro durante el periodo comprendido entre agosto de 1936 y julio de 1937, espacio temporal que acoge íntegramente la obra de la autora, desarrollada en España durante los primeros años de la Guerra Civil. El estudio abarca todos los elementos que rodean y determinan la significación del legado gráfico señalado.Con el fin de analizar los documentos bajo el supuesto de nuestra hipótesis se han revisado todos aquellos factores que intervienen en las fotografías a partir de un método de análisis e interpretación que permite explicar y obtener conclusiones regulares en torno a la producción gráfica que conforma el vasto de la obra de esta autora. Asimismo, nuestro objeto de estudio se circunscribe originariamente en el fecundo terreno del que germina la comunicación visual de los sucesos y este factor ha determinado, además, la revisión del marco en cuanto a la modalidad fotoperiodística en la actividad de las publicaciones periódicas, así como el panorama intercontextual previo que permitiera la actividad de la autora en los circuitos del periodismo gráfico.

[pt] Em Solve et Coagula - dissolvendo Guimarães Rosa e recompondo-o pela ciência e espiritualidade é investigada a importância da espiritualidade na formação do escritor Guimarães Rosa e na confecção de suas obras, principalmente Primeiras Estórias e Ave, Palavra. A partir de relatos de amigos e parentes, entrevistas, cartas e anotações pessoais, analisa-se como esse interesse pela espiritualidade - principalmente pela Cabala, Tarô e Astrologia - aparece nos seus textos, tanto na construção quanto em personagens, linguagem e estórias, em equilíbrio com um pensamento cientificista. Para melhor compreender a questão espiritual do escritor mineiro e o seu desenvolvimento na ficção, também é estudada a visão de religiosidade rosiana analisada por Vilém Flusser e como ela se relacionaria diretamente com a linguagem poética do escritor mineiro. / [en] Solve et Coagula - dissolving Guimarães Rosa and rebuilting him through science and spiritualism analyses the importance of spiritualism in Guimarães Rosa s life and work, mainly in the process of writing Primeiras Estórias and Ave, Palavra. It s studied friends and family testimonials, interviews, letters and his notebooks, to understand how HIS interest IN SPIRITUALISM - SPECIALLY in Kabala, Tarot and Astrology - appears in his books, from the creative process throughout the narrative, characters and language, in balance with a scientific thought. And it s also analysed his feeling of religious studied by Vilém Flusser and how it s related to the poetic language of Guimarães Rosa.