Submitted in fulfilment of the academic requirements for the Degree in Master's in Food Science and Technology, Durban University of Technology, 2017. / Pigeon pea (Cajanus Cajan) is consumed in many parts of Africa as a source of protein and carbohydrate. It is underutilised and mainly grown for subsistence. Researching on pigeon pea may enhance value addition and increase its utilization. In this study, a non-dairy probiotic yoghurt was prepared from pigeon pea milk. Yoghurt samples were prepared, using 100% pigeon pea milk, pigeon pea/soy milk in the ratio 50:50 and 100% soy bean milk. The yoghurts were inoculated with yoghurt starter cultures and divided into two equal parts. One part inoculated with Propionibacterium freudenreichii was referred to as probiotic yoghurt, while the other part served as the control. The nutritional, sensory and some functional properties of the yoghurt were determined. The microbiological quality of yoghurt samples stored at 4, 10 and 21°C, respectively, for 4 weeks, were monitored and analysed for aerobic spores’ formers, E. coli, total plate counts, mould and Propionibacterium freudenreichii weekly. The protein contents of the yoghurt samples varied from 4.54-5.85% for 100% soymilk and 100% pigeon pea yoghurt respectively. The probiotic yoghurt showed slightly lower protein content than pigeon pea yoghurt alone. All the yoghurt samples had considerably high total solids (16.04-17.41%) and were fairly good sources of amino acids. Essential amino acids in the yoghurt samples were comparable to the FAO/WHO (2007) recommended amino acid requirement for adults. Anti-nutritional factors of yoghurt samples were significantly lower (P≤0.05) than their milk counterparts, which may be attributed to the fermentation process. Probiotic yoghurt samples showed higher firmness than non-probiotic samples. Total plate counts (log 7.01- 7.46 CFU/ml) samples stored for 2 weeks at 4° C were similar. Predominant organisms were LAB and Propionibacterium freudenreichii. Storage temperature of yoghurt samples had an influence on the total plate count and LAB. Total plate count and LAB significant increased approximately by log 2 CFU/ml for the first two weeks of storage. However, moulds and E. coli were not detected in all samples. Beyond 2 weeks of storage, there was significant decline in total plate counts and LAB, while mould grew and increased. Aerobic spore formers and moulds were observed in the control yoghurt. However, E. coli was not found in all yoghurt samples throughout storage period. The pH of the milk in which yoghurt mixtures were formulated, ranged from pH 7 to 6.8 for pigeon pea and soymilk declined significantly as a result of acidification. Decline in pH at 4, 10 and 21°C was significant (p≤0.05) with the rate higher at 21, 10 than 4° C. Decline in pH resulted in increased TTA values over storage temperatures and periods. Samples stored at 21°C and 10°C had significantly higher TTA values than samples stored at 4° C. The colour values evaluated were recorded as L*, b*, a* and ∆E* during 4 weeks storage at 4, 10 and 21° C. Significantly high values (p≤0.05) were recorded for L* yoghurt samples with soymilk. The colour scale defines positive (red) and negative (green) for a* and b* positive (yellow) and negative (blue). All a* values both positive and negative were less than 3. There was no negative value recorded for b*. Colour difference ∆E* values trends increased as storage time and temperature increased. There were significant (p≤0.05) differences between samples stored at same and different storage temperatures and periods. Water holding capacity was significantly different (p≤0.05) in all the yoghurt samples stored at 4, 10 and 21°C for 4 weeks. Formulation with 100% soymilk recorded higher values. Soy yoghurt and probiotic yoghurts (100 %) showed higher water holding capacity compared to pigeon pea yoghurt and pigeon pea/soymilk yoghurt. The addition of Propionibacterium freudenreichii did not significantly affect sensory properties of the yoghurts. Acceptable yoghurt was produced from pigeon pea with comparable quality to soy which serves as control. Proximate composition was comparable to previous reports. Microbial quality and profile of all the yoghurt samples were similar. The absence of pathogenic bacteria in all the yoghurt samples confirm their safety. Soy yoghurt was most acceptable amongst the yoghurt samples but all the samples had comparable ratings, and these ratings are within commercially acceptable range (4 to 9) for yoghurt. Storage at 4oC should be the most acceptable, as storage at 21oC encourage proliferation of contaminant / M

Doctor of Philosophy / Department of Entomology / Gerald R. Reeck / John C. Reese / Salivary secretions are a key component of aphid-plant interactions. Aphids’ salivary proteins interact with plant tissues, gaining access to phloem sap and eliciting responses which may benefit the insect. In an effort to isolate and identify key components in salivary secretions, we created a salivary gland cDNA library. Several thousand randomly selected cDNA clones were sequenced. We grouped these sequences into 1769 sets of essentially identical sequences, or clusters. About 22% of the clusters matched clearly to (non-aphid) proteins of known function. Among our cDNAs, we have identified putative oxido-reductases and hydrolases that may be involved in the insect's attack on plant tissue. C002 represents an abundant transcript among the genes expressed in the salivary glands. This cDNA encodes a novel protein that fails to match to proteins outside of aphids and is of unknown function. In situ hybridization and immunohistochemistry localized C002 in the same sub-set of cells within the principal salivary gland. C002 protein was detected in fava beans that were exposed to aphids, verifying that C002 protein is a secreted protein. Injection of siC002-RNA caused depletion of C002 transcript levels dramatically over a 3 day period after injection. With a lag of 1 – 2 days, the siC002-RNA injected insects died, on average 8 days before the death of control insects injected with siRNA for green fluorescent protein. It appears, therefore, that siRNA injections of adults will be a useful tool in studying the roles of individual transcripts in aphid salivary glands.

O amido resistente (AR) é a fração do amido que não sofre a ação das enzimas digestivas, apresentando comportamento semelhante ao da fibra dietética. O objetivo do presente trabalho foi avaliar o teor e as características dos AR obtidos a partir dos amidos de ervilha e de grão-de-bico por diferentes processos de redução de massa molecular. Os amidos naturais ou gelatinizados foram submetidos a processos de hidrólise ácida (HCl 2 M por 2,5 h) ou enzimática (pululanase, 40 U/g por 10 h) previamente a um processo controle, que constou de tratamento hidrotérmico (autoclavagem a 121 °C por 30 min), refrigeração (4 °C por 24 h) e liofilização. O material produzido foi caracterizado quanto ao aspecto geral por microscopia eletrônica de varredura (MEV), teor de AR, teor de fibra dietética total (FDT), índice de absorção de água (IAA), índice de solubilidade em água (ISA), padrão de cristalinidade (difração de raios X), viscosidade (RVA - Rapid Visco Analyser) e propriedades térmicas (DSC - Differential Scanning Calorimeter). O teor de AR para o amido natural de ervilha e grãode- bico foi de 39,8 e 31,9 %, respectivamente. Nos amidos processados esse teor variou de 38,5 a 54,6 % para a ervilha e de 16,4 a 32,3 % para o grão-de-bico. Os melhores tratamentos para elevar o teor de AR foram o tratamento ácido (amido natural e gelatinizado) para o amido de ervilha e o tratamento enzimático (amido gelatinizado) para o amido de grão-de-bico. Os teores de FDT dos amidos processados de ervilha variaram de 22,9 a 37,1 % e foram superiores aos do grão-de-bico, que variaram entre 7,2 e 15,7 %. A MEV revelou a presença de grânulos inteiros ou não fragmentados nos amidos de ervilha dos diferentes tratamentos, enquanto os amidos de grão-de-bico tratados apresentaram apenas massa amorfa, sem a evidência de grânulos. Os padrões de cristalinidade dos amidos naturais foram tipo B e C, respectivamente para os amidos de ervilha e grão-de-bico, entretanto, os amidos processados de ambos apresentaram padrão do tipo B. Os amidos naturais apresentaram endotermas entre 56 e 90 °C, enquanto os amidos processados apresentaram endotermas em temperaturas superiores, entre 131 e 171 °C. A entalpia de gelat inização (H) dos amidos de ervilha processados foi superior à dos amidos de grão-de-bico. Os amidos natural e processados de ervilha, de modo geral, apresentaram viscosidade baixa (< 20 RVU) em RVA. O amido de grão-de-bico natural apresentou viscoamilograma bem definido, característico da fonte. Os amidos resistentes obtidos por hidrólise, de ambas as fontes, apresentaram redução na viscosidade em comparação com o controle. A viscosidade foi inversamente proporcional ao teor de AR nas amostras. A hidrólise e o processamento térmico promoveram o aumento no IAA e ISA dos amidos tratados. Os processos de hidrólises dos amidos de ervilha e de grão-de-bico podem elevar o teor de AR se comparados com o método controle. / Resistant starch (RS) is the fraction of starch that does not suffer the action of digestive enzymes, showing similar behavior to that of dietary fiber. The aim of this study was to evaluate the amounts and characteristics of RS obtained from chick-pea and high amylose pea starches using different processes of molecular weight reduction. The natural or pregelatinized starches were submitted to acid (2 M HCl for 2.5 h) or enzymatic (pullulanase, 40 U / g per 10 h) hydrolysis prior to a control process, which consisted of hydrothermal treatment (autoclaving at 121 ° C for 30 min), refrigeration (4 ° C for 24 h) and liophilization. The material was characterized as to the general appearance by scanning electron microscopy (SEM), RS content, total dietary fiber (TDF) content, water absorption index (WAI), water solubility index (WSI), crystallinity pattern (X-ray diffraction), viscosity (RVA - Rapid Visco Analyzer) and thermal properties (DSC - Differential Scanning Calorimeter). The RS content in pea and chick-pea natural starch was 39.8 and 31.9%, respectively. The processed starches showed contents ranging from 38.5 to 54.6% for pea and from 16.4 to 32.3% for chick-pea starch. The best treatments to raise the level of RS were the acid treatment (natural and gelatinized starch) for pea and the enzymic treatment (gelatinized starch) for chick-pea starch. The FDT amounts in processed pea starches ranged from 22.9 to 37.1% and were higher than those of chick-pea, which ranged between 7.2 and 15.7%. The photomicrographs in SEM revealed the presence of whole grains (not fragmented) in pea starches treatments, while the treated chick-pea starches showed only amorphous mass, without the evidence of granules. The cristallinity patterns of natural starches were B and C types, respectively for pea and chick-pea starch. Both processed starches, however, presented B type pattern. The natural starches showed endotherms between 56 and 90°C, while the processed starches showed endotherms at higher temperatures (131 and 171°C). The processed pea starches gelatinizati on enthalpy (H) was higher than those of processed chick-pea starches. The natural and processed pea starches, in general, showed low viscosity (<20 RVU) in RVA. The natural chick-pea starch presented viscoamylogram well defined, typical of this botanical source. The resistant starches obtained by hydrolysis showed in both sources, a decrease in viscosity compared to the control treatment. The viscosity was inversely proportional to the RS content in the samples. The hydrolysis and the thermal processing promoted an increase in WAI and WSI of treated starches. The hydrolysis process of pea and chickpea starches may raise the level of RS when compared to the control process.

O presente trabalho teve como objetivo avaliar a emissão de metano por cordeiros alimentados em diferentes pastagens tropicais: Panicum maximum cv. IZ-5 (capim aruana) e Cajanus cajan cv. anão (feijão guandu), e suas relações com a composição química destas pastagens. Os trabalhos foram conduzidos na Estação Experimental Agronômica da UFRGS, nos anos de 2015 e 2016. O delineamento experimental foi de blocos completos casualizados com três repetições. O capítulo II relata os resultados da emissão de metano por cordeiros pastejando nos seguintes tratamentos: 1) ARU – somente capim aruana; 2) FG - somente feijão Guandu; 3) AFG – meio piquete com capim aruana, e a outra metade com feijão Guandu. Para avaliação de metano foi utilizado a técnica com marcador SF6 . No experimento do capítulo II, utilizou-se parcela subdividida, sendo a subparcela dois animais testes que receberam polietileno glicol (PEG) para quelar o tanino presente no feijão guandu, e dois que receberam água como controle. As emissões de metano por consumo de matéria seca (EMICONMSDIA) não apresentaram diferença entre os tratamentos, mesmo considerando as dosificações com polietileno glicol (PEG) ou água (P=0,9235). O tratamento FG (P=0,036) apresentou mais altos níveis de taninos condensados do que os demais tratamentos Apesar de diferenças nas suas características químicas, a emissão de metano de cordeiros é semelhante entre pastagens tropicais de capim aruana (Panicum maximum cv. IZ-5), feijão Guandu (Cajanus cajan cv. Anão. Os taninos condensados presentes na forrageira feijão guandu, nas condições experimentais deste trabalho, não demonstraram potencial para contribuir na redução da emissão de metano por cordeiros. No capítulo III, os tratamentos, manejo dos animais e delineamento experimental foram semelhantes ao capítulo II. Os resultados demonstraram que não há uma relação direta entre as características bioquímicas do alimento e a emissão de metano. Essa desassociação entre a emissão de metano e a composição química da pastagem foi constatada tanto quando relacionou-se a emissão por animal (EMI), quanto quando relacionou-se com a emissão por quilograma de matéria seca ingerida (EMICONMSDIA). Conclui-se, então, que não é possível relacionar a emissão de metano de cordeiros com as características químicas das plantas forrageiras tropicais perenes, capim aruana e feijão Guandu. / The researches carried out in the present work had the objective of evaluating the emission of methane by lambs fed on different tropical pastures: Panicum maximum cv. IZ-5 (Aruana grass) and Cajanus cajan cv. dwarf (pigeon pea), and their relationships with the chemical composition of these pastures. The works were conducted at the Experimental Agronomic Station of UFRGS, between January and April 2016, Chapter II; and from February to April 2015, Chapter III. The experimental design was of randomized complete blocks with three replicates. The blocking was carried out with the objective of eliminating variations of slope of the terrain (flat area, sloping at the top and sloping slope). Chapter II reports the results of methane emission by grazing lambs in the following treatments: 1) ARU - only aruana grass; 2) FG - only Guandu beans; 3) AFG - half picket with aruana grass, and the other half with Guandu beans. For methane evaluation, the SF6 marker technique was used. In the experiment of chapter II, a subdivided plot was used, the subplot being two test animals that received polyethylene glycol (PEG) to chelate the tannin present in the pigeon pea, and two that received water as control. Emissions of methane by dry matter intake (EMICONMSDIA) did not show any difference between treatments, even considering the dosages with polyethylene glycol (PEG) or water (P = 0.9235) FG treatment (P = 0.036) presented higher levels of condensed tannins than the other treatments. Despite differences in their chemical characteristics, the methane emission of lambs is similar between tropical pastures of Aruana grass (Panicum maximum cv. IZ-5), Guandu beans (Cajanus cajan cv. Dwarf), and when these forages are offered at will , in two lanes in the picket. The condensed tannins present in the forage pigeon pea, under the experimental conditions of this work, did not demonstrate the potential to contribute in the reduction of the methane emission by lambs. In Chapter III, treatments, animal management and experimental design were similar to Chapter II. The relationships between the chemical composition of pastures of nutritional influence showed to be quite variable in the methane emission response. The results showed that there is no direct relationship between the biochemical characteristics of the food and the emission of methane. This dissociation between the methane emission and the chemical composition of the pasture was verified both when the emission per animal (EMI) was related and when it was related to the emission per kilogram of ingested dry matter (EMICONMSDIA). It is concluded that it is not possible to relate the emission of methane with the chemical characteristics of perennial tropical forage plants Panicum maximum cv. IZ-5, and Cajanus cajan cv. Dwarf.

Dans l’objectif de redynamiser la culture des protéagineux, il est primordial d’améliorer la gestion du risque lié à Aphanomyces euteiches, agent responsable de la pourriture racinaire du pois. Le manque de connaissances sur les mécanismes d’infection d’A. euteiches constitue un frein à l’élaboration de stratégies de contrôle durable. Dansl’optique d’étudier les premières étapes du processus infectieux d’A. euteiches, laconstruction d’une souche A. euteiche-GFP a été entreprise. Transfecter A. euteiches aura permis d’assurer (i) la production de protoplastes par digestion enzymatique du mycélium puis (ii) d’insérer le gène gfp par la méthode de transfection chimique PEG-CaCl2 et (iii) de constater l’insertion stable du gène gfp dont l’expression s'est avérée transitoire. En parallèle, dans l’objectif d’apporter des éléments de réponses quant aux rôles des exsudats racinaires et du Root Extracellular Trap (RET) dans les réactions de défense du pois, une étude comparée des interactions entre Pisum sativum (plante sensible) et Vicia Faba (plante tolérante) au pathogène A.euteiches a été réalisée durant les premières phases de l’infection. Alors que de nombreuses variations au niveau de la composition polysaccharidique du RET et des exsudats ont été observées chez le pois, la féverole a présenté des modifications marginales. Chez le pois, l’infection est intense et rapide alors qu’elle semble réduite chez la féverole. La féverole repousse les zoospores tandis que le pois infecté les attire davantage. La féverole semble pouvoir protéger le pois au travers de mécanismes de communication qu’il convient de caractériser. L’ensemble de ces résultats semblent prometteurs dans le développement de méthode de lutte contre la pourriture racinaire du pois. Enfin, l’étude des propriétés bio-physico-chimiques des sols susceptibles de conditionner l’apparition de la maladie ont permis de confirmer la corrélation positive entre la densité d’inoculum du pathogène et le potentiel infectieux (PI) dans des sols naturellement infestés : les sols possédant des teneurs élevées en sable ou en calcium s'avèrent défavorables au développement de la maladie. Cette étude a aussi permis de mettre en évidence une influence possible des communautés microbiennes des sols, susceptibles d’influencer le processus infectieux d’A.euteiches / Aphanomyces euteiches is a pathogenic oomycete considered to be the most damaging root disease of pea crops in the world and there is currently no registered pesticide for its control. Crop management is the most efficient tool to control root rot, and avoidance of infested soil seems to be the optimal solution. Mechanisms related to A. euteiches root colonization remain poorly understood. In order to better understand A.euteiches infectious cycle, a polyethylene glycol (PEG) – calcium chloride (CaCl2) transformation protocol has been perfected in order to stably express the reporter gene GFP. The data show for the first a transient expression of green fluorescent protein (GFP) which can be observed in A.euteiches mycelium, a Saprolegnia oomycete. Vector pGFPN, containing the ham34 promoter and terminator of the Peronospora oomycete Bremia Lactucae, was introduced in A.euteiches protoplasts. Transient expression of GFP could be observed in A. euteiches mycelium by confocal microscopy. qPCR analyses confirmed the actual gfp gene insertion in its genome. Meanwhile, the influence of both pea and faba bean root extracellular trap (RET) and root exudates has been explored for A. euteiches zoospores by chemotaxis assays, microscopic observations and oomycete DNA quantification. Reciprocally pea and faba bean roots responses to A. euteiches infection have been studied at early stage of infection by biochemical analysis of cell wall polymer content in the RET and root exudates. Whereas infected pea root exudates stimulated A.euteiches zoospores attraction, faba bean exudates had a repellent effect on zoospores. In response to infection, arabinogalactan protein content of root pea exudates was altered. Interestingly, A.euteiches colonization was less intense on faba bean root surface and protect pea root at early stage of infection. Finally, the correlation between inoculum quantity in infested and the inoculum potential (IP) in field has been confirmed by qPCR. Analyses of the influence of abiotic soil parameters on the disease showed that a high calcium concentration or sand content negatively impact the IP. Furthermore, microbial communities proved to play a role in the expression of the disease in some soils. Metagenomics could be applied in order to provide new directions in managing this disease.

La croissance et le développement des plantes sont sous l’influence de nombreux facteurs génétiques et environnementaux. Parmi eux les hormones végétales participent aux multiples processus qui conduisent à la formation d’une plante via la mise en place d’un réseau complexe d’interactions et de rétro-contrôles. Le contrôle de la ramification implique trois d’entre-elles : l’auxine et les strigolactones (SLs) qui inhibent le démarrage des bourgeons et les cytokinines (CKs) qui le stimulent. Différents mécanismes d’interactions entre ces signaux dans le contrôle de la ramification sont connus. L’auxine contrôle les niveaux de SLs et de CKs, et les voies SLs et CKs convergent vers la même cible, le facteur de transcription BRC1.Chez le pois, les mutants hyper-ramifiés ramosus (rms) sont affectés dans la voie SLs. Les gènes RMS1 (PsMAX4) et RMS5 (PsMAX3) contrôlent la biosynthèse des SLs alors que RMS3 (PsD14) (récepteur) et RMS4 (PsMAX2) sont impliqués dans la perception des SLs. En plus de partager un phénotype hyper-ramifié, les mutants rms présentent un phénotype de nanisme. Cependant le rôle des SLs dans le contrôle de la taille des plantes n’était pas encore connu. Nous avons montré que les SLs contrôlent la taille des plantes en jouant sur le processus de division cellulaire indépendamment de la voie gibbérelline.Les mutants rms montrent des caractéristiques physiologiques similaires : un haut niveau d’expression des gènes de biosynthèse des SL et une faible teneur en CKs dans la sève xylémienne (X-CKs). En revanche, le mutant hyper-ramifié rms2 présente une faible expression des gènes de biosynthèse des SLs et une forte teneur en X-CKs. De précédentes études suggèrent que rms2 est affecté dans un signal tige-racine de rétro-contrôle régulant la biosynthèse des SLs et le niveau de X-CKs. La nature biochimique de ce signal est inconnue et il a été proposé que ce signal soit auxine-indépendant.Nous avons montré que le gène RMS2 est l’homologue chez le pois des gènes AFB4/5 d’Arabidopsis codant pour une protéine à boîte-F de la famille des récepteurs de l’auxine TIR1/AFBs (Auxin signaling F-Box). Ce qui suggère que le signal de rétro-contrôle RMS2-dépendant est l’auxine. De plus nos résultats montrent que les SLs jouent un rôle de répresseur du niveau d’auxine dans la tige via la régulation de l’expression des gènes du métabolisme de l’auxine.L’ensemble de ces résultats montrent que dans le processus de contrôle de la ramification les interactions entre auxine et SLs sont complexes. Les multiples mécanismes en jeux aboutissent à la formation d’une boucle de régulation dans laquelle chaque hormone est capable de contrôler la biosynthèse de l’autre. / The different processes of plant growth and development are under the influence of growth regulators which interact in complex hormonal networks and feedback mechanisms. The control of shoot branching involves 3 key plant hormones, auxin, cytokinins (CKs) and strigolactones (SLs). Auxin and SLs repress axillary bud outgrowth whereas CKs stimulate it. Different mechanisms of interactions between these signals have already been suggested in controlling shoot branching. Auxin controls SLs and CKs levels, and SLs and CKs pathways converge on the same target, the TCP transcription factor BRC1 in the axillary bud. In pea, the high shoot branching of ramosus (rms) mutants are known for being impaired in the SLs pathway. RMS1 (PsMAX4) and RMS5 (PsMAX3) genes are involved in SL biosynthesis while RMS3 (PsD14) (receptor) and RMS4 (PsMAX2) are involved in SL perception. In addition to sharing their high branching phenotype, the rms mutants display a dwarf phenotype. However the role of SLs in controlling plant height was unknown. Here we show that SLs control internode length by acting on cell division in a Gibberellin-independent way.The rms mutants show similar physiological characteristics: high expression of the SL-biosynthesis genes and very low xylem-sap CKs (X-CKs) content. In contrast, the rms2 mutant with similar shoot phenotype shows very low expression of SL-biosynthesis genes and high X-CKs content. Previous studies suggested that rms2 was affected in a shoot-to-root feedback signal controlling both SL biosynthesis and X-CKs level. Whether this feedback signal was auxin or not was highly discussed. Here we demonstrated that the RMS2 gene is the pea homologue of the Arabidopsis AFB4/5 gene, encoding an F-box protein which belongs to the TIR1/AFB (Auxin signaling F-Box) auxin receptor family. This suggests that the RMS2-dependent feedback signal is very likely auxin. Moreover our results suggest a role for SLs in the repression of auxin content in pea stem via the regulation of auxin metabolism gene expression. These results highlighted that for the control of shoot branching, interactions between auxin and strigolactones involve multiple mechanisms leading to regulation loop where both hormones are able to regulate the biosynthesis of each other.

Thesis (M. Sc. Agriculture (Agronomy)) -- University of Limpopo, 2019 / Pigeonpea (Cajanus cajan (L) Millsp.) is an important grain legume crop in tropical and subtropical countries, where it provides a cheap source of protein. Smallholder farmers in Limpopo Province cultivate landraces of pigeonpea, which are characterised with late maturity, low grain yield and being sensitive to photoperiod. To increase the productivity of the cropping system involving pigeonpea, several earlymedium maturity varieties have been introduced. However, performance of the varieties has not been tested in strip intercropping in Limpopo Province. Farmers plant these landraces by using mixed intercropping without definite row arrangement. This practice does not optimise plant density; it hinders farm inputs application and is characterised producing low yields. Therefore, the inclusion of early maturing varieties of pigeonpea in an intercrop will enable farmers to select the best variety for planting in future and thus enhance their output as well as their productivity. The objectives of this study were to assess the agronomic performance of five pigeonpea varieties in pigeonpea-maize strip intercropping, to determine the effect of strip intercropping on maize yield and establish the effect of location and season variations on the performance of both component crops under the intercropping system. Experiments were conducted at the University of Limpopo Experimental Farm (UL Farm) and Ga-Thaba village during the 2015/16 and 2016/17 season. Five improved early-medium maturing pigeonpea varieties (ICEAP 001284, ICEAP 00604, ICEAP 87091, ICEAP 00661 and ICEAP 01101-2) from ICRISAT were evaluated under strip intercropping with maize cultivar PAN 6479. The varieties were selected as earlymedium maturing varieties from previous pigeonpea trials. The trials were laid in a split plot design. The main plot comprised cropping systems (intercrop and monocrop), while the subplot comprised the varieties with three replications. Data collected on pigeonpea were number of days to 50% flowering and 90% maturity number of primary branches; plant height (cm); number of pods per plant; pod length (cm); number of seed per pod; hundred seed weight (g); and grain yield (kg ha-1), whereas on maize, number of days to 50% tasselling and silking; plant height (cm); cob length (cm); cob per plant; grain yields (kg ha-1); and stover (kg ha-1) were recorded. LER was calculated to determine intercropping productivity. Data analysis was done using Statistic 10.0; and Least Significance Difference (LSD) was used to separate the means that showed significant differences at an alpha level of 0.05. The results revealed significant differences in nearly all pigeonpea variables expect (pod length, number of seed per pod and hundred seed weight). Variables that showed significant differences in maize were plant height, cob length, grain yields and stover. Number of days to 50% flowering and 90% physiological maturity differed significantly (P ≤ 0.05) among varieties at the UL Farm and Ga-Thaba. Varieties (ICEAP 001284 and ICEAP 00604) exhibited the shortest number of days to 50% flowering and 90% maturity in both locations during both seasons. The interaction between variety x season (V x S) showed significant (P ≤ 0.05) differences in pigeonpea grain yield. The top yielders during 2015/16 at the UL Farm were ICEAP 01101-2 (1555 kg ha-1) and ICEAP 001284 (1280 kg ha-1), while during the 2016/17 season, they were ICEAP 001284 (937 kg ha-1) and ICEAP 01101-2 (912 kg ha-1). High yielder at Ga-Thaba during the 2016/17 season were ICEAP 001284 and ICEAP 01101-2 with grain yields of 671 kg ha-1 and 627 kg ha-1, respectively. Furthermore, varieties that obtained high yields during the 2015/16 season were ICEAP 001284 (504 kg ha-1) and ICEAP 00604 (541 kg ha-1). Most of the varieties during both seasons at the UL Farm and Ga-Thaba yielded more than 500 kg ha-1 under strip intercropping as compared to mixed intercropping, which obtained yields averages of below 400 kg ha-1. The highest maize grain yields of 1450 kg ha-1 were recorded during 2015/16 as compared to 958 kg ha1 during the 2016/17 season at the UL Farm. The calculated total Land Equivalent Ratio (LER) for the two crops in both locations gave positive and higher than 1 values, which suggests a favourable grain yield advantage for maize-pigeonpea strip intercrop over mixed intercropping. Key words: Cajanus cajan, maize, cropping system, maturity, grain yields, land equivalent ratio

AbstractAtmospheric dust is a major component of the Earth System. The optical properties of dust and their roles in cloud nucleation processes have a major impact on Earth’s radiative budget and hydrological cycle. Dusts also take part in many biogeochemical cycles in surface waters of the oceans and on land through their capacity to supply key micronutrients (e.g. Fe, P) sustaining primary production. The aim of this thesis is to improve the understanding of dust cycle by creating new and innovative methods allowing to trace the source regions of dust and quantify their respective contributions. We developed a chromatographic method to isolate and analyze six isotopic systems (i.e. Pb, Nd, Sr, Zn, Cu, Fe) widely used to trace dust source areas. We optimized a new method for single, low-mass dust samples and, in doing so, we observed that the usual rock reference materials (RM) used to calibrate isotopic analysis were not representative of dust. In fact, there is little to no RM for dust and therefore, we set out to characterize precisely the isotopic signatures of two new dust reference materials, ATD and BCR-723. The latter two are representative of natural-like and urban-like dust that we propose now as new standards for atmospheric dust studies. We also investigated dust deposition, along a 250-km transect from the NE Antarctic coastline to the Princess Elisabeth Station area. Using dust samples collected from Sigma-2 passive samplers or isolated from snow samples, we determined the morphology, size distribution and chemical composition of the dust samples at the particle-scale using an automated Scanning Electron Microscope coupled to Energy Dispersive Spectroscopy (SEM-EDS). More than 5500 particles were analysed and the results showed that the grain-size distribution was <5 μm. We also observe difference in mineralogy at the coast compared to the inland section of our transect: dominance of quartz and aluminosilicates at the coast and of Fe-Mg silicates near the Sør Rondane. Based on this discrepancy, we interpret the ‘coastal’ dust samples to come from distal source while Fe-Mg silicate rich samples were hypothesized to originate from the nearby Sør Rondane range. To trace the source of those dust samples, we analysed their REE content and developed a whole new statistical approach to trace and quantify their source(s). The idea is to correlate systematically the REE pattern of those samples with, not only, PSA REE pattern from distal and local rocks but also with all their possible mixing combinations. To do so, we used the correlation coefficient (R), Akaike and Bayesian Information Criterion (AIC-BIC) to determine whether a dust sample traces a single or a mixture of multiple PSAs. Using this numerical method, we determined that local inputs of dust from the Sør Rondane mountains dominate the inland-most section of the 250-km transect. In contrast, coastal sampling sites (up to 50 km inland) are influenced by dust coming from Puna-Altiplano, Patagonia and Southern Africa. As such, this work presents the first unambiguous geochemical evidence that Southern African dust reach North East Antarctic coast. Finally, we also revisited the REE-dataset measured in EPICA Dome-C (EDC, Gabrielli et al. [Quaternary Science Reviews 29 (2010) 265-273]) and EPICA Dronning Maud Land (EDML, Wegner et al. [Climate of the Past 8 (2012) 135-147]) ice cores in order to reconstruct the dust provenance over the last glacial-interglacial interval. Our results showed that,during the Last Glacial Maximum (before 18 kyr BP), dust in both ice cores was predominantly coming from New-Zealand (NZ) with secondary inputs from South-Central Western Argentina (S-CWA) and Patagonia. The glacial-interglacial transition (18-11.6 kyr BP) saw the decline of NZ and S-CWA inputs and the increase of contributions from Patagonia, Southern Africa and Puna Altiplano. The Holocene (after 11.7 kyr BP) is marked by dust inputs coming from Patagonia, Southern Africa and Puna Altiplano while NZ stabilized to a secondary level and S-CWA ceased to supply dust. We demonstrated that variations and relative contributions recorded in ice cores are all related to important climatic changes in source regions having an impact on their capacity to supply dust. Our REE statistical approach provide an unprecedented way to identify and quantify the dust source regions in Antarctic ice core and in doing shed new light of those ‘iconic’ archives of Earth’s climate and atmospheric circulation. / RésuméLes particules atmosphériques (PA) sont un composant majeur du système Terre. Leurs propriétés optiques ainsi que leur rôle au sein des processus de nucléation des nuages ont des impacts majeurs sur le budget radiatif et hydrologique de la terre. Les PA interviennent aussi dans de nombreux cycles biogéochimiques à la surface des océans ou sur terre grâce à leur capacité à fournir des nutriments clés (e.g. Fe, P) soutenant la production primaire. Le but de ce doctorat est d’améliorer la compréhension du cycle des PA en créant de nouvelles méthodes innovatrices permettant de tracer leurs origines et quantifier leurs contributions. Nous avons développé une nouvelle méthode chromatographique optimisée pour les PA afin d’analyser six systèmes isotopiques (i.e. Pb, Nd, Sr, Zn, Cu, Fe) largement utilisés pour tracer l’origine des PA. Afin de combler un manque crucial en terme de matériaux de référence (MR), nous avons quantifié deux nouveaux MR de PA, ATD et BCR-723 (représentatifs des milieux naturels et urbains) et nous les proposons pour toutes les futures études géochimiques de PA. Nous avons aussi étudié les dépositions atmosphériques le long d’un ‘transect’ de 250 km depuis la côte Antarctique jusqu’à la station Belge Princesse Elisabeth. Premièrement, nous avons réalisé des analyses morphologiques et chimiques à l’échelle de la particule à l’aide d’un Microscope Electronique à Balayage à dispersion d’énergie (MEB-EDS). Les analyses ont montré une distribution granulométrique <5 μm ainsi qu’une variation de composition chimique (i.e. minéralogie) depuis la côte jusqu’aux Sør Rondane. Deuxièmement, afin de mieux identifier l’origine de ces PA, nous avons analysé les terres rares (REE) et développé dans son intégralité une nouvelle approche statistique permettant d’identifier les sources ainsi que leurs contributions relatives. Grâce à cela, nous avons déterminé que les échantillons à la côte proviennent du Puna-Altiplano, de Patagonie et du Sud de l’Afrique (SAF). C’est la première fois que des apports du SAF sont formellement identifiés en Antarctique. Finalement, nous avons revisité les data-set de REE des carottes de glace du projet EPICA (EDC et EDML) afin de reconstruire les apports de PA durant la dernière transition glacière/interglaciaire. Nos résultats ont montré que durant la dernière période glaciaire les PA proviennent principalement de Nouvelle-Zélande (NZ) avec des apports secondaires provenant de la partie Sud du centre de l’Ouest Argentin ainsi que de Patagonie. Une transition est marquée entre 18 et 11.6 ka BP jusqu’à un équilibre dès l’Holocène (après 11.7 ka BP) marqué par des apports de sources variées venant de Patagonie, SAF, Puna-Altiplano et NZ. Nous avons aussi démontré que les variations des contributions relatives de sources enregistrées dans les carottes de glaces sont toutes en relation avec des changements climatiques importants au niveau des régions sources impactant leur capacité à générer des PA. Notre approche statistique exploitant les REE apporte une méthode sans précédent pour identifier et quantifier les sources de PA des carottes de glace d’Antarctique et ouvre de nouvelles opportunités sur ces archives du climat et de la circulation atmosphérique de la Terre. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

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Hormones are integral molecules in the human body, controlling most body systems and maintaining homeostasis in the body. They function as signal molecules for communication between cells, and are often secreted by one tissue with another as target. Protein hormones make up the majority of the hormones in the body, are mostly transported in the bloodstream, and bind to receptors on the cell surface since they can not diffuse through cell membranes. Hormones and their associated proteins are linked to many diseases, and could therefore have a lot of potential as biomarkers. With the use of the company Olink’s Proximity Extension Assay (PEA) technology the concentrations of human proteins in blood can be measured. These proteins can be combined into different sets, called panels, to measure biomarkers related to specific diseases or conditions. This project aimed to identify the protein hormones of the human body, and investigate their associated proteins and the pathways and potential diseases they were related to. Suggestions of new panels based on disease areas that were found to be particularly related to protein hormones were also to be put forward. Databases such as UniProt, Reactome, String, Signor, Olink Insight, and the Human Protein Atlas were used to investigate protein hormones and their associated proteins. The result of the research was compiled into three different panels: the overall Protein Hormone panel, the Wellness panel, and the Diabetes panel. These panels were based on the disease areas commonly found associated with protein hormones, and that were deemed to be of interest to Olink and to the research community. The research also resulted in a table detailing all found protein hormones with additional info on pathways and diseases, normal concentrations of the proteins in blood or plasma, and the associations between the hormones and other proteins. The financial viability and marketability of the suggested panels were also investigated in a business case. It was determined that the development of the new panels had potential to be of significant importance to research efforts, healthcare providers, and individual patients. While there are some risks associated with developing and marketing new products, it was concluded that the economical potential of the panels make them an opportunity worth considering for Olink.