Pour cette étude, dans un premier temps, une caractérisation physico-chimique et rhéologique des amidons natifs de deux cultivars locaux de pomme de terre (Sipiera et Tselefou) et de trois de manioc (2425, 4115 et Seedling) a été faite avant leur incorporation dans du pâté de bœuf à 20, 30, 40 et 50g/kg de mêlée. L’influence du type d’amidon et de leur taux d’incorporation sur les propriétés physico-chimiques et texturales des pâtés a été évaluée. Les résultats ont montré que les propriétés physiques, fonctionnelles et rhéologiques des amidons sont étroitement liées à leur origine botanique. L’Analyse en Composantes Principales (ACP) laisse paraître que de tous les amidons natifs, celui du cultivar de pomme de terre Sipiera se rapproche le plus du témoin. Une fois incorporé dans les pâtés ; l’ACP de tous les paramètres texturaux des pâtés aux amidons natifs indique que le pâté à l’amidon du cultivar de manioc Seedling à de 40g/kg de mêlée (PS40), est celui qui se rapproche le plus du pâté témoin. Dans un deuxième temps, les amidons de pomme de terre (Sipiera) et de manioc (2425) ont été sélectionnés pour la modification (acétylation). Ces amidons acétylés ont par la suite fait l’objet des mêmes analyses que les amidons natifs et incorporés dans les pâtés aux mêmes taux que les amidons natifs. Des résultats, il ressort que les propriétés fonctionnelles des amidons natifs sont fortement influencées par l’acétylation et le temps d’acétylation. Les essais d’incorporation des amidons acétylés dans les pâtés montrent que l’amidon Sipiera/20 à un taux d’incorporation de 40g/kg de mêlée ne se distingue pas significativement (p>0,05) du pâté témoin / The first part of this work deals with the physico-chemical and rheological characterisation of native starches of two local cultivars of Irish potatoes (Sipiera and Tselefou) and three cultivars of cassava (2425, 4115 and Seedling) before they are incorporated into beef patty at 20, 30, 40 and 50g/kg ground meat. The influence of the type of starch and the amount of incorporation on the physico-chemical and textural properties of patties was evaluated. Results show that the physical, functional and rheological properties of starches are closely related to their botanical origin. Principal Component Analysis (PCA) showed that Irish potato cultivar Sipiera had properties that were close to reference. The PCA of all the textural properties of patties with native starches show that patty from starch of cassava cultivar Seedling at 40g/kg (PS40) was closest to the reference. In the second part of the work, the starch Sipiera and 2425 were selected for modification. These two starches were then acetylated for 10 and 20min. and this permitted us to have Sipiera/10, Sipiera/20, 2425/10 and 2425/20. The functional properties of the native starches were however strongly influenced by acetylation and the time of acetylation. Incorporation trials of this acetylated starches at different amounts in patty showed that Sipiera/20 starch at an incorporation rate of 40g/kg ground meat is not significantly different from the reference patty

Chez les insectes, les chitinases sont des enzymes principalement impliquées dans la dégradation de la chitine, lors des processus de croissance. Les chitinases représentent donc des cibles d'intérêt dans le développement de moyens de lutte alternatifs aux pesticides utilisés contre les ravageurs des cultures. Au cours de ces travaux de thèse, nous avons été amené à évaluer la pertinence de la dérégulation des activités chitinases chez les pucerons. L'impact des chitinases sur le développement du puceron M. persicae a été évalué par des tests de prise alimentaire réalisés in planta, sur des plantes de pommes de terre exprimant une chitinase d'insecte (Phaedon cochleariae, Coléoptère) et in vitro, en incorporant une chitinase bactérienne (Serratia marcescens) dans un milieu artificiel. Des effets probiotiques ont été mis en évidence dans les deux cas, remettant en cause l'utilisation des chitinases en tant que biopesticide pour lutter contre les pucerons. Compte tenu de ces effets inattendus, nous avons étudié les effets d'une stratégie antagoniste, basée sur l'utilisation d'inhibiteurs de chitinases. Quatre inhibiteurs de chitinases, d'origine et de nature variées, ont ainsi été testés via un milieu artificiel. Nos résultats rapportent pour la première fois une activité inhibitrice de ces molécules sur des pucerons. Nous avons donc orienté nos recherches dans cette voie, afin d'identifier de nouveaux inhibiteurs de chitinases. Deux approches ont été initiées avec d'une part la purification des chitinases du puceron M. persicae et d'autre part par l'évaluation des effets d'oligosaccharides mimétiques de la chitine et des inhibiteurs de chitinases. Les résultats obtenus nous laissent à penser que les inhibiteurs de chitinases constituent une voie prometteuse dans l'élaboration de nouveaux bioinsecticides.

No description available.

The potato (Solanum tuberosum L.) has great importance in human nutrition where it occupies the fourth place among the most consumed foods in the world. It is a highly demanding culture technology especially in the nutritional point of view. Despite the titanium (Ti) is not considered a nutrient, studies have shown beneficial effects of this element when applied to plants. The application of Ti leaf can be an alternative for this element is slightly movable in the soil and is generally present in insoluble forms. Thus, the objective was to evaluate the influence of application rates of Ti foliar in the potato crop. We conducted an experiment in the period from August to November 2014, installed at the experimental station Udi Pesquisa e Development in Uberlândia-MG, with kind Ágata. Variables related to metabolism were evaluated: SPAD chlorophyll content, nitrate reductase activity (NRA), lipid peroxidation (LP), urease, proline, catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD). Nutritional factors such as levels of nutrients nitrogen (N), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) present in leaves and tubers were measured stages of growth, tuber and tuber filling. At the end of the crop cycle was quantified the average mass, diameter, commercial classification and productivity of tubers. The design was a randomized block design with four replications and six treatments. The supply of the Ti compound fertilizer was through for 5% of magnesium oxide, 10% sulfur trioxide and 0,85% titanium complex and the treatments was: T1 - without the application of Ti, T2 -10.2; T3 - 15.3; T4 - 20.4; T5 - 22.9 and T6 - 25.5 g Ti ha-1 divided into three equal applications during the growth phase, tuber and tuber filling. It was concluded that in the growth phase the foliar application of Ti reduces the Mn content in the leaves and there is increased activity of POD and ANR and reduced urease activity. In the tuberization phase the Fe absorption, SOD activity and POD response to increasing Ti dose. In tubers filling stage foliar application of Ti increases chlorophyll levels (Spad value). The application of Ti in the leaf growth stages, tuber and tuber filler results in a lower Zn content in the tubers. The average tuber weight, the average diameter of tubers and the total productivity of tubers are affected by foliar application of Ti. The dose Ti foliar applied for further tuber yield is 5.74 g Ti ha-1. / A batata (Solanum tuberosum L.) tem grande importância na alimentação humana onde ocupa o quarto lugar entre os alimentos mais consumido no mundo. É uma cultura altamente exigente em tecnologias especialmente sob o ponto de vista nutricional. Apesar do titânio (Ti) não ser considerado um nutriente, trabalhos demonstram efeitos benéficos deste elemento quando aplicado às plantas. A aplicação de Ti foliar pode ser uma alternativa pois este elemento é pouco móvel no solo e geralmente está presente em formas insolúveis. Desta forma, objetivou-se avaliar a influência da aplicação de doses de Ti via foliar na cultura da batata. Realizou-se um experimento no período de agosto a novembro de 2014, instalado na estação experimental Udi Pesquisa e Desenvolvimento em Uberlândia-MG, com utilização da cultivar Ágata. As variáveis relacionadas ao metabolismo avaliadas foram: teor clorofila SPAD, atividade da nitrato redutase (ANR), peroxidação lipídica (PL), urease, prolina, catalase (CAT), superóxido desmutase (SOD) e peroxidase (POD). Aspectos nutricionais como os teores dos nutrientes nitrogênio (N), cobre (Cu), ferro (Fe), manganês (Mn) e zinco (Zn) presentes em folhas e tubérculos foram mensurados fases de crescimento, tuberização e enchimento de tubérculos. Ao final do ciclo da cultura foi quantificada a massa média, diâmetro médio, classificação comercial e a produtividade dos tubérculos. O delineamento foi o de blocos casualizados, com quatro repetições e seis tratamentos. O fornecimento do Ti foi através de fertilizante composto por 5% de óxido de magnésio, 10% de trioxido enxofre e 0,85% de complexo de titânio com os seguintes tratamentos: T1 sem aplicação de Ti, T2 -10,2; T3 -15,3; T4 - 20,4; T5 - 22,9 e T6 - 25,5 g de Ti ha-1 divididos em três aplicações iguais durante a fase de crescimento, tuberização e enchimento de tubérculos. Concluiu-se que os teores de Cu não são influenciados pelas doses de Ti nas fases avaliadas. Na fase de crescimento a aplicação foliar de Ti reduz o teor de Mn nas folhas e há aumento da atividade da POD e ANR e redução da atividade da urease. Na fase de tuberização a absorção de Fe e atividade de enzimas SOD e POD tem resposta ao aumento da dose de Ti. Na fase de enchimento de tubérculos a aplicação foliar de Ti incrementa os teores de clorofila (valor Spad). A aplicação de Ti foliar nas fases de crescimento, tuberização e enchimento de tubérculos resulta em menor teor de Zn nos tubérculos. A massa média de tubérculos, o diâmetro médio de tubérculos e a produtividade total de tubérculos são influenciados pela aplicação foliar de Ti. A dose de Ti aplicada via foliar para maior produtividade de tubérculos é de 5,74 g de Ti ha-1. / Mestre em Agronomia

No description available.

The overall aim of this research was to improve the understanding of the ecology and diversity of Trichoderma species within the soil and rhizosphere of onion (Allium cepa L.) and potato (Solanum tuberosum L.) under intensive management in New Zealand. The indigenous Trichoderma population was measured in a field trial at Pukekohe over a three year period under six different crop rotation treatments. The treatments included two continuous onion and potato rotations (intensive), two onion/potato mixed rotation (conventional), and two green manure rotations (sustainable). Results showed that Trichoderma populations were stable in both the rhizosphere and bulk soil (1.5 x 10² to 8.5 x 10³ CFU g⁻¹ ODS). The planting and incorporation of an oat (Avena sativa L.) green manure in the sustainable rotations positively increased Trichoderma colony forming unit (CFU) numbers in the rhizosphere soil from 3.4 x 10² to 2.5 x 10³ g⁻¹ ODS. A Trichoderma species identification method was developed based on colony morphology. Representative isolates were verified using restriction fragment length polymorphism (RFLP) and DNA sequencing. The method allowed for rapid and reliable identification of isolated Trichoderma species. Five species were identified in the Pukekohe soil: T. asperellum, T. atroviride, T. hamatum, T. harzianum and T. koningii. Results showed identical species diversity between the rhizosphere, rhizoplane and bulk soil. The species did not strongly compete between each other for the rhizosphere ecological niche and differences in species proportions seemed to be caused by environmental factors rather than the rotation treatments. The incorporation of oat green manure in pots did not significantly promote the indigenous Trichoderma population size and diversity in the rhizosphere of onion plants up to 4 months old. The identified species were the same as in the field trial. The incorporation of onion scale residues was shown to result in low Trichoderma and high Penicillium CFU numbers and a reduction in plant size. Additionally, the presence of high levels (6.0 x 10⁵ CFU g⁻¹ ODS) of Penicillium CFU was negatively correlated with the presence of Trichoderma CFU. The effect of oat incorporation on Trichoderma saprophytic growth was also investigated in a soil sandwich assay and revealed no significant differences. A series of experiments indicated that onion extract obtained from dry onion scale residues had no antifungal activity against either Trichoderma or Penicillium and instead tended to promote their hyphal growth and sporulation. It also showed that competition between Penicillium and Trichoderma isolates was limited despite the ability of Penicillium to produce a wide range of inhibitory substances. Four indigenous Trichoderma species (T. atroviride, T. hamatum, T. harzianum and T. koningii) were shown to be rhizosphere competent in a split tube experiment over a 6 week period. The results of this experiment revealed that, the Trichoderma species clearly displayed differences in their ability to colonise the rhizosphere of young onion seedlings. Species such as T. koningii had the greatest rhizosphere colonising ability regardless of soil depth while T. harzianum displayed the weakest ability. Results also indicated that when inoculated as a mixture the four species competed with one another to colonise the rhizosphere. Overall, this research indicated that the studied crop rotation treatments and the use of oat as a green manure did not strongly promote indigenous Trichoderma populations. Species diversity was constant throughout the research with T. hamatum and T. koningii being the most frequently isolated species.