Dissertations / Theses on the topic 'Cultures – Floraison'

Cette these est partie integrante d'un programme de recherche-developpement concernant la violette de toulouse, pour permettre la relance de cette production regionale. Trois themes majeurs sont abordes: la connaissance de la plante, les modalites de son transfert en culture hors sol, et le controle de sa floraison. Une description phenologique, morphologique et anatomique est realisee. La violette de toulouse est caracterisee par un dimorphisme floral: elle est exploitee pour ses fleurs chasmogames emises en periode hivernale, les fleurs cleistogames ne presentant aucun interet commercial. La plante semble etre une espece essentiellement hemeroperiodique vis-a-vis de sa floraison chasmogame, la thermoperiode ayant un effet secondaire de type synergique. Les besoins hydriques et mineraux reduits de la violette resultent d'un developpement vegetatif peu eleve. En culture traditionnelle, les exportations sont limitees aux fleurs; l'adaptation de la technique culturale aux particularites du climat toulousain explique la reussite locale de cette production. L'echec du transfert de plants issus de culture traditionnelle en culture hydroponique semble lie a une sensibilite particuliere de ce type de materiel vegetal a l'asphyxie racinaire, qui n'est pas retrouvee sur des plants issus d'in vitro. L'aboutissement du programme pluri-disciplinaire de recherche portant sur la violette de toulouse s'est traduit au cours de l'annee 1992 par le transfert de plants issus d'in vitro en culture en hors sol, en conditions reelles d'exploitation. Le nouveau systeme de production permet un raccourcissement du cycle de culture, ainsi qu'un rendement en fleurs tres superieur a celui obtenu en culture traditionnelle. La production florale est egalement plus homogene, sur une saison plus longue. L'utilisation de regulateurs de croissance a ete experimentee. Les resultats obtenus montrent l'interet de ces substances pour la limitation de la vegetation des plants (reducteurs de croissance) ainsi que pour le controle de leur floraison (acide gibberellique)

L’azote est une ressource importante pour la croissance des plantes, et pour les pathogènes des cultures. L’objectif de cette thèse est de proposer une modélisation mécaniste des dynamiques d’azote dans une plante de blé en post-floraison. Pour cela, une approche structure-fonction a été mise en oeuvre. Des expérimentations ont permis de caractériser les dynamiques spatio-temporelles d’azote dans la tige feuillée. La masse d’azote surfacique des limbes et des gaines diminuait avec la distance depuis le sommet du couvert, mais elle était homogène le long d’un limbe ou d’une gaine. Les dynamiques temporelles étaient identiques pour les gaines et les limbes suggérant que ces deux entités répondent de la même manière à la lumière interceptée et à l’état azoté de la plante. De plus, les dynamiques étaient synchrones pour tous les phytomères et identiques à un facteur d’échelle près. En période d’absence d’absorption d’azote racinaire, ces dynamiques suivaient une cinétique d’ordre un. Ces résultats ont permis de développer un modèle structure-fonction des dynamiques d’azote au sein de la structure botanique d’une tige feuillée. Les principales hypothèses de ce modèle sont: (i) la teneur en azote d’un limbe est déterminée par le turnover des protéines de l’appareil photosynthétique; (ii) les différentes entités de la tige feuillée partagent un pool commun d’azote mobile. Ce modèle a été validé sur une gamme contrastée de conditions environnementales avec un jeu unique de six paramètres. Les relations azote-éclairement sont une propriété émergente des processus décrits à l’échelle locale. Ce travail ouvre des perspectives pour simuler la régulation des dynamiques d’azote dans des modèles individus-centrés de peuplements végétaux

Le maintien des insectes pollinisateurs en milieu agricole est essentiel car ils pollinisent les plantes sauvages et cultivées, il peut reposer sur l’augmentation de la disponibilité des ressources florales. Les cultures à floraison massive (CFM) fournissent des ressources abondantes et de façon discontinue dans le temps, au contraire des prairies et des plantes adventices présentes dans les cultures. Cet aspect temporel a été peu étudié alors que les paysages agricoles sont caractérisés par une dynamique temporelle importante du fait des successions culturales. L’objectif de la thèse est de comprendre l’effet de la distribution spatiale et temporelle des ressources florales dans les paysages agricoles sur les interactions plantes-pollinisateurs et la pollinisation. Nous montrons que les CFM au pic de floraison attirent les pollinisateurs sauvages des prairies et l’abeille domestique et supportent ainsi la fonction de pollinisation à cette période. Au sein des CFM, l’abeille domestique consomme les ressources fournies par les cultures préférentiellement en bordure de parcelle, et semble exclure les pollinisateurs sauvages des fleurs cultivées ceux-ci sont alors maintenus par les plantes adventices. A la fin de la floraison des CFM, les pollinisateurs dispersent vers les prairies et les céréales qui supportent ainsi la pollinisation. A cette période, les plantes adventices à travers leur abondance dans les céréales, et leur diversité dans les prairies supportent les pollinisateurs sauvages. La persistance des pollinisateurs et de la pollinisation dans les paysages agricoles, repose sur (i) le maintien des prairies et des plantes adventices qui assurent la continuité spatio-temporelle de la disponibilité en ressources florales, (ii) les CFM qui supplémentent les paysages en ressources florales, et (iii) la réduction de la taille des parcelles qui facilite l’accès aux ressources florales. Ces mesures sont compatibles avec la production agricole
Maintaining insect pollinators in farmland is essential for ensuring the pollination of crops and wild plants. This partly relies on the increase of floral resource availability. Mass flowering crops (MFC) provide a high amount of resources, but on a short period of time contrary to grasslands or weeds sheltered in fields. This temporal aspect is rarely studied, although it might be crucial in the maintenance of pollinators and insect pollination over the season. The aim of the thesis is to understand how the spatial and temporal distribution of the floral resources in farmland influence plant-pollinator interactions and pollination. Our results indicate that MFC at their peak flowering period, attract wild pollinators from grasslands and the honeybee; thus, supporting the pollination function. Within MFC, the honeybee preferentially consumes floral resources provided by crops, and may exclude wild pollinators from crop flowers which therefore foraged on weeds. After MFC flowering, pollinator insects spillover to grasslands and cereals which support pollination. Weeds, through their diversity in grasslands, and through their abundance in cereals support wild pollinators at this time period. The persistence of pollinators and pollination in farmland landscapes is based on (i) the maintenance of grasslands and weeds that ensure the spatio-temporal continuity of floral resources, (ii) MFC that supplement the landscapes in floral resources, and (iii) the reduction of field size that facilitates the access to the floral resources. Such measures appear to be compatible with crop production

Le transfert du dattier en région tropicale et plus spécifiquement au sahel conduit à des modifications de sa croissance végétative qui est plus rapide et de sa floraison qui suit deux cycles annuels. Ces modifications qui permettent de distinguer le dattier sahélien de son congénère saharo-méditerranéen, apportent des informations sur les possibilités d'extension de l'aire de culture de cette espèce. L'existence d'un cycle annuel supplémentaire est à mettre en relation avec les conditions climatiques, édaphiques et hydriques qui caractérisent la région d'étude. En particulier, la saison des pluies estivale semble jouer un rôle déterminant dans la réalisation de ce cycle, contrairement à la température, considérée comme le facteur inducteur de la floraison des dattiers saharo-méditerranéens, qui n'agit pas suivant les mêmes règles sur les dattiers intertropicaux. La colonisation naturelle rapide des dépressions ou la nappe phréatique est affleurant et l'aptitude à produire deux récoltes de dattes par an pendant la période de soudure, ont favorisé l'intégration du dattier dans les agrosystèmes de la société manga. En moins d'un demi-siècle, les agriculteurs ont progressivement intégré cette espèce dans leur patrimoine, employé l'arbre pour leur sécurisation foncière et utilise ses produits. Sur le plan technique, la définition de pratique culturale (multiplication, entretien, récolte) prenant en compte les contraintes sociales et environnementales a permis d'accroitre la productivité des dattiers et la qualité des dattes récoltées. D'un point de vue pratique, ce travail présente un modèle de fonctionnement et d'appropriation récente du dattier par l'homme.

Dans le cadre de la diversification agricole dans les hauts humides de l'île de la Réunion, la domestication du goyavier-fraise (Psidium cattleianum) est envisagée par une approche agronomique. Celle-ci consiste à rechercher comment s'élaborent des caractères d'intérêt et leur variabilité (le nombre de fruits produits par plant et leur calibre individuel), dans l'objectif de pouvoir agir dessus par des techniques culturales appropriées. Un modèle d'élaboration du nombre de fruits produits et de leur calibre est proposé, structuré autour d'étapes limitantes du cycle phénologique. La floraison, la fécondation-fructification et la croissance du fruit ont été étudiées et modélisées au cours de ce travail. Les résultats montrent l'intérêt de la domestication par une approche agronomique. Elle a permis d'acquérir en peu de temps des connaissances suffisantes pour préconiser des itinéraires techniques pour une nouvelle espèce, et améliorer la conduite d'une parcelle de matériel végétal génétiquement hétérogène par rapport à des objectifs agronomiques. Cette approche ne s'oppose pas à celle basée sur la sélection, mais en est complémentaire. Ce travail est aussi une contribution à l'étude, et à la prise en compte dans les modèles, de la variabilité à différentes échelles dans les mécanismes de l'élaboration du rendement
Strawberry guava (Psidium cattleianum) domestication is studied through an agronomic approach within a crop diversification project in humid highlands of Réunion Island. It consists in identifying how are built-up two characters of interest (the number of fruit produced per plant and the individual fruit weight) and their variability with the objective to act on them using appropriate cultivation techniques. A model representing the process of fruit number and individual fruit weight build-up is proposed, structured around limiting steps of the phenological cycle. Flowering, fecundation-fruit set and fruit growth were studied and modelled in this work. The results show the interest of the agronomic approach of domestication. This latter has provided in a short time a knowledge sufficient to propose adequate cultivation techniques for a new fruit species, and to improve the management of an orchard of genetically heterogeneous plants in relation with agronomical objectives. This approach of domestication is not opposed, but complementary, to that based on plant selection. This work also contributes to the study and integration in models of the variability at different levels in the process of crop yield build-up

Etude faite pour 3 categories de contraintes : application en selection, absence d'enceinte climatisee, encombrement de la plante. Approche principale par l'echelonnement des semis. Etude des exigences en froid. Effets des traitements au ga::(3). Definition de regles de culture a partir de plants de semis. Etablissement de processus experimentaux de culture sequentielle en conteneur

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The soybean crop (Glycine max (L.) Merrill) is of great importance in the world market, being one of the main agricultural commodities in Brazil, which occupies the second place in the world ranking of production. The cultivation of soybeans has occurred in many arthropod species, which often lead to a reduction in crop productivity or a reduction in the quality of seeds and grains and require the application of chemical insecticides. The harmful effects that insecticidal products can cause on pollination by entomophilic agents are of concern, which is currently considered to be essential for the production of the crop. In order to reduce the harmful effects on insect pollinators, the legal restriction of the use of insecticides in this crop has been motivated. The use of genetically modified plants resistant to pests has been widely adopted by farmers; These plants have one or more genes from the bacterium Bacillus thuringiensis (Berliner, 1915) (Bacillales: Bacillaceae) that encode lethal toxins for certain groups of insects. There are concerns about the unfamiliar effects associated with this technology in relation to non-target organisms, including floral visitors. The objective of this work was to investigate the composition and diversity of floral insect species and their population dynamics, evaluating their benefits for the production of soybean cultivars in Bt and non Bt cultivars. The collections of floral insects were carried out during the entire reproductive stage of the crop. Samplings were active with an entomological network for 15 minutes every hour, a total of 12 hours during the daytime period, with sampling every three or four days. It was also evaluated the effect of the presence of these floral visitors on the productivity of the crop. To do so, in each cultivar in the flowering period, 150 plants were randomly selected, composing 50 replicates (three plants per replicate), in which cages were placed in 25 replicates to prevent the presence of floral insects. A total of 549 specimens of floral insects were collected, divided into 30 families and 92 species. Of this total, 279 (50.81%) were present in the Bt cultivar and 270 (49.18%) in the non Bt cultivar. The most abundant species were Apis mellifera (Linnaeus, 1758) (Hymenoptera: Apidae) (35,15%), Musca sp.1 (Linnaeus, 1758) (10,01%) and Lagria villosa (Fabricius, 1783) (Coleoptera: Tenebrionidae) (5.28%), the composition of the species being very similar between the two cultivars, but in the tests of Shannon-Wiener and Simpson, showed greater diversity in the non-Bt cultivar (H = 1.30280; D = 0.86471) when compared to the Bt cultivar (H = 1.22871; D = 0.84557). There were differences in the number of specimens sampled in the four evaluations performed. In the third evaluation, the greatest number of species occurred, while the second evaluation participated with the lowest value of collected species. This is probably explained by the greater offer of floral resources to the visitors that occurred in the third evaluation. The schedules with the greatest richness of species was between 8:00 am and 11:00 am, this period of greater production of resources for floral visitors. When the population dynamics of A. mellifera were observed, this species had the highest occurrence in the hours between 10:00 a.m. and 2:00 p.m. In relation to the pollinator service performed by the pollinator insects, there was an increase in the weight of grains of the order of 84.22% in the open area with free presence of floral visitors in the production of the Intacta cultivar, and 202.52% in the non Bt cultivar. The increase in the number of pods was also considerable, since in the Bt cultivar this increase was of the order of 45.72% in the area open to floral visitors, and of the order of 101.25% in the non Bt cultivar, showing the important role of the visitors Floral for the production of this crop, even soy being a crop with a high index of self-pollination. In both cultivars there was greater grain yield and pods in the upper and middle thirds, corresponding to more than 80% of the plant production in these parts of the plants, this proportion is due to the greater production of reproductive structures in these places. The results obtained in this research demonstrate a great diversity of floral visiting insects in the soybean crop, regardless of whether the cultivar is transgenic with insect resistance or not. It is also evident that the presence of these insects, when in high abundance, causes a significant increase in crop production.
A cultura da soja (Glycine max (L.) Merrill) é de grande importância no mercado mundial, sendo uma das principais commodities agrícolas do Brasil, o qual ocupa o segundo lugar no ranking mundial de produção. O cultivo da soja tem ocorrência de muitas espécies de artrópodes que, frequentemente, ocasionam a redução na produtividade das lavouras, ou redução da qualidade das sementes e grãos e demandam a aplicação de inseticidas químicos. É preocupante os efeitos nocivos que os produtos inseticidas podem causar na polinização realizada por agentes entomófilos, o que, atualmente, vem sendo considerado essencial para a produção da cultura. Visando reduzir os efeitos danosos sobre insetos polinizadores, vem sendo motivada a restrição legal do uso de inseticidas nessa cultura. A utilização de plantas geneticamente modificadas resistentes às pragas vem sendo bastante adotada pelos agricultores; essas plantas possuem um ou mais genes da bactéria Bacillus thuringiensis (Berliner, 1915) (Bacillales: Bacillaceae) que codificam toxinas letais para determinados grupos de insetos. Existem preocupações sobre os desconhecidos efeitos associados a essa tecnologia em relação aos organismos não alvos, incluindo os visitantes florais. O objetivo desse trabalho foi o de investigar a composição e a diversidade de espécies de insetos visitantes florais e sua dinâmica populacional, avaliando seus benefícios para a produção da cultura de soja nas cultivares Bt e não Bt. Foram realizadas as coletas dos insetos visitantes florais durante todo o período de estádio reprodutivo da cultura. As amostragens foram de forma ativa com rede entomológica durante 15 minutos a cada hora, em total de 12 horas no período diurno, sendo feita uma amostragem a cada três ou quatro dias de intervalo. Também foi avaliado o efeito da presença desses visitantes florais sobre a produtividade da cultura. Para tanto, em cada cultivar no período de florescimento foram aleatoriamente escolhidas 150 plantas que compuseram 50 repetições (três plantas por repetição), nas quais foram colocadas gaiolas em 25 repetições para impedir a presença dos insetos visitantes florais. Foram coletados 549 espécimes de insetos visitantes florais, divididos em 30 famílias e 92 espécies. Desse total, 279 (50,81%) estavam presentes na cultivar Bt e 270 (49,18%) na cultivar não Bt. As espécies mais abundantes foram Apis mellifera (Linnaeus, 1758) (Hymenoptera: Apidae) (35,15%), Musca sp.1(Linnaeus, 1758) (Diptera: Muscidae) (10,01%) e Lagria villosa (Fabricius, 1783) (Coleoptera: Tenebrionidae) (5,28%), sendo a composição das espécies muito parecida entre as duas cultivares, mas, nos testes de Shannon-Wiener e Simpson, apresentou maior diversidade a cultivar não Bt (H=1,30280; D=0,86471) quando comparada com a cultivar Bt (H=1,22871; D=0,84557). Houve diferenças no número de espéces amostradas nas quatro avaliações realizadas. Na terceira avaliação ocorreu o maior número de espécies, enquanto a segunda avaliação participou com o menor valor de espécies coletadas. Isso, provavelmente, é explicado pela maior oferta de recursos florais para os visitantes ocorrido na terceira avaliação. Os horarios com a maior riqueza de espécies foi entre ás 8h00min e 11h00min, sendo esse período de maior produção de recursos para os visitantes florais. Quando observada a dinâmica populacional de A. mellifera, essa espécie apresentou maior ocorrência nos horários entre as 10h00min e 14h00min. Com relação ao serviço de polinização realizado pelos insetos polinizadores, houve um incremento no peso de grãos da ordem de 84,22% na área aberta com presença livre dos visitantes florais na produção da cultivar Intacta, e 202,52% na cultivar não Bt. Também foi considerável o aumento no número de vagens, pois na cultivar Bt esse aumento foi da ordem de 45,72% na área aberta aos visitantes florais, e da ordem de 101,25% na cultivar não Bt, mostrando o importante papel dos visitantes florais para produção dessa cultura, mesmo a soja sendo uma cultura com elevado índice de autopolinização. Em ambos as cultivares houve maior produção de grãos e vagens nos terços superiores e médios, correspondendo a mais de 80% da produção da planta nessas partes das plantas, essa proporção é devido a maior produção de estruturas reprodutivas nesses locais. Os resultados obtidos nesta pesquisa demonstram uma grande diversidade de insetos visitantes florais na cultura da soja, independente se a cultivar é transgênica com resistência a insetos, ou não. Também fica evidente que a presença desses insetos, quando em elevada abundância, ocasiona um significativo aumento na produção da cultura.

Étude menée dans une culture de blé dans les bassins parisiens en 1983, 84 et 85. Échantillonnage réalis& à l'aide de pots-pièges, pièges jaunes, d-vac, prélèvements d'épis, bâches et gouttières. Insecticides actifs sur le puceron des épis (sirobion avenae), les diptères phytophages, les homoptères, les thysanoptères, les diptères prédateurs et les araignées. Pas d'action des insecticides sur les d’étripages (sciaridae, chironomidae), les coléoptères prédateurs (carabidae, staphylinidae) et certains microhyteroptères. Pas d'effet des traitements d'une année sur l'autre

La perspective de la culture de variétés transgéniques pose, pour de multiples raisons, le problème de la ségrégation de filières de production basées sur la même espèce dans les paysages agricoles : demande d'une filière " sans OGM " ; coexistence de productions alimentaires et non alimentaires... La réglementation européenne fixe un seuil de présence fortuite d'OGM au-delà duquel un produit, même issu d'une variété non-OGM, doit être étiqueté comme contenant des OGM. La Commission européenne a émis des recommandations sur l'adoption de pratiques favorisant la coexistence entre cultures OGM et non-OGM de façon à ce que les agriculteurs puissent garder la liberté de choisir le mode de production qu'ils souhaitent. Dans ce contexte, il est important de pouvoir estimer a priori le taux d'impuretés OGM dans les récoltes de parcelles non-OGM, en fonction de leur organisation spatiale et du climat, mais aussi de comprendre et prédire l'effet de modifications de pratiques agricoles sur ce taux. L'expérimentation peut apporter des éléments de connaissances des phénomènes, la modélisation s'avère cependant plus pertinente pour répondre aux demandes d'aide à la décision (principalement publique) pour des situations agricoles et climatiques diversifiées. L'objectif de la thèse est donc de dégager un cadre méthodologique générique pour le développement de modèles de flux biologiques combinant de façon dynamique modélisation, évaluation et expérimentation. Le travail de thèse a consisté en la conception et l'évaluation du modèle MAPOD qui simule les flux de gènes chez le maïs à l'échelle du paysage. Ce modèle est basé sur une fonction de dispersion individuelle qui dépend de paramètres biologiques et climatiques et qui calcule une probabilité de fécondation en un point (x, y) en fonction de la distance à la source émettrice de pollen (pollinisation efficace). Il comporte un module de dynamique de floraison qui rend compte des conséquences des synchronismes ou asynchronismes de floraison entre champs sur les taux d'OGM dans les récoltes. Le modèle permet de déterminer l'effet de la distribution spatiale des parcelles de maïs, des caractéristiques variétales, du climat et des itinéraires techniques sur les taux de pollinisation croisée. MAPOD a été mis au point à partir de données de la littérature et d'expérimentations menées par le GEVES. Cette première version a été évaluée grâce à un second jeu de données provenant du GEVES. Elle a aussi fait l'objet d'une analyse de sensibilité. Les résultats obtenus ont permis de définir les pistes d'amélioration de l'algorithme. La qualité prédictive de MAPOD a ensuite été estimée grâce à des données issues de suivis effectués pendant 5 ans dans des parcelles d'agriculteurs en Catalogne, région où le maïs Bt est cultivé à grande échelle. La pertinence des décisions prises grâce aux sorties du modèle a aussi été caractérisée. MAPOD a été utilisé pour simuler différents scénarios d'introduction de variétés OGM dans les systèmes de culture européens. L'efficacité de mesures individuelles de coexistence a été testée. Ensuite, c'est l'effet de combinaison de pratiques qui a été simulé, aboutissant à l'établissement de tables de décision en fonction du contexte de culture. À l'échelle du bassin de collecte, l'efficience des stratégies de ségrégation (spatiale, temporelle) pouvant être mises en place par les organismes de collecte-stockage a aussi été étudiée grâce au modèle. Enfin, les sorties de MAPOD ont servi comme support pour la mise au point d'un outil d'aide à la décision à destination des agriculteurs et de leurs conseillers.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
The present work aimed to study the bee species which visit flowers of cotton (Gossypium hirsutum), cultivar 187 8H, their respective pollination efficiencies in relation to crop pollination requirements, as well as their implications in cotton ball production, quality of fiber and seeds produced. Data were collected from May to August 2006 in commercial cropping areas in the counties of Quixeramobim and QuixerÃ, state of CearÃ, Brazil. The area in Quixeramobim was small (10,000 m2), fertilized, close to native vegetation and used controlled insecticide applications, while the area in Quixerà was large (240,000 m2 ), non-fertilized, surrounded by other crop areas and submitted to systemic use of insecticide at every eight days. The research was split into four investigations: 1 â diversity and abundance of floral visitors to cotton flowers; 2 â foraging behavior of floral vistors to cotton flowers; 3 - floral biology, pollination requirements of cotton flowers, and pollination efficiency of Apis mellifera, and 4 â effect of Apis mellifera pollination in the physiological quality of cotton fiber and seeds. Floral visitors were observed, counted and captured by means of zig-zag walkings between the cropping lines. Experiments included bagging floral buds and hand pollination to evaluate cotton flowersâ pollination requirements and Apis mellifera pollination efficiency. Seed germination tests were carried out in the Seed Laboratory of the Universidade Federal do Cearà and fiber quality was evaluated in EMBRAPA AlgodÃo, Campina Grande-PB. The experimental design was entirely randomized and the crossed factorial Place x Treatment (2x5). Data were analised using Anova F test submitted to variance analysis and compared a posteriori by the Tukey test or by means of General Linear Models, depending on the nature of data. The following insect species were collected visiting flowers in the experimental sites: Apis mellifera, Brachygastra lecheguana, Polybia ignobilis, Ancyloscelis sp. 1, Ancyloscelis sp. 2, Melissoptila uncicornis, Psaenythia sp. and Anthrenoides sp., the last three species being new occurrences in the state of CearÃ. Floral visitors, resources gathered and foraging behavior were similar in both areas. Regarding floral biology, anthesis initiated early in the morning, from 6:00 h onwards, and all flowers were open by 7:00h. Stigmas were receptive from 6:00h to 13:00h, and pollen showed the greatest germinability (75%) after 10 hours of incubation. There were no significant differences (P>0.05) in fruit production among treatments in Quixeramobim and QuixerÃ. However, significant differences (P<0.05) were found among treatments within and/or between localities in variables such as cotton ball weight, seed weight, fiber weight, and number of seeds per fruit. In general, Quixerà showed lower means than Quixeramobim to all variables investigated. It was concluded that floral visitorsâ frequency to cotton flowers was low in Quixerà and Quixeramobim, A. mellifera showed the greatest potential to act as biotic pollinator of cotton flowers due to its large numbers in the areas, but Melissoptila uncicornis Ancyloscelis sp. 1 and Ancyloscelis sp. 2 could become important native pollinators in conditions more favorable to their presence, such as reduced use of insecticides, smaller crop fields, less soil revolving, and more proximity to native vegetation. The cotton plant is a species with an intermediate pollination system, being able of autopollination, however it needs biotic agents and good nutritional conditions to maximize pollination. It was also possible to conclude that natural pollination levels occurring in the areas studied were not sufficient to maximize production and that plants in Quixerà were not in the best nutritional conditions, in opposition to what was observed in Quixeramobim. It was also concluded that A. mellifera bees could be relevant to cotton pollination since they increased the percentage of emergence and the index of plantule emergence velocity in cotton seeds. The intrinsic fiber characteristics were not affected by pollination
O presente trabalho teve por objetivos estudar as abelhas visitantes do algodoeiro herbÃceo (Gossypium hirsutum) cultivar 187 8H, suas respectivas eficiÃncias polinizadoras em relaÃÃo aos requerimentos de polinizaÃÃo da cultura, bem como seus efeitos na produÃÃo de capulhos e qualidade da fibra e das sementes. Os dados foram coletados nos meses de maio de 2006 a fevereiro de 2007, em Ãreas comerciais dos municÃpios de Quixeramobim, e QuixerÃ, sendo a primeira adubada, pequena (10.000 m2), com uso controlado de defensivos agrÃcolas e prÃxima à mata nativa, enquanto que a outra nÃo recebeu adubaÃÃo, era grande (240.000 m2), com aplicaÃÃo de agrotÃxicos a cada oito dias e circundada por outras Ãreas cultivadas. O estudo foi realizado em quatro etapas: 1 - a diversidade e abundÃncia dos visitantes florais do algodoeiro; 2 â o comportamento de pastejo dos visitantes florais do algodoeiro; 3 - a biologia floral, requerimentos de polinizaÃÃo e eficiÃncia polinizadora de Apis mellifera no algodoeiro e 4 â o efeito da polinizaÃÃo por abelha Apis mellifera na qualidade fisiolÃgica da fibra e sementes de algodÃo. Os visitantes florais foram acompanhados, observados em seus comportamentos de pastejo, capturados e identificados ao longo do perÃodo de florescimento da cultura por meio de caminhadas em zigue-zague entre as fileiras do plantio. Experimentos de ensacamento de botÃes florais e polinizaÃÃo manual foram realizados para avaliar os requerimentos de polinizaÃÃo da cultura e eficiÃncia da abelha Apis mellifera na polinizaÃÃo do algodoeiro. Testes de germinaÃÃo das sementes e caracterÃsticas intrÃnsecas da fibra em funÃÃo do tipo de polinizaÃÃo foram utilizados para avaliar a qualidade de sementes e fibra. As anÃlises foram conduzidas no LaboratÃrio de Semente, da Universidade Federal do Cearà e no LaboratÃrio de Fibra, da Embrapa AlgodÃo, em Campina Grande-PB. Os experimentos foram montados em delineamento inteiramente casualizado e os dados analisados por meio de anÃlise de variÃncia com comparaÃÃo de mÃdias a posteriori pelo teste de Tukey, ou atravÃs da metodologia de Modelos Lineares Generalizados, dependendo da natureza dos dados. Os visitantes florais observados foram: Apis mellifera, Brachygastra lecheguana, Polybia ignobilis, Ancyloscelis sp. 1, Ancyloscelis sp. 2, Melissoptila uncicornis, Psaenythia sp. Anthrenoides sp., sendo as trÃs Ãltimas espÃcies novas ocorrÃncias para o estado do CearÃ. Os visitantes florais, a coleta de alimento e o comportamento dos insetos nas flores do algodoeiro foram semelhantes nos dois municÃpios estudados. Quanto à biologia floral, a antese aconteceu a partir das 6:00h, sendo que todas as flores estavam abertas Ãs 7:00h. Os estigmas apresentaram-se receptivos das 6:00h Ãs 13:00h e o pÃlen mostrou maior germinabilidade (75%) apÃs 10 horas de incubaÃÃo. NÃo houve diferenÃas significativas (P>0,05) na produÃÃo de frutos entre os tratamentos em Quixeramobim e QuixerÃ. PorÃm, foram observadas diferenÃas significativas (P<0,05) entre os tratamentos dentro e/ou entre localidades, em parÃmetros como o peso do capulho, peso da fibra, peso da semente, nÃmero de sementes, qualidade da semente e alguns parÃmetros de qualidade da fibra. De uma maneira geral, Quixerà apresentou mÃdias menores que Quixeramobim para todos os parÃmetros investigados. Concluiu-se que a freqÃÃncia dos visitantes florais foi baixa nos plantios de algodÃo de Quixerà e Quixeramobim, Apis mellifera possui o maior potencial para atuar como polinizador biÃtico do algodoeiro devido seu grande nÃmero nas Ãreas, mas Melissoptila uncicornis, Ancyloscelis sp. 1 e Ancyloscelis sp. 2 poderiam tornar-se polinizadores nativos importantes em situaÃÃes mais favorÃveis à sua presenÃa, como um menor uso de defensivos agrÃcolas, Ãreas de plantio menores, menos revolvimento do solo e maior proximidade à mata nativa. O algodoeiro à uma planta de polinizaÃÃo intermediÃria, podendo se autopolinizar, porÃm necessita de agentes biÃticos e um bom estado nutricional para maximizar a polinizaÃÃo. Pode-se concluir tambÃm que o nÃvel de polinizaÃÃo natural nas Ãreas foi insuficiente para maximizar a produÃÃo e que as plantas de Quixerà nÃo estavam adequadamente nutridas, ao contrÃrio das de Quixeramobim. TambÃm se concluiu que as abelhas A. mellifera podem ser importantes na polinizaÃÃo do algodoeiro, jà que levaram à porcentuais de emergÃncia e Ãndice de velocidade de emergÃncia de plÃntulas superiores. As caracterÃsticas intrÃnsecas da fibra nÃo foram influenciadas pelos tipos de polinizaÃÃo

La perspective de la culture de variétés transgéniques pose, pour de multiples raisons, le problème de la ségrégation de filières de production basées sur la même espèce dans les paysages agricoles : demande d'une filière « sans OGM » ; coexistence de productions alimentaires et non alimentaires… La réglementation européenne fixe un seuil de présence fortuite d'OGM au-delà duquel un produit, même issu d'une variété non-OGM, doit être étiqueté comme contenant des OGM. La Commission européenne a émis des recommandations sur l'adoption de pratiques favorisant la coexistence entre cultures OGM et non-OGM de façon à ce que les agriculteurs puissent garder la liberté de choisir le mode de production qu'ils souhaitent. Dans ce contexte, il est important de pouvoir estimer a priori le taux d'impuretés OGM dans les récoltes de parcelles non-OGM, en fonction de leur organisation spatiale et du climat, mais aussi de comprendre et prédire l'effet de modifications de pratiques agricoles sur ce taux. L'expérimentation peut apporter des éléments de connaissances des phénomènes, la modélisation s'avère cependant plus pertinente pour répondre aux demandes d'aide à la décision (principalement publique) pour des situations agricoles et climatiques diversifiées. L'objectif de la thèse est donc de dégager un cadre méthodologique générique pour le développement de modèles de flux biologiques combinant de façon dynamique modélisation, évaluation et expérimentation. Le travail de thèse a consisté en la conception et l'évaluation du modèle MAPOD qui simule les flux de gènes chez le maïs à l'échelle du paysage. Ce modèle est basé sur une fonction de dispersion individuelle qui dépend de paramètres biologiques et climatiques et qui calcule une probabilité de fécondation en un point (x, y) en fonction de la distance à la source émettrice de pollen (pollinisation efficace). Il comporte un module de dynamique de floraison qui rend compte des conséquences des synchronismes ou asynchronismes de floraison entre champs sur les taux d'OGM dans les récoltes. Le modèle permet de déterminer l'effet de la distribution spatiale des parcelles de maïs, des caractéristiques variétales, du climat et des itinéraires techniques sur les taux de pollinisation croisée. MAPOD a été mis au point à partir de données de la littérature et d'expérimentations menées par le GEVES. Cette première version a été évaluée grâce à un second jeu de données provenant du GEVES. Elle a aussi fait l'objet d'une analyse de sensibilité. Les résultats obtenus ont permis de définir les pistes d'amélioration de l'algorithme. La qualité prédictive de MAPOD a ensuite été estimée grâce à des données issues de suivis effectués pendant 5 ans dans des parcelles d'agriculteurs en Catalogne, région où le maïs Bt est cultivé à grande échelle. La pertinence des décisions prises grâce aux sorties du modèle a aussi été caractérisée. MAPOD a été utilisé pour simuler différents scénarios d'introduction de variétés OGM dans les systèmes de culture européens. L'efficacité de mesures individuelles de coexistence a été testée. Ensuite, c'est l'effet de combinaison de pratiques qui a été simulé, aboutissant à l'établissement de tables de décision en fonction du contexte de culture. À l'échelle du bassin de collecte, l'efficience des stratégies de ségrégation (spatiale, temporelle) pouvant être mises en place par les organismes de collecte-stockage a aussi été étudiée grâce au modèle. Enfin, les sorties de MAPOD ont servi comme support pour la mise au point d'un outil d'aide à la décision à destination des agriculteurs et de leurs conseillers
Consumer demand for food free of GMOs is growing and if production standards are to be met, food and non-food chains must be separated. Indeed, European Commission regulations 1829/2003 and 1830/2003 stipulate that food and feed thought to be GMO-free but found to be containing more than a 0.9% portion of an adventitious presence of authorized GMOs have to be distinguished, traced and labelled as such. Moreover, to ensure that producers have a choice a choice among differing types of production, the European Commission has issued recommendations that permit the coexistence of non-GM and GM crops. This poses the problem of how to deal with coexistence in an agricultural supply chain dedicated to handling a single crop species. To help in the elaboration of coexistence rules, and then assess their feasibility and their consequences as well as for setting up monitoring and control schemes, specific field experiments, even if necessary, are not sufficient as their predictive value remains restricted to a given context. It is necessary to be able to forecast the fate of GM crops at the landscape level taking into account the various cropping systems and agricultural practices that may occur across Europe. The key to forecasting spread and behaviour of GM plants and seeds as well as their impacts under a wide range of agro-ecosystems is modelling. Models reproduce the functioning of agro-systems and take into account the relevant factors and processes as well as their interactions. They thus make it possible to simulate the behaviour of agro-systems in non-observed situations and on a long term basis.This doctoral thesis establishes a methodological framework for the development of biological flow models thanks to the dynamic interactions of modelling, evaluation and experimentation. In a first phase, the work involved the design of the MAPOD® model developed in relationship to literature and varietal experiments carried out by GEVES. MAPOD® simulates gene flow between maize crops at the landscape scale. It is based on an individual dispersal function which depends on biological and climatic parameters. It calculates the probability of fecundation at a (x, y) point as a function of distance from the pollen emitter (efficient pollination). Its flowering dynamics module makes it possible to take into account of the consequences of flowering time - lags on GM adventitious presence in harvests. MAPOD® evaluates the effect of the spatial distribution of maize plots, varietal characteristics, and climate as well as agricultural practices on cross-pollination. In this investigation, in a second phase the initial version of MAPOD® was evaluated with another dataset provided by GEVES. Ways to improve the algorithm were thereby defined. In a third phase, the predictive quality of MAPOD® was estimated by comparing model outputs to cross-pollination rates which were obtained by monitoring farmers' fields in Catalonia (Spain) over a 5-year period. The relevance of decisions made according to model output was also evaluated.In a fourth phase, MAPOD® was used to simulate different scenarios involving the introduction of GM varieties into European cropping systems. The efficiency of individual coexistence measures was tested. Afterwards, the effect of combining different types of practices was simulated, leading to a set of decision-support tables elaborated according to the cropping context. At the scale of the collecting basin, with the enhanced version of MAPOD®, the efficiency of segregation strategies (spatial or temporal) that could be implemented by collecting and storing organisations was also studied. Lastly, model outputs were used as a basis for the design of a decision-support tool for use by farmers and extension workers

SILVA, Eva Mônica Sarmento da. Abelhas visitantes florais do algodoeiro (gossypium hirsutum) em quixeramobim e quixeré, estado do ceará, e seus efeitos na qualidade da fibra e semente. 2007. 117 f. Tese (doutorado em zootecnia)- Universidade Federal do Ceará, Fortaleza-CE, 2007.
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The present work aimed to study the bee species which visit flowers of cotton (Gossypium hirsutum), cultivar 187 8H, their respective pollination efficiencies in relation to crop pollination requirements, as well as their implications in cotton ball production, quality of fiber and seeds produced. Data were collected from May to August 2006 in commercial cropping areas in the counties of Quixeramobim and Quixeré, state of Ceará, Brazil. The area in Quixeramobim was small (10,000 m2), fertilized, close to native vegetation and used controlled insecticide applications, while the area in Quixeré was large (240,000 m2 ), non-fertilized, surrounded by other crop areas and submitted to systemic use of insecticide at every eight days. The research was split into four investigations: 1 – diversity and abundance of floral visitors to cotton flowers; 2 – foraging behavior of floral vistors to cotton flowers; 3 - floral biology, pollination requirements of cotton flowers, and pollination efficiency of Apis mellifera, and 4 – effect of Apis mellifera pollination in the physiological quality of cotton fiber and seeds. Floral visitors were observed, counted and captured by means of zig-zag walkings between the cropping lines. Experiments included bagging floral buds and hand pollination to evaluate cotton flowers’ pollination requirements and Apis mellifera pollination efficiency. Seed germination tests were carried out in the Seed Laboratory of the Universidade Federal do Ceará and fiber quality was evaluated in EMBRAPA Algodão, Campina Grande-PB. The experimental design was entirely randomized and the crossed factorial Place x Treatment (2x5). Data were analised using Anova F test submitted to variance analysis and compared a posteriori by the Tukey test or by means of General Linear Models, depending on the nature of data. The following insect species were collected visiting flowers in the experimental sites: Apis mellifera, Brachygastra lecheguana, Polybia ignobilis, Ancyloscelis sp. 1, Ancyloscelis sp. 2, Melissoptila uncicornis, Psaenythia sp. and Anthrenoides sp., the last three species being new occurrences in the state of Ceará. Floral visitors, resources gathered and foraging behavior were similar in both areas. Regarding floral biology, anthesis initiated early in the morning, from 6:00 h onwards, and all flowers were open by 7:00h. Stigmas were receptive from 6:00h to 13:00h, and pollen showed the greatest germinability (75%) after 10 hours of incubation. There were no significant differences (P>0.05) in fruit production among treatments in Quixeramobim and Quixeré. However, significant differences (P<0.05) were found among treatments within and/or between localities in variables such as cotton ball weight, seed weight, fiber weight, and number of seeds per fruit. In general, Quixeré showed lower means than Quixeramobim to all variables investigated. It was concluded that floral visitors’ frequency to cotton flowers was low in Quixeré and Quixeramobim, A. mellifera showed the greatest potential to act as biotic pollinator of cotton flowers due to its large numbers in the areas, but Melissoptila uncicornis Ancyloscelis sp. 1 and Ancyloscelis sp. 2 could become important native pollinators in conditions more favorable to their presence, such as reduced use of insecticides, smaller crop fields, less soil revolving, and more proximity to native vegetation. The cotton plant is a species with an intermediate pollination system, being able of autopollination, however it needs biotic agents and good nutritional conditions to maximize pollination. It was also possible to conclude that natural pollination levels occurring in the areas studied were not sufficient to maximize production and that plants in Quixeré were not in the best nutritional conditions, in opposition to what was observed in Quixeramobim. It was also concluded that A. mellifera bees could be relevant to cotton pollination since they increased the percentage of emergence and the index of plantule emergence velocity in cotton seeds. The intrinsic fiber characteristics were not affected by pollination.
O presente trabalho teve por objetivos estudar as abelhas visitantes do algodoeiro herbáceo (Gossypium hirsutum) cultivar 187 8H, suas respectivas eficiências polinizadoras em relação aos requerimentos de polinização da cultura, bem como seus efeitos na produção de capulhos e qualidade da fibra e das sementes. Os dados foram coletados nos meses de maio de 2006 a fevereiro de 2007, em áreas comerciais dos municípios de Quixeramobim, e Quixeré, sendo a primeira adubada, pequena (10.000 m2), com uso controlado de defensivos agrícolas e próxima à mata nativa, enquanto que a outra não recebeu adubação, era grande (240.000 m2), com aplicação de agrotóxicos a cada oito dias e circundada por outras áreas cultivadas. O estudo foi realizado em quatro etapas: 1 - a diversidade e abundância dos visitantes florais do algodoeiro; 2 – o comportamento de pastejo dos visitantes florais do algodoeiro; 3 - a biologia floral, requerimentos de polinização e eficiência polinizadora de Apis mellifera no algodoeiro e 4 – o efeito da polinização por abelha Apis mellifera na qualidade fisiológica da fibra e sementes de algodão. Os visitantes florais foram acompanhados, observados em seus comportamentos de pastejo, capturados e identificados ao longo do período de florescimento da cultura por meio de caminhadas em zigue-zague entre as fileiras do plantio. Experimentos de ensacamento de botões florais e polinização manual foram realizados para avaliar os requerimentos de polinização da cultura e eficiência da abelha Apis mellifera na polinização do algodoeiro. Testes de germinação das sementes e características intrínsecas da fibra em função do tipo de polinização foram utilizados para avaliar a qualidade de sementes e fibra. As análises foram conduzidas no Laboratório de Semente, da Universidade Federal do Ceará e no Laboratório de Fibra, da Embrapa Algodão, em Campina Grande-PB. Os experimentos foram montados em delineamento inteiramente casualizado e os dados analisados por meio de análise de variância com comparação de médias a posteriori pelo teste de Tukey, ou através da metodologia de Modelos Lineares Generalizados, dependendo da natureza dos dados. Os visitantes florais observados foram: Apis mellifera, Brachygastra lecheguana, Polybia ignobilis, Ancyloscelis sp. 1, Ancyloscelis sp. 2, Melissoptila uncicornis, Psaenythia sp. Anthrenoides sp., sendo as três últimas espécies novas ocorrências para o estado do Ceará. Os visitantes florais, a coleta de alimento e o comportamento dos insetos nas flores do algodoeiro foram semelhantes nos dois municípios estudados. Quanto à biologia floral, a antese aconteceu a partir das 6:00h, sendo que todas as flores estavam abertas às 7:00h. Os estigmas apresentaram-se receptivos das 6:00h às 13:00h e o pólen mostrou maior germinabilidade (75%) após 10 horas de incubação. Não houve diferenças significativas (P>0,05) na produção de frutos entre os tratamentos em Quixeramobim e Quixeré. Porém, foram observadas diferenças significativas (P<0,05) entre os tratamentos dentro e/ou entre localidades, em parâmetros como o peso do capulho, peso da fibra, peso da semente, número de sementes, qualidade da semente e alguns parâmetros de qualidade da fibra. De uma maneira geral, Quixeré apresentou médias menores que Quixeramobim para todos os parâmetros investigados. Concluiu-se que a freqüência dos visitantes florais foi baixa nos plantios de algodão de Quixeré e Quixeramobim, Apis mellifera possui o maior potencial para atuar como polinizador biótico do algodoeiro devido seu grande número nas áreas, mas Melissoptila uncicornis, Ancyloscelis sp. 1 e Ancyloscelis sp. 2 poderiam tornar-se polinizadores nativos importantes em situações mais favoráveis à sua presença, como um menor uso de defensivos agrícolas, áreas de plantio menores, menos revolvimento do solo e maior proximidade à mata nativa. O algodoeiro é uma planta de polinização intermediária, podendo se autopolinizar, porém necessita de agentes bióticos e um bom estado nutricional para maximizar a polinização. Pode-se concluir também que o nível de polinização natural nas áreas foi insuficiente para maximizar a produção e que as plantas de Quixeré não estavam adequadamente nutridas, ao contrário das de Quixeramobim. Também se concluiu que as abelhas A. mellifera podem ser importantes na polinização do algodoeiro, já que levaram à porcentuais de emergência e índice de velocidade de emergência de plântulas superiores. As características intrínsecas da fibra não foram influenciadas pelos tipos de polinização.

Le nouveau genotype wjr::(1629) de tournesol (helianthus annuus l. , seconde plante oleagineuse du monde) est remarquable par son caractere isomature : il possede deux ou plusieurs capitules symetriques qui fleurissent et murissent simultanement. Son interet sur le plan agronomique est prometteur. Il est mis en evidence que la realisation du caractere isomature est sous la dependance de un a trois genes dominants et d'un effet maternel. Ce resultat impliquera necessairement, dans le futur, l'utilisation d'un parent femelle isomature pour le creation d'hybrides commerciaux