Made available in DSpace on 2014-08-20T14:07:36Z (GMT). No. of bitstreams: 1 Dissertacao__Marilia_ W_ Marques.pdf: 521791 bytes, checksum: 960876c449dcc0e6427e3c297bd7b474 (MD5) Previous issue date: 2008-09-05 / The present work purposes to study the fungus Pseudocercospora griseola (Sacc) Crous & U. Braun, causal agent of angular leaf spot on common bean, to evaluate the incidence and severity in produced beans plants from seeds proceeding from pod with different levels of disease, as well as, to verify the effect in the physiological and sanitary quality of the produced seeds. For the development of the experiment, beans plants have been collected with high incidence of angular leaf spot, natural infestation the field. From the collected material it was elaborated a diagrammatic scales varying of 1 the 5, corresponding each note to a severity level on the physical structure of the pod. Parallel experiment was carried out, evaluating symptoms of angular spot in different places of the seed: hilum and coat. The tests carried through in the deriving seeds of the respective treatments had been: tests of germination (TPG), accelerated aging (EA), test of humidity and health. The results had shown that the incidence and the severity of angular leaf spot on common bean had been differed statistical between itself, where the levels of scale 1 and 5 had presented with minor and greater degree of incidence and severity of P. griseola, respectively. Whereas the seeds with symptoms in hilum and in the coat have presented resultes similar to the incidence and severity of the causal agent. The correlation enters the severity of pod and the severity of the disease in the plants was significant. There wasn´t statistical differences between the test of accelerated aging in the tested treatments, resulting a variation of 82-88% of normal seedlings. In the test of germination, treatment 5 differing statistical from the others treatments. In the sanitary analysis the fungus of storage increase incidence to the measure that increased the level of severity of the treatments. It was concluded in this work that pod with 60 % of symptoms of angular leaf spot have the capacity to intervene in the germination of the beans seeds and and that bigger levels of severity of the string beans cause a bigger development of the disease in field. / O presente trabalho teve por finalidade propor um estudo sobre o fungo Pseudocercospora griseola (Sacc) Crous & U. Braun, agente causal da mancha angular, através da avaliação da incidência e severidade em plantas de feijão produzidas a partir de sementes provenientes de vagens com diferentes níveis de severidade da doença, assim como verificar o efeito sobre a qualidade fisiológica e sanitária das sementes produzidas. Para a realização experimental foram coletadas plantas de feijão com alta incidência de mancha angular, infestação natural. A partir do material coletado procedeu-se separação das vagens a partir de uma escala diagramática variando de 1 a 5, correspondendo cada nota a um nível de severidade sobre a superfície da vagem. Experimento paralelo foi realizado, avaliando sintomas de mancha angular em diferentes locais da semente: hilo e tegumento. Os testes realizados nas sementes oriundas dos respectivos tratamentos foram: teste padrão de germinação (TPG), teste de envelhecimento acelerado (EA), determinação do teor de água e analise sanitária. Os resultados mostraram que a incidência e a severidade da mancha angular nas plantas de feijão diferiram-se estatisticamente entre si, onde os níveis da escala 1 e 5 apresentaram-se com menor e maior grau de incidência e severidade de P. griseola, respectivamente. As sementes com sintomas no hilo e sementes com lesões tegumentares apresentaram resultados semelhantes quanto à incidência e severidade do agente causal. A correlação entre a severidade da vagem e a severidade da doença nas plantas foi significativa. Quanto ao teste de envelhecimento acelerado, os tratamentos não diferiram estatisticamente entre si, resultando numa variação de 82 a 88% de plântulas normais. No teste padrão de germinação, o tratamento 5 diferiu estatisticamente dos demais tratamentos. Na análise sanitária, os gêneros fúngicos relacionados a armazenamento apresentaram maior incidência à medida que ocorreu aumento no nível de severidade dos tratamentos. Os resultados permitiram concluir que vagens com 60% de sintomas de mancha angular apresentam a capacidade de interferir no potencial germinativo das sementes de feijão e que maiores níveis de severidade das vagens ocasionam um maior desenvolvimento da doença em campo.

La phaeoramulariose des agrumes (Pseudocercospora angolensis) attaque les agrumes en Afrique tropicale et constitue une menace pour les autres pays producteurs situés en zone tropicale. La lutte chimique est le seul moyen de lutte efficace contre cette maladie. Cependant, elle est couteuse et néfaste pour l'environnement. La mise en place de stratégies de lutte permettant de minimiser l'emploi de fongicides contre est donc nécessaire. La connaissance des facteurs de risque de la phaeoramulariose est une étape préliminaire à cette démarche. Le travail entrepris avait pour but de préciser, à l'aide d'une enquête et des expérimentations, les effets de certains facteurs sur le développement de la maladie. L'enquête a été effectuée dans 39 sites de production des agrumes au Cameroun. Elle a permis de recenser les facteurs pédoclimatiques et biologiques dans l'environnement des arbres et de retenir les plus importants dans l'épidémiologie. Les expérimentations sur 8 sites ont permis de confirmer et évaluer les paramètres retenus après l'enquête. L'altitude, le type de sol, l'espèce d'agrumes et le type de végétation ont été retenus comme principaux facteurs de développement de la maladie. Les relations entre ces facteurs et l'incidence de la maladie sont illustrées dans les arbres de segmentation. Les expérimentations ont confirmé la grande sensibilité des pomélos et orangers vis-à-vis P. angolensis. En revanche, les mandariniers et la lime Tahiti se sont avérés moins sensibles. L'incidence de la maladie augmente avec une élévation en altitude, une diminution de la température et de la pluviométrie. La texture du sol s'est avérée plus déterminante du niveau de la maladie que sa composition. Le rôle de l'ombrage s'est avéré déterminant sur l'incidence de la maladie. L'analyse de la structure spatiale de la maladie a permis de mettre en évidence une structure agrégée. La structure spatiale des sous populations de familles d'arbres d'une parcelle agroforestière était aussi agrégée. La dispersion de la phaeoramulariose au sein d'une telle parcelle entre les différents agrégats d'agrumes serait limitée. L'analyse de régression a permis de déceler des différences entre les paramètres contribuant au développement de la maladie sur pomélos, satsuma et orangers. La possibilité d'une conception des systèmes agroforestiers raisonnés pour diminuer la pression des bioagresseurs est envisagée. / Phaeoramularia leaf and fruit spot disease of citrus (PLFSD) caused by Pseudocercospora angolensis attacks citrus in tropical Africa. It also constitutes a threat for the other producer countries located in tropical zone. Chemical treatment is the only method used for effective control of this disease. However, in addition to causing ecological problems, this method lies beyond the reach local smallholders. The development of ecologically friendly strategies to ensure effective protection of citrus is thus necessary. To this end, knowledge of PLFSD risk factors is pre-required. The purpose of this study was to specify, by means of a survey and experiments carried, the effects of certain biotic and abiotic factors on the development of the disease. The survey carried out in 39 production sites of Cameroon, targetted a collection of environmental and biological tree characteristics. Experiments on 8 sites enabled a confirmation and evaluation of suspected factors. A stepwise logistic regression analysis of survey data made it possible to target altitude, soil type, citrus species and vegetation type as main factors influencing disease development. Relations between these factors and disease incidence are illustrated in segmentation trees. Experiments confirmed the great sensitivity of grape fruit and orange trees, while tangerine and Tahiti lime trees were less sensitive. Disease incidence increased with a rise in altitude and a reduction in temperature and rainfall. Soil texture proved to be more determinant in disease development than its chemical composition. Experimentation showed that trees planted under shade are less affected than those located in sunshine. A spatial structure analysis of the disease made it possible to highlight an aggregate structure indicating small scale disease dispersion. An analysis of the spatial structure of an agro forestry farm showed an aggregate structure of the sub populations of constituent tree families. This structure suggested that the dispersion of PLFSD within such a farm would be limited between the various citrus aggregates. PLS regression analysis suggested that several of these parameters play a determinant role in contributing to the development of disease on grape fruit, orange and Satsuma mandarin trees. The development of integrated agro forest systems which enable a decrease of the pressure of pest and diseases is envisaged.