Selection of Arabica coffee types resistant to coffee berry disease in Ethiopia

Descriptive part. A review is given of: the importance of Coffea arabica to Ethiopia; coffee research; habitus, origin and cultivation of C. arabica ; theoretical aspects of resistance and its implications for the system C. arabica -parasites; Coffee Berry Disease, symptoms, epidemiology, geographic distribution, origin, resistance to CBD, chemical control and control through resistance.Experimental part. Coffee trees (mother trees) were selected that showed a low level of CBD in areas with severe disease. The resistance of these trees was appraised through field observations, field inoculation tests, and seedling inoculation tests. Correlations were determined between field observations and tests. Selection thresholds were determined and their adequacy was assessed through longer term observation of the mother trees. Progenies of mother trees were planted in a heavy CBD area; the CBD resistance of the progenies was reassessed through disease estimates and berry counts in the field, and detached berry tests. The correlations between observations and tests were determined as well as selection tresholds for seed distribution to farmers.The nature of CBD resistance was discussed and additional experiments were made on: the rôle of the cuticle, variation in resistance within and between single-tree progenies, and interactions between host and pathogen. It was concluded that resistance was most likely horizontal. In multilocation trials, differences were found between coffee types with regard to leaf rust, leaf blight and blotch leaf miner. Disease and pest severity were related to provenance of the mother trees. Progenies were found to differ in resistance to tracheomycosis. Through field observations on differences in resistance it was possible to determine indirectly that all progenies possessed adequate resistance to brown eye spot. A final evaluation of the programme is presented

Selection of Arabica coffee types resistant to coffee berry disease in Ethiopia

Descriptive part. A review is given of: the importance of Coffea arabica to Ethiopia; coffee research; habitus, origin and cultivation of C. arabica ; theoretical aspects of resistance and its implications for the system C. arabica -parasites; Coffee Berry Disease, symptoms, epidemiology, geographic distribution, origin, resistance to CBD, chemical control and control through resistance.Experimental part. Coffee trees (mother trees) were selected that showed a low level of CBD in areas with severe disease. The resistance of these trees was appraised through field observations, field inoculation tests, and seedling inoculation tests. Correlations were determined between field observations and tests. Selection thresholds were determined and their adequacy was assessed through longer term observation of the mother trees. Progenies of mother trees were planted in a heavy CBD area; the CBD resistance of the progenies was reassessed through disease estimates and berry counts in the field, and detached berry tests. The correlations between observations and tests were determined as well as selection tresholds for seed distribution to farmers.The nature of CBD resistance was discussed and additional experiments were made on: the rôle of the cuticle, variation in resistance within and between single-tree progenies, and interactions between host and pathogen. It was concluded that resistance was most likely horizontal. In multilocation trials, differences were found between coffee types with regard to leaf rust, leaf blight and blotch leaf miner. Disease and pest severity were related to provenance of the mother trees. Progenies were found to differ in resistance to tracheomycosis. Through field observations on differences in resistance it was possible to determine indirectly that all progenies possessed adequate resistance to brown eye spot. A final evaluation of the programme is presented

Variação intraspecífica do lenho de Pseudopiptadenia contorta (DC.) G.P. Lewis & M.P. Lima (Leguminosae - Mimosoideae) de populações ocorrentes em dois remanescentes de Floresta Atlântica Intraspecific variation in wood anatomy of Pseudopiptadenia contorta (DC) G.P. Lewis & M.P. Lima (Leguminosae -Mimosoidae) in two Atlantic rain forest remnants

O presente trabalho compara populações distintas de Pseudopiptadenia contorta (DC.) G.P. Lewis & M.P. Lima ocorrentes em dois remanescentes de Floresta Atlântica no Estado do Rio de Janeiro. Foram amostradas árvores de diâmetro semelhante retas e sem defeitos aparentes. Os resultados obtidos comprovam estatisticamente a ocorrência de variação intraspecífica na estrutura anatômica da madeira. Os caracteres qualitativos mantiveram-se constantes, enquanto os quantitativos variaram, sendo os significativos, de acordo com o teste t de Student, a freqüencia, comprimento e diâmetro dos elementos vasos, o comprimento e espessura da parede das fibras, a freqüência e largura dos raios. A análise dos componentes principais, utilizando características anatômicas quantitativas ordenou as duas populações separadamente. O eixo I responde por 33% da variância total principalmente pela relação positiva do diâmetro do elemento de vaso, enquanto o eixo II responde por 20% da variância total, principalmente pelo comprimento das fibras.<br>This study compares distinct populations of Pseudopiptadenia contorta (DC) G.P. Lewis & M.P. Lima occurring in two remnants of Atlantic rain forest in Rio de Janeiro state. Trees with similar diameters and with no apparent defects were selected. The results confirm intraspecific variation in wood anatomy. Qualitative features do not change, while according to the Student t test quantitative features showed significant differences in vessel-element frequency, width, and length, fiber length and wall thickness, and ray frequency and width. Principal component analysis showed two separate populations. Factor 1 explains 33% of the total variance, mainly due to the positive relationship of vessel-element tangential diameter; factor 2 explains 20% of the total variance, mainly due to fiber length