Avaliação do nível de resistência do cafeeiro a H. Vastatrix

Preliminary results on the use of quantitative methods for determining the level of resistance of coffee plants to Hemileia vastatrix

NOTA

Avaliação do nível de resistência do cafeeiro a H. Vastatrix¹

Preliminary results on the use of quantitative methods for determining the level of resistance of coffee plants to Hemileia vastatrix

W. M. Costa²; A. B. Eskes³; I. J. A. Ribeiro⁴

SUMMARY

To study horizontal resistance of coffee plants to H. vastatrix quantitative measurements on resistance are necessary. In this paper the results of some greenhouse and laboratory tests are compared to field observations.

Regular field readings within the Icatu population, using a 6 point scale for disease access, have shown that a continuous variation for resistance exists within this population. Grafts of 55 plants of Icatu have been inoculated in the greenhouse with race II of the pathogen. Besides readings using the 6 point scale, estimates on sporulation rate and lesion size were made. The results show a good relation between field and greenhouse observations. Lesion size, however, was less correlated with disease incidence since many plants show large chlorotic areas with only sparse sporulation.

As a laboratory method detached leaves and leaf disks have been inoculated and maintained at high relative humidity. Conservation of detached leaves was unsatisfactory and this method has been subsequently abandoned. Leaf disks, when placed, on wetted filter paper in petri dishes, stayed green and apparently healthy for even more than 120 days. An inoculation experiment, using a susceptible, moderate susceptible and resistant plant of Icatu, indicates that the rate of infection of the leaf disks could be a promising parameter for quantitative disease assessments. Investigation with other plant material will be undertaken to further determine the effectiveness of this method.

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Recebido para publicação em 9 de maio de 1977.

1

Pesquisa parcialmente financiada pelo Instituto Brasileiro do Café. Trabalho apresentado no IV Congresso Brasileiro de Pesquisas Cafeeiras, Caxambu, MG, 23-26 de novembro de 1976. Os autores agradecem ao Dr. Alcides Carvalho, a colaboração na execução dos trabalhos e revisão do texto.

2

Com bolsa de suplementação do C.N.Pq.

3

Bolsista do Conselho Nacional de Desenvolvimento Científico e Tecnológico.

4

Técnico da FAO, junto ao Programa Internacional de Resistência Horizontal.

Datas de Publicação

• Publicação nesta coleção
  21 Dez 2007
• Data do Fascículo
  1978