Early screening of resistance to Phytophthora spp. by means of leaf disc inoculation
Resistance to cocoa black pod disease is quantitative in nature. Field resistance evaluation takes many years of observation in uniform, well-designed trials in order to be reliable. Broad sense heritability of the percentage of rotten pods on individual plants can be 0.6 for nine years of observations but is much lower (0.1 to 0.3) for experiments with only three to five years of observation (Kebe et al., 1999). Broad sense heritability of the leaf disc inoculation method, by applying only one inoculation series, can be as high as 0.6 (Nyassé et al. 1999). Furthermore, it has been shown so far that, at progeny level, this test can give significant correlations with field attack (Kebe and Tahi, in press). Evaluation of individual plant resistance has so far given less conclusive results. The repeatability and effective application of this test will certainly depend on adequate standardization of environmental and physiological factors that influence leaf tissue resistance. These factors, as far as they are known, are indicated in the description of this test. This method is expected to speed up breeding and selection activities such as large scale evaluation of germplasm collections, breeding trials, early selection of individual plants or progenies growing in the nursery or field, and studies on host x pathogen interaction. This working procedure has been adapted from the method applied by Nyassé et al. (1995).
| Main Authors: | , , , |
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| Format: | conference_item biblioteca |
| Language: | eng |
| Published: |
IPGRI
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| Subjects: | H20 - Maladies des plantes, F30 - Génétique et amélioration des plantes, Theobroma cacao, résistance aux maladies, Phytophthora, feuille, méthode, infection expérimentale, sélection précoce, http://aims.fao.org/aos/agrovoc/c_7713, http://aims.fao.org/aos/agrovoc/c_2328, http://aims.fao.org/aos/agrovoc/c_5844, http://aims.fao.org/aos/agrovoc/c_4243, http://aims.fao.org/aos/agrovoc/c_4788, http://aims.fao.org/aos/agrovoc/c_32441, http://aims.fao.org/aos/agrovoc/c_36927, |
| Online Access: | http://agritrop.cirad.fr/475701/ |
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| Summary: | Resistance to cocoa black pod disease is quantitative in nature. Field resistance evaluation takes many years of observation in uniform, well-designed trials in order to be reliable. Broad sense heritability of the percentage of rotten pods on individual plants can be 0.6 for nine years of observations but is much lower (0.1 to 0.3) for experiments with only three to five years of observation (Kebe et al., 1999). Broad sense heritability of the leaf disc inoculation method, by applying only one inoculation series, can be as high as 0.6 (Nyassé et al. 1999). Furthermore, it has been shown so far that, at progeny level, this test can give significant correlations with field attack (Kebe and Tahi, in press). Evaluation of individual plant resistance has so far given less conclusive results. The repeatability and effective application of this test will certainly depend on adequate standardization of environmental and physiological factors that influence leaf tissue resistance. These factors, as far as they are known, are indicated in the description of this test. This method is expected to speed up breeding and selection activities such as large scale evaluation of germplasm collections, breeding trials, early selection of individual plants or progenies growing in the nursery or field, and studies on host x pathogen interaction. This working procedure has been adapted from the method applied by Nyassé et al. (1995). |
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