Integrated management of Phytophthora diseases on cocoa (Theobrama cacao L.) : impact of plant breeding on pod rot incidence
Pod rot, caused by several species belonging to the genus Phytophthora, is the main cause of cocoa harvest losses worldwide. Among the methods making up integrated disease management (IDM), the creation of resistant cultivars has been identified as a priority in cocoa breeding research programmes. To that end, various experiments have enhanced knowledge about the genetic basis of resistance to pod rot. Genetic trials conducted in Cameroon, Ivory Coast and Togo indicated that genetic x environment interactions were relatively low. Rankings of progenitors tested were stable in different conditions, from one country to another. The greater the number of years of field observations, the higher the heritability of the pod rot resistance trait. A protocol for early evaluation of disease resistance on leaf discs has been developed and validated for the selection of more resistant families. The leaf disc test developed was well correlated at the genetic level to the pod test previously used. Heritability of mean disease scores obtained with the leaf disc test after several inoculation rounds is similar to the one of pod rot rate in the field after several years of observations. The potential use of the leaf disc test as breeding tool and its impact on the genetic improvement of black pod resistance are discussed. © 2006 Elsevier Ltd. All rights reserved.
| Main Authors: | , , , , , |
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| Format: | article biblioteca |
| Language: | eng |
| Subjects: | H20 - Maladies des plantes, F30 - Génétique et amélioration des plantes, Theobroma cacao, Phytophthora, http://aims.fao.org/aos/agrovoc/c_7713, http://aims.fao.org/aos/agrovoc/c_5844, http://aims.fao.org/aos/agrovoc/c_1229, http://aims.fao.org/aos/agrovoc/c_7801, http://aims.fao.org/aos/agrovoc/c_4027, |
| Online Access: | http://agritrop.cirad.fr/535276/ http://agritrop.cirad.fr/535276/1/document_535276.pdf |
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| Summary: | Pod rot, caused by several species belonging to the genus Phytophthora, is the main cause of cocoa harvest losses worldwide. Among the methods making up integrated disease management (IDM), the creation of resistant cultivars has been identified as a priority in cocoa breeding research programmes. To that end, various experiments have enhanced knowledge about the genetic basis of resistance to pod rot. Genetic trials conducted in Cameroon, Ivory Coast and Togo indicated that genetic x environment interactions were relatively low. Rankings of progenitors tested were stable in different conditions, from one country to another. The greater the number of years of field observations, the higher the heritability of the pod rot resistance trait. A protocol for early evaluation of disease resistance on leaf discs has been developed and validated for the selection of more resistant families. The leaf disc test developed was well correlated at the genetic level to the pod test previously used. Heritability of mean disease scores obtained with the leaf disc test after several inoculation rounds is similar to the one of pod rot rate in the field after several years of observations. The potential use of the leaf disc test as breeding tool and its impact on the genetic improvement of black pod resistance are discussed. © 2006 Elsevier Ltd. All rights reserved. |
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