Analyse d'essais d'hybrides de cacoayer en Cote d'Ivoire pour la production, la vigueur et la sensibilité a la pourriture brune
Most cacao breeding programmes around the world utilize hybrids between clones. In Ivory Coast, mostly hybrids of the type Upper Amazon x Amelonado or Upper Amazon x Trinitario have been studied. The analysis presented here involves four hybrids trials, obtained by a factorial crossing scheme between 16 Upper Amazon clones, used as female parents and four locally selected Amelonado clones, used as male parents. The experimental set-up of the trials was complete randomization with one tree per plot and 16 to 20 repetitions per trial. Observations were made on individual tree yield between 1982 and 1987, vigor of young trees and size of adult trees, fruit damage due to black pod and rats, and on tree mortality. Results on productivity show superiority of most hybrids in relation to the control, which is one of the hybrids actually distributed in Ivory Coast. The best female parents were SCA6, NA32, T60887, T79/501, PA7 an T85/799. No significant effect of the male parents was observed. The factorial analysis shows additive effects being most important. The high coefficients of variation observed in the trials is due to the environmental variation and probably also due to the heterozygozity of the parents used. The coefficients of variation can be reduced by applying an appropriate co-variable; the average vigor of the nearest neighbour trees. The multilocational analysis shows highly significant effects of localities and hybrids. The effect of interaction, although significant, is relatively small. The same type of analyses have been carried out for the variables measuring vigor. In many cases, a narrow relationship exists between vigor and productivity of the hybrids. Vigor of young trees is not always related to the size of the adults trees. However, the analysis of the relationship between productivity and vigors shows important changes in ranking of the best female parents. Therefore, selection of productive moderately vigorous hybrids can be proposed for high density planting. The analyses of black pod incidence show significant effects of female and male parents. The ranking between trials is quite similar. Additive effects are predominant. The above results are useful for guiding future breeding strategies, for the methodology to be applied to hybrid trials and for the understanding of the relationship between vigor and yield of cacao trees.
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| Format: | biblioteca |
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Montpellier (Francia)
1990
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| Subjects: | THEOBROMA CACAO, HIBRIDOS, PHYTOPHTHORA PALMIVORA, ENFERMEDADES FUNGOSAS, CLONES CRIOLLOS, CLONES FORASTEROS, CLONES TRINITARIOS, RESISTENCIA A LA ENFERMEDAD, SELECCION, VIGOR HIBRIDO, COTE D'IVOIRE, |
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| Summary: | Most cacao breeding programmes around the world utilize hybrids between clones. In Ivory Coast, mostly hybrids of the type Upper Amazon x Amelonado or Upper Amazon x Trinitario have been studied. The analysis presented here involves four hybrids trials, obtained by a factorial crossing scheme between 16 Upper Amazon clones, used as female parents and four locally selected Amelonado clones, used as male parents. The experimental set-up of the trials was complete randomization with one tree per plot and 16 to 20 repetitions per trial. Observations were made on individual tree yield between 1982 and 1987, vigor of young trees and size of adult trees, fruit damage due to black pod and rats, and on tree mortality. Results on productivity show superiority of most hybrids in relation to the control, which is one of the hybrids actually distributed in Ivory Coast. The best female parents were SCA6, NA32, T60887, T79/501, PA7 an T85/799. No significant effect of the male parents was observed. The factorial analysis shows additive effects being most important. The high coefficients of variation observed in the trials is due to the environmental variation and probably also due to the heterozygozity of the parents used. The coefficients of variation can be reduced by applying an appropriate co-variable; the average vigor of the nearest neighbour trees. The multilocational analysis shows highly significant effects of localities and hybrids. The effect of interaction, although significant, is relatively small. The same type of analyses have been carried out for the variables measuring vigor. In many cases, a narrow relationship exists between vigor and productivity of the hybrids. Vigor of young trees is not always related to the size of the adults trees. However, the analysis of the relationship between productivity and vigors shows important changes in ranking of the best female parents. Therefore, selection of productive moderately vigorous hybrids can be proposed for high density planting. The analyses of black pod incidence show significant effects of female and male parents. The ranking between trials is quite similar. Additive effects are predominant. The above results are useful for guiding future breeding strategies, for the methodology to be applied to hybrid trials and for the understanding of the relationship between vigor and yield of cacao trees. |
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