Les hybrides entre Coffea canephora Pierre et C. eugenioides Moore: exemple de crossement entre espece de Coffea diploides africains pour l'amelioration qualitative des cafés produits en basse altitude
These two species were crossed in order to combine the agronomic qualities of C. canephora with the small caffeine content of C. eugenioides (0.2 to O.8 DM). The F1 hybrids have a set of interesting characteristics: satisfactory vigour, average yield, bean size equivalent to that of the parents C. canephora, bean caffeine content (1.2 to 1.5 DM) intermediate between that of the parents, but handicapped by an insufficient fertility (proportion of peaberries greater than 60). The chromosomic pairing observed in metaphase I in the mother cells of the pollen of the F1 hybrids is of the sub-normal diploid type: 35 of the cells contained eleven bivalents. Compared with the parents, the hybrids show a lesser pollen viability and lower female fertility correlated with pairing deficiency. The second hybrid generation varied very greatly, so far as the characters studied were concerned, and contained individuals with normal fertility. It is especially at this level that will be selected the mother plants expressing the interesting characteristics of the "Canephora x Eugenioides" combination. Knowing that the small degree of differentiation found here between C. canephora and C. eugenioides is also found between various African diploid species, the objective in Ivory Coast is to improve low altitude coffee products, principally by combining the potetialities of the species C. canephora, C. liberica, C. congensis and C. eugenioides
| Main Authors: | , , |
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| Format: | biblioteca |
| Published: |
París (Francia)
1979
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| Subjects: | COFFEA CONGENSIS, COFFEA LIBERICA, COFFEA CANEPHORA, COFFEA EUGENIOIDES, HIBRIDOS, DIPLOIDE, NUMERO DE CROMOSOMAS, CRUZAMIENTO, COTE D'IVOIRE, |
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| Summary: | These two species were crossed in order to combine the agronomic qualities of C. canephora with the small caffeine content of C. eugenioides (0.2 to O.8 DM). The F1 hybrids have a set of interesting characteristics: satisfactory vigour, average yield, bean size equivalent to that of the parents C. canephora, bean caffeine content (1.2 to 1.5 DM) intermediate between that of the parents, but handicapped by an insufficient fertility (proportion of peaberries greater than 60). The chromosomic pairing observed in metaphase I in the mother cells of the pollen of the F1 hybrids is of the sub-normal diploid type: 35 of the cells contained eleven bivalents. Compared with the parents, the hybrids show a lesser pollen viability and lower female fertility correlated with pairing deficiency. The second hybrid generation varied very greatly, so far as the characters studied were concerned, and contained individuals with normal fertility. It is especially at this level that will be selected the mother plants expressing the interesting characteristics of the "Canephora x Eugenioides" combination. Knowing that the small degree of differentiation found here between C. canephora and C. eugenioides is also found between various African diploid species, the objective in Ivory Coast is to improve low altitude coffee products, principally by combining the potetialities of the species C. canephora, C. liberica, C. congensis and C. eugenioides |
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