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Designing of direct seeding cropping systems with Northern Cameroonian farmers

Naudin Krishna, Balarabe Oumarou, Guibert Hervé, Abou Abba Abdoulaye, Charpentier Hubert. 2003. Designing of direct seeding cropping systems with Northern Cameroonian farmers. In : Producing in harmony with nature. II World Congress on Conservation Agriculture, Iguaçu Falls, Brésil, 11-15 August 2003. Montpellier : Cirad, 1 p. Congresso Mundial sobre Agricultura Conservacionista. 2, Foz de Iguaçu, Brésil, 11 August 2003/15 August 2003.

Poster
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Abstract : This project aimed at obtaining knowledge and tools for the development of cultivars resistant to the main diseases in South America, by (i) characterizing and evaluating available genetic resources, (ii) studying the genetic structure of the genera Ananas and Pseudananas, (iii) developing and applying resistance screening techniques for important pests and diseases in the region, (iv) testing the potential of partial inbreds in breeding, and (v) building a reference genetic map of molecular markers. In addition, a standard database is being established in collaboration with IPGRI, to promote information and germplasm exchange. The project, which started in 1997 and ended in 2001, has produced an inventory of the germplasm held in the partners' field collections, allowing exchanges and repatriation of lost germplasm. The list of descriptors has been revised. Morphological characterization and evaluation have been undertaken on more than 700 accessions in Martinique and Brazil, showing wide variation in quantitative and qualitative traits. Ten clones were selected for their particularly good agronomic qualities in Martinique and six promising Brazilian accessions are being tested for large-scale cultivation and consumer acceptance in Brazil. Multivariate analyses of the morphological data have produced consistent results. Characterization and evaluation was hampered by insufficient multiplication and germplasm transfer regulation in Venezuela, where only 30 accessions could be observed. Molecular characterization, based on RFLP observed with nuclear probes and cpDNA PCR-RFLP, has confirmed the proximity of Ananas and Pseudananas, the absence of interspecific barriers in Ananas, and the importance of a geographic component of variation. The phenograms and cladograms resulting from both molecular studies consistently show three major clusters, one from the South, gathering Pseudananas and A. fritzmuelleri, one from the basins of Orinoco and Rio Negro, grouping most of the A. parguazensis accessions, and one covering all tropical South America, including all the Ananas species, except for A. fritzmuelleri. The highest genetic diversity was observed in the Guianas, where the pineapple was probably domesticated from the highly variable A. ananassoides. A secondary center of diversity of the cultivated pineapple was identified in the western Amazon. Pineapple taxonomy has been revised and simplified. Genetic mapping was based on isozyme, RAPD, AFLP and ISSR markers and carried out on a hybrid progeny between A. bracteatus and A. comosus, following the pseudo-testcross approach. It resulted in a first map of 413 and 191 DNA markers distributed in 47 and 23 linkage groups for these two species. In the F2, recombination allowed the identification of additional markers and 163 markers were clustered in 37 groups, 24 of which showed correspondence with the F1 groups. The morphological characterization of the F2 was hindered by severe inbreeding depression, delaying the inclusion of morphological markers in the map. Resistance to fusariosis has been identified in 121 accessions out of 246 inoculated, some of which show other interesting traits for the Brazilian producers. According to the first inheritance studies, this resistance seems monogenic and dominant, a result still to be confirmed. Self-progenies obtained from the cultivars Perolera, Primavera, and Roxo de Tefé, showed inbreeding depression, but normal segregation for major leaf traits (spininess, color). Subsequent hybridization of the inbreds restored vigor. The project has significantly renewed the scientific basis of pineapple breeding. The knowledge generated has been widely diffused in specialized symposia as well as international joumals. (Résumé d'auteur)

Mots-clés Agrovoc : Semis direct, Paillis, Mulch vivant, Pratique culturale, Brachiaria, Céréale, Gossypium

Mots-clés géographiques Agrovoc : Cameroun

Classification Agris : F08 - Cropping patterns and systems

Auteurs et affiliations

  • Naudin Krishna, CIRAD-CA-GEC (CMR) ORCID: 0000-0002-9108-2456
  • Balarabe Oumarou, SODECOTON (CMR)
  • Guibert Hervé, CIRAD-CA-COTON (CMR)
  • Abou Abba Abdoulaye, SODECOTON (CMR)
  • Charpentier Hubert, CIRAD-CA-GEC (MDG)

Autres liens de la publication

Source : Cirad - Agritrop (https://agritrop.cirad.fr/517781/)

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