How an improved sorghum variety evolves in a traditional seed system in Mali: Effects of farmers’ practices on the maintenance of phenotype and genetic composition

Deu, M and Weltzien, E and Calatayud, C and Traoré, Y and Bazile, D and Goze', E and Trouche, G and vom Brocke, K (2014) How an improved sorghum variety evolves in a traditional seed system in Mali: Effects of farmers’ practices on the maintenance of phenotype and genetic composition. Field Crops Research, 167. pp. 131-142. ISSN 0378-4290

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Abstract

In Africa, it is mostly the informal seed system that ensures farmers’ seed supply. This is partly because the formal seed systems are not always effective in meeting demand for new seed varieties. Sometimes informal seed recycling and exchange of improved sorghum varieties will take place alongside formal initiatives, as is the case in southern Mali. Focusing on one particular village in the Dioïla district, we analyze the efficacy of farmers’ strategies for preserving varietal seed purity and genetic integrity of an improved inbred-line (Soumba variety). Six seed lots of Soumba, recycled for two to six years by farmers using different practices, were collected and assessed in on-station trials in order to compare their agronomic performance and phenotypic purity (off-type plant frequencies) with control versions of the variety. Additionally, 30 panicle samples were randomly collected from five farmer fields sown with recycled Soumba and assessed for phenotypic purity in a progeny nursery and investigated for molecular diversity using 12 SSR markers. A total of 150 panicles from five other non-Soumba varieties were collected in the village in order to investigate eventual gene flow and its potential genetic consequences for the Soumba variety. In fields sown with recycled Soumba seed, between 2% and 14% of plants showed phenotypic deviations from the typical Soumba variety. The progeny nursery and SSR marker analysis verified the presence of the off-type plants observed in the field. The STRUCTURE program revealed admixtures with other varieties in 23% of Soumba plants, confirming the presence of gene flow. Gene diversity values in Soumba samples ranged from 0.006 for the commercial sample to 0.257 for recycled samples. Introgression and contamination were best minimized when (1) farmers had received specific training in seed production, (2) they could take advantage of isolated fields and (3) they could practise true-to-type panicle selection. Farmerswere generally able to maintain the phenotype, as well as sustain or even improve yield performance of their Soumba variety while at the same time genetically enriching their seed stock.

Item Type: Article
Divisions: RP-Dryland Cereals
CRP: CGIAR Research Program on Dryland Cereals
Uncontrolled Keywords: Sorghum, Seed systems, Seed recycling, Improved varieties, Farmer practices
Subjects: Mandate crops > Sorghum
Others > Genetics and Genomics
Others > Agriculture-Farming, Production, Technology, Economics
Depositing User: Mr B K Murthy
Date Deposited: 31 Mar 2015 08:21
Last Modified: 19 Oct 2016 04:40
URI: http://oar.icrisat.org/id/eprint/8635
Official URL: http://dx.doi.org/10.1016/j.fcr.2014.06.021
Projects: UNSPECIFIED
Funders: UNSPECIFIED
Acknowledgement: We are grateful for the contributions of farmers from the villages of Gouligan, Wéla and especially from Magnambougou in the Dioïla Circle of Mali, who made this study possible. We also thank Adama Gouanlé and Oumar Touré for their contributions. The study would not have been possible without the financial support of the French Agency for Research (ANR, AAP-BDIV07) for the IMAS “Impact des Modalités d'Accès aux Semences sur la diversité des ressources génétiques en agriculture” project. We further wish to thank Jacques Chantereau for his valuable advice during the experimental phase of the study as well as his constructive comments on the drafts of the article. We further thank Anthony McGowan for the English editing of the draft manuscript.
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