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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

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Relation http://oar.icrisat.org/8635/
http://dx.doi.org/10.1016/j.fcr.2014.06.021
10.1016/j.fcr.2014.06.021
 
Title 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
 
Creator Deu, M
Weltzien, E
Calatayud, C
Traoré, Y
Bazile, D
Goze', E
Trouche, G
vom Brocke, K
 
Subject Sorghum
Genetics and Genomics
Agriculture-Farming, Production, Technology, Economics
 
Description 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.
 
Publisher Elsevier
 
Date 2014
 
Type Article
PeerReviewed
 
Format application/pdf
 
Language en
 
Rights —
 
Identifier http://oar.icrisat.org/8635/1/FCR_167_131%E2%80%93142_2014.pdf
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