Maintenance of Sorghum (Sorghum bicolor, Poaceae) landrace diversity by farmers' selection in Ethiopia

We quantitatively examined the relationships between Sorghum landrace diversity at the field level and environmental factors and farmers’ selection practices in north Shewa and south Welo regions of Ethiopia. Surveys were conducted on 260 randomly selected farmers’ fields. The altitude and size of each field were recorded. Sorghum plants at 5 m intervals along transect lines spaced 10 m apart over each field were identified by the farmers and the owner of each field was asked why she/he decided to grow each plant. Soil samples were collected from all of the fields and analyzed for pH, organic content, and sand, silt and clay content. Simple and polynomial regressions and multiple regression analyses showed that Sorghum landrace diversity at the field level had significant relationships with the number of selection criteria used by the farmers, field altitude, field size, pH and clay content. As the number of selection criteria increased, landrace diversity in the fields increased. This relationship was not a result of the correlation between selection criteria and the environmental factors, because it was significant after statistically correcting for the effects of the environmental variables. This study quantitatively confirms the role of traditional farmers in the maintenance of sorghum landrace diversity in north Shewa and south Welo regions of Ethiopia