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The potential gene flow between a crop and its wild relatives is largely determined by the overlaps in their ecological and geographical distributions. Ecogeographical databases are therefore indispensable tools for the sustainable management of genetic resources. In order to expand our knowledge of Sorghum bicolor distribution in Kenya, we conducted in situ collections of wild, weedy and cultivated sorghum. Qualitative and quantitative morphological traits were measured for each sampled wild sorghum plant. Farmers' knowledge relating to the management of sorghum varieties and autecology of wild sorghum was also obtained. Cluster analysis supports the existence of several wild sorghum morphotypes that might correspond to at least three of the five ecotypes recognized in Africa. Intermediate forms between wild and cultivated sorghum belonging to the S. bicolor ssp. drummondii are frequently found in predominantly sorghum growing areas. Crop-wild gene flow in sorghum is likely to occur in many agroecosystems of Kenya.

Highlights A geospatial cloud-based system GeoFarmer was designed and developed. GeoFarmer can be used as smart-monitoring system for agricultural projects. It provides tools for interactive feedback loops between platform users. Results and lessons learned from five pilots illustrate the flexibility of GeoFarmer.

ABSTRACT. In studying indigenous climate knowledge, two approaches can be envisioned. In the first, traditional knowledge is a cultural built-in object; conceived as a whole, its relevance can be assessed by referring to other cultural, economic, or technical components at work within an indigenous society. In the second, the accuracy of indigenous climate knowledge is assessed with western science knowledge used as an external reference. However, assessing the accuracy of indigenous climate knowledge remains a largely untapped area. We aim to show how accurate the culturally built indigenous climate knowledge of extreme climatic events is, and how amenable it is to fuzzy logic. A retrospective survey was carried out individually and randomly among 195 Eastern African farmers on climatic reasons for loss of on-farm crop diversity from 1961 to 2006. More than 3000 crop loss events were recorded, and reasons given by farmers were mainly related to droughts or heavy rainfall. Chisquare statistics computed by Monte Carlo simulations based on 999 replicates clearly rejected independence between indigenous knowledge of drought and heavy rainfall that occurred in the past and rainfall records. The fuzzy logic nature of indigenous climatic knowledge appears in the clear association of drought or heavy rainfall events, as perceived by farmers, with corresponding extreme rainfall values, contrasting with a fuzzy picture in the intermediate climatic situations. We discuss how the cultural built-in knowledge helps farmers in perceiving and remembering past climate variations, considering the specificity of the contexts where extreme climatic events were experienced. The integration of indigenous and scientific climate knowledge could allow development of drought monitoring that considers both climatic and contextual data.

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Little information is available on the extent and patterns of gene flow and genetic diversity between cultivated sorghum and its wild related taxa under local agricultural conditions in Africa. As well as expanding knowledge on the evolutionary and domestication processes for sorghum, such information also has importance in biosafety, conservation and breeding programmes. Here, we examined the magnitude and dynamics of crop-wild gene flow and genetic variability in a crop-wild-weedy complex of sorghum under traditional farming in Meru South district, Kenya. We genotyped 110 cultivated sorghum, and 373 wild sorghum individuals using a panel of ten polymorphic microsatellite loci. We combined traditional measures of genetic diversity and differentiation with admixture analysis, population assignment, and analyses of spatial genetic structure to assess the extent and patterns of gene flow and diversity between cultivated and wild sorghum.Our results indicate that gene flow is asymmetric with higher rates from crop to wild forms than vice versa. Surprisingly, our data suggests that the two congeners have retained substantial genetic distinctness in the face of gene flow. Nevertheless, we found no significant differences in genetic diversity measures between them. Our study also did not find evidence of isolation by distance in cultivated or wild sorghum, which suggests that gene dispersal in the two conspecifics is not limited by geographic distance. Overall our study highlights likely escape and dispersal of transgenes within the sorghum cropwild-weedy complex if genetically engineered varieties were to be introduced in Africa's traditional farming systems.