|Title||Rice genetic resources in postwar Sierra Leone|
|Source||Wageningen University. Promotor(en): Marc Sosef, co-promotor(en): Ronald van den Berg; Bert Visser. - - 161|
|Department(s)||Centrum voor Genetische Bronnen Nederland
Centre for Genetic Resources, The Netherlands
|Publication type||Dissertation, internally prepared|
|Keyword(s)||oryza - rice - plant genetic resources - genetic diversity - war - landraces - varieties - phenotypic variation - farming systems - sierra leone - farmers' knowledge - oryza - rijst - genetische bronnen van plantensoorten - genetische diversiteit - oorlog - landrassen - rassen (planten) - fenotypische variatie - bedrijfssystemen - sierra leone - kennis van boeren|
|Categories||Plant Genetic Resources, Gene Banks|
|Abstract||This research presents the effect of the 10-year long civil war in Sierra Leone on rice genetic resources, using farmers and their seed systems in three selected districts as reference points. The war disrupted all forms of production and development in the country and like other sectors of the economy, agricultural production and the conservation of plant genetic resources at the farm level was severely affected. It emerged that farmers’ effectiveness to cultivate and manage their seed systems and the options to grow rice under insecure conditions were disrupted at different levels in the three districts studied. However, the general consequence of the war in all of the districts was that farmers lost considerable amounts of their seed stocks. Total losses for some rice varieties was averted because of the occurrence of a number of varieties in more than one village in the same region, which was a result of farmers seed exchange systems, and also due to farmer movement during the war. The majority of the varieties that were reported lost were actually “dispersed” in the regions, indicating good options for post-war recovery.
There was little evidence that the genetic composition of rice varieties were significantly altered as a consequence of the war, except for the total loss of upland varieties in one of the districts. The varieties that had the highest survival were those that had wider pre-war distribution, showed plasticity in growing habits wherein they demonstrated the potential to grow in both agro-ecosystems and in the different districts, and the fact that they existed in many different forms.
Statistical analysis showed a clear distinction between upland and lowland varieties, which demonstrated the effectiveness of farmer selection with regard to the two production ecosystems. This was different for the periods defined as pre-war and post-war. Pre-war varieties were less well defined in this respect. Further to this, there was evidence of a change in rice genetic resources between the pre-war and post-war situations, which was demonstrated in the number of varieties for each of the two ecosystems. Despite these changes, and the losses in seed stocks as a consequence of the war, genetic diversity increased in post-war rice varieties.
AFLP results indicated that rice varieties in Sierra Leone possess different levels of intra-variety variation, which makes it difficult to identify homogenous genotypes at the seed unit level. This was attributed to genetic exchanges caused by farmers’ practices of growing different varieties in mixtures. The variation however does not alter the profile of inter-variety genetic differences, which remains large enough to distinguish one variety from the other. It demonstrates that the genetic composition of rice varieties remains distinct from one another, and that variety names in Sierra Leone are good indicators for genetic diversity of rice at the farm level.