Genetic enrichment, a new concept in genetic resource management: the case of sorghum (Sorghum bicolor (L.) Moench) in Ethiopia

Abstract

The importance of maintaining and conserving genetic resources around the world is a well-established fact. Typically, in situ and ex situ conservation are the means applied to maintain genetic diversity in food crops. Notwithstanding the contribution that the ‘green revolution’ has made towards food security throughout the developing world, it has also been singled out as one of the major causes of genetic erosion. The amount of genetic diversity and rate of genetic erosion is quantified in various crops in different parts of the world, in particular in the crop centres of diversity. However, no one has reported on ‘genetic enrichment’ (GEn) – the reverse process of genetic erosion. In order to assess the on-farm genetic enrichment of sorghum, various research methodologies were employed, including focussed group interviews with 360 farmers, key informant interviews with 60 farmers and development agents, and semi-structured interviews with 250 farmers. In addition, diversity fairs were organised with over 1200 farmers. In order to quantify the level of GEn by comparative methods, germplasm collections were initiated in 2000. GEn is described here as the process of addition of genetic variability at gene, gene-complex or varietal level. GEn is a common practice among farmers; in fact, farmer interviews showed that 49.6% had practised GEn. The amount of GEn practised varied by crop ecology but not by farmer's wealth. GEn by variety name and number showed a rate of 2.86% and 1.67% yearly, respectively, which means 2.8 and 1.7 varieties per year are enriched on a regional level. The concept, level of use and supporting evidence of GEn as well as the reasons farmers are practising GEn are outlined. Three models are suggested for the process of GEn, namely the bio-ecogeographic genetic enrichment model, the farmer-induced genetic enrichment model and the farmer-cum-bio-ecogeographic genetic enrichment model. These models explain the factors that shape on-farm genetic enrichment. GEn is practised in order to counteract varietal loss and hence balance the in/out flux of varieties on farms. It is a dynamic process that proceeds according to the prevalent bio-economic and socio-cultural circumstances, dictated by the availability of varieties, and the bio-physical and socio-economic environment of the farmers. In order to enhance farmers’ GEn, reduce genetic erosion and maintain on-farm genetic diversity, the management and utilisation of genetic resources have to be integrated.