Sorghum Genetic Diversity in Africa: A Mini-Review

Abstract

Cultivated sorghum [Sorghum bicolor (L.) Moench] is an important food security crop in the worlds semi-arid regions, including Africa and Asia. Genetic diversity in crops is an essential element necessary for any crop improvement programme. The study seeks to assess the causes of genetic diversity loss in Africa and possible solutions to diversity loss problems in Africa. High genetic diversity at local, regional and continental levels within Africa was reported by most of the studies reviewed. The trend of sorghum diversity in Africa remains unclear as some studies suggest an increase in sorghum's genetic diversity, while others suggest a loss in genetic diversity over the years. Replacement of farmers’ variety with improved variety, population increase, climate change, a shift in the cropping system, and reduced derived benefits from certain crop varieties have reported as the major causes of diversity loss in Africa. The in-situ conservation practiced in the centers of diversity of sorghum has been a predominant key player in mitigating diversity loss in sorghum. This approach emphasizes the vital role of farmers’ selection in generating and maintaining crop diversity in participatory plant selection and introducing new varieties where farmers grow improved varieties. Farmers’ landraces were also found to improve the sorghum's genetic base, thereby mitigating diversity loss in sorghum. The extent and trend of genetic diversity and the causes of diversity loss observed in this study could provide a basis for genetic resource conservation and utilization of sorghum germplasm in Africa.