A Dynamic Sorghum (Sorghum Bicolor (L.) Moench) diversity Management in Situ and Livelihood Resilience in South and Central Tigray Region, Ethiopia

Abstract

Sorghum is an important crop for the south and central parts of Tigray Region of Ethiopia. To assess the level of sorghum diversity, two zones, namely South and Central Tigray were selected and eighteen villages in three woredas, Alamata, Raya-Azebo and Tanqua-Abergelle, were surveyed. A total of 93 randomly selected farmers were interviewed using a structured questionnaire that elicited information on socioeconomic aspects of households, sorghum plots, the number and types of farmers’ local varieties grown in the area, variety characteristics, seed exchange systems and seed flow together with selection criteria’s as well as seed selection process and management. A total of 165 collections belonging to 31 locally named sorghum varieties were retrieved and stored at Mekelle University. High diversity in terms of landrace richness were found the Alamata area (Margalef = 2.92; Menhinick = 1.66) followed by Raya-Azebo (Margalef = 2.61; Menhinick = 1.46) and Tanqua-Abergelle was found to be less diverse in terms of number of named varieties (Margalef = 1.40; Menhinick = 1.0). Diversity estimated based on evenness indices showed that Tanqua-Abergelle has the highest diversity (Shannon =0.86; Brillouin index = 0.86) followed by Raya-Azebo (Shannon =0.85; Brillouin index = 0.85). The lowest evenness was found in Alamata woreda (Shannon =0.77; Brillouin index = 0.77). Based on the varietal richness and use values, four sites (villages) that could serve as seed repositories were identified. The result of the econometric analysis indicated that a combination of factors, such as year of schooling, labour equivalence, tropical livestock unit, and number of parcels were the most important determinants that affect significantly the intra-specific diversity. The regression analysis indicates the positive linkage between land fragmentation and landrace richness. The increase in diversity over temporal scale of ten years found in this study revealed that the level of genetic erosion needs numerical evidence to substantiate. The socioeconomic factors that affect varietal diversity and possible conservation and incentive strategies are discussed.

Key words: Sorghum, Diversity, Seed flow, Genetic erosion, Resilience