Inventory of on-farm sorghum landrace diversity and climate adaptation in Tigray, Northern Ethiopia: implications for sorghum breeding and conservation

Abstract

The study was conducted with the aim of inventorying and assessing the level of sorghum landraces richness, estimating the extent and patterns of phenotypic diversity, identifying race type, and predicting suitable areas of production using future climate scenarios in Tigray, Northern Ethiopia. Overall, 358 landraces from 125 independent farmers’ fields in 20 districts belonging to four zones of Tigray were surveyed. Landraces richness, frequency of character states, and diversity levels were estimated via Margalef’s, Menhinick’s and Shannon–Weaver (H′) indices for each zone and altitude classes. Suitable areas for sorghum cultivation in the future were predicted using DIVA-GIS. Altogether, 140 distinctly named landraces were identified and collected. Southern zone has the highest richness (DMg = 10.74, DMn = 5.0) followed by central (DMg = 8.54, DMn = 3.80). The estimated H′ for the phenotypic character states ranged from 0.24 (seed form) to 0.95 (rachis branch length). Highest diversity estimate was found in northwest (H′ = 0.71) followed by central zone (H′ = 0.64). Respectively, H′ was 0.70, 0.68, and 0.61 in lowland, intermediate, and highland elevations. In general, lowlands of northwest, central, and southern zones are identified as potential sites for germplasm conservation and utilization. The races durra, bicolor, caudatum, and durra-bicolor were found with durra as the dominant race (79%). All the currently surveyed areas and many other sites in Tigray are predicted to be suitable for future sorghum production under the changing climate scenario. Copies of all the 358 sorghum landraces are deposited in the national gene bank for use in future sorghum breeding work. The wealth of sorghum landraces diversity could be used in sorghum improvement programs.