Geographical patterns of morphological variation in sorghum (Sorghum bicolor (L.) Moench) germplasm from Ethiopia and Eritrea:: qualitative characters

Four hundred and fifteen sorghum (Sorghum bicolor (L.) Moench) accessions consisting of 391 landraces collected from different geographical regions in Ethiopia and Eritrea, 8 varieties and 16 introduced elite breeding lines were used for this study. The materials were classified on the basis of regions of origin and adaptation zones. Phenotypic variation for ten qualitative (categorical) characters that displayed two or more classes were estimated using the Shannon-Weaver diversity index (H'). High and comparable levels of phenotypic variation were found between the regions of origin and between the adaptation zones. However, significant levels of variation were found within the regions of origin and within the adaptation zones. Partitioning of the variation into within and between regions as well as into within and between adaptation zones further confirmed that a large portion of the total variation was found within regions of origin and within adaptation zones. Panicle compactness and shape contributed relatively more to regional differentiation. These characters were also found to be disproportionately distributed within the regions of origin with the compact panicles frequently distributed in relatively dry regions. while the loose panicle types were widely found in relatively wet and humid regions. The differential distribution of the different panicle types indicated the adaptive significance of panicle compactness and shape and at the same time reflected the distribution patterns of different races of sorghum in Ethiopia. Chi-square analysis revealed that the occurrence of seed colour was non-randomly associated with that of the other characters.