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 c onsisting of 391 landraces collected from different geographical regions in Ethiopia and Eritrea, 8 varieties and 16 introduced elite breeding lines w ere used for this study. The materials were classified on the basis of regi ons of origin and adaptation zones. Phenotypic variation for ten qualitativ e (categorical) characters that displayed two or more classes were estimate d using the Shannon-Weaver diversity index (H'). High and comparable levels of phenotypic variation were found between the regions of origin and betwe en the adaptation zones. However, significant levels of variation were foun d within the regions of origin and within the adaptation zones. Partitionin g of the variation into within and between regions as well as into within a nd between adaptation zones further confirmed that a large portion of the t otal variation was found within regions of origin and within adaptation zon es. Panicle compactness and shape contributed relatively more to regional d ifferentiation. These characters were also found to be disproportionately d istributed within the regions of origin with the compact panicles frequentl y distributed in relatively dry regions. while the loose panicle types were widely found in relatively wet and humid regions. The differential distrib ution of the different panicle types indicated the adaptive significance of panicle compactness and shape and at the same time reflected the distribut ion patterns of different races of sorghum in Ethiopia. Chi-square analysis revealed that the occurrence of seed colour was non-randomly associated wi th that of the other characters.