Abstract

Sorghum is one of the most important cereal crops grown in arid/semi-arid regions of the world. Understanding and utilising the genetic variation in sorghum accessions is essential for improving the crop to adapt to abiotic and biotic constraints. Several authors have reported the loss of sorghum diversity, but there is limited available information on on-farm sorghum diversity in the major sorghum growing areas in Uganda hence limiting the utilization of diversity for improvement of the crop. This study was carried out to determine sorghum diversity on farmers’ fields in Uganda. Phenotypic data was used to assess diversity in 100 sorghum accessions collected from Northern and Eastern regions of Uganda. The accessions were phenotyped using qualitative and quantitative morphological characteristics. Phenotypic evaluation was done using 10×10 Alpha lattice design with two replications at Pakor village in Agago district. Analysis of variance revealed highly significant (p ≤ 0.01) differences for all quantitative traits measured indicating the existence of a wide genetic variation among accessions. The 100 accessions were grouped into two major clusters which were further subdivided into five sub clusters. The largest cluster had 30 accessions and the smallest cluster had five accessions. The five clusters varied with respect to plant height (202.8 to 379.9 cm), days to 50% flowering (77.3 to 163), number of leaves per plant (10.9 to 24.6), 100 grain weight (2.5 to 4.6 g) and yield (1977.4 to 3475.6 kg ha^-1). The clustering patterns of accessions was not entirely based on geographic origin and/or breeding status, probably due to gene flow. This study showed the existence of wide genetic diversity within the sorghum accessions, which could be exploited in the improvement of the crop through breeding for high yielding, pest and disease resistant varieties.

Key words: Sorghum bicolor, ward clustering, morphological traits, diversity.