Genetic Diversity of Sorghum [Sorghum bicolor (L.) Moench] Genotypes in the Central Plateau Zone of Rwanda for Qualitative Traits

Sorghum is a key cereal in Rwanda, ranking second after maize. However, climate change, pests, and diseases contribute to low yields. To improve its yield, a study was conducted in the central plateau zone of Rwanda to evaluate the genetic diversity of 36 sorghum genotypes based on qualitative traits for the identification of drought-tolerant genotypes to use in future breeding programs. The field experiment was conducted in a simple lattice design at Rubona Research Station, and 10 traits were studied. The descriptive results identified the umuceri genotype with very slight senescence, indicating its possible tolerance to drought. Among collection origins, the Ruhango district recorded the highest diversity index of 0.81 (tillering capacity). For all genotypes, Shannon-Weaver results showed nine polymorphic traits, with tillering capacity (0.96) having a high diversity index. The genotypes showed a diversity index ranging between 0.51 (midrib color) and 0.91 (inflorescence shape) within the collection origins and between 0.09 (inflorescence shape) and 0.49 (midrib color) among the collection origins. Principal component analysis revealed four major components explaining 78.64% of the total variation. Clustering analysis grouped the 36 sorghum genotypes into five main clusters, showing the genotype Umuceri being the most distant and potentially valuable for future sorghum improvement programs.