Association Analysis for Different Morphological Traits in Sorghum [Sorghum bicolor (L.) Moench] of the Central Plateau Zone of Rwanda

Sorghum has the largest share of cultivated land for cereal crops in Rwanda, but the productivity is low due to many constraints, including drought stress and the unavailability of adaptable cultivars with high yields. However, direct selection of genotypes for yield might not be successful since yield is a complex trait controlled by many genes and subjected to high interaction between genotype and environment. This study therefore was carried out to estimate the associations among traits and to determine the direct and indirect effects of traits on the grain yield of sorghum genotypes. Thirty six sorghum genotypes were evaluated for 12 quantitative traits in simple lattice design at Rubona Research Station of the Rwanda Agricultural and Animal Resources Board in 2019. Grain yield had positive and significant genotypic and phenotypic correlations with the number of kernels per panicle, panicle weight, aboveground biomass, inflorescence width, harvest index, leaf area index, and days to 50% flowering. Moreover, aboveground biomass, harvest index, panicle weight, inflorescence width, and leaf area index had direct positive effects on grain yield both at genotypic and phenotypic levels, showing the true associations of the traits with grain yield and indicating that the indirect selection of these traits can be applied to improve grain yield. The results of this study revealed the potential for simultaneous improvement of grain yield and other yield components through selection. Thus, it is concluded that the four traits (aboveground biomass, head/panicle weight, inflorescence width, and leaf area) are suggested for the selection of sorghum genotypes for high yield in the study area of Rwanda.