Evaluation of genetic variability for major agro-morphological and stalk sugar traits in African sorghum genotypes

The study aimed to assess one hundred and twelve (112) accessions of sorghum sourced from Nigeria and other four African countries for their genetic variability, heritability (broad sense) and genetic advance components to identify promising accessions with high grain yield and sweet stalk which can serve as future parents for breeding dual-purpose lines. The accessions were evaluated at Ilora, Oyo State, Nigeria in a randomized complete block design (RCBD) layout with three replicates in two planting seasons (2020 and 2021). The results showed that the phenotypic coefficient of variation (PCV) was higher than the genotypic coefficient of variation (GCV). The highest PCV and GCV were grain yield (51.89%) and inflorescence length (42.26%), respectively, while a hundred seed grain weight had the lowest PCV (17.83%) and GCV (21.55%). The range of genetic advance over mean (GAM) was 28.33% for leaf width and 81.62% for inflorescence length. Inflorescence length had the highest values of heritability and GAM (0.88, 81.62%), while a low value was obtained for grain yield (0.27, 29.32%). Twenty-two accessions had higher grain yields than the yields of check varieties. The high-yielding accessions, SG57, SG31, SG06, and SG12 had grain yields of 3.07 t/ha, 2.89 t/ha, 2.76 t/ha and 2.73 t/ha, respectively. Fourteen accessions had wet stalks, of which 12 of the accessions had soluble stalk sugar (Brix) above 12%, which is comparable to the amount found in sweet sorghum. Three accessions with Brix above 12% (SG16, SG31, SG32) and high grain yields (2.32 t/ha, 2.89 t/ha and 2.02 t/ha) were identified as promising accessions. There is considerable genetic diversity among African sorghum accessions in Nigeria's southwest agroecosystem, which should improve food security and breeding potential.