Ten yellow-fleshed cassava genotypes and two released cassava varieties (check) were evaluated in two agro-ecological zones of Nigeria to access their yield performance, agronomic parameters and genotypes by environment interaction effects. The study was conducted in 2017 and 2018cropping seasons at Umudike (humid rainforest)and Otobi (derived savanna), the trials were conducted in a randomized complete block design (RCBD) with three replications. The combined analysis of variance reveal that there were significant differences among the genotypes for root number (RTNO), root weight (RTWT), cassava mosaic disease severity (CMDS). There was significant difference for cassava anthracnose disease severity (CADS) and genotype x environment interaction for cassava mosaic disease severity (CMDS) at P<0.001.Similarly, highly significant differences were also observed across locations, among genotypes for fresh root yield (FRY), dry matter content (DMC), dry root yield (DRY) and significant genotype x environment interaction for DMC and DRY; across locations for DMC and DRY at P<0.001.The convex-hull drawn from the biplot origin gave 4 sectors with NR070220, NR150025, NR150008 and NR150014 as the vertex cultivars. NR070220 was the vertex and the winning variety in Umudike. NR150025 was the winner in the second mega-environment at Otobi while NR150008 and NR150014 are winner in both (Umudike and Otobi) meaning that these cultivars are the best in these environments. Genotypes NR150025 had the highest FRY of 30.30 t/ha while the lowest value of 3.20 t/ha were recorded for genotype NR150040. Genotype NR150113 had the higher DMC of 37.93% while genotype NR150105 recorded the lowest DMC of 18.13%.Genotypes NR150113, NR150008 and NR150025 had the highest DMC, five genotypes has DMC higher the mean. Also, six genotypes had root yield better than the check indicating need to promote such genotypes in the breeding cycle.

Keywords: Agronomic parameters, biofortification, cropping season, multilocational trial, yellow flesh cassava