Interaction of genotype and environment effects on important traits of cassava (Manihot esculenta Crantz)

General and specific environmental adaptation of genotypes is the main goal of breeders. However, genotype-by-environment (G × E) interaction complicates the identification of genotypes for release. This study aimed at analyzing the effects of G × E interaction on the expression of important cassava traits using two multivariate analyses: additive main effects and multiplicative interaction (AMMI) and genotype stability index (GSI). Total carotene content (TCC), postharvest physiological deterioration (PPD), and reaction to viral diseases were significantly affected by G × E interaction effects. The low percent (%) variation due to genotype for cassava brown streak disease (CBSD) explained the influence of environment on CBSD expression. The % variation due to genotype for TCC was higher (96%) than variation due to environment (1.7%) and G × E interaction (2.4%) indicating a low interaction effect of environment on TCC accumulation. The % variation due to genotype was higher than % variation due to environment for all traits but CBSD root necrosis and CBSD on stems, indicating the influence of environment on the severity of the viral diseases. These findings indicate that screening for disease resistance requires multi-environment trials, whereas a single-environment trial suffices to screen for total carotene content.