Genotype x environment interaction and stability analysis of agronomic traits in cassava (Manihot esculenta crantz) using AMMI model

Abstract

This study investigated the genetic architecture and stability of important agronomic and physiological traits in 224 cassava (Manihot esculenta Crantz) genotypes evaluated across six environments in Nigeria. The trials were conducted during the 2015 and 2016 cropping seasons in three agro-ecological zones: Umudike (rainforest, Abia State), Otobi (derived savanna, Benue State), and Minjibir (semi-arid, Kano State). The genotypes, comprising improved breeding lines and locally adapted landraces, were assessed using a randomized complete block design with three replications per environment. Analysis of variance revealed substantial phenotypic variation among genotypes, with coefficients of variation ranging from 21.8% to 89.03%. Broad-sense heritability estimates were high for starch content (H² = 0.68) and fresh root weight (H² = 0.61), indicating strong potential for effective selection. In contrast, dry matter content (H² = 0.27) and plant vigour (H² = 0.36) were more strongly influenced by environmental factors. Additive Main Effects and Multiplicative Interaction (AMMI) analysis identified significant genotype × environment interactions for all evaluated traits, including plant height, leaf retention, scar level, stomatal conductance, and fresh root weight. The first two interaction principal component axes accounted for most of the interaction effects, demonstrating good model performance. Genotypes NR060251 and AR945 exhibited high stability and broad adaptation across environments,whereas other genotypes showed specific adaptation. The findings highlight starch content and fresh root weight as priority traits for achieving rapid genetic gain and provide valuable insights for developing high-yielding and stable cassava cultivars.