Yield stability analysis of promising potato clones in mid and high altitude regions of Kenya

Eleven promising potato clones possessing late blight tolerance were evaluated for tuber yield performance, stability and adaptation across ten environments of medium and high potential potato growing regions of Kenya. Results of combined analysis of variance for tuber yield showed significant effects of genotypes, environments, and genotype by environment interaction. The mean tuber yield for individual clones ranged from 22.80 to 37.63 t ha-1. When the genotypic tuber yields were subjected to stability analysis against an environmental index, the regression coefficients for individual clones ranged between 0.427 and 1.687. Among the clones tested, KP90188.3 was the most stable genotype across all the ten environments, while four of the highest yielding clones; 387792.5, 378699.2, 381381.20 and 381381.13 appeared to be specifically adapted to favourable growing conditions. Two clones, 381381.13 and 381381.20 exhibited mean superior performance in yield across all environments, and were pre-released in 1996 pending multiplication of sufficient quantities of seed.Onze clones prometteurs de pomme de terre ayant une tol\ue9rance au mildiou ont \ue9t\ue9 \ue9valu\ue9s pour performance en rendement des tubercules, la stabilit\ue9 et l'adaptation dans dix environnements \ue0 potentiel moyen et \ue9lev\ue9 pour la production de la pomme de terre au kenya. Les r\ue9sultats de l'analyse combin\ue9e de la variance du rendement en tubercules ont mis en \ue9vidence des effets significatifs des g\ue9notypes, des environnements, et de l'interaction entre g\ue9notype et environnement. Le rendement moyen en tubercules pour les clones individuels varie de 22, 8 \ue0 37, 6 t ha-1. Lorsque les rendements g\ue9notypiques de tubercules \ue9taient soumis \ue0 l'analyse de la stabilit\ue9 contre un indice environnemental, les coefficients de r\ue9gression pour les clones individuels variaient de 0, 427 \ue0 1,687. Parmi les clones test\ue9s, KP 90188.3 \ue9tait le g\ue9notype le plus stable dans tous les environnements, alors que quatre des clones 387792.5, 378699.2, 381381.20 et 381381.13 semblaient sp\ue9cialement adapt\ue9s aux conditions favorables de croissance. Deux clones, 381381.13 et 381381.20, ont montr\ue9 une performance moyenne sup\ue9rieure \ue0 travers tous les environnements. Ils \ue9taient pr\ue9-diffus\ue9s en 1996 en attendant la multiplication des quantit\ue9s suffisantes de semences