. 2008. Genotype by environment interaction effect on yield and quality of potatoes. Can. J. Plant Sci. 88: 1099Á1107. Colour is an important character in the processing of potatoes for French fries. French fry colour is closely associated with sugar content in the tuber. This study examines the stability of yield, sugar content and French fry colour for eight potato cultivars and advanced selections in four environments. Stability was determined using three approaches based on the Eberhart-Russell, Tai and GGE Biplot analyses. The GGE Biplot analysis provided a better characterization of stability than the other two analyses. The most stable and best performing genotypes for both French fry colour and total sugars were Russet Burbank and Umatilla Russet. Cal White had high yield and yield stability but had average stability for poor (dark) French fry colour. The GGE biplot analysis was able to identify megaenvironments and those environments which optimized differentiation between genotypes. Both factors are important for the optimization of resources for testing new genotypes. Stability for quality factors in potato can be as important or more important than yield for some processing uses. In this study, genotypes with stability for sugar content and French fry colour were identified and these may be used as parents in breeding for stability.Key words: Potato, yield stability, quality, French fry Affleck, I., Sullivan, J. A., Tarn, R. et Falk, D. E. 2008. Interaction du ge´notype et de l'environnement, et incidence sur le rendement et la qualite´des pommes de terre. Can. J. Plant Sci. 88: 1099Á1107. La couleur est une importante caracte´ristique pour la transformation des pommes de terre en frites. La couleur des frites est e´troitement lie´e a`la concentration de sucre dans le tubercule. Cette e´tude porte sur la stabilite´du rendement, la teneur en sucre et la couleur des frites de huit cultivars et se´lections avance´es de pomme de terre dans quatre milieux. La stabilite´a e´te´e´tablie de trois fac¸ons d'apre`s les analyses de Eberhart-Russell, de Tai et a`double projection GGE. L'analyse a`double projection GGE caracte´rise mieux la stabiliteq ue les deux autres me´thodes. Les ge´notypes les plus stables et les plus performants en ce qui concerne la couleur des frites et la concentration totale de sucre sont Russet Burbank et Umatilla Russet. Le ge´notype Cal White a un rendement e´levet re`s stable, mais la pie`tre couleur (fonce´e) de ses frites est mode´re´ment stable. L'analyse a`double projection GGE permet d'identifier les me´ga-environnements et les environnements qui optimisent la diffe´renciation des ge´notypes. Ces deux e´le´ments reveˆtent de l'importance si l'on veut optimiser les ressources pour tester de nouveaux ge´notypes. La stabilite´des facteurs de qualite´chez la pomme de terre a parfois autant sinon plus d'importance que le rendement, selon la destination des tubercules en transformation. La pre´sente e´tude identifie les ge´notypes dont la concentration en sucre et la couleur des fri...

Affleck, I., Sullivan, J. A., Tarn, R. and Yada, R. 2012. Stability of eight potato genotypes for sugar content and French fry quality at harvest and after storage. Can. J. Plant Sci. 92: 87–96. Processing quality of potatoes for French fries is partially determined by reducing sugar content of the tuber. Much of the potato crop is processed after a storage period when sugar content can change and affect processing quality. In this study, the stability of sugar levels in eight potato genotypes was studied over four environments (i.e., two locations over 2 yr). The GGE biplot analysis was used to measure the stability of, and the association between, quality traits and sugar content. Quality and sugar content were measured 105 and 120 d after planting and 60 and 120 d after storage. The biplots indicated a change in French fry colour scores and stability between the 105 and 120 d after planting harvest dates. Genotypic differences were noted for French fry colour scores and glucose content. Genotypes were identified that were stable for French fry colour during the two storage periods indicating low genotype by environment interaction. The GGE biplot identified mega-environments that encompassed a group of environments with similar attributes. Based on this finding potatoes from only one environment within the mega-environment would need to be stored for quality evaluations.