Genotype × environment interaction of potato chip colour

Ten potato genotypes were tested in replicated trials over three sites in New Brunswick. Five of them were tested in 1991, 1992 and 1993, and another five in 1992 and 1993. Tubers were harvested and put in storage rooms with two temperature regimes: 7 °C and 13 °C. Prior to testing glucose content and chip colour, a portion of tubers stored in 7 °C was sampled and subjected to reconditioning for 2 and 4 wk in a storage room with the temperature regime of 21 °C. High relative humidity (>80%) was maintained in all storage rooms. Glucose and colour score of chips were determined during November in each of the three years. Analysis of variance revealed genotype × environment interactions for both traits. Since variation of chip colour is controlled primarily by glucose content in potatoes, this causal relationship was used as a basis to perform path regression analysis for each of the genotypes, based on all available data of the two traits. The regression equation is composed of two terms: an average chip sc...