Since the complementary action of Fg1 and Fg3 in producing kaempferol 2G-glucosyl-gentiobioside (Buttery and Buzzell, 1975) is associated with deleterious effects on chlorophyll concentration, photosynthetic rate and yield (Buttery and Buzzell, 1976), the bringing together of these two genes in crosses may necessitate selection against the Fg1-Fg3-genotype in the segregating material. For example, with the cross of 'Corsoy' (Fg1 fg3) x 'Hawkeye' (fg1 Fg3) at Iowa State University, visual selection was carried out against "chlorophyll deficient" types during inbreeding in order to develop lines for a physiological study. At the time of selection it was not known that flavonol-glycoside genes were involved. Advanced lines were later classified using thin layer chromatography (Buttery and Buzzell, 1973)