DETERMINING YELLOW-FLESH INTENSITY IN POTATOES

For the yellow-flesh fresh market, potato (Solanum tuberosum L.) varie ties with intense yellow flesh are desired. Twenty-five yellow-flesh c lones, including 24 U.S. Dept. of Agriculture (USDA) selections and th e check variety 'Yukon Gold', were evaluated for tuber yellow-flesh co lor, as measured by a reflectance colorimeter, and for individual tube r weight in replicated field trials in Presque Isle, Maine, in 1991 an d 1992. There were significant differences among clones for yellow-fle sh intensity. Yellow-flesh intensity in two USDA selections was signif icantly less than in 'Yukon Gold'. In four USDA selections, yellow-fle sh intensity was significantly greater than in 'Yukon Gold'. In genera l, there was an inverse relationship between tuber weight and yellow-f lesh intensity. Subsamples of tubers whose weight fell between the 10 to 90, 25 to 75, 35 to 65, and 40 to 60 percentile were compared to th e full sample. There was good agreement between the 10 to 90 and 25 to 75 percentile subsample and the full sample regarding the average yel low-flesh intensity and in the consistency of pairwise comparisons bet ween individual selections and 'Yukon Gold'. For determining yellow-fl esh intensity, the 25 to 75 percentile subsample was as informative as the full sample.