Evaluation location: Wisconsin, United States
Overlaid on these materials were investigations to determine the effects due to environment in which the tubers were produced, and tuber maturity differences resulting from longer storage. The default environment for tuber generation was randomized units in 6 inch clay pots in potting medium in either the winter greenhouse or summer screenhouse at USPG, with storage of 1 month or less at 5 degrees such that tubers were firm with no sprouting. The effects of various methods of sample preparation were also assessed. The default sampling technique was to place representative samples of washed whole tubers in self-sealing plastic bags, freeze at -20 degrees, thaw to room temperature, crush to express and homogenize juice, and measure pH in the bag with a "Hanna Instruments pH 210" processing meter using a Corning #476346 probe calibrated with 4.0 and 7.0 standard buffers. Unless otherwise noted below, these default tuber generation and preparation standards apply. Standard ANOVA and Pearson's correlation was used to assess the statistical significance of mean separations, and size and significance of paired observations, respectively.