Chemical composition of potatoes. VIII. Effect of variety,location, and year of growth on the content of nitrogen compounds

Free amino acid content, total nitrogen, extractable nitrogen, ratio of extractable to total nitrogen, solids content, and specific gravity in Cobbler, Katahdin, Kennebec, Red Pontiac, and Russet Burbank potatoes was studied. Each variety was grown in six different locations (Idaho, Maine, Pennsylvania, Wisconsin, Long Island, and the Red River Valley) during the years 1961 through 1963. The mean values for each factor, with significant differences indicated, are listed along with the high and low range, the coefficient of variation and the overall mean. The percent of total variance contributed by each of the variables and their interactions also are listed. Long Island potatoes had the highest nitrogen and amino acid content. Varietal differences were less significant. Proline was the most variable of the constituents measured. Aspartic and glutamic acids had the highest variability with respect to years grown. The effect of each variable varies from one constituent to another.