A study of the factors influencing the improvement of the potato / by Edward M. East.

  • Edward Murray East
Date:
1908
Catalogue details

Licence: In copyright

Credit: A study of the factors influencing the improvement of the potato / by Edward M. East. Source: Wellcome Collection.

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    190S.] 10. VARIATION OF THE POTATO IN CHJiMICAL COM- POSITION AS A BASIS FOR ITS IMPROVEMENT In 1902 work was started to determine whether there were sufficient variations of the proteid content within a variety of potatoes to warrant selection of individuals high in protein to endeavor to raise the average protein content of the variety. It was expected later that this work would throw some light upon Jo- hannsen’s theory that in “pure lines” (self-fertilized lines), fluc- tuations regress completely to the mode of the pure line and not toward the mode of the general population. If this is true, abso- lutely no change could be made by selecting partial fluctuations. Johannsen’s work was not reported until after the results of these two seasons had been obtained, but the data are here reported just as it was collected in 1904. About two bushels of potatoes of uniform type were selected from a carload of the variety Rural New Yorker No. 2. They were all grown in the same county in Wisconsin, but it could not be definitely stated that they were all grown in the same field or upon the same type of soil although the latter is likely. They were of good appearance and average 223 g. in weight. The smallest potato used weighed 141 g. and the largest 328 g. Over one-half of the tubers varied less than 30 g. from the average. The table quality was good for the time of the year, it being the month of May. Total nitrogen, dry matter and specific gravity determinations were made on one hundred seventy-nine tubers. The total nitrogen was determined by the regular Kjeldahl method; dry matter by drying to constant weight at I04°C in a glycerol oven in a current of hydrogen; and the specific gravity by the weight in air and the weight in distilled water at 20°C. Considerable variation was shown in the content of the dry matter and the average was found to be very low for potatoes of such good quality. This condensed table shows the extent of the variation, the extremes being 15.18 percent and 28.27 percent. Table 14. Variation in Dry Matter in Rural New Yorker No. 2, Crop OF 1901 Dry matter, percent 15-16 16-17 17-18 18-19 19 20 20-21 21-22 Frequency 1 7 9 17 32 39 34 Dry matter, percent 22-23 2Z-2A 24-25 25-26 26-27 27-28 28-29 Frequency 18 11 3 5 2 0 1