COMPARISON OF GROWTH AND TUBER DEVELOPMENT IN THREE POTATO CULTIVARS WITH DIVERSE CANOPY SIZE

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Abstract
The basis of differences in tuber and plant development in potato, due to differences in canopy size, was studied by measuring changes in plant dry weight and leaf area throughout the growing season. Differing canopy sizes were obtained by selecting three cultivars from the Canada Potato Breeding Program. These were F57048, Grand Falls, and F62008, which normally produce small, medium and large sized canopies respectively, with similar tuber yields. Differences in total and tuber dry weight through the season were slight compared to differences observed in leaf and stem growth. The branching capacity of the cultivars appeared to be the major determinant of canopy size. In these three cultivars, as canopy size increased, the initial tuber growth rate immediately following tuberization decreased. Thus, in the two smaller cultivars, the early tuber growth rate was more critical in determining final yield than was the case in the large-canopied cultivar, F62008. As expected, the net assimilation rate increased as canopy size decreased. The evidence indicated that the demands of the developing tubers exerted the greatest influence on the net assimilation rate.