TEMPERATURE AND OTHER FACTORS AFFECTING THE REST PERIOD OF POTATO TUBERS

Abstract

The storage of potato tubers at an average temp. of 30[degree]-35[degree] C. for 4 weeks was effective in breaking the rest period. Potatoes stored in a barn loft during July at about 30[degree] C. gave a good sprouting, while those stored in a cellar at 20[degree] C. made a much slower start. Potatoes from the loft storage planted in warm (25[degree] C.) soil were not further stimulated by chemical treatment, indicating that the rest period was completed. The size of tuber from which the seed piece was cut influenced the rate of sprouting. One-ounce clipped tubers grew more slowly than 1-ounce pieces cut from 4-ounce tubers from the same hill. Soil temp. of 25[degree]-30[degree] C. gave more rapid germination than 20[degree]-25[degree] C. Available N increased the rate of sprouting of pieces in the rest period but did not affect non-dormant tubers. Low humidity in storage gave a shorter rest period for a given temp., but resulted in injury from the long exposure. Any shriveling in storage was followed by heavy rot losses on planting; completely dormant pieces also rotted, particularly when planted whole.