It affects not only potato yield, but also the profitability of potato farming. Tuber set is influenced mainly by potato variety, physiological age of seeds, soil temperature, moisture, nutrition, daylight length and intensity, growth regulators, and diseases. Intermediate soil temperatures of 15-18 C are ideal for tuber set. Short days with high light intensity and lower temperature generally stimulate tuber initiation. Over-application of nitrogen can stimulate foliage growth and delay or inhibit tuber formation.
Growth regulators can increase tuber initiation.
The period of tuber initiation is fairly short and usually occurs 5 to 7 weeks after planting. During this stage, assimilates produced by the foliage are used for stolon growth and tuber initiation. The number of tubers formed per plant is called tuber set. Early in the season, a potato plant may form 20-30 tubers, however, only 5 to 15 mature tubers are normally found on each plant at harvest. Some of the small tubers that are initially set are used by the growing plant while the remaining tubers continue to grow until harvest.