To understand the abnormalities of potatoes, we must first understand what is normal and what the healthy development of potatoes should look like. Tuber initiation refers to the time at which tubers begin to swell at the end of rhizomes. The exact timing will depend on location, planting date, climate, soil type and cultivar.
Tubers form when the plant produces more carbohydrates than what is needed for top growth.
Varying conditions can affect the plants causing a deficit of carbohydrates and resulting in uneven tuber formation. It is believed that many of the small tubers originally set are used by the growing plant as a source of nutrients or absorbed by larger tubers. Optimum moisture and nutrient levels are therefore important for the maintenance and development of tubers very early in the growing season. Fluctuating temperatures, moisture, and level of nitrogen, especially in the tuber development stage can cause malformed tubers. An over-application of N can delay maturity by up to 15 days, which may be critical in Saskatchewan, considering our short growing season.