INFLUENCE OF NITROGEN, PHOSPHORUS AND POTASSIUM ON THE COOKING QUALITY OF POTATOES

Abstract

In general, the dry matter content (as indicated by specific gravity) of Katahdin potatoes grown on seven different soils in 1955 and 1956 was sometimes increased by phosphorus, slightly decreased by nitrogen, and consistently decreased by potassium chloride fertilizer applications. On the other hand, the consumer preference index (based on a sensory evaluation of the texture, flavour and colour of the cooked tubers by a panel of three judges) was increased by both phosphorus and potassium chloride applications and was variable for nitrogen. Because potato cooking quality is the summary effect of the texture, flavour and colour of the cooked product, the consumer preference index should be a better measure of this quality than the dry matter content, which refers only to the textural component. The differences, i.e. increases or decreases in dry matter content or consumer preference index due to fertilizer treatment, were small in relation to those associated with differences in soils and weather. However, chemical fertilizers may have a marked effect on the yields obtainable.