The relation between length of growing period and cooking quality of potatoes

Abstract

1. The scoring system, designed by the Working Group “Potato Quality Research” of the European Association for Potato Research has proved valuable in defining differences in quality properties in potatoes of varying ripeness. 2. Colour and discoloration of cooked potatoes were barely influenced by dates of planting or lifting. 3. Both lifting and planting date influenced texture properties of the varietyLibertas grown on sandy soild in Drenthe. The influence of lifting date was often curvilinear. This curvilinearity was not observed in the influence of planting date (fig. 1 and 2). 4. Interactions were present between “field” and planting date and “field” and lifting date (fig. 4), which means that the influence of these dates varied from field to field. Furthermore, there was an interaction between planting date and lifting date (fig. 3), indicating that the influence of lifting date on texture properties became greater the later was the planting date. Consequently the chance that potatoes are insufficiently mealy by reason ofe.g. an early and severe attack of blight is greater if the farmer has been forced to plant very late. 5. If planted at the normal time (April) and lifted at the normal time (not before the second half of September) the texture properties of the highly blight-resistant varietyLibertas will not deviate much from “normal” (fig. 5). Other varieties will require growing periods of different length, but blight susceptibility will be more important in determining the actual length of the growing period required.