INTRODUCTION

The potato is the most important field crop for arable farming in the Netherlands. In the past 10 years the area under potato has varied from 160 000 to 173 000 ha. Well over 40% is used for the cultivation of ware potatoes, nearly 40% for starch potatoes and about 20% for seed potatoes. In each case a large part of the produce must be exported, either fresh or in processed form. The cost price therefore has to be low and the quality requirements high.

Breeding has done a great deal for farmers trying to meet these requirements. Furthermore, a comprehensive system of assessment of the value for cultivation and use has made it possible for new, improved, products of breeding to be identified rapidly, while on the basis of the same objective data the introduction of less promising entries has been prevented.

The importance of potato varieties in the Netherlands is demonstrated by the fact that 96 of the 262 recommended varieties of field crops which are registered in the Descriptive List of Varieties of Field Crops are potato varieties. A few of these 96 are grown on a very large area, and as many as 48 are grown on more than 500 ha and/or cover 100 ha for the production of seed potatoes (Anon. 1985; Daemen 1985).