INTRODUCTION

A method has been developed for growing commercial-type potatoes from true potato seed (TPS) sown directly into fields. The productivity, quality and uniformity of such crops are usually inferior to those of tubergrown crops; however, plants superior in many important characteristics can be selected for subsequent clonal evaluation. Direct-seeded TPS populations are exposed to diseases, pests and cultural or environmental stresses and selected for resistance. The full-grown, mature tubers produced can be selected for type, productivity, quality, handling, storability and processing characteristics. Tubers from selected seedlings provide normal-size seedpieces that are planted as single tubers or in replicated plots for evaluation in the first clonal generation. This first clonal generation is again exposed to a wide range of selection pressures. This contrasts with single hills normally grown from pot-grown tubers where over 99% of the genetic potential of segregating populations is discarded based on cosmetic attributes of tubers from single hills grown from tiny, variable-sized seed tubers under minimal stresses and selection pressures. This new method provides more information about each clone and increases the chances of finding and saving valuable genotypes.

PROCEDURE FOR DIRECT SEEDING TPS

During the past nine years crops have been grown annually from TPS sown directly into fields in eastern Washington and Oregon (Martin 1978a, 1983a,b). They have been grown on soils ranging from light sandy, through various loams to heavy clay, using either sprinkle or furrow irrigation.