Breeding for Resistance To the Potato Root Eelworm in the

Abstract

A review of research and breeding work on resistance to the potato root eelworm (Heterodera rostochiensis) is given. Though in the Netherlands a start with this work was made in 1946, it lasted until 1951 before it could be developed successfully, owing to the discovery of the resistance in S. andigenum. Breeding work was relatively simple on account of a clearly defined difference between resistant and susceptible seedlings. Resistance proved to be dominant. Some complications arose because S . tuberosum as well as S. andigenum are tetraploid. Introduction of resistant genes is easy, but combining resistance with other desirable features is a very arduous task. For the execution of the breeding programme the method of repeated backcrossing is used. Private breeders were involved by a large-scale distribution of seeds derived from crosses with resistant seedlings. The nature of the resistance is discussed. No positive indications of the occurrence of physiological races of the eelworm have been found, but the assumption of such a possibility makes the broadening of the basis for resistance desirable.