Some data on the resistance against the potato root-eelworm (Heterodera rostochiensis W.) in Solanum kurtzianum

Abstract

Some local races of the potato root eelworm Heterodera rostochiensis W. show a high degree of reproduction in the roots of CPC 1673-offspring which had been provisionally found to be resistant. Therefore search has been made for new starting material with protection against such races.

The foregoing sub-races are being classified in race B; the populations which are not capable of reproduction in the roots of CPC 1673 are classified in race A.

Varieties of the diploid species Solanum kurtzianum have been included in the investigations. This species belongs to the series Tuberosa and has its habitat in North-Argentina. Its resistance is based on two dominant polymeric factors. The classification of seedlings of the crosses between Sol. kurtzianum and susceptible cultivated diploid species (Sol. goniocalyx and Sol. stenotomum) presents no difficulties because transitional types as concerns cyst coverage are lacking.

Examinations of the behaviour of a number (42) of B-provenances of the parasite have shown that 35% of them is able to attack the resistant kurtzianum-hybrids heavily. From this it can be concluded that the race B can be divided into two subraces which provisionally are indicated as race B₁ and race B₂.

No difficulties are encountered in including Sol. kurtzianum in the breeding work. Seeds of the first backcross generation are at our disposal.

A potato variety harbouring the genes for resistance derived from CPC 1673 and Sol. kurtzianum would be resistant against approx. 90% of all the strains of the parasite in the Netherlands. This condition of a combination of the two genes is necessary because it is still unknown whether Sol. kurtzianum is resistant against all A-populations of the parasite.