The assessment of the tolerance of partially resistant potato clones to damage by the potato cyst nematode Globodera pallida at different sites and in different years

A range of potato cultivars and clones was grown at three sites infested with Globodera pallida in each of four years (1983 – 1986). Comparison of yields from nematicide treated plots with those of untreated plots provided estimates of yield losses due to G. pallida. The proportional yield losses were calculated for each genotype at each site as a measure of nematode tolerance. There were significant differences between genotypes with regard to tolerance of damage by G. pallida. There were also significant interactions between the different genotypes and the sites and years, but the interactions between years and genotypes represented only a small proportion of the observed variation. The interactions between sites and years indicate that not all of the genotypes behaved consistently between sites and years. The extent of yield losses caused by the nematodes varied significantly between sites. The implications of these results are discussed in relation to potato breeding programmes and assessing resistance and tolerance to G. pallida.