Although potato breeding strategy must take account of new developments such as in vitro tissue culture, somatic fusion, dihaploids and true potato seed, further improvements still need to be made in the classical techniques, including the selection of parents, the choice of crosses, and hybridization and selection of resulting progeny. This report discusses selection in early generations.

It is well known that the identification of desirable genotypes is complicated by variability in yield and other characters due to such factors as year, location, agronomy and experimental method. These environmental factors affect all stages in the breeding programme but are a particular problem in the early stages when there is no replication and only 1–10 plants per clone; nevertheless 99% of the initial population is discarded at this stage in the Omsk programme.

The influence of year, agronomy, variety and plant spacing on yield, starch content and protein content of individual tubers has been studied. Overall, genotype had a greater influence on starch content than on yield and protein content. There was a close correlation between protein content and fertilizer treatment. The correlations between first tuber generation, or A clones, and second tuber generation, or B clones, varied between r = -0.014 and r = +0.301 depending on the character (Table 1).