Selection of diploid potato genotypes that produce high frequencies of 2n-pollen grains in different environments is an important requirement for analytic breeding as well as for true potato seed production. In this context, quantitative estimates of 2n-pollen formation were made in two type of diploid potato populations. One population set consisted of the progeny from diallel crosses of five well-known diploid potato clones (A=US-W 5293.3, B=US-W 5295.7, C=US-W 5337.3, D=US-W 7589.2 and E=772102-37). Another population set was obtained by pollinating three genotypes of Solanum phureja, IvP35, IvP48 and IvP101 with clones A, C and E. It was observed that the behaviour of the parental clones with respect to 2n-pollen grains formation in different environments, such as in Europe and China, was stable. The correlation coefficient between means of 2n-pollen grains frequency of combinations and percentage of genotypes with more than 5% 2n-pollen grains in a given combination were estimated and that between mean and maximum frequency of 2n-pollen grains formation in each combination. The results showed that the former coefficients were significant wheareas the latter were not. The combining ability analysis revealed variation in 2n-pollen grains formation between families. Specific combining ability (SCA) effects contributed much more than general combining ability (GCA) to the variation in 2n-pollen grains formation. The broad-sense heritability of 2n-pollen grains formation was estimated to vary between 0.45 and 0.53 and the narrow-sense heritability was calculated to be 0.15 and 0.20 in the two types of populations. This means that additive variance was relatively low. Two to four genes were estimated to control the inheritance of 2n-pollen grains formation.
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