Summary: | Inbreeding depression (ID) is caused by increased homozygosity in the offspring after selfing. Although the self-compatible, highly heterozygous, tetrasomic polyploid potato (<i>Solanum tuberosum</i> L.) suffers from ID, some argue that the potential genetic gains from using inbred lines in a sexual propagation system of potato are too large to be ignored. The aim of this research was to assess the effects of inbreeding on potato offspring performance under a high latitude and the accuracy of the genomic prediction of breeding values (GEBVs) for further use in selection. Four inbred (S<sub>1</sub>) and two hybrid (F<sub>1</sub>) offspring and their parents (S<sub>0</sub>) were used in the experiment, with a field layout of an augmented design with the four S<sub>0</sub> replicated in nine incomplete blocks comprising 100, four-plant plots at Umeå (63°49′30″ N 20°15′50″ E), Sweden. S<sub>0</sub> was significantly (<i>p</i> < 0.01) better than both S<sub>1</sub> and F<sub>1</sub> offspring for tuber weight (total and according to five grading sizes), tuber shape and size uniformity, tuber eye depth and reducing sugars in the tuber flesh, while F<sub>1</sub> was significantly (<i>p</i> < 0.01) better than S<sub>1</sub> for all tuber weight and uniformity traits. Some F<sub>1</sub> hybrid offspring (15–19%) had better total tuber yield than the best-performing parent. The GEBV accuracy ranged from −0.3928 to 0.4436. Overall, tuber shape uniformity had the highest GEBV accuracy, while tuber weight traits exhibited the lowest accuracy. The F<sub>1</sub> full sib’s GEBV accuracy was higher, on average, than that of S<sub>1</sub>. Genomic prediction may facilitate eliminating undesired inbred or hybrid offspring for further use in the genetic betterment of potato.
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