Evaluation and utilization of diploid and tetraploid potato germplasm

Five Tuberosum haploid x species hybrid populations were evaluated for agronomic and reproductive characters in two Wisconsin environments. Significant variation was found among Tuberosum haploids and species for tuber yield, haulm maturity, specific gravity and chip color. The species Solanum sparsipilum, Solanum chacoense, Solanum berthaultii, and Solanum tarijense influenced acceptable scores for Specific gravity and chip color in progenies.; Phenotypic recurrent selection for 2n eggs was performed in a base population of 24-chromosome hybrids between Tuberosum haploids and the species S. berthaultii, S. bukasovii, S. chacoense, S. infundibuliforme, and S. sparsipilum. 2n egg frequency was determined by seed set in 2x x 4x crosses. After one cycle of recurrent selection, the population mean was increased by 24.4%. The narrow sense heritability calculated by parent-offspring regression was estimated at 0.47. Further, clones were identified that produced 31-61 seeds/berry in 2x x 4x crosses.; The frequency and variability of 2n egg production of seven clones was evaluated by seed set per berry in 2x x 4x crosses during two years. Significant differences for number of seeds/berry were detected among the clones. The feasibility of hybrid seed production by open pollination was demonstrated by interplanting diploid clones that produce only 2n eggs and diploid clones that produce 2n pollen.; Five populations generated by intercrossing commercial tetraploid varieties to selected clones of the University of Wisconsin Potato Breeding Program, were evaluated under transplanting conditions in two Wisconsin environments for reproductive and agronomic traits. There were significant differences among populations for haulm maturity, weight of tubers per plant and number of plants at harvest. The most heterozygous population performed better than the others for weight of tubers per plant and number of plants at harvest.; Thirty-six clones, selected from nine tetraploid haploid-species x haploid-species hybrid families and three commercial varieties were evaluated in two Wisconsin environments for agronomic and processing traits. Some clones outperformed two of the varieties for yield of tubers per plant, specific gravity, maturity and chip color.