published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

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Typescript, etc. / Digitized by Kansas Correctional Industries

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These studies compared giant hill strains of Russet Norkotah and Umatilla Russet to the parent varieties. Selections were initially based on late maturity and increased vine vigor. Subsequent evaluations emphasized yield and quality parameters in comparison to the parent varieties. Giant hills were collected from the Columbia Basin and Central Oregon in 1999. Seed was tested and increased in a greenhouse during the winter of 1999 and in the field in 2000. Clones were inspected for viruses and other diseases in both years. Replicated performance trials were conducted at the Hermiston Agricultural Research and Extension Center in the Columbia Basin and at the Central Oregon Agricultural Research Center, near Madras, in 2001. Trials were grown using commercial management practices common to the areas. Tubers from the Madras trial were retained for use in future plantings. Relative yields of Russet Norkotah strains differed drastically between sites even though the growing seasons were similar in length. Several Russet Norkotah strains preformed better than the parent variety at Madras when the strains achieved good vine growth and the parent variety did not. Vine growth was subnormal at Madras in 2001 primarily due to delayed emergence and the subsequent short growing season. Few performance differences and no advantages were evident when Russet Norkotah strains were grown in the Columbia Basin under conditions with less environmental stress than usual. All strains of Umatilla Russet grown under a long season in the Columbia Basin out-yielded the parent variety; however, many strains also produced a high percentage of malformed tubers. In general, Umatilla Russet strains failed to produce adequate yields and tubers of acceptable size when delayed emergence shortened the growing season at Madras. At Madras, strains of Umatilla Russet with high biomass tended to have lower yields while strains of Russet Norkotah with high biomass tended to have high yields. Some strains performed better than the parent varieties at the two trial sites. Superior strains have been submitted to the Oregon Potato Variety Development Program and Oregon Foundation Potato Seed Project for further evaluation. / Graduation date: 2002

Thesis (Ph. D.)--Swedish University of Agricultural Sciences, 2001. / Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references.

Thesis (Ph. D.) in Plant Science--University of Maine, 2000. / Includes vita. Includes bibliographical references (leaves 147-160).