Degree Type


Date of Award


Degree Name

Doctor of Philosophy



First Advisor

K. J. Frey


Recurrent selection has been conducted in various ways. In this study, three recurrent selection regimes for increasing groat-oil content of oat (Avena sativa L.) were compared. In regimes 1 and 2 selection was based on field- and greenhouse-grown S[subscript]0 plants, respectively, whereas in regime 3 selection was practiced among field-grown S[subscript]0 plants followed by selection among and within greenhouse-grown S[subscript]0:1 progenies. In a replicated experiment conducted over two years in the field and greenhouse, 48 oat lines were evaluated for groat-oil content. The results indicated that gain in groat-oil content from selection in the greenhouse would be 68% as effective as from selection in the field. The predicted annual gains in groat-oil content were 9.45, 4.57, and 11.58 g kg[superscript]-1 for regimes 1, 2, and 3, respectively. The actual response in groat-oil content to the three recurrent selection regimes was evaluated in a replicated field experiment grown at two locations. The annual gains were 6.04, 5.85, and 11.98 g kg[superscript]-1 for regimes 1, 2, and 3, respectively. Regime 3 was the most effective for increasing the groat-oil content. Gains for regimes 1 and 2 were not significantly different. A line was developed that had 162.85 g kg[superscript]-1 groat-oil. Significant genetic variation for groat-oil content was present in all cycles of selection, so continued progress from selection can be expected. A correlated increase in oil yield and decreases in grain yield, seed weight, and test weight occurred in regimes 1 and 3. The fatty acid composition of groat-oil changed significantly over cycles of selection in regime 1. The ratio of unsaturated to saturated fatty acids increased. A new regime that utilizes selection among field-grown S[subscript]0 plants, selection among and within replicated field-grown S[subscript]0:1 progenies, and a restricted selection index, was proposed.



Digital Repository @ Iowa State University,

Copyright Owner

Harm Schipper



Proquest ID


File Format


File Size

150 pages