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Doctor of Philosophy




An accumulating body of evidence suggests that breeding oats (Avena sativa L.) for high groat (caryopsis)-oil content may be well advised agriculturally, possible biologically, and efficacious economically;Four studies have provided information pertinent to an oat breeding program for high oil content and for fatty-acid composition of the oil. (1) The relative importance of genotype x environment interaction for groat-oil content and grain yield and the correlations of oil content with yield and maturity were evaluated for a sample of oat cultivars grown at three Iowa locations in each of two years. (2) Heritabilities and inheritance patterns of palmitic, oleic, linoleic, and linolenic acids were studied in six matings among adapted cultivars. (3) A generation means analysis of four matings among adapted cultivars was used to study the inheritance of three fatty acids and total oil content. (4) F(,2) plants from 12 (3 x 4)-factorial matings between high-oil A. sativa and high oil A. sterilis (L.) parents were grown to identify transgressive segregates;Environment x genotype interaction effects were small relative to genotype effects for fatty-acid composition and total oil content. The interaction effects were smaller for total oil than for grain yield. Correlations of groat oil with grain yield were 0.62* and 0.63* and with maturity they were -0.28 and -0.48. Fatty acid heritabilities were moderate on the basis of single plots and high using progeny-mean data. Palmitic, oleic, and linoleic acid inheritances were polygenic. Additive genetic effects were the most important component of generation means for content of the three fatty acids and total oil. However, in matings between parents with similar levels of these traits, both different alleles and gene interactions conditioned similar parental phenotypes. F(,2)-progeny means were similar to the midparent value in all but two interspecific matings. Lines that may represent significant transgressive segregation for both high and low groat-oil content were found in the interspecific matings, evidence that the high-oil parents from the two species carry different alleles for this trait;One cycle of recurrent selection has shown a genetic gain estimated to be between 1.7 and 2.1% in oil content. The groat-oil content of selected individuals for the second cycle ranged from 9.5 to 12.5%. This research is being continued at the Iowa Agricultural Experiment Station.



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Ann Marie Thro



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150 pages