Comparison of three recurrent selection regimes for increasing groat-oil content of oat
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.