Selection for high [beta]-glucan content in oat grain
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Oat (A. sativa L.) beta-glucan lowers serum cholesterol in humans when is consumed in the daily diet. Development of oat cultivars with greater groat beta-glucan content would increase the nutritional and economical value of the crop. The first objective of this study was to determine the progress from phenotypic selection of individual So plants for high beta-glucan content in two oat (Avena sativa L.) populations. The second objective was to determine the predominant gene action for beta-glucan content and to estimate changes in genetic variances and broad sense heritability in those populations. The third objective was to estimate the correlated response of unselected agronomic and grain quality traits and genetic covariances and correlations between these traits and beta-glucan content in the same populations;The initial (C0) and selected (C1) generations of two genetically broad-based oat populations, IABG1 and IABG2, were evaluated in a field experiment in 1996 and 1997 at two Iowa locations. Mean beta-glucan content increased 5.9 g kg-1 and 2.6 g kg-1, and the genetic variance decreased 9.3% and 21.8%, following selection in IABG1 and IABG2. Heritability estimates ranged from 0.49 to 0.65 on a sample-basis and from 0.80 to 0.88 on a line-mean basis. Additive variance was the only substantial component of genetic variance. Genotype-by-environment interaction was significant. However, ranking of S0:1 lines for beta-glucan content across environments was generally consistent, with correlations of genotypic beta-glucan contents ranging from 0.63 to 0.82 across pairs of environments. Phenotypic selection for high groat beta-glucan content will be effective to develop cultivars with elevated levels of beta-glucan;Mean yield, biomass, and test weight were significantly reduced by 19, 17, and 2%, respectively, in IABG2, and were not affected in IABG1. Mean protein content significantly increased by 4.9% in IABG1, whereas the mean oil content and heading date did not change in any population. The genotypic variance of all traits was not affected, except for that of plant height, which increased in IABG2. Selection increased negative genetic correlations of beta-glucan content with yield, biomass, and oil content in both populations, and with heading date and height in one population.