OAT GRAIN BETA-GLUCAN CONTENT AS AFFECTED BY NITROGEN LEVEL, LOCATION, AND YEAR

Beta-glucan is a hypocholesterolemic water-soluble fiber component of oat (Avena sativa L.) grain. Despite beneficial physiological effects associated with beta-glucan, few data are available on the effects of environment on beta-glucan content. The objective of this study was to examine the effect of N fertilizer, location, and year on oat grain beta-glucan concentration. Plantings were made at East Lansing and Caro, MI, in 1987, 1988, and 1989. The experimental design was a split plot with three replications. Whole plots consisted of each of three N levels (0, 37, and 74 kg ha-1), and subplots consisted of five oat cultivars (Heritage, Korwood, Ogle, Pacer, and Porter). Increased levels of applied N tended to increase groat beta-glucan content. No significant differences in mean beta-glucan concentration were found between locations or among cultivars used in the study. Beta-glucan concentration was affected by year, with lowest mean values in 1988, intermediate concentrations in 1987, and highest values in 1989. Cultivar x year and cultivar x location interactions were significant. Correlations between beta-glucan content and test weight, hull percentage, grain yield, or groat weight were mostly small or nonsignificant. Correlations between groat protein and groat 5-glucan were significant, relatively large and positive in 1987 and 1989, but were nonsignificant in 1988. The results of this research indicate that environment, especially soil N and year-to-year climatic variability, is important in determining oat grain beta-glucan concentration.