Genetic and environmental variation in beta-glucan content and quality parameters of barley for food

High beta-glucan content is desirable in barley (Hordeum vulgare L.) for many food uses. The effects of environment, head type, and starch-hull type on total beta-glucan and protein content, extract viscosity, and seed color in barley were tested. Barley cultivars varying in head (two row and six row), starch (normal, waxy, high-amylose, and fractured), and hull (covered and hull-less) phenotypes were grown in single-row plots at one location from 1989 to 1991. Higher mean beta-glucan content and extract viscosity occurred in 1989, a low-moisture, hot gear. Cultivars with the two-row and six-row head type did not differ for any of the traits analyzed. Waxy hull-less cultivars had the highest mean beta-glucan content (69.3 g/kg) and extract viscosity (29.1 cP) compared with the normal covered cultivars (38.0 g/kg and 4.6 cP, respectively). Single degree-of-freedom contrasts found differences between normal starch and waxy starch isotypes consistent among the background genotypes ('Azhul', 'Betzes', 'Bowman', 'Robust'). Dietary fiber analysis of selected samples grown in 1990 found the highest soluble fiber content in cultivars having waxy or high amylose starch and hull-less seed. In a separate experiment, 'Wanubet', a waxy hull-less cultivar, was grown in 42 commercial fields from 1989 to 1991. beta-glucan content varied from 45.5 to 94.6 g/kg, extract viscosity from 8.9 to 108.2 cP, and protein content from 98.0 to 186.0 g/kg. Seed color varied but was unrelated to these components. The significant effect of environment on all of the characteristics indicates the need for food barley quality standards and tests.