Production of dryland barley for human food: quality and agronomic performance
Grain β-glucan content is the most important attribute for barley (Hordeum vulgare L.) varieties destined for the human food market. This trait is important because of the blood glucose and cholesterol-reducing properties of β-glucans. High levels of grain protein content, test weight, and seed size and endosperm color may also add value. Seed yield potential, in part, determines the economic feasibility of producing human food varieties. To determine the potential of food barley production in the dryland production areas of the Pacific Northwest of the United States, 33 cultivars and advanced lines reported to vary in β-glucan content were grown in 2006 and 2007 at two locations in northeastern Oregon under dryland cropping conditions. Seed yield, test weight, percentage of plump kernels, grain β-glucan, and grain protein were measured on replicated samples from the four environments, allowing for assessment of average performance as well as genotype x environment interaction. Estimates of variance components showed that 66% of the variability in β-glucan content was attributable to genotype. Cultivars and lines with waxy starch had an average β-glucan value of 55 g kg–1 compared with 35 g kg–1 for cultivars and lines with nonwaxy starch. We found significant two- and three-way interactions, but these accounted for much less of the total variation in the measured phenotypes than the main effects of variety, year, and location. Hulless accessions produced an average of 3580 kg grain ha–1 compared with 4260 kg grain ha–1 for the hulled accessions. Hulled, waxy-starch varieties appear to have the greatest agronomic potential for dryland production, as they combine high yield potential and grain β-glucan percentage.