Variation across environments in patterns of water uptake and endosperm modification in barley varieties and variety mixtures

The malting barley varieties Chalice, Chariot, Optic and Prisma and all four three-component mixtures derived from them were grown at three sites in eastern Scotland in 2000. Following harvest, malting samples were obtained for each trial entry from grain retained by a 2.5 mm sieve. Water uptake during the steeping phase of malting was determined on all samples at two of the sites. Of the varieties, Chariot was shown to have more extensive and also, at one site, more even hydration than the other varieties, whereas the mixtures were generally similar to the other three varieties in water uptake. Malt samples were tested for cell wall modification using a fluorescence method that assessed individual grains, so enabling both homogeneity and extent of modification to be calculated. There were significant differences between genotypes and between sites, with Chariot and Chalice showing poor modification at one site, which led to reduced levels of hot water extract. The variety Prisma had a lower level of predicted spirit yield at another site, possibly owing to over-modification, and Optic was the only variety to give consistently high spirit yield at all three sites, despite considerable variations in levels of modification. The mixtures had better consistency in their malting results than the varieties, with the exception of Optic, and also performed well at sites where modification was sub-optimal. Differences in spirit yield were greater between sites than between varieties, indicating that genotypic constitution may not always be a reliable predictor of phenotypic expression of malting quality. Copyright © 2006 Society of Chemical Industry