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Patterns of Barley Grain Development in Spain and Scotland and Their Implications for Malting Quality

¹Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, Scotland. ²Corresponding author, Fax: +44 (0)1382 562426, E-mail: jswans@scri.sari.ac.uk ³Institut de Reserca i Technologia Agroalimentaries (IRTA), Reus, Spain. ⁴Universidad de Lleida /IRTA, Lleida, Spain.

To determine whether patterns of grain filling were consistent between seasons and different between sites in northern and southern Europe, the cultivar Troubadour and TR49, a mutant derived from it, were grown, over two seasons, at sites in Scotland and northern Spain. Differences in sowing date and climate were reflected in different patterns of grain filling. Ear emergence in Scottish grown barley occurred around the time when daylight hours were maximal; optimal photosynthesis was the likely explanation for the rapid increase in grain size observed at the Scottish site. Differences between the sites in temperature and rainfall were most evident during the last month of the growing season. In Scotland, where ripening occurred in cooler, more humid conditions, synthesis of hordein and β-glucan followed the pattern of grain filling, reaching a peak at ~600 degree days after anthesis (the product of days after anthesis and average temperature). Levels then remained fairly constant until harvest ripeness was reached. In Spain, levels of hordein and β-glucan rose virtually throughout the growing season. Differences observed at maturity, between Scottish and Spanish grown grain, in total nitrogen and β-glucan levels were due to this accumulation in the later stages of growth. This was accompanied by a major change in the ratio of the constituent polypeptides of the storage protein and differences in the relative proportions of soluble and insoluble β-glucan.