Thermostabilities of grain β-amylase and β-glucanase in Finnish landrace barleys and their putative past adaptedness

Thermostability of beta-amylase activity was a general feature in a sample of 32 Finnish barley landraces. One of two Finnish landraces probably contributed the thermostability to cv. 'Pirkka' in crosses performed about 70 years ago. The stability is less evolved in beta-glucanase activity although the most tolerant types appeared in landraces and in Pirkka with a Finnish landrace background. Selection pressure for thermostability in grains may have been a feature of traditional crop management practices among Finns in the past: drying grain crops, including premature barley, above an oven in a special drying house at temperatures exceeding 55 degrees C, and germination in black, sunlit slash-and-burn soils, with a measured surface temperature of 63 degrees C. A positive, though small correlation between the thermotolerance ratios of the two enzymes may be a remnant of their common long selection pressure ending tens of generations prior to collection in the 1960s and 1970s.