DEVELOPMENT OF BARLEY-GRAIN - COMPARISONS BETWEEN CULTIVARS FOR GROWTH-RATE AND ALPHA-AMYLASE ACTIVITY

Grains from ears of known anthesis time in 7 spring barley cultivars were measured for dry weight and .alpha.-amylase activity at regular intervals during grain maturation. During the period 10-31 days after anthesis, dry weight increase of the grain was substantially linear in all the cultivars. Comparisons between linear slopes fitted for this phase of growth provided an objective means of comparing grain growth rates in different cultivars. .alpha.-Amylase activity per grain reached a peak in all except 1 cultivar at 10-16 days after anthesis but declined rapidly during the linear phase of grain growth. .alpha.-Amylase activity per gram grain dry weight decreased exponentially during this period, and transformation of the data to logarithms allowed a substantially linear fit to be made. Slopes for each of the cultivars were compared. Differences were found between cultivars in grain growth rates, total .alpha.-amylase activity and rates of fall of .alpha.-amylase activity per gram 10-31 days after anthesis. No relationship could be found between grain growth rate and either the absolute level of .alpha.-amylase activity achieved in the grain or the rate of fall in activity during development.