Enzyme Activity in Dormant and Nondormant Large Crabgrass(Digitaria sanguinalis)Seeds Following Hydration

Abstract

In order to germinate successfully, large crabgrass [Digitaria sanguinalis(L.) Scop.] seeds require a period of after-ripening. Some changes, either physical, biochemical or both, must occur in these seeds during this after-ripening process. This paper reports the differences in the activities of several enzymes between dormant (non-after-ripened) and nondormant (after-ripened) large crabgrass seeds at various periods of hydration. The total protein content of dormant seeds does not change during imbibition but increases greatly in nondormant seeds at 48 and 76 h of hydration. Initially, nondormant seeds exhibit high alpha-amylase activity and low peroxidase and acid phosphatase activities. Alpha-amylase activity remains unchanged relatively in both dormant and nondormant seeds up to 36 h of hydration, but increases greatly in nondormant seeds at 48 and 76 h of hydration. Peroxidase activity, which is initially low in nondormant seeds, increases substantially at 48 and 76 h of soaking. Acid phosphatase activity in dormant seeds does not change following hydration but is gradually elevated in nondormant seeds with duration of soaking. Lipase activity in dormant seeds remains fairly constant upon hydration. In nondormant seeds, however, the activity gradually decreases with duration of soaking, the decrease being 3 to 4 fold at 76 h of imbibition. Except for lipase, there is a positive correlation in the activities of alpha-amylase, peroxidase, and acid phosphatases with the increase of total protein content of nondormant seeds.