The effect of dormancy release of seeds of Strelitzia juncea by oxygen on their alcohol dehydrogenase activity, cytosolic malate dehydrogenase activity and ethanol content

The fact that the dormancy of certain types of seeds can be alleviated by incubation in oxygen, had previously been associated with either the oxidation of germination inhibitors or the stimulation of oxygen-dependent respiratory processes. In this respiratory study on Strelitzia juncea Ait. seed dormancy, it was found that ethanolic fermentation of the embryos of dormant normoxically incubated seeds resembled that of hyperoxically incubated seeds. ADH activity was similar over the first four incubation days, and therefore before the beginning of radicle emergence. Ethanol content of the embryos was significantly lower on incubation days 1 and 3. MDH activity was higher on days 3 and 4 as a result of hyperoxic treatment. A close relationship between supernatant ADH and MDH activity was found for individual extracts, and its possible significance is discussed. The overall 4-day average ADH activity (NADH oxidation) was 0.17 μmol min − 1 emb − 1 (4.5 μmol min − 1 g − 1 fresh mass), while the average MDH activity (NADH oxidation) of the embryos was 0.52 μmol min − 1 emb − 1 (55.3 μmol min − 1 g − 1 fresh mass). The ratio of the ADH forward reaction (NAD reduction) to ADH reverse reaction (NADH oxidation) was 8.30 ± 0.37. The ethanol content of embryos of normoxic incubated seeds was 6.0 μmol emb − 1 (59.5 μmol g − 1 fresh mass) and of hyperoxic incubated seeds 4.8 μmol emb − 1 (47.7 μmol g − 1 fresh mass).