OXYGEN REQUIREMENT AND TOXICITY IN SEEDS
The rate of germination of most seeds is optimum for oxygen partial pressure close to that in air i.e. 21 KPa. This rate is reduced when the pO2 is lowered. Nevertheless dramatic differences are observed depending on the seeds: fatty seeds do not germinate below about 2 kPa in comparison to starchy seeds which are able to germinate slowly at much lower pO2. This phenomenon can be explained by the relative contribution of oxidative phosphorylation and fermentation to ATP production by the two groups of seeds under hypoxic or anoxic conditions.
Although molecular oxygen is required for seed germination, various oxygenated molecules or oxy-radicals are increasingly implicated to explain the loss of viability in seeds during storage. Recent progress in this field will also be discussed.