Background and AimsDespite differences in physiology between dry and relative moist seeds, seed ageing tests most often use a temperature and seed moisture level that are higher than during dry storage used in commercial practice and gene banks. This study aimed to test whether seed ageing under dry conditions can be accelerated by storing under high-pressure oxygen.MethodsDry barley (Hordeum vulgare), cabbage (Brassica oleracea), lettuce (Lactuca sativa) and soybean (Glycine max) seeds were stored between 2 and 7 weeks in steel tanks under 18 MPa partial pressure of oxygen. Storage under high-pressure nitrogen gas or under ambient air pressure served as controls. The method was compared with storage at 45 °C after equilibration at 85 % relative humidity and long-term storage at the laboratory bench. Germination behaviour, seedling morphology and tocopherol levels were assessed.Key ResultsThe ageing of the dry seeds was indeed accelerated by storing under high-pressure oxygen. The morphological ageing symptoms of the stored seeds resembled those observed after ageing under long-term dry storage conditions. Barley appeared more tolerant of this storage treatment compared with lettuce and soybean. Less-mature harvested cabbage seeds were more sensitive, as was the case for primed compared with non-primed lettuce seeds. Under high-pressure oxygen storage the tocopherol levels of dry seeds decreased, in a linear way with the decline in seed germination, but remained unchanged in seeds deteriorated during storage at 45 °C after equilibration at 85 % RH.ConclusionsSeed storage under high-pressure oxygen offers a novel and relatively fast method to study the physiology and biochemistry of seed ageing at different seed moisture levels and temperatures, including those that are representative of the dry storage conditions as used in gene banks and commercial practice.

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Oilseeds are more susceptible to deterioration due to membrane disruption, high free fatty acid level in seeds and free radical production. These factors are tended to less vigorous seed. Priming treatments have been used to accelerate the germination and seedling growth in most of the crops under normal and stress conditions. For susceptible and low vigor soybean seed, this technique would be a promising method. At first, in separate experiment, effects of hydropriming for (12, 24, 36 and 48 h) with control (none prime) were evaluated on germination traits of soybean seed lots cv. 'Sari' (include 2 drying method and 3 harvest moisture). Then, next experiment was conducted to determination the best combination of osmopriming in soybean seed lots, hence 3 osmotic potential level (-8, -10 and -12 bar) at 4 time (12, 24, 36 and 48 h) were compared. Analysis of variance showed that, except for seedling dry weight, the other traits include standard germination, germination rate, seedling length and vigor index were influenced by osmopriming. Hydropriming had no effect on these traits and decreased rate of germination. Finally the best combination of osmopriming were osmotic potential -12 bar at 12 hours for time, that submitted acceptable result in all conditions and recommended for soybean seed lots cv. 'Sari' .

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