| On the basis of feasibility of ultradry seed storage, peanut, soybean, mung bean, rice and maize seeds were chosen to investigate the relationship between seed prominent storage substances and the speed of dehydrating or the ability of ultradry-tolerance. This study was focused on soluble sugars, heat-stable proteins and the metabolism of active oxygen in seeds to discuss the reasons for ultradry-tolerance and prolonging storage longevity of ultradried seeds. The aim of this study was to provide theory for exploit the technology of ultradried seed storage for germplasm preservation.1. Seeds were dried by silica at 25degree centigrade temperature, the moisture content was measured at stated time intervals. The result showed that the speed of dehydrating of peanut seed was quickest than that of others seeds. Comparing with the prominent storage substances in different seeds, there was a positive correlation between the speed of dehydrating and the oil content of seeds. The speed of dehydrating of embryo was slower than of cotyledon of peanut seed, however, the speed of dehydrating of embryo and cotyledon was similar in soybean and mung bean seeds. It was showed that there was a position effectivity of embryo, which influences the dehydrating speed of seeds.2. Comparing the vigors of different moisture contents peanut, soybean, mung bean, and rice seeds, the vigor of peanut seed with less 1% moisture content did not decreased, but the vigor of soybean, mung bean and rice seeds would decreased when the moisture content was reduced to a certain level. The result showed that the ability of ultradry-tolerance was different, the higher oil content varieties had better ultradry-tolerance ability than seeds rich in protein and amylum.3. The relationship between soluble sugars, heat-stable proteins or metabolism of active oxygen and ultradry-tolerance ability was studied after ultradrying. The result showed that: (l)Ultradried seeds could increase the ratio of non-reducing sugars/reducing sugars in peanut, soybean and mungbean seeds, however, excessive ultradrying treatment could decrease the ratio in soybean and mung bean seeds. No significant changes on the ratio of sucrose/ oligosaccharides could be observed in ultradried seeds. There was a positive correlation between the ability of ultradry- tolerance and the ratio of non-reducing sugars/reducing sugars of seeds. Ultradrying treatment reduced the activity of invertase and a -galactosidase in embryo of peanut seed, which approved that the interconversion of sugars might occur in dry seeds, explained the reason of accumulating sucrose, raffinose and stachyose in peanut seed. 昅aillard reaction products in embryo of peanut seed were decreased after ultradrying treatment, which approved that ultradried peanut seeds had less reducing sugar. (2)Ultradrying treatment did not induce new heat-stable proteins. Moderate ultradrying treatment could induce to accumulate heat-stable proteins in embryo of peanut and mung bean seeds, but not soybean seed. It suggested that the heat-stable of protein was improved. The content of heat-stable proteins in peanut seed was significantly greater than soybean and mung bean seeds, which was the possible reason of different ultradry-tolerance ability in different seeds. (3)The change of metabolism of active oxygen in dry peanut seed during ultradrying was studied. After ultradrying treatment, superoxide-producing rate significantly increased, content of MDA didn't evidently increase, the ability of eliminating free radical was improved, there was no harmful effect on SC^ CAT, AsA-POD and LOX activity in ultradried seeds, suggesting that the system of scavenging active oxygen and the ability of superoxide-resistance in ultradried seeds were better.4. Ultradried seeds had higher vigor than control seeds after accelerated aging, especially in moderate ultradried seeds. The result showed the storability of moderate ultradried seeds was improved greatly. The relationship between soluble sugars, heat-stable proteins or metabo...
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