Studies On Ultra-dry Storage And Detecting Seed Vigor In Welsh Onion Seeds (Allium Fistulosum L.)

The effects of ultradried treatment on seed vigor and aging-resistance of welsh onion seeds with different moisture content were studied in these tests; the law of the changes on seed vigor for welsh onion seeds during normal and ultradry storage were analyzed, and the mechanism of aging and ultradrying for welsh onion seeds were investigated; meanwhile, the correlation between various physiological indexes of welsh onion seeds and seedling emergence: were analyzed, efficient methods and systems for seed vigor evaluation of welsh onion seeds were established. The main research results were showed as follows:1.There was no effect on seed vigor of welsh onion seeds when the moisture content decreased from 8.4% to 5.5%~2.5%; but when dried to extremely low moisture content (=2.0%), the seed vigor would drop significantly. After artificial aging, the seed vigor in moderately dried seeds(5.5%~2.5%) would keep at a higher level, and the aging-resistance of welsh onion seeds would be remarkably improved.2. The seed vigor of welsh onion seeds decreases with the extending of storage time. The seed vigor, the activities of dehydrogenase, the activities of SOD and POD have decreased remarkably; and electric conductivity, the content of soluble sugar, the content of MDA have raised significantly, after stored at room-temperature for 12 months. The lipid peroxidation induced by free radicals is the essential reason for welsh onion seeds aging.3. Storage longevity of ultradried welsh onion seeds was improved remarkably. After stored at room-temperature for 18 months, the germination rate, germination index, vigor index, the activities of dehydrogenase, electric conductivity, the content of soluble sugar, the activities of SOD, the activities of POD and the content of MDA have not varied significantly in ultra-dried welsh seeds(3.5%); but the seed vigor have decreased significantly in non-ultra-dried seeds(8.4%).4. There was correlation between seedling field emergence rate, seedling field emergence speed and germination index, vigor index, the activities of dehydrogenase, electric conductivity, the content of soluble sugar, the activities of SOD and POD, they were the best ones used to evaluate seed vigor indexes; but there was no significant correlation between the germination rate and seedling field emergence speed, and germination rate can't be used to evaluate welsh onion seed vigor.