Studies On The Conservation, Physiological And Biochemical Mechanism And Genetic Stability In Ultra-Dry Seed Of Several Crops

Seeds of 11 varieties in 9 species (Chinese onion etc.) were dried to different moisture contents ranging from 1.2% to 12.7%. Seeds with different moisture contents packaged with aluminum foil or paper bags were stored at different temperatures (50℃,35℃, 20℃,-18℃) and room temperature in different climate areas in China. The vigor and viability of stored seeds were tested after seeds were stored for different periods ranging from 4 weeks to 6 years. These results were used to analysis the relationship among the storage temperature, the optimum moisture contents and the optimum relative humidity. The longevity and the affecting factors of stored seeds were also discussed. Through the testing of respiration, ethylene release amount, sugar contents, fatty acid contents of stored seeds, the physiological and biochemical mechanism of ultra dry seed were studied. The chromosome aberration rates in root tip cell of wheat and lettuce seeds were observed to see the heredity variation in cell level. Four kinds of isozyme charts of stored rice seeds or rice seedling were tested to see heredity variation in protein level. The seedlings of wheat were tested with AFLP and SSR molecular marker techniques. The heredity variations of ultra dried seed of wheat in molecular level were analyzed. Seeds were dried and stored for four to six years, the research results showed as following:Seeds were stored at 50℃ - 35℃ and 20℃ for four to six years, The optimum moisture contents of Chinese onion seeds are 1.8% , 1.8~5.1 and 1.8~8.1 % respectively. The optimum moisture contents of rape seeds are 2.0% , 3.0% and 4.1 % respectively. The optimum moisture contents of lettuce seeds are 2.0~3.0%, 1.9~4.0% and 1.9~6.4% respectively. The optimum moisture content of seed decreases as the storage temperature increase. The optimum equilibrium relative humidity of stored seeds decreases as the storage temperature increase. Seed longevity increase as the storage temperature decrease. Seed longevity increase ten times as the storage temperature decrease 15℃ in the rang of 50 ℃ to 20℃. Seed longevity increase as the seed moisture content decrease. Seed longevity increase 1.1 times as the seed moisture content decrease 1% in the range of 2% to 12% seed moisture content. There is a relationship of logarithm regression between seed moisture content and seed longevity. The relation model is Y=b+mLnX. Where Y is seed moisture content(%), b and m are constant, X is seed longevity (day).Seed stored in different climate areas for two years in china. The results showed Drying and hermetic package is not needed for seed stored in the climate areas of dry area of temperate zone and the climate area of altiplano. Seed can be stored safely without drying and hermetic package in these areas for at least two years. However, Drying and hermetic package is needed for seed stored in the climate areas of tropic, subtropics, warm temperate zone and humid area of temperate zone. Otherwise, seed will loss vigor and viability quickly in one or two years.Through the studying on physiological and biochemical mechanism of Chinese onion and rape seeds stored at different temperature for 12~16 months, the results showed that seed respiration was enhanced as the seed storage temperature increased, and also seed respiration was enhanced as the seed moisture content increased. The ethylene released amount of seed decreases as the seed moisturecontent decreases. The results also showed the galactose content of seed increase as the storage temperature increases. However, the glucose, fructose, sucrose and raffinose content of seed decrease as the storage temperature increases. The galactose content of seed decreases as the seed moisture content decrease. However, the glucose, fructose, sucrose and raffinose content of seed increase as the seed moisture content decreases, but this kind of change is not clear if seed was stored at lower temperature. The contents of palm acid, stearic acid, oleic acid, suboleic acid and flex acid increase as the storage temperature increases, b...