Effects Of Low Temperature Storage On The Seed Vigor And Related Properties Of Hybrid Rice Parental Seeds

Low temperature storage of seeds has become an important measure to preserve seed vigor and purity of hybrid rice parental seeds.To explore the variation of seed vigor in hybrid rice parental seeds after low temperature storage,and to investigate the application methods of these seeds,selected Y58S、Zhun S、Feng S、Guangzhan63-4S and T98 A that stored in low temperature seed bank with temperature 8℃~10℃ and relative humidity 55% for different years as material.The properties of seed vigor,seedling establishment,seed aging,seed water absorption and growth and development in field were researched.The results were as follows:1 The germination energy,germination rate,germination index and vigor index of five parental seeds showed a downward trend as the time of low temperature storage was prolonged.Germination rate of the parental seeds within five years was over 60%,and the yearly mean decline rate of germination rate were the range of 0.2% to 5.67%.The yearly mean decline rate of germination rate of Y58 S was less than Zhun S、Guangzhan63-4S and T98 A.The conductivity in soaked solution with soaking for 24 h of parental seeds was significantly increased with the low temperature storage time prolonged and there were significant or extremely significant negative correlations between the electrical conductivity and the germination energy,germination rate,germination index and vigor index of parental seeds.The decline of seed viability was affected by the initial germination rate and the variety storability.2 The germination energy,germination rate,germination index and vigor index of four parental seeds,which were Y58S、Zhun S、Guangzhan63-4S and T98 A,showed a downward trend as the time of low temperature storage was prolonged after low temperature seed soaking.Compared to the non-soaking seed,the variation of germination energy and germination rate was not obvious within 2 years low temperature storage,but the germination index and vigor index was increased.There were obvious decline that the various vigor indexes of the parental seeds stored in low temperature bank more than 4~5 years.Low vigor seed with long-term storage at low temperature was easily suffered by cold damage and imbibitional injury.3 The seeds emergence rate,seedling rate,root length,white root,base stem width and seedling dry weight of five parental seeds showed a downward trend as the time of low temperature storage was prolonged.The emergence rate,seedling rate and white root of the same varieties were significant differences between each treatment.There were no significant difference between two seedling qualities of parental seeds within 3-5 years low temperature storage.4 The germination rate of five parental seeds was a obviously downward trend after out-storage.The rapid decline period of germination rate of Y58 S and Zhun-S was earlier than that of Feng S,T98 A and which was earlier than that of Guangzhan63-4S.The decline of germination rate of low temperature storage seeds after out-storage was affected by seed vigor and seed self-properties.5 The germination rate of the five parental seeds with soaking for 12 h was the maximum or the second maximum.The germination rate of low vigor seeds with soaking for 12 h was significantly higher than that with soaking for 6h and 24 h.Effects of seed soaking time on seed germination rate decreased gradually as increase of seed vigor.6 The duration from seeding to heading of Y58 S,Zhun S and Feng S was shortened as the time of low temperature storage was prolonged,which of the same parent had a maximum difference of 4d.The variation of heading period of four parental seeds was not obvious,only a difference of 1 ~ 2d.