【作者】 黄先晖；

【导师】 姜孝成； 杨远柱；

【作者基本信息】 湖南师范大学 ， 植物学， 2010， 硕士

【摘要】 本文主要探讨了常规水稻ZR02的种子和杂交水稻株1 S/ZR02和金23A/ZR02的种子在发育过程中的生物学性状变化,采用硅胶脱水(快干)和室内自然风干(慢干)对种子进行脱水处理,通过测定脱水前后种子的萌发率、简化活力指数、电解质渗漏率、可溶性蛋白、可溶性糖、SOD酶等的变化,比较了它们的脱水耐性形成的规律和差异、在不同含水量状态下贮藏(硅胶干燥贮藏和室内开放贮藏)一段时间后两类种子抗老化能力的差异及其生理机制。结果表明,常规水稻ZR02与杂交水稻株1 S/ZR02和金23A/ZR02的种子从开花至成熟的全生长期均约17 d,随发育过程的进行,颖果的颜色从绿色→黄绿色→黄色转变。种子含水量在发育过程中呈现相似的规律性下降变化,5 DAA-9 DAA是其快速下降期,此后下降速率明显放缓,三个品种的种子在发育过程中鲜重和干重的变化较为一致,5 DAA-13 DAA是其快速增长期,至17 DAA时趋于恒定。因此种子采收不宜早于17 DAA。三个水稻的7 DAA种子开始有萌发能力,此后随发育进程其萌发能力逐渐升高。不同发育时期新鲜种子的萌发率相对较低,无论快干还是慢干至含水量0.11 g H2O·g-1DW时,其萌发能力明显提高；同一发育时期的种子(特别是发育前期成熟度不高的种子)慢干和快干至相同含水量时,慢干更有利于提高种子的萌发能力。三个水稻的成熟种子快干和慢干至平衡含水量(分别为0.04 gH2O·g-1DW和0.11 g H20·g-1DW)时,其萌发率和简化活力指数都比脱水前的高；同时,在脱水过程中,无论常规水稻还是杂交水稻的种子,当处于同一含水量水平时,皆是慢速脱水的种子比快速脱水的种子的萌发率高。说明水稻种子能忍耐深度脱水,是正常性种子。但杂交水稻与常规水稻的种子的脱水耐性存在差异：最初轻度的快速脱水(至0.25gH2O·g-1DW)对常规水稻种子的萌发率的影响很小；而两个杂交水稻种子的萌发率有较大程度的下降,随着脱水程度的加大,种子萌发率又不断提高。慢速脱水和快速脱水至平衡含水量时,常规水稻种子的萌发率几乎相等,而快速脱水的两个杂交水稻种子的萌发率明显低于慢速脱水的种子。相关生理指标的测定结果表明,慢干较快干更有利于种子内可溶性蛋白和可溶性糖的形成,且使SOD活性保持在较高的水平。11DAA以前的种子,脱水处理后种子浸泡液的电解质渗漏率明显升高,而11 DAA以后的种子,相同的脱水处理使种子浸泡液的电解质渗漏率的上升幅度明显变小,说明在11 DAA以前种子的脱水耐性形成之初始阶段,脱水对细胞膜的伤害较大。另外,脱水会导致种子中丙二醛含量明显升高,其升高的幅度与种子发育过程负相关,进一步证明脱水耐性是在发育过程逐渐形成的。三个水稻的成熟种子在室内开放贮藏或硅胶干燥贮藏3个月再经历15d的老化处理后,萌发试验的结果表明,常规水稻ZR02比两个杂交水稻株1 S/ZR02和金23A/ZR02的种子更抗老化；两个杂交水稻的不同发育时期种子的抗老化能力也有差异,但皆以17 DAA种子的抗老化能力最强。对15 DAA种子老化前后的部分生理指标的测定分析发现,老化导致种子中可溶性糖,可溶性蛋白和SOD活性都下降,而且杂交水稻种子比常规水稻种子下降幅度更大。更多还原

【Abstract】 This thesis mainly investigated seeds of conventional rice ZR02 and hybrid rice Zhu1S/ZR02 and Jin23A/ZR02 of the changes of biological characteristics during development, and with dehydration by silica gel in a closed glass container (rapid dehydration, RD) and natural air on the indoor platform (slow dehydration, SD), the germination percentage, simplified vigor index, electrolytic conductivity of seed-soaked solution, content of soluble sugars and soluble proteins and the activity of SOD etc of seeds were measured to evaluate the formation of desiccation tolerance of rice seeds and compare the difference of the desiccation tolerance between seeds of conventional rice and hybrid rice, the difference of anti-aging ability of seeds which were stored at different condition (with dry silica or indoor open condition), and investigated the relative physiological mechanism.The results showed that the whole growth time of seeds of three varieties conventional rice ZR02, hybrid rice Zhu1S/ZR02 and Jin23A/ZR02 was all about 17 d. The caryopsis color changed from green to yellowish green then to yellow with ongoing development. The moisture content of seeds showed a similar downward tendency during development, but it rapidly declined at 5 DAA-9 DAA (days after anthesis), and then slowly declined down, the fresh and dry weight of seed of the three varieties during development showed a consistent changing mode:5 DAA-13 DAA was the rapid growth period, and went to a constant level at 17 DAA, therefore seed harvesting should not be earlier than 17 DAA.At 7 DAA, seeds of all three rice varieties began to have the ability to germinate when they were placed in suitable germination condition. The germination percentage of fresh seeds was relatively lower, either rapid or slow dehydration was obviously able to enhance the germination of seeds when dehydrated to moisture content of 0.11 g H2O·g-1DW. When the seeds with the identical developing stage dehydrated to the same moisture content with SD and RD separately, those with SD treatment improved the germination percentage and simplified vigor index by a greater extent, especially the ones having not developed to maturity yet.Dehydrated to the equilibrium moisture content 0.04 g H2O·g-1DW and 0.11 g H2O·g-1DW by RD and SD separately, the germination percentage and simplified vigor index of the mature seeds (21 DAA) of all three rice varieties were higher than the initial value of fresh seeds. Meanwhile, when the seeds dehydrated to the identical moisture content, no matter conventional rice or hybrid rice, those ones with SD showed the higher germination percentage than that with RD. These results demonstrated that rice seeds are orthodox which are able to tolerate extreme dehydration. On the other hand, there exists difference of the desiccation tolerance between conventional and hybrid rice seeds:firstly, the initial gentle dehydration with RD (to 0.25 g H2O·g-1DW) had only slight influence on the germination of conventional seeds, but reduced the germination percentage of seeds of two hybrid rice by a distinct extent, although it would go up again as the moisture content went down with the continuing dehydration; secondly, dehydrated to the equilibrium moisture content by RD and SD separately, seeds of the conventional rice had almost the same germination percentage, while the germination percentage of seeds of two hybrid rice with RD was obviously lower than that of ones with SD.To analyze the physiological mechanism to seed desiccation tolerance, some relative physiological indices such as the content of soluble sugar, soluble protein and MDA, as well as the SOD activity were measured. Compared with RD, SD was more conducive for seed to accumulate soluble protein and soluble sugar, and remain the SOD activity at a high level. Moreover, SD was able to increase the SOD activity of mature seeds. The electrolytic conductivity of seed-soaked solution of the seeds after dehydration treatment was significantly higher than that of fresh ones before 11 DAA. However, to the seeds after 11 DAA, the identical dehydration made the electrolytic conductivity of seed-soaked solution to get increased very slightly. So the seeds before 11 DAA should be at the initial phase of the formation of seed desiccation tolerance, dehydration on seeds more easily injured cell membrane which resulted in the membrane permeability ascending. In addition, dehydration led to MDA content in seeds to increase significantly, and the upgrade degree was negative to seed development level, but the seeds of the identical development stage at SD produced lower content of MDA than the ones at RD. These results demonstrated that the desiccation tolerance of rice seeds gradually formed as seed developed.After 3 months of preservation in indoor open condition or in dry silica gel in closed condition, followed by artificial aging for 15 days, seeds of conventional rice ZR02 were more anti-aging than those of two hybrid rice Zhu1S/ZR02 and Jin23A/ZR02 did. While comparing to the anti-aging capacity of seeds of two hybrid rice with different degree of development, after the same preservation and artificial aging as above,17 DAA ones showed the highest. Analyses of physiological indices to 15 DAA seeds before and after aging treatment indicated that aging led to rice seeds to reduce the content of soluble sugar and soluble protein and the activity of SOD significantly, and the reduce degree in hybrid rice seeds was greater than that in conventional rice ones.更多还原