【作者】 钱红格；

【导师】 陈存根；

【作者基本信息】 西北农林科技大学 ， 生态学， 2009， 硕士

【摘要】 为探讨榆属树种种子萌发的生理活动的变化特征,种子老化及劣变机理,探明种子萌发的一些生理生化变化规律和种子活力下降的原因,本文以白榆(Ulmus pumila Linn.)和沙地榆(Ulmus pumila L. var. sabulosa)、春榆(Ulmus propinqu Koidz)三种榆林地区较为常见榆属树种为材料,研究了盐分和水分胁迫对种子萌发的影响,种子在自然条件和人工加速老化条件下萌发的所发生的一系列生理生化变化,在此基础上探索反映种子活力水平的显著指标,试验结果如下:1.不同浓度的盐胁迫和水分胁迫对几种榆属树种种子的萌发具有明显的抑制作用,表现在降低种子的萌发率,推迟种子的初始萌发时间、延长种子的萌发时间上。NaCl溶液处理的种子发芽率显著高于等渗的PEG溶液处理,水分胁迫的抑制作用远大于等渗的盐胁迫,表明榆属植物中起主要抑制作用的是渗透胁迫。2.自然条件下种子在吸水萌发的过程中,3个树种种子活力生理指标大小比较结果是:沙地榆>春榆>白榆。萌发过程中淀粉被分解,可溶性糖含量的变化趋势是先升后降,还原糖含量一直在增加,说明在后期种子萌发的过程中消耗的可溶性糖主要是非还原性的蔗糖。3.一般在干的种子中主要是β-淀粉酶或完全是β-淀粉酶,但是3种榆属树种干种子α-淀粉酶也存在。种子α-淀粉酶活性比较结果为沙地榆>春榆>白榆。β-淀粉酶在萌发的过程中不断被消耗,在萌发的过程中β-淀粉酶活性在大多数时间较α-淀粉酶活性要高,而且变化幅度也大,说明在榆树种子萌发过程中起主导作用的淀粉酶是β-淀粉酶。4.对于供试的3个树种,随着老化时间的延长,发芽势、发芽率和活力指数都呈下降趋势,且这三个发芽指标其不同老化天数之间均存在极显著差异。其中发芽势和活力指数的下降幅度比发芽率大。由此说明随着老化加深,种子活力先于生活力衰退,表现为发芽速率减慢,出苗不整齐,幼苗的健壮程度下降,生活力降低。由此可见,人工老化种子活力先于生活力衰退,老化时间越长,种子的生理劣变越深。5.供试的3个树种种子的SOD、POD、CAT和脱氢酶活性本身存在较大差异,并随着种子老化的加剧而明显递减,因此SOD、POD、CAT和脱氢酶活性活性下降是导致榆属树种种子活力降低的一个重要原因。6.种子浸出液相对电导率和MDA含量均随种子老化程度的加深而升高,说明老化对细胞膜系统影响较大,电导率和MDA含量的大小能在一定程度上反映膜脂过氧化作用的强弱和细胞膜系统的完整性程度。7.将包括脱氢酶活性、相对电导率在内的6个指标进行主成分分析。结果表明,这些指标可分为两类,第一类包括SOD活性、POD活性、CAT活性和脱氢酶活性,它们是种子活力变化的主要原因,也是衡量种子活力的可靠指标,第二类是相对电导率和MDA含量。更多还原

【Abstract】 In order to discuss physiological activity during seed germination progress, seed aging and deterioration mechanism, search for some physiological and biochemical changes and reasons of decline in seed vigor, the author carried out three common elm species including Ulmus pumila Linn, Ulmus pumila L. var. sabulosa, Ulmus propinqu Koidz in yulin area in this paper, conducted a serious laboratory tests to study effects of water and salts tress on seed germination and a series of physiological and biochemical changes of seeds germination under natural conditions and under conditions of artificial accelerated aging, in order to explore the significant indicators of seed vigor. The results are as follows.1. Different concentrations of salt stress and water stress on several elm species seed germination is inhibited with a performance in the reduction of seed germination rate, delayed the initial seed germination time, extend the time of seed germination. Seed germination rate was significantly higher under iso-osmotic NaCl and iso-osmotic PEG had a greater inhibitory effect than iso-osmotic NaCl, suggesting that osmotic stress was the main factor affecting elm seed germination.2. The comparison result of seed vigor’s physiological index of three elm species under natural conditions was: U. pumila L.var. sabulosa >U.propinqua Koidz.> U. pumila L. The starch was broken down during germination process, the changes trend of soluble sugar content first up and then down, reducing sugar content had been on the increase. This showed that consumption of seed germination in the latter part in the process was the main soluble sugar of non-reducing sugar.3. There is mainly or totallyβ-amylase in the dry seeds, but three elm species hasα-amylase in the dry seeds. The comparison result ofα-amylase activity was: U. pumila L. var. sabulosa > U.propinqua Koidz. > U. pumila L.β-amylase in the process of germination had been consumed,β-amylase activity is higher thanα-amylase activity at most of the time in the germination process, It showed thatβ-amylase played a leading role in the amylase on elm seed germination.4. With Prolonging of the aging, germination energy, germination percentage and vigor index of the seeds tested had a dropping tendency and there were obvious difference in the three indexes during different aging days, which indicate the vigor of the manual aged seed declines quickly than its life-force. The longer the aging lasts the more seriously the seed deterioration.5. SOD activity, POD activity, CAT activity and dehydrogenase activity of the seed tested had obvious difference themselves, and the four indexes significantly reduced with the aggravated aging. So the descent of these four indexes another important reason causing the vigor descent of elm species seed.6. Relative conductivity and MDA content of the seed’infiltrating solution both rose with the more serious degree of the seed aging, which showed the aging has a high effect on the cell membranous system. And conductivity and MDA content change will illustrate, to a certain extent, the strength of the membrane lipid peroxidation and the integration degree of the cell membranous system.7. Results of the principal component analysis of the six indexes, including dehydrogenase activity and the relative conductivity, showed that these indexes maybe classified into two categories. The first category includes SOD, POD, CAT activity and dehydrogenase activity which are not only the main factors of the vigor change but also the reliable indexes to examine the seed vigor. Another category has relative conductivity and MDA content. .更多还原