青藏高原东缘季节性冻土对粗枝云杉和色木槭种子萌发的影响
文献类型：学位论文
| 作者 | 秦纪洪 |
| 学位类别 | 博士 |
| 答辩日期 | 2009-05-01 |
| 导师 | 刘庆 |
| 关键词 | 季节性冻土 粗枝云杉 色木槭 抗氧化酶 活性氧物质 零下低温 seasonally frozen soil Picea asperata Acer mono Maxim antioxidant enzymes reactive oxygen species subzero temperature |
| 其他题名 | Effects of Seasonally Frozen Soil on Germinability of Picea asperata and Acer mono Maxim Seeds in Eastern Qinghai-Tibetan Plateau, China |
| 中文摘要 | 自19世纪以来，全球正经历着以变暖为主要特征的气候变化。1860年至今，地表平均温度大约上升了0.6℃±0.2℃。在IPCC的设定情境下，青藏高原到2100年气温将上升2~3.6℃，最大升温将出现在冬季。冬季和春季增温会导致全球冻土格局的改变，对高纬度或高海拔地区的季节性冻土层分布也有巨大的影响。据最大估计，1901~2002年季节性冻土层面积缩小了7%，在北半球春季冻土面积减少量高达15%。本研究在属于川西亚高山地带的四川省理县境内米亚罗301林场和夹壁人工林以及天然林内进行，以粗枝云杉、色木槭种子为实验对象，研究了种子从落地经历季节性冻土期到次年萌发结束整个周期中体内活性氧物质代谢以及抗氧化酶系统对季节性冻土的响应。该实验分为三个处理：（1）非季节性冻土处理，即土壤增温，地温一直保持0℃以上（NF）；（2）种子埋在土壤下5cm处（F5）；（3）种子埋在土壤下10cm处（F10）。其目的是为了研究粗枝云杉和色木槭种子萌发对季节性冻土改变的响应，以及活性氧物质和抗氧化酶系统在这种响应中所起到的作用。具体结果如下： （1）在川西亚高山地区，季节性冻土会促进粗枝云杉和色木槭种子的萌发，季节性冻土的消失可能会导致这两种植物的种子萌发失败。如果全球变暖达到一定程度导致某些地区的季节性冻土消失，则可能导致在本地区这两种植物更新的失败。但是适当增加零下低温，则可能提高这两种植物种子的自然萌发率。 （2）从活性氧代谢方面对不休眠的粗枝云杉种子和休眠的色木槭种子进行的研究中发现，活性氧物质与种子生活力的保存有一定关系，活性氧物质积累增加会导致种子萌发率的下降，但不同的活性氧物质对这两种植物种子的影响又不同。在粗枝云杉种子萌发的过程中，超氧阴离子呈现逐渐增加的趋势，但是它和膜脂过氧化产物与粗枝云杉种子萌发失败并没有表现出直接的联系。这种趋势在色木槭种子中也有类似表现。但是过氧化氢含量的变化在粗枝云杉种子体内呈逐渐减低趋势，而在色木槭种子中呈现逐渐上升趋势，可能是因为粗枝云杉种子体内抗氧化酶活性能更好的控制过氧化氢的积累。两者的研究表明，过氧化氢与粗枝云杉以及色木槭种子萌发降低有着较为密切的联系；同时，非季节性冻土处理下的活性氧物质积累高于季节性冻土处理，尽管有时候并不明显。 （3）对于休眠的色木槭种子而言，初期活性氧物质增加可能是为了打破色木槭种子的休眠，而扮演一种信号传递者的角色。但是当活性氧物质大量积累，抗氧化酶系统无法清除过量的活性氧物质时，活性氧物质超过一定的阈值，则开始导致种子细胞的损坏，逐渐导致种子的劣变以及生活力的降低。 （4）从抗氧化酶系统（超氧化物歧化酶SOD，过氧化氢酶CAT，抗坏血酸过氧化物酶APX）的研究来看，抗氧化酶系统与粗枝云杉以及色木槭种子萌发成功有着密切的关系。在非季节性冻土处理下的种子中抗氧化酶活性明显低于季节性冻土处理。在季节性冻土处理的F5处理下，其萌发率较F10处理低，其体内的抗氧化酶活性也比F10处理显著降低。但是在两种不同的种子中，抗氧化酶活性的变化也有所不同，在粗枝云杉种子体内，抗氧化酶的活性在种子萌发的全过程中呈现先升后降的趋势，但是在色木槭种子体内则呈现逐渐下降的趋势。可见抗氧化酶系统在不同的种子体内有不同的响应。 Enrichment of atmospheric greenhouse gases resulted from human activites such as fossil fuel buring and deforestation has increased global mean temperature by 0.6℃±0.2℃ since 1860. It is predicted that in Qinghai-Tibetan Plateau temperature will increase by 2-3.6℃ until 2100 and the maximum increase will be occurred in winter. The temperature increase in winter and spring could make intense change on global frozen ground, especially in high-latitude or high-altitude region. The estimated maximum extent of seasonally frozen ground has decreased by about 7% in the NH from 1901 to 2002, with a decrease in spring of up to 15%. The experiment was conducted in Miyaluo 301 forest farm, Jabi Picea asperata platation and Jabi primary forest, Sichuan Province, China. The seeds of Picea asperata and Acer mono Maxim were used as model seeds to assess the effects of seasonally frozen soil on seed germination and oxidative metabolism-related changes.The experiment were conducted in field sites, including three treatments: (1) non-frozen soil treatment (NF, soil temperature >0℃); (2) seeds buried at depths of 5cm (F5); (3) seeds buried at depth of 10cm (F10). The objective of this study was to investigate whether seasonally frozen soil can facilitate germination of Picea asperata and Acer mono seeds and the function of reactive oxygen species (ROS) production, antioxidant enzymes in seeds germination or dormancy allevatiation. The results were as follows: The nonfrozen treatment resulted in near failure of germination of P. asperata and was associated with relatively high levels of hydrogen peroxide (H2O2) and low activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxide (APX). Germination of P. asperata seeds at 10 cm under the seasonally frozen soil was higher than that at 5 cm. This higher germination rate was associated with the recovery of SOD, CAT, and APX activities. The levels of malondialdehyde (MDA) in seeds from seasonally frozen treatments were higher than those in the nonfrozen treatment, implying greater lipid peroxidation and that frozen seeds might have suffered from oxidative stress. Acer mono seeds almost lost their ability to germinate in non-freezing soil. However, seasonal frozen soil treatments facilitated the germination compared with non-freezing treatment, and a slight increase in freezing temperature was able to reduce the frozen stress and markedly improve the germination rate of Acer mono seeds. The accumulation of ROS was similar in non-freezing treatment and seasonal frozen treatments of 5cm, while it was higher than that in seasonal frozen treatment of 10cm. The higher contents of MDA in seasonal frozen soil treatment indicated that frozen stress occurred in mono maple seeds. The highest contents of SOD, CAT and APX were observed in seasonal frozen treatment of 10cm with the highest germination. The observation revealed that ROS and lipid peroxidation was not the major reason for the germination failure, but partly involved in loss of seed viability under frozen stress. The results indicate that seasonally frozen soil facilitated the germination of P. asperata and Acer mono seeds and that germination was closely related to the resumption of antioxidant enzymes activity. Overall, these findings suggest that the disappearance of seasonally frozen ground caused by global warming might result in failure of regeneration of P. asperata and Acer mono. |
| 学科主题 | 植物学 |
| 语种 | 中文 |
| 公开日期 | 2010-11-24 |
| 页码 | 88 |
| 源URL | [http://210.75.237.14/handle/351003/244]  |
| 专题 | 成都生物研究所_生态研究 |
| 推荐引用方式 GB/T 7714 | 秦纪洪. 青藏高原东缘季节性冻土对粗枝云杉和色木槭种子萌发的影响[D]. 2009. |
入库方式： OAI收割
来源：成都生物研究所
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