中国科学院昆明植物研究所机构知识库
Advanced  
KIB OpenIR  > 昆明植物所硕博研究生毕业学位论文  > 学位论文
题名: 不同生境的植物种子的生理生态特性的比较研究
作者: 唐安军
学位类别: 博士
答辩日期: 2008-01-26
授予单位: 中国科学院昆明植物研究所
授予地点: 昆明植物研究所
导师: 龙春林
关键词: 种子脱水敏感性 ; 种子贮藏行为 ; 酶促抗氧化系统 ; 休眠机制 ; 萌发模式 ; 生态适应性 ; 短命植物
学位专业: 植物学
中文摘要: 脱水耐性是种子在成熟过程中逐渐获得的。根据种子的脱水耐性和低温敏感性(贮藏行为),植物种子可分为三大类:正常性种子、顽拗性种子和中间性种子。成熟种子的千粒重、大小、种皮比例、脱落时的含水量及其生境特点等相关信息,可以作为判断种子脱水敏感性程度的重要指标。种子休眠是植物在长期的进化过程中形成的一种重要特性,以适应多变的环境。特殊的种子休眠与萌发机制确保了植物在合适的时空下萌发和幼苗的生长发育。比较分析不同种子的贮藏行为、休眠机理和萌发模式以及与生境的关系,对种子的长期有效保存、植物多样性的保护和可持续利用具有深远的意义。在工作假说“种子诸多的特性变化是与生境相关的”的指导下,我们分析比较了生境迥异的8种植物种子的特性,获得了较多的基础数据,主要结果(论)如下: 1、刺芋(Lasia spinosa)种子是顽拗性的,其适宜的萌发温度介于25-30℃之间;新鲜种子的最适宜的湿藏温度是10℃。当含水量从68.8%(约2.02 g H2O g -1 dry wt)下降到25.9%(约0.35 g H2O g -1 dry wt)时,种子活力下降约50%;在4℃下,含水量为37%的种子被贮藏6个月后的萌发率是18%。西班牙樱桃(Mimusops elengi)种子是中间性的。种子的适宜萌发温度是25、30和20/30℃。当含水量从41.8%下降到10.7%时,种子萌发率是87%;当含水量为5.4%时,种子萌发率仅有23%。在4℃下贮藏1、3或6个月后,含水量为9.8%的西班牙樱桃(M. elengi)种子的萌发率分别为84%、83%和79%。鉴于上述2种种子特性与生态环境的关系,我们推测脱水敏感性种子的成熟脱落与生境的高的水分获得性是一致的,其空间特点比时间模式更显著。 2、在脱水过程中,西班牙樱桃(M. elengi)种子的膜脂过氧化(LP)程度加剧;同时,抗氧化酶的活性也发生显著的变化。在种子脱水过程中,超氧化歧化酶(SOD)的活性先缓慢增加(此时,含水量≥6.1%),而后降低;过氧化氢酶(CAT)和过氧化物酶(POD)的活性的变化趋势相似:先逐渐增加(此时的含水量≥10.7%),而后降低;抗坏血酸过氧化物酶(APX)的活性的总的变化趋势是随种子活力的下降而不断下降;脱氢抗坏血酸还原酶(DHAR)和谷胱甘肽还原酶(GR)的活性变化模式相似,即随着含水量的降低,先缓慢增加(此时,种子的含水量≥10.7%),而后迅速下降。这些结果表明,在脱水过程中,种子活力的下降与活性氧的氧化胁迫紧密相关;同时,在严重脱水时,抗氧化酶不能有效地清除具细胞毒性的自由基(包括活性氧),从而导致种子活力下降或丧失。 3、地涌金莲(Musella lasiocarpa)种子具有物理、形态和生理的复合休眠,这种休眠方式是一种新的休眠组合类型。种子的吸水性很差,去除种子的孔盖,水分成为非限制性因子时,种子仍然不能萌发。在层积过程中,胚缓慢地进行器官分化,但是,在暖层积(室温、15和20℃)下,胚的生长和分化较冷层积(4℃)下的快。在层积5个月后,胚的分化虽已完成,而种子却仍然不能萌发。在室温下(18-25℃)层积9个月后,种子的萌发率为仅有3%。在4℃、室温、4/15、15和20℃下层积的种子的萌发率分别是17、32、29、32和37%。随着贮藏时间的延长,除4℃下的种子萌发率降低外,在其他温度下层积的种子萌发率均有所增加。这些结果说明,温度影响胚的分化和生长;胚在形态和生理上达到成熟,是地涌金莲(M. lasiocarpa)种子休眠解除的基础;深度休眠是地涌金莲(M. lasiocarpa)有性繁殖受阻的主要原因,因此,在自然状态下难以通过有性繁殖方式延续后代。在15℃下层积的过程中,地涌金莲种子的内源激素GA3和ABA的含量波动较大。同时,种子的α-淀粉酶和β-淀粉酶逐渐增强;在层积6个月后,α-淀粉酶的活性较缓慢地增加,而β-淀粉酶的活性呈线性增加。这表明,β-淀粉酶活性更能反应种子休眠状态的变化。 4、抱茎独行菜(Lepidium perfoliatum)和无苞芥(Olimarabidopsis pumila)(十字花科,Cruciferae)、细叶鸦葱(Scorzonera pusilla)(菊科,Compositae)、鸢尾蒜(Ixiolirion tataricum)(石蒜科,Amaryllidaceae)和伊犁郁金香(Tulipa iliensis)(百合科,Liliaceae)等5种植物,是生长于同一生境下的短命植物,其种子是正常性的,小而轻,初始含水量<9%,能快速吸水。抱茎独行菜和无苞芥的种子在成熟时是休眠的;完成后熟的抱茎独行菜和无苞芥的种子是光敏性的,其萌发适宜的温度介于15-25℃之间。细叶鸦葱、鸢尾蒜和伊犁郁金香的种子是非休眠的,在低温(4、5和4/10℃)下能很好地萌发,且光对萌发没有显著的影响;土壤水分是影响种子萌发的最主要的因子。由此推知,同一生境下的植物有着不同的萌发模式,并受温度、光照和土壤水分等生态因子的调控。
英文摘要: Tolerance to desiccation is acquired continuously during seed maturation. Three categories of seed storage behavior are generally recognized among plant species: orthodox, intermediate and recalcitrant, depending on response to desiccation and low temperatures. Some indices, such as 1000-seed weight, seed coat ratio (SCR), water content at shedding and habitat, can be used to predict the desiccation sensitivity in seeds. Also, seed dormancy, which has developed in the course of long-term evolution, is a trait of major adaptive importance to their survival in a certain habitat, reflecting the intimate connection between dormancy and seed development and germination. Special dormant mechanisms and germination pattern ensure seed germination and resultant establishment in a favorable temporal and spatial condition. Comparative analyses of different storage behavior, dormant mechanisms and germination pattern in seeds of plant species growing in different habitats are highly valuable for ex situ preservation and sustainable use of plant diversity in the future. Based on the working hypothesis of habitat-correlated variation in seed nature, we investigated distinct seed characteristics of eight plants inhabiting in heterogenous environments. The major results and correlative conclusions were shown as following: 1. Lasia spinosa (Araceae) seeds were recalcitrant and not dormant at maturity. The favorable germination temperature was between 25℃ and 30℃, and the appropriate temperature for wet storage of freshly-mature seeds appears to be 10℃. On desiccation from 66.9% to 25.9% moisture content (mc), viability of seeds was reduced by 50%. After seeds with 37% mc were hermetically stored for 6 months, their viability was reduced to 18%. Mimusops elengi (Sapotaceae) seeds were intermediate. The favorable temperatures for germination were 25, 30 and 20/30℃. Seed tolerated desiccation to 10.7%, but viability was reduced to 23% on desiccation to 5.4% moisture content. After M. elengi seeds with 9.8% mc were hermetically stored at 4℃ for 1, 3 and 6 months, respectively, they germinated at 25℃ to 84, 83 and 79%, respectively. Based on the relationship between the habitat and seed characteristics of two seeds described above, we inferred that desiccation-sensitive seeds are shed to coincide with high water availability, albeit in this case related to spatial rather than temporal patterns. 2. Cellular membranes of M. elengi seeds were seriously damaged during desiccation, resulting in loss of viability of seeds. During desiccation, free radical, which includes reactive oxygen species (ROS), was strong oxidants and caused peroxidation of membrane lipids leading to impairment of membrane structure and function. At the same time, anti-oxidative enzyme activities also changed significantly. When desiccated to low moisture content, the activities of superoxide dismutase (SOD) in seeds firstly increased (6.1% mc) and then decreased. There was a similar pattern in catalase (CAT) and peroxidase (POD)activities, that is, firstly enhanced (10.7% mc) and then declined. Unlike the changes of SOD, CAT and POD activities, the enzyme activity of ascorbate peroxide (APX) decreased in whole on desiccation to 5.4% mc. The activities of dehydroascorbate reductase (DHAR) and glutathione reductase (GR), however, initially increased (10.7% mc) and then sharply decreased. We conclude that a decrease in enzymic protection agaist oxidative attack in M. elengi seeds was directly associated with lipid peroxidation and cyto-toxic free radical formation and that these events taken together might contribute to the loss of viability in the intermediate seeds. 3. M. lasiocarpa (Musaceae) seeds represented a new kind of combinational dormancy (PY+MD+PD) which consisted of physical dormancy (PY), morphological dormancy (MD) and physiological dormancy (PD). Water uptake was passive and germination poor after an experimental period of 5 months in mature, potentially viable seeds. Removal of the operculum of the Musella seeds permitted water to reach the embryo, but did not result in germination. This indicated that water entering the seed is unable to hydrate the embryo, which meant Musella must have an embryo imposed dormancy. During stratification at room temperature, 4, 15 and 20℃, the embryos differentiated gradually, and the rate of embryonic differentiation was faster at room temperature, 15 and 20℃ than that at 4℃. A rudimentary embryo is small and inverse T-shaped. Musella seeds which had stratified for 5 months and differentiated organs did not germinate. However, the final germination of the seeds stratified for 9 months at room temperature was only 3%, and the germination increased to 17, 32, 29, 32 and 37%, respectively, at 4, room temperature, 4/15, 15 and 20℃ after 12-month stratification. With the extension of stratification duration, with the exception of 4℃, the germination of the rest increased slightly during extended stratification. These results confirmed that embryonic differentiation and growth in seeds were temperature-depended and a matured embryo in morphology and physiology was prerequisite of loss of dormancy. Also, the particular deep dormancy of M. lasaicarpa seeds was the major block of sexual regeneration. We inferred that it was difficult for population extension of this species in the field. During warm stratification (15℃), the contents of endogenous GA3 and ABA in Musella seeds significantly fluctuated. Meanwhile, enzyme activities of both α-amylase and β-amylase enhanced. Judging by the relationship between seed dormancy and amylase activity, β-amylase might be considered to be more significant in germination. 4. Lepidium perfoliatum (Cruciferae), Olimarabidopsis pumila (Cruciferae), Scorzonera pusilla (Compositae), Ixiolirion tataricum (Amaryllidaceae) and Tulipa iliensis (Liliaceae) are desert spring ephemeral plants inhabiting the same habitat. Their seeds were small and light, and absorbed water well and exhibited orthodox storage behavior. Seed water contents of the five species were < 9% at shedding. Seeds of L. perfoliatum and O. pumila regenerating only by seeds were dormant at maturity, and undergone after-ripening under heat (30℃, which occurs in summer) or chilling (4℃) conditions. As additional afterripening occurred, L. perfoliatum and O. pumila germinated well in light between 15 and 25℃. In addition, light is required for seed germination of L. perfoliatum and O. pumila. However, the seeds of S. pusilla, I. tataricum and T. iliensis were not light-requiring and germinated very well at low temperatures, such as 4, 5 and 4/10℃. Soil moisture was frequently the overriding factor controlling the timing of germination in deserts. The results indicated that there is more than one germination pattern in a given habitat.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/276
Appears in Collections:昆明植物所硕博研究生毕业学位论文_学位论文

Files in This Item:
File Name/ File Size Content Type Version Access License
10001_200518010615020唐安军_paper.pdf(1657KB)----限制开放-- 联系获取全文

Recommended Citation:
不同生境的植物种子的生理生态特性的比较研究.唐安军[d].中国科学院昆明植物研究所,2008.20-25
Service
Recommend this item
Sava as my favorate item
Show this item's statistics
Export Endnote File
Google Scholar
Similar articles in Google Scholar
[唐安军]'s Articles
CSDL cross search
Similar articles in CSDL Cross Search
[唐安军]‘s Articles
Related Copyright Policies
Null
Social Bookmarking
Add to CiteULike Add to Connotea Add to Del.icio.us Add to Digg Add to Reddit
所有评论 (0)
暂无评论
 
评注功能仅针对注册用户开放,请您登录
您对该条目有什么异议,请填写以下表单,管理员会尽快联系您。
内 容:
Email:  *
单位:
验证码:   刷新
您在IR的使用过程中有什么好的想法或者建议可以反馈给我们。
标 题:
 *
内 容:
Email:  *
验证码:   刷新

Items in IR are protected by copyright, with all rights reserved, unless otherwise indicated.

 

 

Valid XHTML 1.0!
Copyright © 2007-2017  中国科学院昆明植物研究所 - Feedback
Powered by CSpace