龙眼种子的休眠特性及萌发生理

本文对有休眠现象的顽拗型龙眼(Dim-ocarpus longan )品种“乌圆”种子的休眠生理特性作了一些检测,获得如下几个方面结果。1.与温度的关系新采收的龙眼种子(含水量约为37.5％)于5～35℃下可以萌发,5℃下萌发的速度极慢,15～25℃下发芽率均可达100％,其中25℃下萌发的时间最短,只需7天,15℃下则需20天,而于30℃和35℃下萌发20天的发芽率却分别只有76.7％和73.3％(图1)。将置于30℃和     

凤丹种子的休眠和萌发特性

先高温后低温处理可以解除凤丹种子的休眠,凤丹种子萌发需要经历严格有序的后熟,长根和长芽三个阶段,某一阶段的条件不能满足或不按上述顺序进行,即不能萌发成苗。ＧＡ３可代替低温提高凤丹种子的萌发率。     

不同处理方法对油楠成熟和过熟种子萌发特性的影响

为破除油楠(Sindora glabra Merr.ex de Wit)种子的物理休眠,研究不同处理方法对油楠种子萌发特性的影响。结果表明,所有处理方法对油楠成熟和过熟种子萌发均产生显著影响。40℃热水和50 mgL~(-1)萘乙酸有利于成熟种子的萌发,发芽率超过55%,较对照显著提高约10%,而其他方法处理的成熟种子发芽率为4.0%~46.0%,低于对照。采用98%浓硫酸浸泡25 min最有利于过熟种子的萌发,其发芽率、发芽势和发芽指数分别较对照显著提高90%、76%和7以上,且发芽时间显著缩短了9 d,对过熟种子处理的其他方法均能不同程度地促进萌发。因此,对于成熟种子,推荐采用低温热水浸泡或弱腐蚀性的化学处理;而对于过熟种子,宜采用浓硫酸浸泡25 min的处理。     

西双版纳地区4种榕树果实的资源分配及其种子萌发特性

为了解榕树果实的资源分配和种子萌发特征,对西双版纳地区的垂叶榕(Ficus benjamina)、高山榕(F.altissima)、聚果榕(F.racemosa)和无柄雅榕(F.concinna)的果实营养、繁殖资源分配,以及种子萌发特性进行了研究。结果表明,4种榕果的营养分配存在差异,榕果重的种类果肉亦多,榕果大者果腔较大,且种子数量较多,但雄花和榕小蜂数量不一定多。榕果分配给雌性功能及雄性功能繁殖的小花比例也不相同,聚果榕在雌性功能上的分配显著大于雄性功能,其它3种榕果则分配于雄性功能的资源比雌性功能的多,但程度不同。此外,4种榕树的种子大小及重量存在显著的种间差异,以至于影响到种子的萌发率及根茎生长,果实最大的聚果榕种子最多,萌发率高,但由于种子最小,其根茎生长缓慢且短;果实适中的垂叶榕和高山榕种子较大,不但萌发率较高,其根茎生长也较快;果实和种子都小的无柄雅榕,种子萌发率低,根茎生长慢。生长在水热环境好的榕树比生长在相对贫瘠环境的榕树,由于极少面临水热光照等限制,更容易进化出较小的种子,萌发能力和速度也相对较差。这说明不同生境中榕树进化出了不同的繁殖分配机制及资源利用策略来适应环境变化。     

青藏高原东缘灌木种子的萌发特性

种子萌发和种子大小是植物生活史中的两个关键性特征,它关系到幼苗的建成、存活、竞争和个体未来的适合度。对青藏高原东缘43种灌木（12种优势种,31种常见种）种子的萌发特性、萌发模式以及种子大小对萌发能力的影响进行了比较研究。结果显示,萌发率在80%以上的物种：优势种有3种（鲜卑花、千里香杜鹃和山生柳）,占25%;常见种有1种（白毛银露梅）,占3.23%。萌发率在60%～80%的物种：优势种有1种（中国沙棘）,占8.33%;常见种有12种（红毛杜鹃、蒙古绣线菊、短叶锦鸡儿等）,占38.71%。萌发率在40%～60%的物种：优势种有1种（锥花小檗）,占8.33%;常见种有5种（暴马丁香、密叶锦鸡儿和肋果沙棘等）,占16.13%。萌发率在20%～40%的物种：优势种有2种（烈香杜鹃和小叶金露梅）,占6.45%;常见种有1种（紫丁香）,占3.23%。萌发率在20%以下的物种：优势种有5种（置疑小檗、高山绣线菊和岩生忍冬等）,占41.67%;常见种有12种（甘肃小檗、刚毛忍冬、陕甘花楸等）,占36.36%。优势种和常见种的萌发主要有爆发型、过渡型、缓萌型和低萌型。优势种具有较多的过渡型和缓萌型种,有较少爆发型和低萌型种;常见种中过渡型、缓萌型和低萌型物种比例均在30%左右,爆发型仅有3.32%。优势种中的爆发型要多于常见种,而低萌型的种要少于常见种。萌发率和萌发速率与种子大小呈显著的负相关关系,萌发开始时间和萌发持续时间与种子大小有较弱的关联性。     

弥勒苣苔种子的休眠萌发特性

弥勒苣苔为中国特有的濒危植物,一度被认为灭绝后又被重新发现,引起了学界及公众的广泛关注.种子库是保护珍稀濒危物种的一种有效手段,对物种开展种子保存需要较为深入的了解其种子休眠及萌发特性;但对于弥勒苣苔,现有资料十分有限,本研究系统地探讨了弥勒苣苔种子的休眠状态及萌发习性.在对其种子进行X光透视后,发现其种子的胚发育完全,且基本充满整个种子,因此认为该种子不具有形态休眠.在多个变温及恒温条件下对新鲜种子进行萌发测试,发现在较高温度(高于20℃)下萌发率很高且萌发迅速,赤霉素及低温层积处理能够显著提高种子在较低温度下(低于20℃)的萌发率,因此可以判定其种子存在浅的生理休眠.种子在恒温下的萌发率比相应的变温下萌发率要高,可能是其对所处荫蔽环境的一种适应.硝酸钾对种子萌发有显著的促进作用,在野外环境下,硝酸钾有对生境空窗及较少竞争的指示作用.     

肥皂草种子的休眠和萌发特性初探

用刀片切破肥皂草种子的种皮,可以有效地破除肥皂草种子休眠,第2天就达到完全萌发。变温0℃/25℃(12 h黑暗/12 h光照)处理可以有效地促进肥皂草种子的萌发,达到完全萌发需要20 d。     

不同产地车前种子重量、萌发特性及其影响因子

利用国内8个省21个居群的车前(Plantago asiatica)种子,测量其在15℃,15％平衡相对湿度下的重量;通过25/10℃下的萌发实验,统计了种子的萌发率及腐烂率,并通过未萌发新鲜种子的比例对种子可能的休眠程度做出估计.收集采集地的地理及气象信息,对车前种子重量、萌发率、腐烂率及休眠率与地理及气象因子之间的关系做双变量相关分析.结果表明,车前50粒种子的重量在0.0047 ～0.0408g之间,平均值为0.0156 g;种子重量与分布区降水量呈极显著的正相关性,同时温度与种子重量也有显著的正相关性;随着温度升高与降水增多,种子重量呈增大的趋势.腐烂率与海拔呈极显著的负相关性,而与经度、年均温及降水量呈极显著的正相关性;休眠率与年均温及降水量分别呈显著或极显著的正相关性.随着海拔升高、经度减少,温度及降水量下降,车前种子的腐烂率呈下降趋势,休眠程度也逐渐降低;因此西部高海拔地区分布的车前种子具有较浅的休眠及较高的库存活力,因而萌发率较高.车前种子在重量、休眠及萌发习性方面的多样性是其对不同环境适应的一种表现.     

不同天然居群小檗种子萌发障碍因子研究

以西天山野果林霍城居群、新源居群和特克斯居群黑果小檗以及特克斯居群红果小檗种子为试验材料,研究了4组野生小檗种子生物学特性、吸水特性以及去种皮、低温层积和不同浓度GA₃处理对小檗种子休眠与萌发特性的影响,结果表明：（1）4组野生小檗种子的吸水率均表现出逐渐增加的趋势,黑果小檗种子与红果小檗种子吸水率差异不明显,其种皮透水透气性相似;（2）霍城居群、新源居群和特克斯居群黑果小檗种子的种皮对萌发存在强烈的抑制作用;而新源居群红果小檗种子的种皮抑制作用不明显;（3）4℃低温层积处理对4组野生小檗种子萌发影响很大,随层积时间的增加小檗种子发芽率均逐渐提高,3组黑果小檗种子层积90 d时,休眠基本被解除;红果小檗种子层积30 d时,休眠基本被解除;（4）浓度为200 mg·L^-1的GA₃溶液处理可显著提高4组小檗种子发芽率,浓度过高或过低均会对小檗种子萌发起到抑制作用。层积60 d时霍城居群、新源居群和特克斯居群黑果小檗去种皮种子用200 mg·L^-1的GA₃溶液处理2 h后,发芽率分别为85.00%、83.33%和86.67%;红果小檗层积15 d时去种皮种子用浓度为200 mg·L^-1的GA₃溶液处理后,发芽率可达86.67%。研究结果将为今后野生小檗的种质资源保护,利用及可持续发展提供技术支持和科学依据。     

储藏和萌发温度对青藏高原东缘12种灌木种子萌发的影响

研究了青藏高原东缘2个储藏条件下的12种灌木种子在10、15、20、25℃恒温培养下和5/25℃变温培养下的萌发特性及其与种子大小和生境的关系。结果表明:12种灌木室内干储种子在5/25℃变温培养下种子平均萌发率最高、萌发速率最快,室外埋藏种子10℃、5/25℃下种子平均萌发率相近且最高,但萌发速率5/25℃最快,10℃下最慢,4个恒温下的室内干储和室外埋藏种子的萌发速率均随温度升高而变快;10、15、20和25℃恒温培养下的室外埋藏种子平均萌发率、平均萌发速率均高于室内储藏,而5/25℃变温下则是室外埋藏种子平均萌发率、平均萌发速率均低于室内储藏;室内干储的12种灌木种子在5/25℃变温下的萌发率、萌发速率与种子大小呈显著负相关,而室外埋藏的种子在10℃以及5/25℃变温下的萌发率、萌发速率与种子大小均呈显著负相关,20℃下,只有萌发速率与种子大小呈显著负相关;其他储藏和温度下的萌发率、萌发速率与种子大小均没有显著相关;无论室内干储还是室外埋藏,阳坡灌丛物种在5个温度下的萌发率、萌发速率均显著高于阴坡灌丛物种,阴坡灌丛种子萌发率随温度升高而降低;变温有利于种子萌发,贮藏条件对种子的萌发特性的影响具有变温依赖性,种子的萌发特性与种子大小以及生境的关系具有明显的培养温度和储存条件依赖性。     

Variation in seed dormancy and germination among populations of Silybum marianum (Asteraceae)

Milk thistle (Silybum marianum) is a medicinal plant; however, lack of consistency in past dormancy studies has hindered propagation of this species from seeds. We tested the germination responses of freshly harvested and after-ripened (stored for 2 and 7 months; 25°C at 50% relative humidity) seeds from three populations (P1, P2 and P3) in Iran at varying constant or alternating temperatures, with or without GA₃ and in light and continuous darkness. No germination occurred in freshly harvested seeds incubated at any condition without GA₃ application, indicating that all the seeds were dormant. Seeds from P1 and P2, which developed under relatively dry, warm conditions, germinated over a wider range of temperatures after 2 months of dry storage, indicating type 6 of non-deep physiological dormancy (PD). Seeds from P3, which developed under relatively wet, cool conditions, incubated at constant temperatures (especially on GA₃), exhibited an increase in maximum temperature for germination, indicating type 1 of non-deep PD. Light improved germination of after-ripened seeds, and GA₃ application substituted for the light requirement for germination. This is the first report that environmental conditions during seed development may be correlated with differences in the type of non-deep PD. We conclude that milk thistle seeds are positively photoblastic and photodormant and the germination responses of after-ripened seeds from different populations are different under darkness. Therefore, the impacts of genetic differences and maternal effects on the induction of dormancy during seed development should be considered in attempts to domesticate this medicinal plant.     

喀什霸王的结实和种子萌发特性

喀什霸王(Zygophyllum kaschgaricum)是生长于中国新疆南部荒漠环境的稀有种及二级保护植物。当前, 该物种在自然种群中呈分散式及片段化分布, 且种群密度低, 种群老龄化较严重。因此, 为了了解该物种种子萌发特性及其对荒漠环境的响应, 该文采用室内控制实验方法, 对该物种的自然坐果率、结籽率、种子吸水特性、种子休眠和萌发特性及对干旱胁迫的响应进行了比较研究。结果表明: 喀什霸王在自然种群中的坐果率及结籽率较低, 且种子的败育率较高。不同干藏时间种子的吸水速率间存在显著差异; 随着干藏时间的延长, 种子的吸水率逐步增强。刚成熟的种子在不同温度及光周期下均可萌发; 其中高温(10/20 ℃, 20/30 ℃)及黑暗条件下的萌发率比低温(10/5 ℃, 5/2 ℃)及光照条件下的萌发率高。不同干藏时间的种子在不同浓度赤霉素(GA₃)下的萌发率均较高; 但低温储藏时间对该物种种子的打破休眠及萌发率没有促进作用。以上结果说明该物种存在非深度生理休眠; 而干藏时间、高温且黑暗及高浓度(50 mmoloL ^-1) GA₃是打破休眠及促进种子萌发的最合适条件。高温条件下的干旱胁迫对喀什霸王种子萌发具有抑制作用; 春季和秋季降水量决定种子的萌发率。总之, 喀什霸王种子在物候上表现出的春秋季萌动及非深度生理休眠以提高幼苗存活力及保障种群稳定性, 是一种对新疆南部干旱及高温胁迫荒漠环境的适应策略。     

枫香树种群种子与果实表型性状变异分析

为了明确我国枫香树(Liquidambar formosana)种子与果实表型变异程度和变异规律, 采用方差分析、相关分析和回归分析等方法对36个天然种群枫香树的10个种子与果实的表型性状在种群间和种群内表型变异和地理变异模式进行探讨。研究结果表明, 枫香树平均表型分化系数为57.55%, 种群间的变异是其表型变异的主要来源; 种子和果实表型性状的变异丰富, 变异幅度为10.05%-24.31%, 平均变异系数为15.83%; 不同种群间变异差别明显, 安福种群平均变异系数最大(16.73%), 建阳种群平均变异系数最小(11.48%)。枫香树多数种子与果实表型性状在地理变化上是随机的, 地理相近种群在表型上没有显著相关性。地理气候因子中1月平均气温、海拔和纬度对种子与果实性状起主要的影响。种子与果实性状与海拔相关分析表明, 枫香树种子长宽比随海拔的升高而减小, 种子长宽比可以推测种群所在的海拔高度。探讨枫香树种群表型多样性, 可为野生优异种质的收集、多目标品种选育等工作提供依据。     

The control of seed germination in Trollius ledebouri A model of seed dormancy

Treatment of Trollius ledebouri seeds with gibberellins A₄+A₇ promotes germination. The efficacy of the treatment is dependent upon the duration of imbibition in distilled water prior to GA₄₊₇ application. Presoaking increases both the final percentage germination attained and also its rate of achievement. No presoaking effect is exhibited by seeds induced to germinate by testa removal in the absence of GA₄₊₇. Active washing of Trollius seeds enhances the presoaking effect and the eluent from washed seeds is inhibitory to germination. The results support the hypothesis that the presoaking effect exhibited by Trollius is the result of the leaching of a germination inhibitor from the seeds which is antagonistic to GA₄₊₇. Additionally, treatment of Trollius seeds with the gibberellin-biosynthesis inhibitor (2-chloroethyl)-trimethylammonium chloride (CCC) prior to testa removal retards germination. The inhibitory effect of CCC on germination is overcome by GA₄₊₇. Although CCC inhibits embryo growth during the presoaking of intact seeds, it does not affect the increased sensitivity of presoaked seeds to GA₄₊₇. Therefore, although endogenous gibberellins may be involved in the germination process, they do not contribute to the presoaking phenomenon. The expansion of isolated endosperm tissue is not affected by CCC. However, the chemical markedly inhibits endosperm expansion in intact seeds and implicates the embryo as both the site of production of the germination inhibitor and of gibberellin. These results are discussed in relation to previous studies and a model is presented to account for the characteristics of germination in Trollius.Abbreviations GA gibberellin - CCC (2-chloroethyl)-trimethylammonium chloride     

生长素调控种子的休眠与萌发

植物种子的休眠与萌发,是植物生长发育过程中的关键阶段,也是生命科学领域的研究热点。种子从休眠向萌发的转换是极为复杂的生物学过程,由外界环境因子、体内激素含量及信号传导和若干关键基因协同调控。大量研究表明,植物激素脱落酸(Abscisic acid, ABA)和赤霉素(Gibberellin acid, GA)是调控种子休眠水平,决定种子从休眠转向萌发的主要内源因子。ABA与GA在含量和信号传导两个层次上的精确平衡,确保了植物种子能以休眠状态在逆境中存活,并在适宜的时间启动萌发程序。生长素(Auxin)是经典植物激素之一,其对向性生长和组织分化等生物学过程的调控已有大量研究。但最近有研究证实,生长素对种子休眠有正向调控作用,这表明生长素是继ABA之后的第二个促进种子休眠的植物激素。本文在回顾生长素的发现历程、阐释生长素体内合成途径及信号传导通路的基础上,重点综述了生长素通过与ABA的协同作用调控种子休眠的分子机制,并对未来的研究热点进行了讨论和展望。     

MicroRNA在种子发育、休眠与萌发过程中的作用

植物microRNA(miRNA)是一类小分子非编码RNA,对植物的生长发育发挥着重要调控作用。种子发育、休眠与萌发是植物生命进程中的重要阶段。在这一阶段内,种子受各种环境因子及内源激素调控,并且不同植物种子具有不同发育及休眠特性。随着人们对种子发育、休眠及萌发机理的探究,越来越多miRNA被鉴定,它们能够基于植物激素信号传导、抗氧化作用、关键转录因子调控等途径参与种子形态建成、物质代谢及各种胁迫响应。本文主要综述了近年来植物miRNA的形成及调控机理,以及在种子发育、休眠及萌发过程中发挥的调控作用,旨在为今后的研究方向提供参考。     

The role of light in regulating seed dormancy and germination

Seed dormancy is an adaptive trait in plants. Breaking seed dormancy determines the timing of germination and is, thereby essential for ensuring plant survival and agricultural production. Seed dormancy and the subsequent germination are controlled by both internal cues (mainly hormones) and environmental signals. In the past few years, the roles of plant hormones in regulating seed dormancy and germination have been uncovered. However, we are only beginning to understand how light signaling pathways modulate seed dormancy and interaction with endogenous hormones. In this review, we summarize current views of the molecular mechanisms by which light controls the induction, maintenance and release of seed dormancy, as well as seed germination, by regulating hormone metabolism and signaling pathways.     

Seed germination traits of Ailanthus altissima,Phytolacca americana and Robinia pseudoacacia in response to different thermal and light requirements

Invasion of alien plant species (IAS) represents a serious environmental problem, particularly in Europe, where it mainly pertains to urban areas. Seed germination traits contribute to clarification of invasion dynamics. The objective of this research was to analyze how different light conditions (i.e., 12-hr light/12-hr darkness and continuous darkness) and temperature regimes (i.e., 15/6°C, 20/10°C and 30/20°C) trigger seed germination of Ailanthus altissima (AA), Phytolacca americana (PA) and Robinia pseudoacacia (RP). The relationship between seed germination and seed morphometric traits was also analyzed. Our findings highlight that temperature rather than light was the main environmental factor affecting germination. RP germinated at all tested temperatures, whereas at 15/6°C seeds of AA and PA showed physiological dormancy. RP had a higher germination capacity at a lower temperature, unlike AA and PA, which performed better at the highest temperatures. Light had a minor role in seed germination of the three species. Light promoted germination only for seeds of PA, and final germination percentage was 1.5-fold higher in light than in continuous darkness. Seed morphometric traits (thickness [T], area [A] and volume [V]) had a significant role in explaining germination trait variations. The results highlight the importance of increasing our knowledge on seed germination requirements to predict future invasiveness trends. The increase in global temperature could further advantage AA and PA in terms of germinated seeds, as well as RP by enhancing the germination velocity, therefore compensating for a lower germination percentage of this species at the highest temperatures.