喜盐鸢尾种子休眠与萌发特性初步研究

喜盐鸢尾(Iris halophila）是一种干旱地区野生观赏花卉,种子萌发困难,限制了该种在园林绿化中的应用,也为育种工作带来难度。从吸水性和萌发性两个方面对喜盐鸢尾种子休眠原因和打破休眠的方法进行了探索。研究表明,在25/10 ℃（高温/低温）条件下,喜盐鸢尾种子萌发率最高,达到44.33%;胚乳中的萌发抑制物质是限制喜盐鸢尾种子萌发的主要原因;种皮可限制胚乳萌发抑制物质的释放。砂纸摩擦、切除部分胚乳和赤霉素(GA3)处理都能提高种子的萌发率。综合考虑经济费用和可操作性等因素,砂纸摩擦后蒸馏水浸种处理是打破喜盐鸢尾种子萌发行之有效的方法。     

野榆钱菠菜的果实多型性及其萌发对策

野榆钱菠菜有3种形态的果实和种子,这3种果实在形状、大小、颜色、着生方式及包被其苞片的大小上均有差异.以野榆钱菠菜的3种果实(种子)为材料,在暗/光为5 ℃/25 ℃,5 ℃/15 ℃,15 ℃/25 ℃,暗周期和光周期同为12 h的条件下,进行萌发实验.结果表明:新采收的C型种子成熟后具有一定的萌发能力,并且在5 ℃/25 ℃下的萌发率最高(＞90%);A型和B型种子存在休眠现象.划破种皮后,A型和B型种子在3个温变处理下的萌发率显著提高,12 星期的低温层积处理也能有效地加速和提高A型和B型种子的萌发率,表明A型和B型种子的休眠属于非深度生理休眠.     

苦豆子种子发芽特性研究

对苦豆子破除种子硬实、提高活力指数的方法及最适发芽的土壤含水量和播深进行了测定与研究,结果表明:苦豆子种子发芽困难的原因是种皮致密,吸胀困难;提高发芽率的措施是砂纸摩擦或65%H2SO4处理20 min;提高种子活力的措施是65% H2SO4处理20 min后,再用0.02%GA3处理;苦豆子种子萌发的适宜土壤含水量为8%～12%,播种的最适深度是0～3 cm.     

苍耳种子解除休眠的物理方法研究

苍耳种子的休眠主要受种皮质地坚硬而形成的对种子机械束缚力及种皮内封闭的薄膜质层影响。流水浸泡＋挫伤种皮,种子发芽率达到86.47%,流水浸泡发芽率达到80.14%,挫伤种皮发芽相对较低,为68.97%。物理解除避免了化学解除休眠处理中强酸、强碱及氧化剂对种子内部有效成分的破坏。     

不同温度、水热条件对3种植物种子物理休眠解除的影响

研究种子物理休眠解除机制及其影响因素是了解种子休眠生态学和种群适应策略的重要途径。准噶尔无叶豆(Eremosparton songoricum)、银沙槐(Ammodendron bifolium)和乌拉尔甘草(Glycyrrhiza uralensis)是在干旱区分布的3种豆科珍稀物种,其种子均存在物理休眠现象。以3种植物种子为研究对象,探讨冷层积(5℃)、夏季高温及干/湿处理对种子物理休眠解除的作用。研究表明:1 3种植物种子的硬实率高,种皮透水性低,划破种皮的处理方法可有效解除3种植物种子的物理休眠。2冷层积对3种植物种子的物理休眠解除无显著影响。3高温、干/湿条件和处理时间显著影响3种植物种子的萌发率,其中,湿热条件更能有效解除3种植物种子的物理休眠。准噶尔无叶豆和银沙槐种子的物理休眠解除率与温度呈正相关,在80℃和65℃湿热条件下其萌发率最高,分别达到(70.48±2.92)%和(78.13±3.67)%,而乌拉尔甘草种子的物理休眠解除率与温度呈负相关,40℃湿热条件下的萌发率最高,达到(85.23±3.82)%。表明荒漠地区夏季的极端高温有利于种子物理休眠的解除,但较少的降水量却限制了种子的萌发,这可能是导致该地区3种植物自然种群实生苗稀少,有性更新弱的主要原因之一。     

NdCl3对渗透胁迫下小麦种子萌发的影响

在３５μｍｏｌ／ＬＮｄＣｌ３存在下，小麦种子在不同浓度聚乙二醇（ＰＥＧ）中发芽势均有所提高，以２０％ＰＥＧ作为胁迫处理，发现ＮｄＣｌ３在促进小麦种子萌发时，提高了α－淀粉酶和脂酶的活力，但使过氧化物酶活性下降。ＮｄＣｌ３对胁迫下萌发小麦的培养介质电导率有显著降低作用。     

鹅观草种子萌发及出苗特性

在实验室和温室条件下研究不同温度、光照、水势、盐分对鹅观草种子萌发以及埋土深度对鹅观草出苗的影响。结果表明,鹅观草种子萌发的昼/夜温度范围为20℃/10℃~35℃/25℃,最适昼/夜温度为25℃/15℃;黑暗条件下,鹅观草种子萌发率较光照下略有提高,说明鹅观草萌发不需要光照;鹅观草种子对水势胁迫较敏感,水势从0下降至-0.8 MPa时,发芽率从93%直线下降至0;鹅观草种子对盐分胁迫具有一定耐受性,当NaCl浓度≤50 mmol/L时,种子均能保持80%以上的萌发率。50%萌发抑制率时的水势和NaCl浓度分别约为-0.4 MPa和100 mmol/L。埋土深度为0.5 cm时,鹅观草出苗率最高,埋土深度≥3 cm时出苗率显著下降。表明鹅观草种子萌发具有较强的环境适应性,通过耕作将其种子带入4 cm以下土层,可有效抑制鹅观草的危害。     

温周期及果翅对梭梭种子萌发行为的调控

种子萌发行为的受控机制是生殖生态学的重要研究内容.通过对适宜的温周期下,不同贮藏时期果翅对梭梭种子萌发影响的研究.结果表明:梭梭种子在温周期为5℃/25℃,5℃/15℃和15℃/25℃(暗/光=12 h/12h)中均能快速萌发.果翅对秋天新成熟种子的萌发有显著的抑制作用,使种子处于强迫休眠状态;果翅对种子萌发的抑制作用随着贮藏时间的推移逐渐降低,到翌年春天(4月)解除这种抑制作用.果翅对梭梭种子萌发行为的调控作用确保了种子在合适的时间萌发与种群的成功定居,这也是梭梭在荒漠地区广泛分布的主要原因.     

大豆疫病的检疫研究——种子带菌及检验技术

本文通过人工接菌和对自然条件下的大豆疫病种子的研究，证实大豆疫病可以种子带菌，并以卵孢子和菌丝体存在于种子的种皮、胚和子叶里，且卵孢子只产生于种皮。提出大豆疫病种子检验只需检查种皮，以种皮里大豆疫病卵孢子存在与否为标准。采用ＭＴＴ染色法测定种子带菌卵孢子活性，检查出存放３年的病种子里活性卵孢子占３０％。     

菠菜种子发芽试验

利用不同发芽处理研究菠菜种子的休眠和萌发特性，旨在解决菠菜种子发芽中的困难。结果表明：带果皮的菠菜种子在纸床和沙床上均难以萌发，在土床上的发芽率为85％；而去果皮的种子在纸床、砂床和土床上的发芽率为92％；完整菠菜种子的渗液显著抑制去果皮菠菜种子的萌发；低温处理可以打破休眠，提高种子的发芽率。菠菜果皮结构致密以及果皮内含有的抑制性物质是控制休眠的关键因素。     

Weed seed movement and dispersal strategies in the agricultural environment

This paper reviews the current knowledge on weed seed movement in an agricultural environment. Seed movement is analyzed both from an agronomic and ecological perspective, focusing predominantly on horizontal seed movement. Abiotic (anemochory and hydrochory), as well as biotic (autochory, myrmecochory, epizoochory, and endozoochory) weed seed dispersal typologies are examined, highlighting the mechanisms involved, the specializations displayed by weed species that have evolved by exploiting a particular dispersal mechanism, and their adaptive interaction with the surrounding ecosystem. Emphasis is also placed on the crucial role of human activity (anthropochory), which can affect natural (biotic and abiotic) weed seed dispersal at several stages, partly via the worldwide commercial seed trade but, above all, by crop management operations, thereby potentially facilitating the entry and spread of alien weed species. This phenomenon, together with the invasive expansion of existing weeds that more successfully coevolve and adapt to the new environment, might exert an adverse effect on biodiversity. In-depth knowledge of weed seed dispersal, survival, and germination mechanisms is therefore essential for effective and eco-compatible management of the weed phytocoenoses present in the agroecosystem in order to promote a rational trade-off between agricultural productivity and environmental protection.     

Impacts of snow on seed germination are independent of seed traits and plant ecological characteristics in a temperate desert of Central Asia

Seed germination profoundly impacts plant community composition within the plant life cycle. Snow is an important source of water for seed germination in the temperate deserts of Central Asia. Understanding how seed germination responds to variations in snow cover in relation to seed traits and plant ecological characteristics can help predict plant community sustainability and stability in Central Asia under a scenario climate change. This study investigated the seed germination of 35 plant species common to the Gurbantunggut Desert in Central Asia under the three snow treatments: (1) snow addition; (2) ambient snow; and (3) snow removal. Two-way analysis of variance (ANOVA) tests were performed to assess interactions among the impacts of snow treatments, seed traits and plant ecological characteristics on seed germination. Phylogenetic generalized least-squares (PGLS) model was used to test the relationships between seed traits and seed germination. The results demonstrated that snow variations had no significant impacts on seed germination overall. Seed germination under the snow addition treatment was similar with that under the ambient snow treatment, irrespective of seed traits and plant ecological characteristics. Snow removal only had negative impacts on seed germination for certain groups of seed traits and plant ecological characteristics. Seed mass positively affected seed germination, showing a linear increase of arcsin square root-transformed seed germination with log-transformed seed mass. Seed shape also profoundly impacted seed germination, with a higher germination percentage for elongated and flat seeds. Seed germination differed under different plant life forms, with semi-shrub species showing a significantly higher germination percentage. Most importantly, although snow treatments, seed traits and plant ecological characteristics had no interactive effects on seed germination overall, some negative impacts from the snow removal treatment were detected when seeds were categorized on the basis of seed mass and shape. This result suggests that variations of snow cover may change plant community composition in this temperate desert due to their impacts on seed germination.     

Dormancy and viability of Phalaris minor seed in a rice–wheat cropping system

Seed placement, soil temperature and soil moisture content influenced the process of after-ripening in Phalaris minor seeds. Seeds of P. minor collected from the soil just after wheat harvesting exhibited higher germination than seeds from P. minor threshed directly. There was a pronounced impact of periodic inhabitation of seed into the soil on germination after its dispersal. Germination was strongly inhibited when the seed was kept in soil at more than field capacity (FC) or in water. Maximum germination of seed incubated in soil at FC occurred at 30°C while a temperature of 40°C favoured after-ripening of seed when mixed with dry soil or kept dry without any medium. Release from conditional dormancy was quicker in the seed retrieved from the soil kept at 20°C than at 10°C. Seed release from conditional dormancy and germination increased with a rise in temperature from 30 to 40°C when the seed was retrieved from incubation in soil at FC for 70 days. The seed kept immersed in water was least responsive to a rise in temperature. Seed recovered from dry soil, or kept without any medium, responded quickly at both temperatures. Light enhanced the germination of Phalaris minor seed. The seedbank subjected to rice (Oryza sativa) field management conditions lost vigour in comparison with the seed stored in laboratory. There was significant variability in seed viability when exposed to differential water management conditions in rice.     

盐和PEG模拟干旱胁迫对沙米种子萌发及幼苗生长的影响

研究不周浓度盐溶液(NaCl、MgSO4、盐渍土壤)和PEG模拟干旱胁迫对沙米种子吸胀、萌发和幼苗生长的影响,并观察胁迫解除后种子的反应.结果表明:随着NaCl、MgSO4和PEG浓度的升高,沙米种子吸胀率先升后降,种子萌发率呈现不同程度降低,盐渍土壤溶液对萌发率没有显著影响;对沙米种子萌发和幼苗生长的胁迫效应是NaC...     

种子传播提高生物多样性的机制

种子是保存物种遗传信息的载体,保护种子资源是植物保护和生物多样性保护的重要内容。种子传播不仅对保护植物自身的繁殖和生存至关重要,而且对群落稳定甚至生态系统功能具有重要意义。该文综述了种子传播的方式、干扰因素以及种子传播通过提高生物多样性来促进植物保护的机制,即丰富的生物多样性降低了病虫害对植物的危害。种子传播易受人为活动和气候变化等因素干扰传播媒介和破坏生境;需要采取构建廊道等措施来降低因生境破碎化引起的负面影响。种子传播提高生物多样性的机制主要通过增加基因交流来提高遗传多样性,通过增加种子扩散效率和存活率等来提高物种多样性、稳定群落结构和通过连通生境斑块来提高生态系统多样性。因此,构建基于生态系统的种子传播网络对保护生物多样性具有重要意义。     

3种菊科入侵植物白花鬼针草、胜红蓟和假臭草的种子生物学特性比较研究

为探讨菊科入侵植物种子的繁殖特性,从种子的形态特征及种子萌发率等指标入手,对胜红蓟(Ageratum conyzoide)、白花鬼针草(Bidens alba)及假臭草(Eupatorium catarium)3种菊科入侵植物的种子特性进行比较研究。结果表明,白花鬼针草种子的冠毛芒最短及最少,沉降速度最大,种子的风媒传播能力最弱,但种子全身具长倒钩刺,主要通过人畜和货物等实现远距离散播。假臭草种子冠毛芒较胜红蓟的长和多,种子沉降速度较胜红蓟的小,其风媒传播能力较胜红蓟的强。白花鬼针草种子千粒质量、发芽指数、胚根、胚芽和胚轴均最大或最长,发芽率和发芽势也较高,其种子质量和种子活力为三者中最高。假臭草的千粒质量、胚根、胚芽和胚轴与胜红蓟无显著差异,但发芽势及发芽指数均显著高于胜红蓟,说明假臭草种子活力较胜红蓟的高。假臭草发芽率为三者中最小,这可能与其种子含水率(19%)高有关,高含水率隐含着种子在潮湿环境下易发生霉变。胜红蓟种子除了发芽率较高外,千粒质量、发芽势、发芽指数、胚根、胚芽和胚轴等指标均较小或大,反映其种子质量和活力较小。     

Seed dormancy and soil seedbank of the invasive weed Chenopodium hybridum in north‐western China

Seed dormancy and persistence in the soil seedbank play a key role in timing of germination and seedling emergence of weeds; thus, knowledge of these traits is required for effective weed management. We investigated seed dormancy and seed persistence on/in soil of Chenopodium hybridum, an annual invasive weed in north‐western China. Fresh seeds are physiologically dormant. Sulphuric acid scarification, mechanical scarification and cold stratification significantly increased germination percentages, whereas dry storage and treatments with plant growth regulators or nitrate had no effect. Dormancy was alleviated by piercing the seed coat but not the pericarp. Pre‐treatment of seeds collected in 2012 and 2013 with sulphuric acid for 30 min increased germination from 0% to 66% and 62% respectively. Effect of cold stratification on seed germination varied with soil moisture content (MC) and duration of treatment; seeds stratified in soil with 12% MC for 2 months germinated to 39%. Burial duration, burial depth and their interaction had significant effects on seed dormancy and seed viability. Dormancy in fresh seeds was released from October to February, and seeds re‐entered dormancy in April. Seed viability decreased with time for seeds on the soil surface and for those buried at a depth of 5 cm, and 39% and 10%, respectively, were viable after 22 months. Thus, C. hybridum can form at least a short‐lived persistent soil seedbank.     

黄土高原不同地区杜松的种子萌发特性及其与生态因子的相关性

选取黄土高原5个地区杜松(Juniperus rigida)种子,采用种子萌发实验及相关分析的方法,研究其大小特征、萌发特性及其与生态因子的相关性,以了解不同地区杜松的种子萌发特性。结果表明,不同地区杜松的种子大小差异显著,府谷地区的种子最大、最重,平均长6.83 mm,宽3.56 mm,千粒重为25.89 g;种子长及种子长宽比随纬度的升高、土壤全磷含量的增加而变小;种子千粒重随1月和7月均温的增加而增加,随土壤有机质、速效磷、全氮含量的增加而减少。种子大小对萌发特征影响显著,种子萌发率、萌发势及发芽指数均随种子长、种子长宽比的增加呈减小的趋势。不同地区杜松的萌发差异显著,武川的种子萌发最快最高,府谷与贺兰山最慢、最低;萌发率、萌发势及发芽指数均随纬度的升高而增加,萌发势和发芽指数随土壤全磷含量的增加而增加。研究认为武川及浑源地区是杜松优良的选种地。     

Inter-population variabilities in seed mass and germination of Panicum turgidum and Pennisetum divisum in the desert of Kuwait

Understanding variability in seed germination among populations is essential for planning an effective germplasm collection for restoration and conservation purposes.The knowledge of germination and dormancy patterns among populations of desert grasses is crucial for determining the potential of the species and populations to be used for restoration and conservation as well as forage production.Variability in seed germination of Panicum turgidum Forssk and Pennisetum divisum(Gmel.)Henr.in the desert of Kuwait was evaluated in different populations in May 2017.Experiment of seed germination(25 seeds and 4 replicates)was conducted for each population at night/day temperatures of 15℃/20℃and 20℃/30℃under the following light condition:continuous darkness or 12 h/12 h light/dark.Results showed that seed masses of both species strongly varied according to their seed provenances,and both species produced heavier seeds in population with a higher soil electrical conductivity.Seed germination percentage considerably varied between two species,and the variation in P.turgidum was greater(17%–49%)than that of P.divisum(72%–93%).Germination percentage in P.turgidum was greater at high temperature(20℃/30℃)than at low temperature(15℃/20℃).However,temperature regimes had no effect on germination percentage of P.divisum seeds.Mean germination time of both species exhibited significant inter-population variability.This result is especially relevant to assure the selection of the best population of each species and the regeneration success of the species.Besides this,inter-population variability also provides valuable information for enhancing our understanding of the mechanisms that regulate seed germination and how they might be related to seed provenance.     

层积处理对野慈姑种子萌发的影响

探讨层积处理方法对野慈姑种子萌发的影响,以期为今后以野慈姑种子为萌发材料的相关试验研究与田间防除提供理论依据。试验结果表明：低温层积处理能够提高野慈姑种子的发芽率,处理5～10 d,种子能够发芽,但发芽率低;处理15 d时,种子发芽率大幅度提高,随后提高幅度减小;处理35 d后,种子逐渐达到低温层积处理的最高发芽水平,且与经过自然越冬的种子相比,发芽率无显著差异;处理60 d后种子发芽率不再提高;室温层积处理5～90 d野慈姑种子的发芽率均不高于4．00％,可见室温层积处理不能提高野慈姑种子的萌发率。