植物遗传资源的种子基因库保存

一个物种的灭绝是与其受生物因子和非生物因子的威胁程度相关的。随着物种的加速绝灭,保护生物多样性受到广泛地关注。保护生物多样性的最有效的生物技术之一是建立种子基因库,进行迁地保护。种子库理想的贮藏条件主要取决于种子含水量、贮藏环境(如温度和湿度)和贮存种子的容器。进行种子贮藏,了解种子生命力和活力的影响因子的作用机理是十分重要和必要的。除了种子自身的生理特征外,种子的贮藏寿命与种子成熟度、收获技术、加工处理方法也是息息相关的。即使在最适的库存条件下,种子也会随时间发生劣变。因此,必须根据种子特定的贮藏行为,加以考虑影响种子存活的3个主要方面(贮藏环境、贮藏期和植物种类)而选择有效的贮藏方案。本文试图讨论种子贮藏生理的几个重要方面及其需解决的技术问题,以便更好地通过种子基因库,长期有效地保存植物种质资源。     

箭根薯种子的贮藏与萌发

就温度、光照和土壤水分对箭根薯 (TaccachantrieriAndre )种子萌发的影响及种子贮藏条件进行了研究 ,结果表明 ,箭根薯种子是需光性种子 ,萌发温度较窄且要求有较充分的土壤水分 ,其萌发的最适宜温度为 2 5～ 30℃ ,最适宜土壤水分为 6 0 %～ 70 %;室温干燥贮藏比室温常规贮藏效果好 ,而高温高湿和低温高湿都导致其发芽率迅速下降。箭根薯种子耐脱水、耐低温和耐贮藏 ,可以用种子库常规的种子保存技术实现长期保存。研究认为 ,目前箭根薯的濒危状态既有物种自身的原因也有生境破坏的原因 ,该物种宜采取就地保护、迁地保护和种子保存相结合的方法进行种质资源保存。     

度胁迫对罂粟种子萌发影响及其活力变化规律的研究

为妥善保存罂粟种质资源及防止种子老化,研究了温度对罂粟种子萌发及种子活力的影响。结果表明:罂粟为高温敏感低温萌发型种子,发芽的适宜温度为10～20℃,最适温度为18℃左右,低于5℃和高于20℃的温度,种子萌发受到抑制;在对其进行丸化包衣时,加热温度应控制在60℃以内,时间应控制在60min以内;在常温库存条件下,罂粟种子活力随贮藏年限的增加而下降,贮藏时间超过五年后,发芽率低于50%,不宜作种用,在作为种质资源保存时,须每隔五年繁殖一次。     

一个预测贮藏在低温种质库的小麦种子寿命的方程

为探讨将种子发芽率转化为存活比,促使种子存活曲线转变成直线,并用于预测种子寿命的可行性,3个含水量水平的3种8个种子批的小麦种子被贮藏在20℃、30℃和40℃的温度下长达810d,以获取发芽率数据。比较和分析了概率、存活比与贮藏时间绘制的种子存活曲线、构建的概率回归和存活比线性回归方程的拟合性比,以及贮藏温度和种子含水量对种子死亡时间分布标准差的影响。结果表明,和概率值相比,存活比更容易使种子存活曲线直线化,和贮藏时间的线性回归方程的拟合性也更优于概率回归方程;贮藏温度和种子含水量的交互作用对种子寿命的影响是真实的,其作用也大于单独的温度、水分或水分的对数;只包含贮藏温度和种子含水量交互作用的预测种子寿命的存活比线性回归方程,即Gi/G0=A-P/10KE-CWH(t譵),被贮藏在低温种质库的小麦种子的实际发芽率和贮藏时间证明,是适合用于预测贮藏在低温种质库的小麦种子寿命的,尤其在预测发芽率时较预测贮藏时间有更高的准确性。     

三种保存条件下水稻和小麦种质资源安全保存期的分析

种子从入库保存至其发芽率降至更新发芽率标准的贮藏时间即为种质的安全保存期。在低温种质库以及室温等条件下,还未见有种质安全保存期的文献报道。本研究以水稻和小麦种子为例,分析了在国家长期库、广西中期库以及不同气候区室温保存的生活力监测数据,以了解种质安全保存期。结果表明,在国家长期库保存20~22年的3500份水稻和3279份小麦种子的生活力仍保持在较高水平;99%以上的水稻种子和96%以上的小麦种子在长期库的安全保存期超过20年。中期库保存17~19年的801份水稻种子中,有96%以上种子的安全保存期超过17年。水稻和小麦种子在6个气候区室温保存的监测结果显示,北方低温地区保存效果普遍好于南方高温地区,北方低温地区适宜含水量种子的安全保存期超过14年,可达中期保存要求。分析发现种子的安全保存期不仅与保存温度、种子含水量等保存条件有关,还与种子的初始质量、品种类型等诸多因素有关。     

顽拗性种子

通常影响种子寿命两个最重要的因素:种子含水量和种子贮藏温度。对于正常性的种子来说,因其在成熟过程中,随着种子含水量的急剧下降,生理代谢活动也显著降低,并转入休眠状态,从而能耐干燥和低温贮藏。如果种子的含水量保持在5%至6%,并贮藏在零度以下的环境中,其种子仍能维持较长的生活力。然而对于许多热带和亚热带的果树,以及一些重要的林木种子,例如木菠萝、橡胶、芒果、龙眼、荔枝、榴莲、板栗、坡垒和青皮等植物,由于它们的种子在贮藏过程中,既不耐低温,也不耐受干燥,当种子含水量低于一定值时,发芽力便迅速下降;即使把它们贮藏在潮湿环…     

珍稀濒危植物三棱栎种子的储藏特性鉴定

由于三棱栎种子存在较高败育率,导致无法准确检测种子初始萌发率,因此对三棱栎种子的储藏特性一直不清楚,无法对该珍稀濒危物种提供最佳长期保存方案。本研究通过种子重力分离技术和X光成像系统检测技术,对三棱栎（Formanodendron doichangensis）的成熟种子进行优化清理,成功排除了空瘪种子对萌发实验的影响,通过研究脱水、低温和超低温对三棱栎种子活力的影响,明确鉴定了三棱栎种子的储藏特性,为该珍稀濒危物种提出最佳长期储藏方案。结果表明,种子重力分离技术有效地将三棱栎种子的饱满率从处理前的47%,提高到处理后的86%。根据国际种子储藏特性鉴定方法,三棱栎种子的含水量降到5%以下,种子活力为95%,仍与对照（92%）一致。极低含水量 （〈5%）的种子,在低温（-20℃）和超低温（-196℃）保藏处理3个月后,其活力仍为90%和91%。以上数据表明,三棱栎的种子能够耐受极端脱水和低温保藏,属于正常型种子,可以运用常规的种子库保存技术和储藏条件（即脱水低温条件）长期保存,该方法是珍稀濒危植物三棱栎种质资源进行长期保藏的最佳方法。     

植物种质资源超低温保存概述

简要回顾了植物种质资源超低温保存的历史,说明了超低温保存植物材料的多样性,阐述了超低温耐性的生物学基础及超低温伤害产生的原因和类型,介绍了各种常用超低温保存方法的技术要点,并对生产顽拗性种子的植物种质资源的超低温保存作了专门的论述,分析了生产顽拗性种子的植物种质资源超低温保存的潜力、现状和困难,指出顽拗性种子的超低温保存是植物种质资源超低温保存的重点和难点,而真正实现用超低温保存技术贮藏顽拗性植物种质资源还有很长的路要走。     

濒危植物西康玉兰种子休眠、萌发及贮藏特性

研究了西康玉兰(Magnolia wilsonii)种胚的形态大小,温度、层积、硝酸钾、浸种处理和GA_3对种子休眠及萌发的影响.通过将种子脱水至不同含水量和在两种温度(4℃和一20℃)下贮藏100 d后测其生活力,分析各处理对西康玉兰种子活力的影响.结果表明:西康玉兰种子胚尚未分化完全,需经过低温层积完成生理后熟;低温层积和GA3可打破种子休眠.种子最适萌发温度为25/20℃.由此推测,西康玉兰种子具有形态生理休眠特性.西康玉兰种子当含水量降至5.39%,存活率为53.50%.不同含水量的种子贮藏在-20℃条件下,100 d后种子全部死亡;但在4℃下含水量为10.31%的种子存活力高达76%.因此,西康玉兰种子极可能属于中间性种子,其适宜贮藏环境为4℃下的干藏或湿藏.     

九里香种子脱水耐性和萌发生理的研究

九里香种子自花后 42～ 77d,含水量和电导率逐渐降低 ,种子干重、发芽率、发芽指数和活力指数逐渐增加。硅胶脱水 1～ 6d后 ,种子含水量下降 1 0 %～ 3 5 % ,发芽率、发芽指数和活力指数均有不同程度的降低 ,不同发育时期九里香种子的脱水耐性有别 ,花后 42～ 70d不断增强 ,77d有所减弱。花后 70d的种子含水量降至 1 0 % ,种子发芽率无明显降低 ;含水量为 9%的种子在 4°C和 2 0°C的低温条件贮存 3 0d和 42d ,多数种子仍能萌发 ,这表明九里香种子是一种正常型种子。光照能促进种子的萌发 ;在 2 0～ 3 0°C、室温和 2 0 /3 0°C变温条件下种子萌发较好 ;光照和温度对种子萌发有单独影响 ,但又相互作用 ,同时光照对萌发的影响还与种子含水量有关。     

Seed size, shape and vertical distribution in the soil: indicators of seed longevity

1. We investigated the vertical distribution of seeds in the soil, using data from nine studies in five European countries. We discovered significant correlations between seed shape and distribution in the soil.
2. The classification of the longevity of seeds of plant species has been improved by the introduction of a 'longevity index', expressing on a continuous scale the most recent information on seed longevity represented as the proportion of non-transient seed bank records in the database of Thompson et al. (1997 ). Remarkably, no difference in seed longevity was found if the index was based on direct observations only when compared with the index based on the complete data set where indirect, 'depth-derived' observations were included.
3. Seed longevity was best estimated using a multiple regression model with an integrated measure of seed size and shape and depth distribution of seeds.
4. The shape of seeds, known to be a consistent character of species, was shown to be constant within species, whereas depth distribution of seeds was highly variable among sites. This is consistent with the variability of seed longevity found in published seed bank data.     

Water and Seed Survival

Between about –350 and –14 MPa the rate of lossof viability in orthodox seeds is a positive function of waterpotential. The relative effect of water potential has been analysedin an oily seed (lettuce) and a non-oily seed (barley) and foundto be more or less identical. The lower limit for the relationin various species coincides with a seed moisture content (wetbasis) between about 2 and 6%. Below this level there is littleor no improvement in longevity with reduction in moisture content.The upper limit coincides with moisture contents of between15 and 28%, depending on whether the seeds are oily or non-oily.A water potential of about –14 MPa is the threshold forrespiration which increases more-or-less linearly with increasein water potential above this level. Above this threshold, andproviding oxygen is available to sustain respiration, seed longevityincreases with increase in water potential except that, unlessthe seeds are dormant, germination may be initiated at a waterpotential of about –1·5 to –0·5 MPa.In the absence of oxygen there may be a slight further declinein longevity with increase in water potential above –14MPa before longevity reaches a minimum value Since they cannot be dried very much without immediate lossof viability, recalcitrant seeds survive longest in the presenceof oxygen at maximum water potential commensurate with preventinggermination. The threshold water potential for immediate lossof viability has not been determined for most species but itis probable that it is close to the water potential typicalof the permanent wilting point in these plants, say –2MPa Lactuca saliva L., lettuce, Hordeum oulgare L., barley, seed storage, moisture content, relative humidity, water potential, temperature, oxygen     

Optimizing Seed Water Content: Relevance to Storage Stability and Molecular Mobility

This research was conducted to determine the optimum moisture content (MC) that gave maximum longevity to seeds. Three species were used to represent seeds with different dry matter reserves, which gives them different sorption properties: maize (Zea mays L.), elm (Ulmus pumila L.) and safflower (Carthamus tinctorius L.). The seeds of elm, safflower, and maize embryos with MC ranging from 0.00–0.15 g H₂O/g dry weight (DW) were stored at 35 °C for different periods of time. The results showed that the optimum MC for seed and embryo storage varied between species (0.057 g H₂O/g DW for maize embryos, 0.045 g H₂O/g DW for elm, and 0.02 g H₂O/g DW for safflower). Drying below this optimum MC increased the aging rate and there were detrimental effects of drying. The relative humidity corresponding to optimum MC in embryos of maize, elms and safflower was about 15%, 12% and 7% respectively, according to the lipid composition of the embryos. The data provided confirmatory evidence that molecular mobility (ΔAzz) in elms, maize and safflower embryos was compatible with the optimum moisture content.     

金线兰种子萌发及其原球茎的增殖培养

研究了影响金线兰种子非共生萌发的因素,并应用正交试验研究基本培养基、6-BA、ZT、NAA四种因素对原球茎增殖的作用。结果表明:授粉类型对金线兰种子非共生萌发影响较大,异株异花、同株异花以及同株同花授粉所得的种子的萌发率分别为78.53%、69.62%、39.87%;蒴果成熟度以生长150d为宜,采收后萌发率可达78.59%;冷藏影响种子的活力,种子的萌发率随冷藏时间的延长而降低;使用次氯酸钠浸泡后的种子与对照相比,其萌发率无明显差异;NAA对原球茎增殖作用显著,适宜于原球茎增殖的培养基为1/2MS+ZT0.5mg/L+NAA1.0mg/L。     

Seed bank classification and its importance for the restoration of species-rich flood-meadows

Abstract. This paper focuses on the persistence of seeds in the seed bank of a formerly fertilized flood-meadow into which seeds from an original Alopecurus pratensis-Sanguisorba officinalis community have been introduced. The longevity of seeds in the seed bank of the original community is also estimated. The established vegetation was compared with the seed bank, as divided into two layers (0 - 5 cm and 5–10 cm); this allowed a classification of species into three groups, with (1) transient, (2) short-term persistent and (3) long-term persistent seed bank. The majority of the species of the unfertilized flood-meadow community have a transient or short-term persistent seed bank with seeds showing a large variance in shape i.e. flattened or elongate. Because of this, the characteristic flood-meadow species will disappear soon after the beginning of fertilizer application and will not re-establish from the seed bank, once the fertilizer application is ceased. The formerly fertilized flood-meadow contains many ruderal and arable weed species, the seeds of which tend to be compact or round. Significantly more seeds were found in the seed bank of the formerly fertilized flood-meadow under cattle-grazing than under sheep-grazing and no grazing.     

氨基酸厂废水对植物种子萌发和幼苗生长影响的研究

水稻、大麦、油菜等种子在不同条件下的发芽试验,表明氨基酸厂废水对植物种子萌发存在明显的抑制作用,且这种抑制作用主要表现在出芽阶段生物化学代谢最旺盛的时期,发现淀粉性种子对废水的忍耐程度要低于油脂性种子,同时进行的植物幼苗试验显示,大麦土培时废水最适宜的浓度为１：１００－１：１５０（废水原液与清水体积之比,下同）,水稻砂培为１：１００。     

Seed longevity and fire: germination responses of an exotic perennial herb in NW Patagonian grasslands (Argentina)

Fire affects grassland composition by selectively influencing recruitment. Some exotic species can increase their abundance as a consequence of fire-stimulated seed germination, but response may depend on seed age. Rumex acetosella L. (Polygonaceae, sheep's sorrel) is a cosmopolitan herb that has invaded NW Patagonia's grasslands. This species forms persistent soil seed banks and increases after disturbances, particularly fire. We studied how fire and seed longevity influence R. acetosella germination. In 2008, we conducted laboratory experiments where we exposed different-aged seeds (up to 19 years old) to heat, smoke, charcoal, ash and control treatments. Total percentage germination and mean germination time depended on both seed age and fire treatment. Germination of younger seeds decreased with increasing temperature. There was no general pattern in germination responses of different-aged seeds to smoke, charcoal and ash. While smoke improved the germination of fresh seeds, charcoal decreased germination. Germination of untreated seeds was negatively correlated with seed age, and mean germination time increased with seed age. In most treatments, fresh seeds had lower germination than 1-5-year-old seeds, indicating an after-ripening requirement. Smoke stimulates R. acetosella germination, causing successful recruitment during post-fire conditions. Fresh seeds are particularly responsive to fire factors, possibly because they have not experienced physical degradation and are more receptive to environmental stimuli. Knowing the colonisation potential from the soil seed bank of this species during post-fire conditions will allow us to predict their impact on native communities.     

Seed dynamics of resprouting shrubs in grassy woodlands: Seed rain,predators and seed loss constrain recruitment potential

Abstract Measuring the fate of seeds between seed production and seedling establishment is critical in understanding mechanisms of recruitment limitation of plants. We examined seed fates to better understand the recruitment dynamics of four resprouting shrubs from two families (Fabaceae and Epacridaceae) in temperate grassy woodlands. We tested whether: (i) pre‐dispersal seed predation affected seed rain; (ii) post‐dispersal seed predation limited seed bank accumulation; (iii) the size of the seed bank was related to seed size; and (iv) viable seeds accumulated in the soil after seed rain. There was a distinct difference in seed production per plant between plant families with the legumes producing significantly more seeds per individual than the epacrids. Seed viability ranged from 43% to 81% and all viable had seed or fruit coat dormancy broken by heat or scarification. Pre‐dispersal predation by Lepidopteran larvae removed a large proportion of seed from the legume seed rain but not the epacrids. Four species of ants (Notoncus ectatomoides, Pheidole sp., Rhytidoponera tasmaniensis and Iridomyrmex purpureus) were major post‐dispersal seed removers. Overall, a greater percentage of Hardenbergia (38%) and Pultenaea (59%) seeds were removed than the fleshy fruits of Lissanthe (14%) or Melichrus (0%). Seed bank sizes were small (<15 seeds m^?2) relative to the seed rain and no significant accumulation of seed in the soil was detected. Lack of accumulation was attributed to seed predation as seed decay was considered unlikely and no seed germination was observed in our study sites. Our study suggests that seed predation is a key factor contributing to seed‐limited recruitment in grassy woodland shrubs by reducing the number of seeds stored in the soil.     

Study on the Change and Judgment of Tobacco Seed Maturity

Study and judgment of tobacco seed maturity, and then chose the optimum harvest time have important significance to some agriculture production problems, such as: high quality germplasm resource conservation, utilization, development and improve seed quality and production. This study research the changes during tobacco seed maturity, including morphological changes (seed color), physiological changes within the seeds (water content, germination) and chlorophyll fluorescence (CF) in seed coat changes; and presented the application of these metric to judge the tobacco seed maturity; further studies in this fields and issues that be occurred are also addressed in the paper.     

Seed dormancy of Cardiospermum halicacabum (Sapindaceae) from three precipitation zones in Sri Lanka

• This study investigated seed germination of Cardiospermum halicacabum, a medicinally important invasive species.
• We compared mass, moisture content (MC), dormancy and dormancy‐breaking treatments and imbibition and germination of scarified and non‐scarified seeds of C. halicacabum from a low‐elevation dry zone (DZ), low‐elevation wet zone (WZ1) and mid‐elevation wet zone (WZ2) in Sri Lanka to test the hypothesis that the percentage of seeds with water‐impermeable seed coats (physical dormancy, PY) decreases with increased precipitation.
• Seed mass was higher in WZ2 than in DZ and WZ1, while seed MC did not vary among the zones. All scarified DZ, WZ1 and WZ2 and non‐scarified DZ and WZ1 seeds imbibed water, but only a few non‐scarified WZ2 seeds did so. When DZ and WZ1 seeds were desiccated, MC and percentage imbibition decreased, showing that these seeds have the ability to develop PY. GA₃ promoted germination of embryos excised from fresh DZ and WZ1 seeds and of scarified WZ2 seeds.
• At maturity, seeds from DZ and WZ1 had only physiological dormancy (PD), while those from WZ2 had combinational dormancy (PY+PD). Thus, our hypothesis was not supported. Since a high percentage of excised embryos developed into normal seedlings; this is a low‐cost method to produce C. halicacabum plants for medicinal and ornamental purposes.