干旱胁迫与不同储藏时间对杠柳种子萌发的影响

为了阐明干旱胁迫与不同储藏时间对杠柳种子萌发的影响机理,在室内采用不同浓度的聚乙二醇（PEG）模拟干旱胁迫条件,对3种不同储藏时间的杠柳种子进行了萌发期对比试验,观测了种子的总萌发率、发芽势、活力指数和胚根的生长情况,分析了抗旱特性,结果表明：不同程度的干旱胁迫与储藏时间对杠柳种子萌发均有一定的影响,当PEG-6000浓度为5%,对储藏1年杠柳种子的萌芽率和发芽势起促进作用,对储藏2年种子萌芽率轻度抑制,对储藏3年种子抑制影响较大,当PEG-6000浓度>5%,3种种子的萌芽率和发芽势均呈下降趋势,但当胁迫浓度增大到25%时,种子基本没有萌发。在不同的水分胁迫处理中,3种种子的活力指数和胚根生长速度一直呈下降趋势,尤其3年种子的下降幅度最大。不同储藏时间杠柳种子对干旱胁迫的适应性有差异,储藏1~2年的杠柳种子在PEG-6000浓度为5%~15%中萌发效果较好,且储藏1年种子好于2年种子,3年种子较差。3种种子的耐旱能力由强到弱依次为：1年种子>2年种子>3年种子。     

盐胁迫对二色补血草种子萌发的影响

以二色补血草(Limonium bicolor)种子为试验材料,用不同浓度的NaCl、Na2SO4及二者质量比为1:1的混合盐在其种子萌发过程中进行胁迫,调查盐胁迫对种子萌发的影响,并测定萌发过程中种子蛋白质含量、淀粉酶活力及还原糖和总糖含量的变化.结果表明:盐胁迫使二色补血草种子的发芽势、发芽指数和发芽率明显降低,而且随着盐浓度的增鲻加,抑制作用增强;3种盐对种子萌发的抑制作用强度依次为NaCl>混合盐>Na2SO4;二色补血草种子耐盐适宜范围为Na2SO4 1.2%、混合盐0.8%、NaCl 0.5%,耐盐半致死浓度为Na2SO4 2.1%、混合盐1.4%、NaCl 1.1%,耐盐极限浓度为Na2SO4 3.5%、混合盐2.4%、NaCl 2.0%.盐处理后不萌发的种子转入蒸馏水后重新萌发的试验结果表明,盐分胁迫主要是通过渗透效应,抑制种子中蛋白质和总糖的分解,进而延缓或抑制了种子的萌发.     

低温处理对糖槭（Acer saccharum）种子萌芽效应的研究

槭属某些种的种子具有休眠生物学特性,如糖槭(Acer saccharum)和茶条槭(Acer ginnala)。本试验采用低温处理糖槭种子,打破它的休眠,获得高达95%的种子萌芽率,并用这种已萌芽的种子播种,出苗速度快,缩短了播种管理时间。试验还表明,主要存在于糖槭种子子叶、种皮中抑制种子萌芽的调节物质,在0—8℃低温、相对湿度90—100%(遮光)的条件下,能够被逐渐转化、消失,使种子得以萌芽出苗。不经低温处理的种子则不能萌芽,而且低温处理只有伴随高湿的条件才会发生良好的效应。     

罗布麻EMS突变体库构建及黄酮变异突变体筛选

罗布麻(Apocynum venetum L.)突变体的获得是人工创新种质资源的有效途径,也是开展品种选育、功能基因组研究的基础。本研究以采自东营野生罗布麻种子作为材料,预试验结果表明0.7%的甲基磺酸乙酯(EMS,ethylmethylsulfone)溶液诱变罗布麻种子13 h能够达到半致死剂量。在此浓度和处理时间下构建了一个1452株的突变体群体,对获得的M1植株进行农艺性状和总黄酮含量性状筛选,初步获得125份农艺性状突变材料,其中包括8株白化植株、23株叶型变异株、16株叶色黄纹突变体、32株苗期分枝植株以及46株叶位变异突变体,突变频率分别为0.55%、1.6%、1.1%、2.2%和3.2%。此外,还筛选到2株总黄酮含量明显高于野生型和1株低于野生型的材料。在突变群体中对黄酮代谢途径中编码黄烷酮-3-羟化酶的基因(F3H,flavanone 3-hydroxylase gene)进行测序鉴定,结果鉴定到3株F3H基因的突变体。本研究构建的罗布麻突变体库表型丰富且突变位点可以鉴定,是罗布麻新种质筛选、品种选育以及基因功能研究的良好材料。     

胜红蓟种子萌发/出苗对环境因子的响应

胜红蓟为我国南部低海拔区域农田和果园恶性杂草。为揭示胜红蓟环境适应规律、明确其危害性,评价和分析了胜红蓟种子萌发对光照、温度、pH、盐度、渗透势等环境因子的响应特征。结果表明:胜红蓟种子在10—30℃内均能萌发,最适萌发温度为20℃,交替温度处理可提高种子的萌发率。胜红蓟种子萌发对光照敏感,无光照处理种子不萌发。土壤相对湿度在50%—100%范围内,种子出苗率均高于55%,最适相对湿度为70%。胜红蓟种子仅能在土壤表面萌发,1 cm的播种深度完全抑制种子萌发。pH值在5—10之间,种子萌发率高于85%,最适pH值为7。NaCl浓度在0—80 mmol/L以内种子萌发率超过88%,浓度为160 mmol/L时萌发率接近30%。渗透势在-0.40—0 MPa以内种子萌发率高于70%,渗透势为-0.6 MPa时种子不能萌发。由此可见,胜红蓟种子萌发具有广阔的环境适生范围,对农作物具有较强的早期危害性。     

NaCl胁迫对疣苞滨藜种子萌发和早期幼苗生长的影响

在光/暗(12 h/12 h)条件下研究了温度、苞片和NaCl浓度对疣苞滨藜种子萌发及其恢复的影响,同时观察萌发后幼根在NaCl中的生长和恢复情况.结果显示:(1)疣苞滨藜种子在温度周期为5℃/2℃、15℃/5℃、20℃/10℃、25℃/5℃、25℃/15℃中处理12 d后种子萌发率均达到80%以上,其最适萌发温度为25℃/15℃.(2)苞片对种子萌发不存在抑制作用,但能够延缓萌发时间.(3)低浓度的NaCl能促进种子萌发和幼根的伸长,且在0.2 mol/L时达到最大,在0.8 mol/L时完全抑制种子萌发和幼苗的生长.(4)经过不同浓度NaCl预处理后的种子,其萌发恢复率随原处理浓度的升高而升高,且最终萌发率都高于对照.研究表明,NaCl处理对疣苞滨藜种子没有造成伤害,其抑制萌发是通过渗透效应而不是离子毒害;疣苞滨藜种子和幼苗对盐分的耐性是其适应盐渍荒漠环境的重要原因.     

中草药浸提液对小列当种子发芽的影响

选用240种常用中草药,研究其蒸馏水和甲醇浸提液原液及其10倍、100倍和1 000倍稀释液对小列当种子发芽的影响.结果表明:小列当种子在蒸馏水浸提液刺激下发芽率超过70%的中草药有灯心草、降香和莲须,在甲醇浸提液刺激下发芽率超过70%的中草药有百部、桑椹、谷芽和萆薢;蒸馏水浸提液对小列当种子发芽抑制率超过50%的中草药有菊花、棕榈、苦杏仁和黄柏,甲醇浸提液对小列当种子发芽抑制率超过70%的有续断、地黄、肉豆蔻、地肤子、黄连、木贼和胡黄连.大部分中草药浸提液在10倍稀释液条件下对小列当种子发芽的刺激或抑制作用最明显.研究发现,一些参试中草药蒸馏水和甲醇浸提液能够刺激或抑制小列当种子萌发,并且其对种子萌发的影响程度随浸提液浓度的变化而异,不同中草药最佳处理浓度不同,而且用甲醇浸提液可筛选出更多种具有化感作用的中草药.     

浑善达克沙地黄柳种子发芽和幼苗生长特性的研究

在实验室通过模拟野外自然条件,研究了土壤水分、沙埋厚度和温度对黄柳种子发芽与幼苗生长的影响。结果表明:(1)黄柳种子对水分条件很敏感,发芽的适宜土壤含水量为3%~20%,低于3%或高于20%发芽都会受到抑制;(2)种子萌发需要沙土覆盖,适宜覆沙厚度为0.1~0.4 cm,此条件下第5天种子发芽率达80%以上;但当沙埋厚度超过0.6 cm时,种子出苗就会受到抑制;当沙埋厚度超过1.2 cm时,将不能出苗;(3)种子发芽的适宜温度为15~35℃,当温度高于45℃时种子将不能萌发并最终死亡;(4)幼苗的耐热性较强,40℃处理下幼苗出现热害症状,并且热害症状发展缓慢,60℃处理下90 min后幼苗干枯死亡;(5)种子的寿命为120 d左右。     

氯化钠浓度对宽口光唇鱼精子活力的影响

本文观察了不同氯化钠浓度对宽口光唇鱼Ａｃｒｏｓｏｃｈｉｌｕｓｍｏｎｔｉｃｏｌａ精子活力的影响,并进一步建立数学模型进行分析论证,得出结论：在氯化钠浓度０—０５１％的范围内,精子快速运动时间和寿命相对延长,但在浓度超过０５１％,精子活动开始受到抑制,活动强度减弱,寿命缩短。     

EMS处理对小麦种子萌发和幼苗生长的影响

甲基磺酸乙酯(EMS)是一种常用的诱变剂,在作物诱变育种上应用广泛。EMS在诱变种子的同时也是一种非生物胁迫,能显著降低种子的发芽率。该实验以小麦‘扬麦15’种子为实验材料,设置了7个EMS浓度处理梯度(0%、0.6%、0.8%、1.0%、1.2%、1.4%和1.6%),每个浓度设置3个处理时间(10 h、12 h、14 h),在种子萌发后测定发芽势和发芽率,并对种子进行生物量测定和形态结构观察,探讨EMS处理对小麦种子萌发和幼苗生长的影响机制。结果表明：(1)随着EMS浓度的提高和处理时间的延长,小麦种子的萌发率逐渐降低;幼苗的生长逐渐变得缓慢,根长和叶长明显变短。(2)随着EMS处理浓度的升高和处理时间的延长,小麦种子胚乳内淀粉体的降解速率变缓。(3)同一处理时间下,EMS的浓度越高,小麦根系越短,根部横截面积、维管束面积以及皮层面积也越小。研究发现,EMS处理会明显降低小麦种子的发芽率,减缓种子贮藏物质的降解速度,抑制小麦根系的生长。     

罗布麻离体培养及快繁技术的研究

采用野生罗布麻(Apocynum venetamL.)顶芽及芽下茎段为外植体进行离体培养及快繁技术优化的研究。结果表明:适宜罗布麻离体培养的基本培养基为MS,适宜外植体起始分化的培养基为:MS BA 1.8mg/L KT 0.5mg/L,分化率为88.9%以上;适宜茎段增殖的培养基为MS BA 2.0mg/L KT 0.5mg/L,繁殖系数最高达5.67倍,通过切段繁殖还可提高繁殖系数3倍;适宜生根的培养基为MS IBA 0.5mg/L NAA 0.02mg/L,生根率达90%以上。     

Plant regeneration from encapsulated somatic embryos of Carica papaya L.

Carica papaya L. (papaya) single somatic embryos (2.0 mm diameter) produced in a high-frequency liquid production system were encapsulated in two different synthetic encapsulation compounds. The frequency of regeneration from encapsulated embryos was significantly affected by (1) the concentration of sodium alginate, (2) the presence or absence of nutrient salts in the capsule, and (3) the duration of exposure to calcium chloride. A 2.5% sodium alginate concentration in a half-strength MS salts base resulted in significantly higher germination frequencies than other treatments. A relatively short (10 min) exposure to CaCl₂ provided uniform encapsulation of embryos and the highest frequencies of successful germination (77.5%). Germinated artificial seeds produced normal plantlets. Received: 12 March 1997 / Revision recieved: 24 June 1997 / Accepted: 18 July 1997     

Bracteoles affect germination and seedling establishment in a Mediterranean population of Atriplex portulacoides

The germination and subsequent seedling establishment of Atriplex portulacoides from a population in SW Spain were investigated in response to the presence or absence of attached bracteoles, at a range of NaCl concentrations (0–6%). Increasing salinity reduced both the final germination percentage and the speed of germination. The presence of bracteoles greatly inhibited germination and this effect was more marked with increasing salinity; bracteoles completely inhibited germination at salinities higher than 2%. The effects of salinity were substantially reversible, as cumulative germination after transfer of ungerminated seeds to distilled water was similar in all salinity treatments. This enforced dormancy could serve to prevent germination of floating fruits during dispersal in seawater. However, after transfer to distilled water the germination of seeds with bracteoles was still significantly lower than those without them, as a result of both higher dormancy and lower viability (as revealed by tetrazolium testing). Bracteoles thus also appear to enforce some physical dormancy. Seedlings derived from seeds with bracteoles demonstrated higher survival rates in fresh water than those derived from seeds without bracteoles but at 2% salinity there was no difference, and at higher salinities no seedlings of either type survived.     

The effect of Sea Water and Temperature on the Germination Behaviour of Crithmum maritimum

The seeds of Crithmmm maritimum L. were germinated floating on various concentrations of sea water up to 50% at constant temperatures of 5, 10, 15, 20, and 25°C and at alternating temperatures of 5 and 15°C. 5 and 25°C. and 15 and 25°C. Significantly higher germination was obtained at alternating than at constant temperature. When two constant temperatures at which no germination occurred were alternated, good germination was obtained. There was reduced germination and increase in time of first germination as sea water concentration increased, in the absence of sea water, high temperature caused not only severe inhibition of germination but also permanent injury to the seeds. The results help to explain the germination behaviour of the species in nature.     

SEED GERMINATION OF AMERICAN POKEWEED (PHYTOLACCA AMERICANA). I. LABORATORY TECHNIQUES AND AUTOTOXICITY

Seeds of pokeweed (Phytolacca americana L.), an underinvestigated species, were studied to determine optimal conditions for laboratory germination. Soaking seeds in acid solutions prior to sowing increased rates of germination. Concentrated (conc) H₂SO₄ was more effective than conc NO₃ or conc HCl acids. Physiological evidence from seed germination studies suggests that autotoxicity, or intraspecific inhibition, exists in pokeweed, a species known to possess several biologically active compounds. Seed germination was investigated in the laboratory with aqueous extracts of vegetative and reproductive structures of the plant. The presence of extracts from most plant parts correlated with reduced or no germination by seeds of its own species, whereas the presence of distilled water correlated with high percentages of germination by control seeds. Whether diluted with water by 5-fold (20% v/v) or undiluted, juice of pokeweed fruits completely inhibited the laboratory germination of pokeweed seeds. Also, extracts of freshly harvested mature leaves, stems, and immature fruits inhibited seed germination. However, results with root extracts, obtained from a single individual, depended more on concentration, since the highest concentration (50% v/v) inhibited germination, and lower concentrations (10 and 20% v/v) increased germination percentages over control samples. Results with extracts of juvenile leaves correlated with neither inhibition nor promotion of germination. Thus, except for juvenile leaves and the root, most extracts of the pokeweed plant inhibited seed germination with more mature structures exerting more inhibition and less mature structures exerting less or no inhibition. The ecological implication of autotoxicity is that seeds are more dispersed through time and space. In regard to seed germination by other species, especially those taxa known to possess biologically active compounds, these and other results suggest that the phenomenon of autotoxicity might be more widespread than previously suspected.     

Seed Germination Ecology of Feather Lovegrass [Eragrostis tenella (L.) Beauv. Ex Roemer & J.A. Schultes]

Feather lovegrass [Eragrostis tenella (L.) Beauv. Ex Roemer & J.A. Schultes] is a C₄ grass weed that has the ability to grow in both lowland and upland conditions. Experiments were conducted in the laboratory and screenhouse to evaluate the effect of environmental factors on germination, emergence, and growth of this weed species. Germination in the light/dark regime was higher at alternating day/night temperatures of 30/20 °C (98%) than at 35/25 °C (83%) or 25/15 °C (62%). Germination was completely inhibited by darkness. The osmotic potential and sodium chloride concentrations required for 50% inhibition of maximum germination were -0.7 MPa and 76 mM, respectively. The highest seedling emergence (69%) was observed from the seeds sown on the soil surface and no seedlings emerged from seeds buried at depths of 0.5 cm or more. The use of residue as mulches significantly reduced the emergence and biomass of feather lovegrass seedlings. A residue amount of 0.5 t ha^-1 was needed to suppress 50% of the maximum seedlings. Because germination was strongly stimulated by light and seedling emergence was the highest for the seeds sown on the soil surface, feather lovegrass is likely to become a problematic weed in zero-till systems. The knowledge gained from this study could help in developing effective and sustainable weed management strategies.     

Allelochemical stress produced by aqueous leachate of <Emphasis Type="Italic">Nicotiana plumbaginifolia</Emphasis> Viv.

The effects of aqueous leachate of Nicotiana plumbaginifolia Viv. on germination, seedling growth, amylase activity, sugar and starch contents of germinated seeds of maize (Zea mays L. cv. Uttam) were examined. Effects of leachate on photosynthetic pigments, protein content, activities of nitrate reductase and some antioxidants were also studied. Higher concentration of aqueous leachate of N. plumbaginifolia reduced the germination rate (GR). However, final germination percentage remained almost unaffected. Lower concentration of leachate stimulated the amylase activity and resulted in higher sugar content and GR. The increasing concentrations of leachate inhibited the conversion of starch into sugars. Allelochemicals decreased the amount of chlorophyll a, chlorophyll b, carotenoids, protein and nitrate reductase activity (NRA). The leachate of lower concentrations stimulated the activity of peroxidase but slight decrease was recorded in higher concentration. Superoxide dismutase and catalase exhibited concentration dependent increase except in seedlings treated with 100% concentration of leachate. Impairment of various metabolic activities due to leachate resulted in decreased root and shoot length.     

盐胁迫对蓝蓟种子萌发及早期幼苗的影响

研究了不同浓度盐(NaCl)处理对蓝蓟种子发芽势、发芽率及幼苗生长的影响。结果表明:(1)不同盐胁迫处理对蓝蓟种子的萌发具有显著影响。随着盐处理浓度的增加,发芽率呈下降趋势,蓝蓟在无盐环境(蒸馏水)和低盐环境中(0.05 mol/L)长势最好、发芽率最高、发芽速度最快。(2)将不同盐溶液处理5 d的未萌发种子转移到蒸馏水后,蓝蓟种子的萌发能力均可恢复,原来较高盐浓度(0.3 mol/L～0.5 mol/L)下的种子在恢复后,其萌发恢复率均在75%以上,发芽率基本上随着原浓度的升高呈上升的趋势。研究表明,NaCl处理对蓟种子没有造成伤害,其抑制萌发是通过渗透效应而不是离子毒害。     

外源ALA、SNP和Spd对NaCl胁迫下桔梗种子萌发特性的影响

以药用植物桔梗为研究对象,通过测定不同浓度的ALA、SNP和Spd对NaCl胁迫下桔梗种子发芽势、发芽率、萌发指数和平均根长等萌发指标的影响,寻找提高桔梗种子及幼苗在盐胁迫条件下抗性能力的途径.实验结果表明,75 mmol·L-1 NaCl胁迫下的桔梗种子萌发受到显著抑制,但是用不同浓度的ALA、SNP和Spd对桔梗种...     

Large Scale Production and Storability of Encapsulated Somatic Embryos of Mothbean (Vigna aconitifolia Jacq)

Storability and germination of sodium alginate encapsulated somatic embryos of Vigna aconitifolia (Jacq.) cv. BMB-43 were tested on half strength Murashige and Skoog (MS) basal medium fortified with coconut water (10% v/v). The frequency of regeneration from encapsulatd embryos was affected significantly by concentration of sodium alginate and the duration of exposure to calcium chloride. Embryos encapsulated with 2.5 % sodium alginate dissolved in MS basal salts solution recorded significantly higher germination than other treatments. A relatively short (5 min) incubation with calcium chloride solution provided uniform encapsulation of embryos that gave the highest percentage (65%) of germination. Synthetic seeds could be stored at 4üC for 50 days without reduction in viability as opposed to non - encapsulated somatic embryos which showed 6% viability after 20 days at 4°C. Germinated synthetic seeds produced normal plantlets.