新疆狗牙根制种田土壤杂草种子库的研究

对新疆狗牙根制种田土壤杂草种子库进行了研究,结果表明:土壤种子库杂草种类有灰藜(Chenopodium album)、野西瓜苗(Hibiscus trionum)、狗尾草(Setaria viridis)、稗(Echinochloa crus-galli)、反枝苋(Amaranthus retroflexus)、田旋花(Convolvulus arvensis)和扁蓄(Polygonum avicu-lare)等,均主要分布在0~10 cm的土层内,杂草种子量达9180.83粒/m2,其中又以灰藜、反枝苋为优势种,占杂草总量的50%以上。0~10 cm,10~20 cm和20~30 cm土层杂草种子发芽率均在20%以下,总活力在50%左右。同时,阐述了新疆狗牙根制种田土壤种子库杂草种子的来源,提出了减少杂草种源的对策。     

伊犁绢蒿年际结实量、土壤种子库及幼苗输入特征

连续3年对伊犁绢蒿（Seriphidium transiliense）种子结实量和萌发行为进行了测定，并对土壤种子库和幼苗输入特征进行了分析。结果表明，种子结实量主要受围栏和年度气候条件两因素的影响，围栏内种子产量明显高于围栏外，年际间种子产量的变动更为剧烈，表现为2007＞2009＞2008年。伊犁绢蒿单株种子产量对围栏和年度气候条件两因素的响应都极为敏感，在围栏内外和年度间均表现为差异极显著（P<0.01），但结实模式未发生明显变化。围栏内外种子萌发率存在显著差异（P<0.05），但年度间差异不显著（P>0.05）；土壤种子库内可萌发种子数在年度和围栏内外均变化剧烈，均存在极显著差异（P<0.01）；围栏内春季新生幼苗数量多于围栏外，新生幼苗数量在年度间差异不显著；幼苗存活数量不论在围栏内外还是在年度间都比较少，但围栏能够显著提高幼苗存活率。伊犁绢蒿从结实、种子库、幼苗发生到存活各阶段的转化率均比较低，在整个生活史过程中表现出明显的r对策。     

Germination Ecology of Cenchrus biflorus Roxb.: Effects of Environmental Factors on Seed Germination

Better understanding related to germination and seedling emergence of plant species assists in predicting the potential distribution and provides insight for efficient management. Cenchrus biflorus Roxb. has been considered as potential forage species in arid environment due to its high nutritive values, prolific seed production, and tolerance to extreme temperature and prolonged drought conditions. A series of laboratory and greenhouse assays were conducted to determine the effect of different environmental factors, such as temperature, light, pH, salinity, osmotic potential, and seed burial depth on the germination and seedling emergence of C. biflorus. The maximum germination (95%) was recorded at 35°C/25°C, followed by 40°C/30°C; however, minimum germination was observed at 45°C/35°C (17.5%). Light significantly promoted the germination with maximum percentage (97.5%) when seeds were exposed to altering light and dark conditions (12/12 h). The osmotic potential for the 50% inhibition of C. biflorus germination was –0.4 MPa, although some seed germinated at –0.8 MPa (12.5%). Germination decreased from 97.5% to 12.5% as salinity stress increased from 0 mM to 200 mM sodium chloride (NaCl) with no germination > 200 mM. Seed germination was significantly affected by pH levels and was between 27.5% and 92.5% at 5–8 pH, respectively. No seedling emerged when seeds were placed on the soil surface; maximum seedling emergence (90%) at 2-cm burial depth and emergence decreased considerably as seeding depth increased above 2 cm. Its tolerance to drought and salinity make C. biflorus a potential candidate to be used as an alternative source during periods of forage scarcity under harsh climatic conditions, and it could possibly be used for rangeland rehabilitation purposes in arid environments.     

盐胁迫对桑种子发芽及幼苗生理生化特性的影响

桑树在盐碱地栽培 ,受盐害最为严重的时期是种子萌发及幼苗期。采用不同浓度的NaCl溶液胁迫桑种子 ,研究高盐逆境条件下对种子发芽、幼苗生长及生理效应的影响。结果表明 :随NaCl浓度增大 ,桑种子的萌发率、发芽率逐渐下降 ,发芽滞后且发芽后的幼苗生长被抑制 ,当NaCl的浓度达到 5 0mmol/L时 ,子叶长出率、幼苗鲜质量明显下降 ,在 15 0mmol/L浓度下种子无法长出子叶 ;各处理区叶片的含水率、叶绿素的含量也随NaCl的浓度升高而下降 ;脯氨酸含量则随NaCl浓度增大呈先升高后降低的趋势。     

温度、光照和水分对飞扬草种子萌发和幼苗生长的影响

为明确热带常见杂草飞扬草(Euphorbia hirta)的种子萌发特性,本研究运用培养皿滤纸法和盆栽法,分别研究温度、光照和水分条件对飞扬草种子萌发和幼苗生长的影响。结果表明,飞扬草种子在20~40℃范围内均可萌发,其中30℃为种子萌发的最适温度(萌发率和萌发指数均最大),25℃时幼苗生长最好(根长/苗长为1.031)。恒温条件(25℃)下,光照8~24h时的种子萌发率无显著差异(平均值94.07%)、光/暗0h/24h时萌发率降至52%(P0.05),萌发指数随光照时间缩短先增大后降低,光/暗16h/8h时最大(93.93),0h/24h最低(30.59);有光照时幼苗的根长均显著大于苗长,无光照时苗长显著大于根长(P0.05)。变温条件(光/暗,35℃/25℃)下,光照时长对飞扬草种子萌发率和幼苗苗长无显著影响(P0.05),随光照时长缩短萌发指数和幼苗根长均显著减低(P0.05)。综合各指标,12~16h光照为飞扬草种子萌发和幼苗生长的最佳光照条件。25℃、光/暗12h/12h条件下,飞扬草在土壤最大持水量60%时的种子出苗率达39%、幼苗根长苗长比为1.10∶1。     

不同活力种子的萌发与出苗特性

摘要：研究测定了老化处理后几种禾本科牧草种子的萌发、幼苗以及出苗期的相关指标,进一步分析其相关性。结果表明,1）除羊草（Leymus chinensis）种子外,老化处理显著降低其他参试种子的发芽势、发芽率、发芽指数、活力指数,胚根、胚芽以及幼苗长度,出苗率、出苗速率;2）牧草种子的耐老化能力因种而异,休眠可显著提高种子自身的耐老化能力,如羊草;3）除羊草种子外,其他种子的发芽势、发芽率、发芽指数、活力指数,胚根、胚芽以及幼苗长度与出苗率、出苗速率极显著正相关(P<0.01);4) 相比其他萌发指标,发芽率用于种子活力批次的划分在所有物种中表现相对较好。     

不同前茬作物下苜蓿地土壤杂草种子库的特征

为了探讨前茬作物对紫花苜蓿（Medicago sative）地杂草种子库的影响,采用诱萌法,于2010年在内蒙古林西县研究青贮玉米(Zea mays)、尖叶胡枝子(Lespedeza hedysaroides)和沙打旺(Astragalus huangheensis)3种前茬作物下生长第2年的紫花苜蓿地土壤杂草种子库的特征。结果表明,前茬为青贮玉米时苜蓿地杂草主要是马齿苋(Portulaca oleracea)和反枝苋(Amaranthus retroflexus),前茬为尖叶胡枝子时主要是马齿苋、刺藜(Chenopodium aristatum)和反枝苋,前茬为沙打旺时主要是刺藜和反枝苋;前茬作物为尖叶胡枝子时,土壤杂草种子库的密度与其他两种前茬作物之间存在显著差异（P＜0.05）;土壤种子库杂草的种子主要集中在0～5 cm的土壤耕作层,下层分布较少。     

Disturbances Impact on Longevity of Grass Seeds,Semi-Arid South African Rangeland

The effect of plant and soil disturbances on seed density, species richness, and seed longevity of the soil seed bank was quantified for a semi-arid rangeland, over a 5-yr period (2002/2003–2006/2007 growing seasons). The different soil and plant treatments included fire, tillage (intended as a trampling surrogate), and blocked seed rain (simulating heavy grazing). These three experimental factors were combined in a factorial arrangement. Seed responses were evaluated in the soil seed bank before the new seed set, after the first seed production event, and after the second seed production event. Before disturbance (physical impact on the plant and soil), soil seed bank was dominated by early successional species: conversely, aboveground vegetation was mainly dominated by perennial grasses. After only 4 yr of blocked seed rain, seedling emergence of Decreaser grass species ceased totally both in the field and seed bank, with lower effect on Increaser grass species. Emergence of both Decreaser and Increaser grass species decreased in the seed bank with tillage, whereas the opposite occurred in the field. By contrast, tillage increased the emergence of weeds in the seed bank. The decrease in emergence of Decreaser grass species in both seed bank and field was still evident 4 yr after the rangeland was burnt. The grass species Themeda triandra was the most sensitive to fire in terms of seedling emergence. Blocked seed rain treatment significantly decreased (P < 0.05) species richness. Regardless of treatments applied, there was poor similarity between aboveground vegetation and the associated seed bank. Differences in the soil seed bank are likely to reflect manifested properties rather than short-term changes. Several characteristics of seed banks (species composition, seed abundance, and longevity) must be considered in order to understand the dynamics of plant communities following disturbances.     

早春短命植物绵果荠无菌苗组织培养相关因素研究

为建立绵果荠（Lachnoloma lehmannii）无菌苗培养体系,以种子作为试验材料,对不同消毒方法的效果进行了比较,并对影响种子萌发、幼苗生长相关因素进行了探讨。结果表明,1）种子消毒适宜方法为种子流水冲洗1~2 min,70%酒精浸泡1 min,0.1% HgCl2消毒1.5 min;2）光照对种子萌发有促进作用,而幼苗的不同部位对光照有不同响应;3）种子萌发对低温有依赖性,而幼苗生长需要一定的高温;4）适宜激素对种子萌发有促进作用,而幼苗的不同部位对激素有不同反应。因此,绵果荠种子萌发和幼苗生长适合培养体系为把种子消毒后接种无激素的MS,放在变温为15 ℃/5 ℃的光照条件下培养4~5 d,萌发后转至温度为（25±1） ℃的光照条件下培养,发芽率达到90%,比对照高16%,且幼苗长势良好。     

Response of Seed Germination and Seedling Growth to Sand Burial of Two Dominant Perennial Grasses in Mu-Us Sandy Grassland,Semiarid China

Sand burial is an important selective pressure for growth, survival, and distribution of sand dune plants. Its effects on seed germination and seedling establishment, however, for different species are quite different. Experiments were conducted in the Mu-Us Sandy Grassland of North China to determine the effects of sand burial on seed germination and seedling growth of dominant perennial grasses Psammochloa villosa (Trin.) Bor and Leymus secalinus (Georgi) Tzvel. Small, medium, and large seeds of P. villosa and small and large seeds of L. secalinus were buried at 0-, 1-, 2-, 4-, 6-, and 8-cm depths in sand. P. villosa seed germination and seed dormancy in sand were significantly influenced by sand burial depth but not by seed size, whereas seed germination and seed dormancy of L. secalinus were significantly influenced by both sand burial depth and seed size. Emergence percentages for large seeds were higher than those for smaller seeds, suggesting that larger seeds are ecologically better adapted to dune habitats. Seeds that did not germinate in sand were in enforced dormancy and formed a soil seedbank, which can enhance plant survival on sand dunes. One-week-old and 2-wk-old P. villosa seedlings could tolerate 75% and 100% of their shoot height of sand burial, respectively, and the shoot elongation growth was enhanced by the burial stress. Both 1-wk-old and 2-wk-old seedlings of L. secalinus only tolerated up to 75% sand burial. The growth of L. secalinus seedling was inhibited by sand burial due to the decreased biomass and slow shoot elongation. The lack of tolerance of seedlings of this species to total sand burial might restrict its distribution on sand dunes.     

沙生针茅种子发芽试验

采用不同方法处理沙生针茅(Stipa glareosa)种子,测定沙生针茅种子发芽率和种子出苗率,以探明影响沙生针茅种子萌发和播种出苗的制约因素。结果表明:60℃蒸馏水浸泡种子24 h,种子吸水率、发芽率、发芽势分别为26.3%,38.0%和32.0%;-20℃、20℃低温变温处理96 h,发芽率和发芽势分别为46%和48%;用80 mg/L GA_3水溶液浸泡种子24 h,发芽率和发芽势分别为54%和48%;沙埋深度会影响沙生针茅种子发芽和出苗,沙埋0.5 cm沙生针茅的种子发芽率和幼苗出土率最高;埋深超过2cm的深度,发芽率和出苗率降低;埋深6~8 cm,随着沙埋深度增加,出苗率显著减少;当埋深8 cm的深度,沙生针茅出苗率为0。     

高寒草地凋落物覆盖对狼毒生长微环境及种苗定居的影响

种子萌发和幼苗定居是植物生活史中最为脆弱的两个阶段。为了探明高寒草地狼毒（Stellera chamaejasme）种苗定居的生境选择,本研究在其原生境下通过人工控制试验,研究凋落物覆盖对土壤微环境（温、湿度）的影响以及狼毒种子在不同生境条件下的出苗和定居表现。结果表明：凋落物覆盖总体上能够降低土壤温度,提高土壤含水量,且能显著降低表层土壤温度和含水量的日振幅;与对照（土壤裸露）相比,凋落物覆盖显著降低狼毒种子的出苗率和成苗率,但对其越冬存活率的影响并不显著;土壤埋深对狼毒种子的出苗产生显著影响,埋植于表层土壤（< 0.5 cm）的狼毒种子其出苗率和越冬成活率均显著高于深层土壤（2 cm和4 cm）的种子。分析表明,高寒草地凋落物的存在或种子埋植太深均不利于狼毒种苗的定居;因此,草地裸露或促使土壤浅表化的扰动均可促进狼毒种群建立,是导致退化草地狼毒种群扩散的主要生态因素。     

温度和干旱胁迫对3种牧草种子萌发的影响

对扭黄茅Heteropogon contortus、鸭茅Dactylis glomerata、高羊茅Festuca arundinacea 3种牧草,进行了3个不同温度、4个不同干旱胁迫强度的种子萌发试验,分别测定了牧草品种的发芽率、发芽势和萌发指数,并进行了统计分析。研究结果表明：在自然条件下,扭黄茅种子萌发是在常温条件下完成的。不同温度和聚乙二醇胁迫强度处理影响下,扭黄茅种子均先于鸭茅和高羊茅种子萌发23 d,扭黄茅萌发指数均高于鸭茅和高羊茅。低胁迫干旱强度有助于扭黄茅种子萌发,当干旱胁迫强度超过一定程度（-3 Pa）时不利于种子萌发。扭黄茅对干热河谷生态条件的适应性主要由种子萌发后的植株生长适应性决定的。     

环境因子对云南扁穗雀麦种子萌发和出苗的影响

扁穗雀麦是近年由牧场逃逸至农田的恶性入侵杂草。为了解入侵和生态适应性规律,通过室内试验测定了温度、湿度、深度、pH、盐和渗透势对扁穗雀麦种子萌发的影响。结果表明,30/20 ℃的变温处理下种子萌发率最高,达到92.1%;随着日平均温度的降低种子萌发率逐渐降低;日平均温度接近10 ℃种子几乎不萌发。在pH 5~10的环境条件下,种子萌发率均能达到90%,弱酸和弱碱处理的种子萌发率显著高于中性处理。低于20 mmol·L^-1的NaCl处理与对照无显著差异,160 mmol·L^-1的处理种子萌发率仍可达到85%以上。-0.1 MPa的渗透势下种子萌发率最高,渗透势高于-0.2 MPa的处理种子萌发率与对照无显著差异,-0.4 MPa处理种子的萌发率仍高于80%。在60%相对湿度的土壤中,种子的萌发率和萌发势均最高。播种于土表的种子萌发势和萌发率均最高,播种深度达到10 cm时,种子几乎不萌发。由此可见,扁穗雀麦种子萌发对环境条件的生态适合度高,因此在多数区域气候温暖干旱的云南具有入侵广阔生境的可能性。     

苦豆子种子形态特性及发芽条件研究

野生苦豆子种子硬实率高,因种皮不透水和不透气,而具有深休眠性。本研究观测了野生苦豆子种子的形态特征、种子大小、千粒重和硬实率,并对H₂SO₄破除种子硬实的处理浓度和时间,植物生长调节剂和聚乙二醇(PEG)处理对种子萌发和幼苗生长的影响,以及种子田间萌发的适宜土壤含水量和播种深度进行了研究。结果表明:苦豆子种子长为3.865mm,宽为3.358mm,厚为2.321mm,千粒重为20.775g,硬实率达99%;破除硬实处理适宜的H₂SO₄浓度为65%,时间是20min;0.02%GA3对提高种子发芽速度和幼苗生长量具有显著的作用,此外PEG处理种子能显著提高幼苗的生物量;苦豆子种子田间萌发的适宜土壤含水量为8%～12%,播种的最适深度是1～3cm。     

东祁连山高寒人工草地土壤种子库大小及物种构成

通过野外调查和种子萌发试验,研究了东祁连山高寒地区常见的垂穗披碱草(Elymus nutans)和燕麦(Avena sativa)人工草地群落土壤种子库大小及物种构成,并与相邻天然草地进行比较,旨在为东祁连山人工草地植被恢复提供支持信息。结果表明:垂穗披碱草草地、燕麦草地和天然草地的土壤种子库种子密度平均数分别为22611.45±4725.88,4210.88±1913.44和2937.01±2471.60 个·m^-2。垂穗披碱草草地种子库萌发的幼苗中共发现4种植物,分别是高山紫菀(Aster alpinus)、迷果芹(Sphallerocarpus gracilis)、甘肃马先蒿(Pedicularis kansuensis)和萼果香薷(Elsholpzia bensa var. calycocarpa);燕麦草地种子库萌发的幼苗中共发现6种植物,分别是独行菜(Lepidium apetalum)、旱雀麦(Bromus tectorum)、微孔草(Microula sikkimensis)、迷果芹、蓝翠雀花(Delphinium caeruleum)和萼果香薷;天然草地种子库萌发的幼苗中共发现6种植物,分别是异针茅(Stipa aliena)、二裂委陵菜(Potentilla bifurca)、高原毛茛(Ranunculus tanguticus)、黄花棘豆(Oxytropis ochrocephala)、独行菜和蓝翠雀花。垂穗披碱草草地和燕麦草地土壤种子库可萌发的幼苗多为一年生植物;垂穗披碱草草地与燕麦草地和天然草地之间可萌发土壤种子库数量差异较大,后二者之间差异较小;天然草地与燕麦草地物种构成差异较小,与垂穗披碱草草地物种构成差异较大。     

高寒草甸鼠丘土壤种子库结构特征的研究

本研究以青海省河南县高山嵩草高寒草甸高原鼠兔鼠丘土壤种子库为研究对象,采用野外取样和室内镜检、萌发试验,探究了鼠丘土壤种子库的种子数量状况、垂直分布格局及季节动态规律,旨在为鼠丘土壤植被的恢复演替提供科学依据。结果表明：天然草地土壤种子库中的种子数量和种子质量均高于鼠丘土壤种子库,10-11月土壤种子库无论在种子数量上还是质量上均较高;发芽率表现为天然草地土壤种子库 > 新鼠丘 > 旧鼠丘;旧鼠丘土壤种子库种子数量多于新鼠丘;原生植被的土壤种子库呈明显的上层多下层少的垂直分布格局,新、旧鼠丘上下层间无明显的垂直分布规律;鼠丘土壤种子库与天然草地土壤种子库的相似性越高,鼠丘植被向原生植被恢复演替的几率越大。     

生物种衣剂包衣对桑种子萌发和幼苗生长的影响

将不同质量浓度的黄腐酸(50、200、600 mg/L FA)+高吸水树脂+多菌灵以及不同质量浓度的赤霉素(25、50、100 mg/L GA3)+高吸水树脂+多菌灵制作成6种生物种衣剂,对隔年桑种子进行包衣处理。包衣后的桑种子发芽率以及脂肪酸含量、α-淀粉酶活力、幼苗根系活力、可溶性蛋白含量以及出苗率、幼苗根长及幼苗鲜质量均比对照提高,其中赤霉素种衣剂2号(含50 mg/L赤霉素)和黄腐酸种衣剂2号(含200 mg/L黄腐酸)的效果最好:分别使桑种子发芽率提高21%、16%;分别使桑种子萌发时的脂肪酸含量提高79%、63%,α-淀粉酶活力提高34%、30%,根系活力提高82%、55%,可溶性蛋白含量提高5%、12%;分别使出苗率提高27%、29%,幼苗根长提高5%、7%,幼苗鲜质量提高22%、19%。依据试验结果认为,采用生物种衣剂对桑种子进行包衣处理,对桑种子的萌发及幼苗的生长均有一定的促进作用。     

不同播种深度对羊草出苗率和幼苗生长的影响

利用盆栽研究了7种播种深度(0cm、1cm、2cm、3cm、4cm、5cm和6cm)对羊草出苗率和幼苗生长的影响。结果表明,羊草出苗率与种子萌发率呈极显著正相关(r=0.9147),而与播深呈极显著负相关(r=-0.9408)。在浅播(0～2cm)条件下,羊草初始出苗时间为5.0～7.7d,最终出苗率为70.0%～80.7%;在深播(4～5cm)条件下,初始出苗时间延迟到16.3～20.0d,羊草种子萌发率下降到41.0%～43.0%,但出苗率不足7%,株高不超过2cm;当播深在6cm以上时,其萌发率为37.0%,但出苗率为0。此外,播种深度显著影响羊草幼苗株高、茎叶鲜重及叶片数量。     

Factors Affecting Bromus Tectorum Seed Bank Carryover in Western Utah

Cheatgrass (Bromus tectorum L.) is a winter annual weed that presents a serious obstacle to rangeland restoration in the Intermountain West. The objective of this study was to evaluate factors regulating the size and persistence of cheatgrass carryover seed banks on semiarid sites in western Utah. We prevented current-year seed production in each of four habitats, then tallied emerging seedlings over the next 44 yr. Twoyr. Two iterations of the study were conducted during consecutive years. One year before initiation of each iteration, we estimated seed rain at each site. Above-average precipitation in 1998–1999 resulted in relatively high seed rain (13942 seeds·m⁻²) for the first iteration, whereas seed rain for the second iteration averaged only 3567·m⁻² because of drought conditions in 1999–2000. Mean total number of seedlings emerging from carryover seeds for the first and second iterations were 1304 and 270 seedlings·m⁻². Seedling emergence from carryover seed was positively correlated with production-year seed rain (R² = 0.69). The fraction of seed rain that carried over tended to be lower when precipitation the year following production favored fall emergence of the transient seed bank. First-year emergence of carryover seeds averaged 96% of total emergence, whereas third-year emergence averaged < 1% and was zero for six of eight cases. Carryover seeds persisted somewhat longer at the xeric black greasewood site than at more upland sites. Our study shows that cheatgrass seeds rarely persist beyond the second carryover year even on semiarid sites. Emergence from the carryover seed bank can be predicted from site attributes and precipitation patterns in previous years.