濒危植物长柄双花木自然种群结实的花粉和资源限制

长柄双花木（Disanthus cercidifolius Maxim．vsr．longipes H．T．Chang）只零星分布于湖南、江西和浙江等省的少数县,已处于濒危状态。通过对其野外自然种群试验,研究了花粉和资源的有效性对雌性生殖的影响,并进一步探讨了长柄双花木“花多果少”的生殖机制。结果表明：不同来源的花粉对长柄双花木结果率及结籽率均产生显著影响。花粉来源而不是花粉数量对长柄双花木结实存在显著影响。自然条件下,长柄双花木“花一果转化率”约为54馏,“胚珠-种子转化率”约为83．19。施肥处理有利于花芽发育,可使植株花芽败育率明显下降,开花比例升高;同时座果率和结籽率均显著提高,而果实败育率则显著降低。随剪除叶片量的增加,结果率明显降低,但果实败育率在处理间无显著差异;剪除弱小枝条及病虫枝后,个体总开花数虽有所下降,但是结果率和结籽率均显著提高。去除花后,长柄双花木平均单果重、单粒种子重均显著降低。营养水平的时空异质性使自然种群结籽率受到资源和花粉的限制;补充资源可以通过增强花对传粉者的吸引而间接影响传粉。长柄双花木自然种群的坐果率极低,而且存在严重的“大小年”结果现象,不同的因子可能对其低水平坐果率产生相互作用。选择性败育、子房供应和雄性功能假说似乎是长柄双花木“花多果少”的生殖策略的最合理解释。     

青阳参种子的萌发

青阳参（Cynanchum otophyllum）种子在11月成熟时有休眠习性。收获后将其种子种植在自然温室内,到第二年的春天种子才会萌发,且大多数种子在3月28至4月4日间萌发,这期间的日平均最高和最低温度分别为19．0℃和9．9℃。层积能有效地打破青阳参种子的休眠,休眠种子通过大约1周的层积便能萌发。种子在有光的条件下层积1周后转移到25／15℃的黑暗条件下萌发率可达到75．4％。青阳参种子不论在有光的条件下还是在黑暗环境中层积2～3周后转入30／20和25／15℃进行变温处理,其萌发率最低能达到66．4％,而转入20／10℃变温处理其萌发率最多只能达到20．1％,但若层积6周,即便在20／10℃变温处理的情况下其萌发率也可以达到65．3％以上。     

青阳参小孢子发生和雄配子体发育

利用常规石蜡制片技术、荧光显微技术、光镜细胞化学技术、电子显微镜技术对青阳参小孢子发生和雄配子体发育进行了详细观察。结果显示,小孢子孢原细胞起源于皮下组织并在两个地方分化;孢原细胞平周分裂形成初生壁层和初生造孢层,初生壁层细胞再经过平周分裂形成2层细胞,其中最内一层即为绒毡层,绒毡层为分泌型绒毡层,既为小孢子发育提供营养来源,又分泌分泌物形成包围花粉粒的膜;初生造孢层细胞直接行使小孢子母细胞的功能;成熟花粉粒中含有大量淀粉粒、蛋白质、内质网、叶绿体、脂体和大液泡;包围花粉粒的膜和花粉粒之间的膜含有蛋白质成分和脂类成分;小孢子细胞核分裂形成营养细胞和生殖细胞,营养细胞和生殖细胞间没有细胞板形成,生殖细胞呈透镜型、比营养细胞小。     

华北驼绒藜自然种群结实的花粉和资源限制

运用人工授粉、补充无机营养、去叶处理以及疏花处理研究了华北驼绒藜自然种群花粉和资源有效性对结实的影响,并进一步探讨了该植物的选择性败育现象和繁殖对策。结果表明:花粉来源而不是花粉数量对华北驼绒藜结实存在显著影响;同枝授粉结籽率和结实率均低于自然授粉,异株授粉则显著高于同枝授粉和自然授粉;异株授粉种子千粒重显著高于自然授粉和同株异枝授粉,极显著高于同枝授粉。华北驼绒藜结实存在资源限制,补充施肥提高了单枝开花数和结籽率。随摘除叶片数量的增加,结籽率明显降低,摘除叶片处理与对照之间均形成显著差异,摘除1/2叶、3/4叶以及去全叶处理使种子千粒重显著低于对照。人工疏花实验表明华北驼绒藜存在选择性败育现象。华北驼绒藜可根据花粉和资源的可利用性来调整性分配、授粉方式和结实以获得最大适合度,具有复杂的繁殖对策,表现出较好的环境适应性。     

青阳参的大孢子发生与雌配子体发育

利用常规石蜡制片技术、荧光显微技术、光镜细胞化学技术、电子显微镜技术对青阳参大孢子发生、雌配子体形成过程进行了详细观察。结果显示,青阳参为边缘胎座,胚珠倒生、短珠柄,单珠被,薄珠心型,珠心细胞含有大量的淀粉粒、线粒体和内质网等;大孢子孢原细胞起源于下表皮并直接行使大孢子母细胞的功能;合点端的大孢子分裂形成8-核胚囊;蓼型胚囊;成熟胚囊中有大量淀粉粒;珠孔受精;胚乳在早期发育阶段以游离核形式存在,约在16~32核的阶段细胞壁形成,通常情况下胚乳核的分裂比合子的分裂早,成熟胚乳细胞单核、形状不规则,没有胚乳吸器;胚的发育经过原胚、球型胚和心型胚阶段,茄型;成熟的种子具有种毛,位于珠孔端的珠被表皮细胞是种毛长出的区域,种子中含有大量的脂肪。     

青阳参的组织培养和植株再生

1植物名称青阳参(Cynanchum otophyllumSchneid.),别名青洋参。2材料类别成熟种子。3培养条件(1)芽诱导培养基:MS+6-BA2.0mg·L-1(单位下同)+NAA1.0;(2)芽增殖培养基:MS+6-BA2+NAA0.2;(3)生根培养基:1/4MS。以上培养基中除生根培养基蔗糖含量2%外,其余均为3%。pH5.8,琼脂含量为0.8%。培养温度(25±2)℃,光照12h·d-1,光强为40μmol·m-2·s-1。4生长与分化情况4.1无菌苗的获得将种子用洗衣粉水洗净,流水冲洗30min后,在无菌条件下先用75%酒精浸泡30s,无菌水冲洗3次,再用0.1%升汞水浸泡10min,无菌水冲洗5次,消毒滤纸吸干表面水分,接…     

野慈姑花粉限制评估的影响因素

以野慈姑为材料,研究补充授粉的处理水平(单花、花序)和花粉质量(自花花粉、异花花粉)对花粉限制评估的影响.结果表明: 补充授粉的处理水平会造成花粉限制的程度不同(P=0.0021),单花水平的授粉会导致花朵之间的资源重新分配,从而影响结实;补充授粉的花粉质量会对结实造成影响,补充异花花粉比自花花粉能产生更多的种子(P=0.0497),且萌芽率更高(P=0.0428),表明该体系的花粉限制不是数量的限制,而是优质花粉的限制.不同的试验水平和花粉质量可能对花粉限制的评估造成影响,相关研究应尽量对整个花序或者植株进行补充授粉,材料允许时还应考虑自异花粉的对比试验,有利于更客观地认识和检测花粉限制.     

青阳参的一个新C21甾体苷

从萝藦科药用植物青阳参(CynanchumotophyllumSchneid)的乙酸乙酯提取物的酸水解液中,分离得到一个新的C21甾体苷类化合物,通过现代波谱技术,确定其结构为去乙酰藦萝苷元3-O-β-D-夹竹桃吡喃糖基-(1→4)-α-D-夹竹桃吡喃糖苷。     

植物生长调节剂对火龙果坐果率和果实生长的影响

以‘红龙果Ⅱ’为试材,研究不同生长调节剂处理对火龙果坐果率和果实生长的影响。结果表明：浓度为30 mg/L GA3或100 mg/L 6-BA对提高火龙果坐果率及促进果实生长效果最佳。     

枣不同品种花粉量和花粉萌发率的研究

以20个枣品种为试材,测定了花粉萌发率和单药花粉量。结果表明,枣不同品种在同一时期及同一品种在不同花期花粉量和花粉萌发率差异显著,初花期单花药花粉量最多的品种达5556粒,最少的为0。花粉量与花粉萌发率之间无显著的相关性。枣树的单药花粉量在6月中下旬最高,而花粉萌发率在6月中旬出现高峰。发现了无花粉、高含仁率的优异雄性不育新种质JMS3,并进一步证明了JMS1的无花粉性状稳定。     

Pollen limitation meets resource allocation: towards a comprehensive methodology

The standard method of measuring pollen limitation is to add pollen to a number of flowers, preferably to a whole plant, and to compare fruit and seed set with that of naturally pollinated flowers on other plants. In 25 yr of research, this method has yielded valuable data, but it is difficult to use in large plants. This has caused a bias in the available data towards smaller, herbaceous plants with relatively few flowers. I argue that, in order to widen our knowledge of how pollen limitation affects plants, we should go beyond whole-plant pollen addition and change our concept of how a flowering plant functions. The traditional method does not take into account the variation in and dynamics of resource allocation and pollen availability. The concept of integrated physiological units (IPUs) does, but, although it has been applied to pollination biology, it has not received the attention it deserves. I use this article to present its merits again, to propose a step-by-step methodology for studying pollen limitation, and to examine factors influencing possible plant strategies.     

Pollinator‐mediated phenotypic selection does not always modulate flower size and number in the large‐flowered Mediterranean shrub Cistus ladanifer (Cistaceae)

Flower size and number usually evolve under pollinator‐mediated selection. However, hot, dry environments can also modulate display, counteracting pollinator attraction. Increased pollen deposition on larger flower displays may not involve higher female fitness. Consequently, stressful conditions may constrain flower size, favouring smaller‐sized flowers. The large‐flowered, self‐incompatible Mediterranean shrub Cistus ladanifer was used to test that: (1) this species suffers pollen limitation; (2) pollinators are spatially–temporally variable and differentially visit plants with more/larger flowers; (3) increased visits enhance reproduction under pollen limitation; (4) stressful conditions reduce female fitness of larger displays; and (5) phenotypic selection on floral display is not just pollinator‐mediated. We evaluated pollen limitation, related floral display to pollinator visits and fruit and seed production and estimated phenotypic selection. Flower size was 7.2–10.5 cm and varied spatially–temporally. Visitation rates (total visits/50 min) ranged from 0.26 to 0.43 and increased with flower size. Fruit set averaged 80% and seed number averaged 855, but only fruit set varied between populations and years. Selection towards larger flowers was detected under conditions of pollen limitation. Otherwise, we detected stabilizing selection on flower size and negative selection on flower number. Our results suggest that selection on floral display is not only pollinator‐dependent through female fitness in C. ladanifer. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176 , 540–555.     

Proximate Limitations to Fruit and Seed Set in Phellodendron amurense var. sachalinense

Abstract Fruit and seed set in a dioecious tree, Phellodendron amurense var. sachalinense grown in isolation, were studied for three years in Hokkaido, northern Japan. Hand pollination did not affect fruit set during the three years, but did affect seed-set by increasing the proportion of fruits with higher seed numbers. Artificial defoliation resulted in decreased mean seed mass, but caused no significant differences in mean seed number per fruit. Total seed mass per infructescence increased with inflorescence size except with artificial defoliation where it reached an upper limit. Although the results of the artificial defoliation treatment indicate that resources are most important for fruit and seed set, it is concluded that fruit and seed set of the tree are not limited by resources, since the number of fruits increased with inflorescence size and an artificial defoliation treatment did not decrease seed-number.