【作者】 孙颖；

【导师】 卓丽环；

【作者基本信息】 东北林业大学 ， 园林植物与观赏园艺， 2009， 博士

【摘要】 百子莲属系单子叶植物纲天门冬目,其原种分布于南非,早花百子莲（Agapanthuspraecox）是该属中的一个常绿种。本论文以上海市农林职业技术学院五厍实习基地为研究地点,通过对引种地条件下百子莲的花部综合特征及其繁育系统、开花物候及其传粉机制、生物量分配动态及生殖配置、结实格局及结实限制、种子发育及萌发特性、光合特性等的研究,探讨了该物种的繁殖生物学特性,结果表明:1.繁育系统:引种条件下,百子莲单花花期为2～3d,单株花期长度一般在15～30d。柱头可授性与花粉成熟时间相比有延迟性。柱头自开花第2天起在单花萎蔫前均有可授性。开花过程中没有明显的开花高峰期。在单株花期内能够保证每日都有一定量的单花开放,为百子莲的结实提供有效的花粉流和传粉媒介。由于杂交指数等于4,花粉-胚珠比等于25622,结合人工套袋和授粉实验的结果,可以确定该物种的繁育系统属于异交为主,部分自交亲和,传粉过程需要传粉者。2.开花物候:百子莲在引种地的开花时间为5月末至7月末。种群花期历时40d左右。种群内2007年与2008年的各项开花物候指标相差约7～9d。种群开花进程为渐进式的双峰曲线。百子莲的种群花期重叠时间较长,2年的平均开花同步指数分别为0.663、0.695。植株个体相对开花强度主要分布频度在50%～70%之间。开花物候指数与座果率的相关分析表明:始花时间、花期长度、开花数目、座果数之间均存在显著相关关系。其中始花时间与开花数目、座果数、花期长度之间成显著负相关,开花数目与座果数、花期长度之间以及花期长度与座果数之间成显著正相关。说明始花时间早的植株比始花时间晚的植株花期更长,开花数目多的植株比开花数目少的植株花期更长,花期长的植株比花期短的植株座果率更高。作为引种植物,百子莲开花物候年度间的相似性说明,其在引种地可以适应环境压力,形成稳定的开花时间与开花模式。较长的花期重叠和大量的开花数目可以吸引较多的传粉者访问,为其生殖成功打下良好基础。3.传粉机制:2年内共发现访花昆虫23种,分属于5目、17科。其中传粉昆虫有10科13种,主要有中华蜜蜂、熊蜂、玉带凤蝶、菜粉蝶和黑带食蚜蝇。访花频率在不同昆虫之间差异显著,在不同花期（始花期、盛花期）间差异不显著。各昆虫单日的访花频率存在一定规律,其中蝶类传粉活动集中在上午,蜂类传粉持续长,早7:00至晚17:00均有出现。昆虫访花效率和虫体解剖镜观察表明,蜂类的传粉效率明显高于蝶类和蝇类。补充授粉实验表明,百子莲花期存在传粉昆虫不足现象。百子莲的主要传粉报酬为花蜜,其在诱导昆虫传粉中起主要作用。去雄和切除花瓣实验表明,花瓣在传粉昆虫的访花活动中,起到了吸引昆虫到访及提供昆虫着落平台的积极作用。开花式样控制观察试验表明10～15朵花是百子莲较为有效的保证传粉效率的开花式样。4.生殖配置:百子莲总生物量在整个花期成上升趋势,7月和8月总生物量上升幅度最大。营养器官的生物量显著大于生殖器官。从生物量分配比例来看,根和茎所占总生物量的比例随着生长发育显现出降低的趋势。叶生物量则在7月初以后所占比例有所增加。生殖器官的生物量分配比例始终维持在较低水平,在7月中旬达到最高峰。百子莲茎、叶及生殖器官的全氮含量和全磷含量变化趋势为:现蕾初期含量高,然后逐渐降低,座果期达到最低。而全钾含量在生殖生长前期没有显著变化,果实成熟期则有一个显著的提高。5.结实结籽特性:座果率的高低顺序为:果序基部＞果序中部＞果序顶端。结籽率高度顺序为:果实顶端＞果实中部＞果实基部。百子莲单株种子产量只占潜在种子产量的6.67%。说明百子莲的实际产量要远远低于潜在产量,在产量上存在很大的上升空间。百子莲花序开放顺序为由基部逐渐向上,最早开放的花在资源吸收和利用上占有主动,因此基部果实成熟的可能性最高。分析去叶、去花、施肥的结果,结合百子莲生殖生长期生物量的变化规律,认为百子莲在生殖生长初期资源积累不足,同时营养生长和生殖生长存在竞争,因此百子莲的结实存在资源限制现象。同时,自然条件下柱头接受的花粉数小于其胚珠数,认为花粉数量是限制百子莲结实的一个因素。同株异花授粉及自化授粉的座果率并没有提高,而异花授粉后座果率得到了显著提高,说明百子莲具有较强的自交不亲和性。由此判断,花粉来源也是限制百子莲结实的因素。6.种子发育过程:（1）百子莲种子发育前2周种子生长量最大;种子干重在授粉后42d趋于稳定。（2）淀粉在种子发育初期积累迅速,总体上呈“上升—下降—上升”的趋势;可溶性蛋白质含量呈逐渐上升趋势;可溶性糖含量呈逐渐下降趋势。淀粉含量、可溶性蛋白质含量与种子干重、种子大小呈显著正相关;可溶性糖含量与淀粉含量、种子干重、种子大小呈显著负相关。（3）POD、PPO、α-淀粉酶的含量在种子发育过程中变化显著;POD、PPO活性与可溶性蛋白质含量呈显著正相关;α-淀粉酶活力与种子大小成显著正相关。（4）在百子莲种子萌发过程中,可溶性糖含量呈显著上升趋势,淀粉含量呈下降趋势,说明种子淀粉进行了分解,转化为供种子萌发所需的各种糖分。引种地采收的种子萌发率很低,通过种子发育过程中生理生态变化的研究,发现百子莲在种子发育过程中存在一定的问题,这与引种地环境因子的具体关系还需要进一步考察和确认。7.光合适应特性:在全光照、30%、60%和80%遮光条件下,对引种植物百子莲叶片结构特征和光合特性进行了研究。结果表明,遮光处理后,百子莲叶面积随遮光率增加而逐渐增加,叶片厚度和比叶重则随遮光率增加而逐渐减小。气孔器长度随遮光率增加有逐渐变大的趋势,而气孔密度有逐渐降低的趋势。同时,叶绿素含量随着遮光程度的提高不断增加,叶绿素a/b值有小幅下降。说明百子莲叶片逐渐适应隐蔽环境并逐渐向阴性植物特征转变。4种处理条件下,百子莲的光饱和点均低于1000μmol·m^-2·s^-1,光补偿点均低于20μmol·m^-2·s^-1,这一结果与耐荫性植物的一般指标一致。全光照条件下,叶片Pn日变化有2个高峰值,Pn值在光强最高的中午时段反而降低了,说明出现了光抑制现象。而遮光后叶片Pn日变化曲线为单峰,没有出现“午休”现象,这表明了遮光可以减轻或避免强光辐射下光合作用的光抑制。3种遮光条件下百子莲叶片PSⅡ原初光能转化效率（Fv/Fm）和潜在活性（Fv/Fo）均比全光照高,说明遮光后光合电子传递速率升高。随着遮光程度的提高,百子莲叶片的ΦPSⅡ逐渐下降,说明遮光抑制了PSⅡ的实际光化学效率。遮光也造成了荧光光化学猝灭系数（qP）的逐渐下降,表明遮荫抑制了百子莲叶PSⅡ光合电子传递活性,且随遮荫强度的增大,抑制程度加强。更多还原

【Abstract】 Agapanthus belonged to monocotydoneae,Asparagales.Its original species occurred in South Africa.Agapanthus praecox was an evergreen species in Agapanthus.According to the data from the field observation,we studied the characteristics of reproductive biology of A. praecox ssp.Orientalis ’Big Blue’ including floral syndromes and breeding system,flowering biotemperature and pollination mechanism,biomass dynamic and reproductive allocation,seed setting pattern and seed setting limiting factors,seed development process and seed germination characteristics,effects of shading on leaf structure and photosynthetic characteristics and so on.All the research putted in practice at WuShe practice base in Shanghai Vocational Technical College of Agriculture & Forestry,Shanghai,China.1.Breeding system:In artificial populations in Shanghai,the individual flower longevity was 2 to 3 days and individual inflorescence duration was about 15～30d.Stigma had receptivity since the next day of flowering.On the day of flowering,the styles were shorter than the filaments.Spatial positioning of stigma and anthers was spatially desperation.Stamens and pistils matured asynchronous.There were not peaks in individual inflorescence duration and there were a certain amount of opening flowers per day.The total value of OCI was 4 and the value of P/O was 25622.The seed setting ratio with different treatments showed that its breeding system can be determined as outcrossing with partly self-compatible and needed pollinators during the pollination.2.Though calculating relative flowering intensity and synchrony indices we analyzed the influence of flowering phonology to reproduction.The results showed that the flowering span of population was May to July in Shanghai.Population duration was about 40d.The census date of flowering phonology was late 7～9d from 2007 to 2008.The curve of open flowers proportion showed two major peaks.The synchrony indices of two years were 0.663 and 0.695 and it showed that the time of florescence overlap was long。The correlation analysis among onset,duration,flowers and fruit set showed marked relations.There were significantly negative correlations between onset and flowers,fruit set and duration.On the other hand,there were significantly positive correlations between flowers and fruit set,duration.The individual with an early starting date showed a longer duration than the individual with a later starting date.The individual with more flowers showed a longer duration than the individual with less flowers.At the same time,the individual with a longer duration showed a higher fruit set than the individual with a shorter duration.As a exotic plant,the similarity of flowering phonology within two years suggested that A.praecox ssp. orientalis ’Big Blue’ can adapt to the environmental pressure and exhibited a steady flowering onset date and flower pattern.The longer florescence overlap and mass flowers may be regarded as an advantage to attract more pollinators and ensure its reproductive success.3.During 2007 to 2008,a total number of 23 species of insects were recognized as the flower visitors.Among which 13 species were pollinators including Apis cerana cerana, Bombus festivus Smith,Papilio polytes Linnaeus and Pieris rapae Linnaeus.The visiting frequency was different between various insects and similar between various anthesis.Visiting frequency in one day varied distinctly.Butterflies’ visiting activity mainly fastens on a.m.and bees’ visiting activity was longer than others.Comparing the efficiency of pollinators,it was found that bees were much more effective than butterflies and flies.Stereoscopic microscope observation on insects’ body also supported this point.Added pollen showed that the pollinators were not enough.Treatment of emasculation and perianth removal showed that the reward of nectar was more attractive than pollen to pollinators.Added pollen showed that the pollinators were not enough.Moreover,insects’ visiting activities were relation to the floral display.Floral display at 10 to 15 was more effective for pollination.4.Reproductive allocation:Total biomass ascended during the anthesis and increased rapidlly at July and Augest.Biomass of nutrition organ was bigger than generation organ. Biomass allocation ratios of roots and stems descended during the anthesis at the same time biomass allocation ratio of leaves ascended after July.Biomass allocation ratio of generation organ maintained low level.The dynamic change of nitrogen and phosphorus content was:The content was higher in initial phase of flowering and then descended gradually.The change of potassium content was not significantly during initial phase of reproduction growth and then ascended markedly during maturation period of fruit.5.Seed setting and fruit setting:The order of fruit setting ratio was base of inflorescence＞center of inflorescence＞apex of inflorescence.The order of seed setting ratio was:base of fruit＞center of fruit＞apex of fruit.Seed yield was 6.67%to potential yield which indicated the actual yield below potential yield markedly and there was fairly space in yield.The opening order of inflorences was base to top and the flowers of opening early were predominant in resources obsorbtion and utilization.Therefore the possibility of fruit maturation was highest at base of inflorescence.Combining regular pattern of biomass change and conclusion of cutting leaves,flowers removal as well as fertilizer-added,we considered that there were pollen limitation and resource limitation in seed set and fruit set.6.Seed development and germination:（1）The seed length reached the maximum on 56～63d after pollination,and the mass growth increased rapidly in the first two weeks.The dry weight of seeds leveled off on about 42d after pollination.（2）Starch content accumulated rapidly at the early stage of seeds development and the trend was“up-down-up”;Level of soluble protein tended to rise gradually while level of soluble sugar dropped gradually.There were remarkable positive correlations between starch content,soluble protein content and dry weight,seeds length.On the other hand,there were remarkable negative correlations between soluble sugar and starch content,dry weight,seeds length.（3）Significant changes in contents of POD,PPO and a-amylase occurred during the process of seed development.There were remarkable positive correlations between enzymatic activity of POD,PPO and soluble protein content,so as the correlation between a-amylase activity and seeds length.（4）Soluble sugar content tended to rise gradually during seed germination whereas starch content tended to rise gradually which meant starch decomposed to sugar on order to suppling seed germination. Seed germination ratio was low.This problem should be solved in breeding in the future.7.Photosynthetic characteristic:Shading（0,30%,60%,and 80%）was applied to A. praecox ssp.orientalis ’Big Blue’ to determine a theoretical basis for morphological and photosynthetic characteristics.Results showed that leaf area,length of stomata apparatus, chlorophyll content increased under limited light conditions,but thickness of leaf,leaf weight ratio,chlorophyll a/b and density of stomata apparatus decreased.All of those indicated that the leaves made a quick adjustment to shading environment and changed gradually to cheliophytes.The LSP was less to 1000μmol·m^-2·s^-1and LCP was less to 20μmol·m^-2·s^-1which in keeping with indicators of shade enduring plant.Daily variety curve of net photosynthetic rate showed two peaks in full sunlight and one peak in shading condition,which indicated“noon break”occurred only in full sunlight and shading could lighten or avoid photoinhibition in strong light.Under limited light conditions,Fv/Fm and Fv/Fo higher than those in full sunlight,which meant electron transfer rate ascended.Following shading aggravated,ΦPSⅡand qP descended which meant shading limited photochemical efficiency and electron transfer activity.更多还原