北京地区蒿柳的开花物候期及单花序开放过程中花粉活力和柱头可授性变化

Flowering phenology and flowering dynamics of female and male inflorescences of Salix viminalis Linn. in Beijing were observed in 2015 and 2016, and changes in pollen activity and stigma receptivity were also investigated. The results show that early flowering stage of S. viminalis in Beijing is happened in early?March, flowering period is 11-18 d, and flowering pattern is the first opening type of male flower. Flowering period of single inflorescence in male and female plants is 10-15 d and 8-10 d, respectively, which can be divided into five stages:emerging color stage, initial flowering stage, half flowering stage, full flowering stage and withered stage. Flowering date of male plant is earlier about 3-4 d than that of female plant. However, the difference of full flowering stage between male and female plants is only 1 d. Pollen germination rate and stigma receptivity show a trend of firstly increasing then decreasing during blossom process. Pollen germination rate reaches the highest of 72% at full flowering stage, and stigma receptivity is more than 90% at half and full flowering stages. Therefore, it is suggested that pollen collection and pollination in mid?March can improve success rate of cross breeding of S. viminalis.     

珍稀濒危植物距瓣尾囊草(Urophysa rochkii)的开花物候和繁育系统特性

通过野外观察,运用套袋授粉和联苯胺-过氧化氢法等实验方法对距瓣尾囊草开花物候以及种群的繁育系统特性进行研究。研究结果:1)距瓣尾囊草为两性花,聚伞状花序,花期较长,从头年12月持续到次年4月,单花花期持续8—15 d,种群花期可持续4个月左右。2)距瓣尾囊草在花朵未开放前花粉没有活力,花药开裂当天花粉活力达到94.8%,第2天为90.3%,第3天为81.6%,第4天为62.9%,此后其花粉活力明显减弱;柱头可授性于散粉后第3天开始出现,散粉后4—5天最强,散粉后第8天柱头失去可授性;柱头可授性和花粉活力有5 d左右的重叠期。3)其花粉胚珠比P/O为938.5±250,按照Cruden标准划分,其有性繁育系统为兼性异交。4)按照Dafni的标准,距瓣尾囊草的OCI=4,即繁育系统为异交、部分自交亲和、需要传粉者。5)人工异花授粉结实率达80%以上,略高于自然结实率78.94%;直接套袋结实率为5.71%;去雄套袋和去雌套袋均不结实。以上结果表明,距瓣尾囊草繁育系统表现为异交为主、部分自交亲和并且不存在无融合生殖现象,其开花物候、花部特征和繁育系统为适应特殊的环境提供了一定的生殖保障,本次研究结果为距瓣尾囊草的迁地保护和种群的繁衍复壮提供理论依据。     

迁地保护条件下两种沙冬青的开花物候比较研究

沙冬青属(Ammopiptanthus)植物是我国西北荒漠区唯一的常绿阔叶灌木。作者对吐鲁番沙漠植物园迁地保护的两种沙冬青的开花物候进行了详细的比较观察,旨在探讨它们在同一生境条件下开花特性的异同点及其影响因素。主要结果如下:(1)两种植物在开花频率、花序开放顺序、开花振幅曲线及单花寿命等开花参数上相似,但在始花时间、单株花期、花序的开花数及开放持续时间与频率分布、开花振幅等参数上明显不同;(2)在个体和群体水平上,蒙古沙冬青(A.mongolicus)始花时间均比新疆沙冬青(A.nanus)早,蒙古沙冬青开花全过程为20–21d,新疆沙冬青为13–14d;(3)蒙古沙冬青花序的开花数比新疆沙冬青多、开放持续时间长,两者在开花数(F=17.51,P<0.01)和持续时间(F=14.08,P<0.01)上均存在显著差异;(4)花序上的花大多从近基部向两端开放,开花振幅呈单峰曲线,但新疆沙冬青的开花振幅较高;(5)花序开放持续期的频率分布明显不同,新疆沙冬青较蒙古沙冬青更为集中,但两者的单花寿命稳定,均在7d左右;(6)花序上每天的开花数与其座果数呈正相关(蒙古沙冬青,r=0.885,P<0.05;新疆沙冬青,r=0.827,P<0.01),但其开花数和座果数与始花时间存在不同程度的相关关系,这些特点可能与开花对传粉者的吸引以及物种本身的遗传特性有关。对上述观察结果及其影响因素的分析表明,两种植物在开花参数上所表现出的一致性可能是受系统发育限制的,而彼此间的差异可能与其进化历史及所处的环境异质性有关,是在与环境的长期适应过程中分别形成的一些可遗传的变异;而不同年份间两种沙冬青在花序的开花数及开放持续时间上表现出的差异可能与环境温度的变化有关。这些结果对于探讨该属植物的繁殖生物学特性及其保护对策具有重要意义。     

早春草本植物开花物候期对城市化进程的响应——以北京市为例

植物物候对城市化的响应是全球变化与城市生态环境效应研究的重要内容。2012年3月到6月,结合气象观测数据,对北京市西北向城市化梯度上7种早春草本植物开花物候期进行观测与研究,发现温度因子和早春草本植物开花物候期均随城市化梯度发生变化,即越靠近城市中心区,温度和积温累计值越高;早春草本植物开花物候期出现时间越早,平均提前2—4 d;但开花期持续时间与开花速率并不随城市化梯度发生明显变化。此外,研究发现北京市7种早春草本植物开花期对5℃积温变化响应最为敏感;开花期提前时间梯度变化显著性与生活型密切关联,多年生草本植物对城市化梯度变化的响应比一年生或一二年生草本植物明显。未来城市植物物候期研究中,应更关注城市化进程中土地利用/覆被变化与热岛效应对城市气候及植物生理生态特征的累积影响特征,以期进一步揭示植物物候期对城市化及气候变化的响应规律。     

科尔沁沙地两种蒿属固沙半灌木的开花物候比较研究

对科尔沁沙地的乌丹蒿和差不嘎蒿的开花物候进行了调查研究,从头状花序、花序枝、个体以及群体水平比较两种植物的开花物候特性。结果表明:(1)乌丹蒿的群体始花期为6月18日,较差不嘎蒿的早9 d,持续时间为19 d,差不嘎蒿开放持续16 d,两种植物群体花期重叠约10 d。在个体水平上,乌丹蒿始花日期比差不嘎蒿早7 d,单株花期长2 d;(2)乌丹蒿二级花序枝上头状花序数比差不嘎蒿的少,开放持续时间更长。两种植物开花频率均为单峰型,二级花序枝开放持续时间频率均以8 d为最高,其次为9 d,头状花序水平上两者开放持续时间频率较高的均为5 d、4 d、6 d,5 d频率最大;(3)差不嘎蒿二级花序枝上近基部的头状花序先开放,自基部向上的第2和第3个位置最先开放的频率相对为高,分别为12.7%和11.9%。而乌丹蒿则是顶端的头状花序先开放,最先开放的频率高达56.3%;(4)两种植物的开花振幅曲线均呈单峰曲线,其中乌丹蒿开花后第9 d开花量达到高峰,差不嘎蒿开花后第6 d开花量达到高峰。两种植物开花物候的相似性反映出它们的亲缘关系及对共同环境的适应性,不同点尤其是最先开放顺序的差异性,表明了两者长期进化的遗传差异。     

新疆野杏开花物候与花器官对海拔的响应

新疆野杏(Prunus armeniaca Lam.)是天山野果林的优势种,具有重要的生态与资源价值。野果林的生境条件与其分布及生长密切相关。为了明确新疆野杏在不同海拔下的开花物候与花器官变化规律,于2021年3月—4月,选择新疆新源县吐尔根杏花沟野杏林为研究区,在野杏集中分布的1000—1500m的山地,由低到高划分Ⅰ—Ⅴ级海拔梯度设置样地,监测环境条件,对野杏群体开花物候期与花器官发育特征进行调查。结果表明：(1)新疆野杏群体开花物候期历时32d左右,各海拔梯度最长相差2d,第Ⅰ级与第Ⅱ级海拔的开花物候期差异不明显,其他海拔梯度间均存在显著差异,开花最晚的第Ⅴ级比最早的第Ⅰ级晚9d,但群体开花期长4d,海拔梯度与开花物候期呈显著正相关,而温度与开花物候期呈显著负相关;(2)新疆野杏的花萼长度和宽度、子房高度和宽度均是第Ⅱ级海拔的最大;花冠直径、花瓣纵径和横径均是第Ⅰ级的最大,花药长度和宽度均是第Ⅳ级的最大;花柱长度是第Ⅴ级的最大。海拔与花的外部器官、雌蕊呈显著负相关,与雄蕊呈显著正相关;光照强度与花的外部器官、雌蕊呈显著负相关;(3)新疆野杏开花期气候因子,第Ⅳ级、第Ⅴ级与第Ⅰ级存...     

华山新麦草开花物候期观测和自然种群基因流的间接估测

华山新麦草（Psathyrostachys huashanica keng)为我国特有种,仅分布在陕西华山。通过对自然种群传粉物候期观测发现,华山新麦草的传粉高峰期与海拔有一定关系。海拔每升高200m,传粉物候期就推迟2－3d;海拔差异超过500m的亚种群,传粉物候期就不会出现重叠。同时应用等位酶分析技术和E－统计分析间接估测华山新麦草自然种群的基因流（Nm）,其值较一般风媒传粉植物低。通过华山新麦草资源状况、生长环境的调查以及移栽试验的观察,认为该物种稀的主要原因之一 可能是其生存竞争能力弱,最终被迫生长在其它物种所不能生存的环境。     

葎草雌雄植株开花物候和花器官对干旱的响应差异

摘要：以蓓草（Humulusscandens）为实验材料,在控制土壤水分的条件下探究干旱对雌雄异株植物开花物候和花器官形态的影响,结果表明：干旱胁迫将导致蓰草雌雄种群花期提前．花期持续时间延长,雌花将比雄花提早开放;干旱胁迫下雄花的花序轴长、花序轴直径和花药粒径长均分别显著减小24．81％。29．07％和5．14％（P〈0．001,P=0．003,P=0．024）,花粉活力和花粉含量显著下降：干旱胁迫导致雌花的花序轴长、柱头长度和花序的平均花数量显著增大9．78％,70．62％和57．04％（P=0．039．P〈0．001．P〈0．001）;干旱胁迫下种子粒径长、种子粒径宽、种子单粒重和种子千粒重分别显著下降12．12％、12．59％、43．43％和15．38％（显著度水平均为P〈0．001）;干旱胁迫下雌雄植株的地上部分生物量均显著降低（P=0．002,P=0．020）,且雌株的生殖投入在干旱胁迫下显著高于雄株（P=0．049）。研究结果表明了蓰草雌雄植株开花物候及花器官对干旱的响应明显不同。与雄株相比．雌株在干旱胁迫下增加了生物量向生殖器官的分配,从而最大程度地减轻胁迫对其繁殖能力的影响。     

观赏蕨类引种栽培及其物候期的观察

对中华水韭、福建观音座莲、华南紫萁、西南凤尾蕨、剑叶铁角蕨、翅轴蹄盖蕨、东方荚果蕨、同形鳞毛蕨、圆顶耳蕨等30种蕨类进行了引种栽培和物候期观察.结果表明:(1)引种成活率高;(2)管理粗放;(3)多数种类四季常青,形态优美,具有较高的观赏价值,能够在怀化市安全越冬,值得在亚热带地区开发利用;(4)华南紫萁、小黑桫椤、光蹄盖蕨、长江蹄盖蕨、翅轴蹄盖蕨、三相蕨、同形鳞毛蕨、圆顶耳蕨、镰羽贯众等9种蕨类在展叶时,同时长出孢子囊;(5)多数蕨类的孢子囊在长出后1个月左右发育成熟;(6)在叶开始萌动时引种栽培的蕨类,当年的营养叶萌发期和展叶期都推迟半个月左右,但孢子囊群的出现期和成熟期不受影响;(7)不同蕨类的孢子囊群形成期具有差异性,同种蕨类的孢子囊群形成期具有相对稳定性,因此,可以作为鉴别物种的依据之一。建议在编写、修订《中国植物志》和地方植物志时增加蕨类孢子囊群形成期的描述。     

不同风信子品种在南京地区的物候期及生长特性分析

对从荷兰引进的17个风信子(Hyacinthus orientalis L. )品种在南京地区的物候期、观赏特性和生长状况进行了调查分析.调查结果表明,17个风信子品种的耐寒性较强,出苗期最早在1月下旬,多数品种的出苗期在2月中下旬;绝大多数风信子品种的叶片展开期集中在3月14日至20日;花现色期多为2月底至3月初,第1朵花的开花期在3月中上旬;大部分品种的单花序开花持续时间和群体开花持续时间较长,分别达20～22 d和27～31 d.17个风信子品种的花均具有非常浓烈的香味,花蕾与花脉颜色相同,花色从花脉辐射至花瓣边缘并逐渐变淡,花色艳丽, 观赏性强. 少数品种具1个花枝, 多数品种具2个花枝, 花茎长度12.7～21.9 cm, 多数品种的花茎长度在17 cm以上;主花序长度多在11 cm以上,约占整个花茎长度的2/3;单花序花朵数为20～61.各品种的花瓣数和花药数基本一致,多以6为基数;17个风信子品种的花粉均有一定的萌发能力,其中9个品种的花粉萌发率较高,均超过40%.多数品种的叶片数为6或7,叶片长18～29 cm,宽2.2～3.6 cm.除品种'阿姆斯特丹'、'简波斯'和'福特'外,其余品种均可以分生出籽球,其中,品种'蓝星'、'蓝夹克'和'爱丽斯'的籽球分生能力最强,分生率达66%以上;不同风信子品种的籽球直径也各不相同,多数籽球直径较大,为3～5 cm.结果显示,风信子可作为早春花卉在南京进行种植,但具体种植条件尚待深入研究.     

Latitudinal cline of flowering and fruiting phenology in Fagaceae in Asia

The seasonal timing of flowering and fruiting is crucial for the reproductive success of plants and for resource availability to animals. Although plants synchronize their reproductive timing to coincide with appropriate seasons by responding to environmental cues, seasonal variations in temperature and precipitation vary minimally in very wet tropical environments. To explore the latitudinal cline in the reproductive phenology of the Fagaceae in Asia, we analyzed phenology data for a total of 94, 121, and 219 species from Thailand, Malesia, and China, respectively, in the three genera of Fagaceae, Quercus, Castanopsis, and Lithocarpus. We found that Quercus and Castanopsis showed flowering peaks in April in China. In Thailand, the peak shifted to an earlier month, and the peak disappeared in Malesia. The flowering period lengthened with decreasing latitude in the animal-pollinated genera Castanopsis and Lithocarpus. However, this was not the case for the wind-pollinated genus Quercus. The fruiting period lengthened with decreasing latitude in all three genera. We examined the relationship between reproductive phenology and climatic factors. The combination of monthly temperature and precipitation best explained the monthly change in the proportion of flowering and fruiting species in China in all three genera. However, climatic factors had almost no impact on the predictive ability of the model in Malesia. Our results on phenological shifts in the family Fagaceae, from the temperate climates and seasonal tropics to the humid tropics, provide valuable information for predicting phenological changes in future climate change.     

Time after time: flowering phenology and biotic interactions

The role of biotic interactions in shaping plant flowering phenology has long been controversial; plastic responses to the abiotic environment, limited precision of biological clocks and inconsistency of selection pressures have generally been emphasized to explain phenological variation. However, part of this variation is heritable and selection analyses show that biotic interactions can modulate selection on flowering phenology. Our review of the literature indicates that pollinators tend to favour peak or earlier flowering, whereas pre-dispersal seed predators tend to favour off-peak or later flowering. However, effects strongly vary among study systems. To understand such variation, future studies should address the impact of mutualist and antagonist dispersal ability, ecological specialization, and habitat and plant population characteristics. Here, we outline future directions to study how such interactions shape flowering phenology.     

Density effects of flowering phenology and mating potential in Nicotiana alata

Summary We investigated effects of plant density on floral phenology and potential mating in artificial populations of the outcrossing ornamental Nicotiana alata planted at three densities. Path analysis revealed that increasing plant density yielded significantly earlier peak flowering dates, significantly earlier last flowering dates, and significantly lower plant biomass. Direct effects of density on final flower number were not significant. Variation among replicate plots for first date of flowering was larger than variation among densities, indicating that factors other than density influence floral initiation.We did not record actual mating, but determined from phenological data the number and identity of potential mates. Increased density had several effects on potential mating patterns and on potential N_e, effective population number. At high density, fewer focal plants flowered for shorter durations. This led to less overlap in flowering time among plants, decreasing the number of potential parental combinations possible among the progeny. Two outcomes of high density, the lower total number of plants flowering and the lower number of plants flowering at most census dates, tended to reduce potential N_e. In contrast, it was low density, where variance in flower number was greatest, that was most likely to yield the greatest reduction in N_e due to variance in progeny number.At high density the potential for assortative mating among tall plants was much greater and occurred later than among large plants at low density. Much of the potential high density assortative mating occurred late in the phenology of individual plants, when there was likely to be lower fruit set.We discuss how ecological agents that alter flowering phenology can potentially alter the genetics of populations, the level and timing of assortative mating and, if genetic variation for response to such ecological agents exists, the potential selection regime.     

Effects of experimental shifts in flowering phenology on plant-pollinator interactions

Climate change has led to phenological shifts in flowering plants and insect pollinators, causing concern that these shifts will disrupt plant-pollinator mutualisms. We experimentally investigated how shifts in flowering onset affect pollinator visitation for 14 native perennial plant species, six of which have exhibited shifts to earlier flowering over the last 70 years and eight of which have not. We manipulated flowering onset in greenhouses and then observed pollinator visitation in the field. Five of six species with historically advanced flowering received more visits when flowering was experimentally advanced, whereas seven of eight species with historically unchanged flowering received fewer visits when flowering earlier. This pattern suggests that species unconstrained by pollinators have advanced their flowering, whereas species constrained by pollinators have not. In contrast to current concern about phenological mismatches disrupting plant-pollinator mutualisms, mismatches at the onset of flowering are not occurring for most of our study species.     

Density-dependent flowering phenology,outcrossing, and reproduction in Impatiens capensis

Summary We investigated the effects of plant density on cleistogamous (CL) and chasmogamous (CH) flowering phenology and seed production in a natural Impatiens capensis population, by censusing individually marked plants at experimentally reduced and natural densities. CL flowering was earlier at natural density. This plastic density response may have resulted from a stress-related threshold for CL flowering; slower growing plants at natural density flowered earlier. Although apparently triggered by slow early growth, early CL flowering also involved an additional cost for later growth rate. In contrast, CH flowering was unrelated to relative growth rate, but apparently required a size threshold. Experimental density reduction resulted in earlier CH flowering and a dramatic increase in the percentage of plants producing CH flowers. Individual CL and CH flowering duration and flower production were greater at reduced density. These density-dependent effects caused differences between treatments in the shape and location of population flowering phenology curves. Moreover, the percentage of CH seeds produced per individual was much higher at reduced density. At natural density total seed production per plant was lower and more hierarchical than at lower density, suggesting that dominance and suppression shape jewelweed fitness distributions.     

Meta-analysis of phenotypic selection on flowering phenology suggests that early flowering plants are favoured

Flowering times of plants are important life-history components and it has previously been hypothesized that flowering phenologies may be currently subject to natural selection or be selectively neutral. In this study we reviewed the evidence for phenotypic selection acting on flowering phenology using ordinary and phylogenetic meta-analysis. Phenotypic selection exists when a phenotypic trait co-varies with fitness; therefore, we looked for studies reporting an association between two components of flowering phenology (flowering time or flowering synchrony) with fitness. Data sets comprising 87 and 18 plant species were then used to assess the incidence and strength of phenotypic selection on flowering time and flowering synchrony, respectively. The influence of dependence on pollinators, the duration of the reproductive event, latitude and plant longevity as moderators of selection were also explored. Our results suggest that selection favours early flowering plants, but the strength of selection is influenced by latitude, with selection being stronger in temperate environments. However, there is no consistent pattern of selection on flowering synchrony. Our study demonstrates that phenotypic selection on flowering time is consistent and relatively strong, in contrast to previous hypotheses of selective neutrality, and has implications for the evolution of temperate floras under global climate change.