白及果实形态与种子结实率相关性研究

该研究以果实大小有明显差异的26个白及果序共87枚果实为材料,分析了果实形态(包括果实重量、长度及直径)与种子结实率的相关性。结果表明:果实重量与结实率的相关性最为密切,相关系数为0.786,达到中等正相关;其次是果实直径,相关系数为0.634;最后是果实长度,相关系数为0.553。对10枚果实及种胚大小测量结果显示,果实形态与种胚大小相关性为弱相关,不同果实种胚大小相差较大,种胚直径和种胚长度平均分别为177.9μm和359.0μm,最大分别为241.9μm和528.6μm,最小分别为64.5μm和114.3μm;单粒白及种子平均重3.90μg,87枚果实中,单枚果实平均种子数量为10 436粒,最大为39 488粒。该研究结果表明果实重量及饱满程度(直径),可以作为评价白及果实质量(种子结实率)的参考指标。     

南亚热带森林木本植物种子萌发和储存

研究了南亚热带森林 90种木本植物的种子和果实的大小、含水量等特征及种子萌发 ,并对其中有足够萌发个体的种 (45种 )进行了萌发分析和对有足够萌发个体和足够种子的种 (41种 )进行了种子或果实储存对萌发影响的研究。肉质果实种子和肉质种子萌发率较干燥种子高 ,两者差异显著。大多数种播种 6 0d内萌发。肉质果实的种子和肉质种子较干燥种子的休眠期长 ,留土萌发种子较出土萌发种子休眠期长。大种子种与小种子种之间、夏季成熟的肉质果实的种子与冬季和春季成熟的肉质果实的种子之间休眠期长短差异不显著。萌发率与新鲜种子含水量无显著的相关 ,但种子中水分含量的减少明显影响萌发率 ,尤其是在种子自然干燥的最初 3d。当种子的水分含量减至 2 0 % (约在种子自然干燥 10～ 14d)时 ,种子萌发率降至很低。萌发率随储存时间 (密封 ,(4± 1)℃ )而下降 ,但储存一个月下降不大 (- 8.3% ) ,储存 3个月后 ,显著下降。果实储存与种子储存之间、大种子种与小种子种储存之间、肉质果实的种子和肉质种子储存与干燥种子储存之间 ,萌发率差异一般不显著。     

异子蓬二型种子的萌发与休眠特性及其生态适应

异子蓬为中亚荒漠的特有种,其果实为胞果,花被片在结果时宿存包被果实形成浆果状的散布单位.对异子蓬的散布单位、果实形态进行比较观察,并在5/15℃、5/25℃、15/25 ℃(暗/光=12h/12h)3个温变周期下进行种子萌发实验,结果表明:(1)异子蓬的散布单位绿色、浆果状,有大小两种形态;大小两种散布单位内包被的果实在形状、大小、颜色上存在着明显差异.(2)大的散布单位内包被的果实圆形,扁平,褐色,无光泽,直径(2.64±0.03) mm,重量(3.68±0.04) mg;小的散布单位内包被的果实双凸镜形,黑色,有光泽,直径(2.40±0.04) mm,重量(2.86±0.06) mg.(3)褐色种子在3个温变周期下的萌发率都在81%以上,萌发速度快,而黑色种子萌发率低,萌发慢,具有休眠现象.(4)划破种皮及低温层积处理可显著提高黑色种子在3个温变周期下的萌发率,延长储存时间也可有效地促进黑色种子的萌发,表明黑色种子处于非深度生理休眠状态.异子蓬产生的两种不同类型的种子及其在时间和空间上的萌发差异对荒漠异质环境具有重要的适应意义.     

南亚热带森林木本植物种子萌发和储存

研究了南亚热带森林90种木本植物的种子和果实的大小、含水量等特征及种子萌发,并对其中有足够萌发个体的种(45种)进行了萌发分析和对有足够萌发个体和足够种子的种(41种)进行了种子或果实储存对萌发影响的研究.肉质果实种子和肉质种子萌发率较干燥种子高,两者差异显著.大多数种播种60 d内萌发.肉质果实的种子和肉质种子较干燥种子的休眠期长,留土萌发种子较出土萌发种子休眠期长.大种子种与小种子种之间、夏季成熟的肉质果实的种子与冬季和春季成熟的肉质果实的种子之间休眠期长短差异不显著.萌发率与新鲜种子含水量无显著的相关,但种子中水分含量的减少明显影响萌发率,尤其是在种子自然干燥的最初3 d.当种子的水分含量减至20%(约在种子自然干燥10～14 d)时,种子萌发率降至很低.萌发率随储存时间(密封,(4±1) ℃)而下降,但储存一个月下降不大(-8.3%),储存3个月后,显著下降.果实储存与种子储存之间、大种子种与小种子种储存之间、肉质果实的种子和肉质种子储存与干燥种子储存之间,萌发率差异一般不显著.     

西双版纳地区4种榕树果实的资源分配及其种子萌发特性

为了解榕树果实的资源分配和种子萌发特征,对西双版纳地区的垂叶榕(Ficus benjamina)、高山榕(F.altissima)、聚果榕(F.racemosa)和无柄雅榕(F.concinna)的果实营养、繁殖资源分配,以及种子萌发特性进行了研究。结果表明,4种榕果的营养分配存在差异,榕果重的种类果肉亦多,榕果大者果腔较大,且种子数量较多,但雄花和榕小蜂数量不一定多。榕果分配给雌性功能及雄性功能繁殖的小花比例也不相同,聚果榕在雌性功能上的分配显著大于雄性功能,其它3种榕果则分配于雄性功能的资源比雌性功能的多,但程度不同。此外,4种榕树的种子大小及重量存在显著的种间差异,以至于影响到种子的萌发率及根茎生长,果实最大的聚果榕种子最多,萌发率高,但由于种子最小,其根茎生长缓慢且短;果实适中的垂叶榕和高山榕种子较大,不但萌发率较高,其根茎生长也较快;果实和种子都小的无柄雅榕,种子萌发率低,根茎生长慢。生长在水热环境好的榕树比生长在相对贫瘠环境的榕树,由于极少面临水热光照等限制,更容易进化出较小的种子,萌发能力和速度也相对较差。这说明不同生境中榕树进化出了不同的繁殖分配机制及资源利用策略来适应环境变化。     

啮齿动物对不同大小和种皮特征种子的取食和搬运

在宁夏六盘山区的辽东栎灌丛,以不同大小的辽东栎种子、野李和华山松种子为材料,研究了种子大小和种皮特征对啮齿动物取食和搬运行为的影响.结果表明:辽东栎小种子和华山松种子的就地取食率均显著高于辽东栎大种子和野李种子;具有厚而坚硬种皮(内果皮)的野李种子被啮齿动物搬运后的取食率和贮藏率均最高.辽东栎大种子被啮齿动物搬运后取食的距离最大(3.10 m),被搬运后贮藏的距离(6.48 m)显著大于其他类型种子.除野李种子外,其他3种类型种子的单个种子取食点都在80％以上,所有种子的单个种子贮藏点都在90％以上,含2个以上种子的取食点和贮藏点较少.较高比例的华山松种子在灌丛基部和洞穴以外的其他环境被取食,其他3种类型种子被啮齿动物搬运后主要集中在灌丛基部和洞穴中取食;种皮(内果皮)厚而坚硬的种子以土壤埋藏方式贮藏的比例偏高.     

药物植物桃儿七不同种群种子产量初步研究

对药用植物桃儿七5个不同种群种子产量的研究表明：各种群中每花平均胚珠数、每果实平均种子数及种群平均结实率与种群所在的海拔高度呈正相关;不同种群个体平均胚珠数的变异范围为58.97-87.97,平均种子数变异范围为40.02-80.58,平均结籽率变异范围为61.29%-91.60%;果料内单粒种子平均干重与种群分布海拔呈明显负相关,与果实内种子数呈弱负相关;同一种群在不同年份间平均各上子产量差异不大;种子产量除主要受个体营养状况影响外,还受海拔及其它因素的影响;果实内种子数与果实大小及重量呈正相关,但单粒种子平均重量与果实大小及果实内种子总重量无显著相关。     

准噶尔荒漠异苞滨藜(Atriplex micrantha)的种子二型性及其萌发行为

异苞滨藜的果实(种子)存在二型性,这两种类型的果实在形状、大小、颜色及包被其苞片的大小上均有差异。黑色果实果皮光滑,有光泽,直径1.481mm±0.186mm,包被果实的苞片较小;褐色果实扁平,直径2.642mm±0.254mm,包被果实的苞片较大。以异苞滨藜的两种果实(种子)为材料,在3个变温条件(5/25℃、5/15℃、15/25℃,暗12h/光12h)下进行萌发实验,褐色种子成熟后即具有一定的萌发能力,最终萌发率都在80%以上。黑色种子仅在低的夜间温度(5℃)和高的昼间温度(25℃)条件下有较高的萌发率(>70%),而在5/15℃、15/25℃条件下,种子的最终萌发率较低(<20%),2星期的低温层积处理能够有效地加速和提高黑色种子在3个变温条件下的萌发,划破果皮和种皮也能不同程度的加速和促进黑色种子的萌发,表明黑色种子处于非深度生理休眠状态。苞片中盐含量低,苞片对褐色种子萌发无抑制作用。异苞滨藜的果实(种子)二型性及其萌发行为是对荒漠异质环境的适应。     

小果野芭蕉种子散布和不同时空尺度上种子被捕食格局

 以分布在云南西双版纳地区的大型先锋草本植物小果野芭蕉(Musa acuminata)为研究材料,研究其种子初次散布过程和不同时空尺度上种子被 捕食格局。小果野芭蕉的成熟果实有75%在夜间被取食和传播,在白天消失的果实则占25%。蝙蝠是其最主要的种子传播者,鸟类在其种子传播 过程中也起到一定的作用。人工摆放种子试验结果显示小果野芭蕉种子的主要转移者是小型啮齿类(鼠类)和蚁类：在开放处理下3 d后转移率为 86%,排除蚁类(鼠类可进入)处理下种子转移率为69%以及排除鼠类(蚂蚁可进入)处理下种子被转移率为56%。季节、地点和生境均显著影响人工 摆放种子被转移强度：雨季显著高于旱季(p<0.001), 野芭蕉生境显著高于与其相连的自然森林和荒地(p<0.001),在人为干扰较少的补蚌自然 保护区显著低于西双版纳热带植物园和新山,而后两者之间并无显著差异(p>0.05)。同时,地点和生境以及季节、地点和生境都有显著的交互 作用。与相邻的森林和荒地相比,野芭蕉群落中种子被鼠类捕食的强度最大且受蚁类二次转移的比例最少,森林和荒地中种子被鼠类捕食的强 度相对较小且蚁类对种子的二次转移比例较高,从而更好地帮助种子逃避鼠类捕食。因此,依赖于食果动物(主要是蝙蝠, 也包括鸟类)的初次 散布是小果野芭蕉种子逃避捕食的关键。     

濒危植物金花茶果实、种子形态分化

对濒危植物金花茶5个天然居群和1个人工居群的果实、种子形态进行了研究.结果表明:6个金花茶居群按果实、种子大小进行排序为:广西植物所(GXIB)＞那子山中海拔2(NZSH2)＞大王江(DWJ)＞庚毛山(GMSH)＞那子山高海拔3(NZSH3)＞那子山低海拔1(NZSHI);表型性状在居群内和居群间均存在一定程度的变异,不同形态性状在居群间变异系数的平均值从0.429(种子质量/果,SWPF)到0.069(果实整体形态,FT/FD),果实整体形态最为稳定,各居群形态性状变异系数的平均值从0.287(NZSH3)到0.155(GXIB)不等;在调查的15个性状中,果实直径、果实质量等3个性状在居群间的差异达到显著水平(P＜0.05),种长、种宽等7个性状在居群间的差异达极显著水平(P＜0.01),多数居群已产生较明显的形态分化;聚类分析结果表明,在居群水平上,形态分化并不与居群间的地理距离远近相关联.影响果实、种子表型性状变异的主导因子为海拔高度、土壤有机质、土壤含水量和乔木层透光率.     

THE INFLUENCE OF THE MATING SYSTEM ON SEED SIZE VARIATION IN CRINUM ERUBESCENS (AMARYLLIDACEAE)

We present evidence that extreme seed size variation in fruits of Crinum erubescens (range: 0.1 to 66.5 g per seed) occurs when mating pairs are inbred, either from selfing or biparental inbreeding. Several relatively uniform seeds of intermediate size are produced when pollen from several pollen donors is applied simultaneously to a flower. Selfed fruits and some fruits pollinated with a single pollen donor produce both large and small seeds, although selfed fruits produce fewer seeds than outcrossed fruit. These results are contrary to the hypothesis that variation in seed size is attributable to either pollen competition or differential allocation of maternal resource to seeds of different genotypes.     

Constraints on plant signals and rewards to multiple mutualists?

Many plants invest substantial resources in signaling to and rewarding two kinds of ‘interguild’ mutualists, pollinators and seed dispersers. The signals and rewards are expressed via traits of flowers and fruits. Pollinators and seed dispersers could act in synergistic or antagonistic ways to influence selection on these traits. Here, we address the issue of whether plant species might be constrained in signaling to and rewarding multiple mutualists that provide different types of benefits to plants. Specifically, does investment in one type of mutualist limit investment in another? We examined the correlation between flower size and fruit size for 472 plant species spanning three regional floras. Our analyses made the assumption that structure size is related to plant investment in signals and/or rewards. We expect that a constraint due to interguild mutualisms would be evidenced by a negative correlation between flower and fruit size. Instead, we found significantly positive relationships between flower size and fruit size in all three regional floras. These relationships remained robust after correcting for plant evolutionary history using phylogenetically independent contrasts. These patterns may reflect synergies in selection by pollinators and seed dispersers, genetically-based or resource-based constraints on investment in reproductive tissues, and/or an underlying trade-off in structure size versus number.     

RE-EVALUATING THE SIGNIFICANCE OF CORRELATIONS BETWEEN SEED NUMBER AND SIZE: EVIDENCE FROM A NATURAL POPULATION OF THE LILY,CLINTONIA BOREALIS

The basis for the negative correlation between seed number and seed size was experimentally investigated in a natural population of Clintonia borealis. Clones of this species vary significantly in estimated self-compatibility (ratio of seed set with selfing to that with outcrossing) and this appears to affect the number and size of seeds set in individual flowers of each. Clones estimated to be largely self-compatible set more seeds per flower than incompatible ones under natural pollination. However, naturally pollinated flowers of self-compatible clones set smaller seeds than those of incompatible clones, and the significance of the negative relationship between seed number and size in individual flowers was removed by holding variation due to compatibility constant. Supplementing resources per flower (by reducing the number of fruits competing for resources per stem) significantly increased total seed mass but had no effect on the negative relationship between seed number per flower and seed size. In contrast, supplementing cross pollination did not significantly influence total seed mass per flower but changed the relationship between seed number and size to positive, regardless of resource level. In other words, with plentiful cross pollination maternal genets capable of setting more seeds per flower also produced heavier ones. Thus, evidence is provided that the balance between seed number and seed size in this population is regulated by the interaction of maternal self-compatibility with natural pollination.     

The effect of fruit age on seed germinability of a heterocarpic species, Atriplex sagittata

Atriplex sagittata is an annual heterocarpic plant that produces three different fruit types (termed A, B, and C). To examine the consequence of heterocarpy on germinability patterns over long time periods, we compared seed germinability of different fruit types that had been stored for up to 8 years. While germinability of non-dormant type C fruits in distilled water was high (up to 100 %) in the first 2 years, it rapidly decreased over time. Dormant fruit types A and B showed increased germinability up to 7 years, though loss of germinability was lower for type B than for type A fruits. Eight-year-old fruits of all types had significantly lower germinability than younger fruits, probably due to loss of viability. Heterocarpy, therefore, ensures that emergence rates for seedlings of A. sagittata will be maintained over relatively long periods, even in years of strong disturbance when all adult plants may be destroyed. The experiment further showed that germinability of all fruit types in high concentrations of salt, as compared with water treatment, changed over the course of 8 years. Whilst dormant types (A and B) of A. sagittata show increased germinability with age of the seed in water treatment, they significantly lose germinability over time with salinity treatment. Type C fruit was not influenced by salt in the first year, but germinability rapidly decreased with time. It follows that the species is able to germinate under high salt concentration in the first year, but this advantage gradually disappears.     

海拔对全缘叶绿绒蒿植株性状和花特征的表型选择分析

为了研究海拔差异对植株性状、花特征表型选择的影响,以青藏高原高寒草甸的全缘叶绿绒蒿（Meconopsis integrifolia）为研究材料,于盛花期内,测定不同海拔（4 452、4 081和3 681 m）种群中个体植株性状、花特征、单果结实数并进行统计分析,采用线性回归模型估计不同海拔种群间植株性状、花特征所受的表型选择（选择差与选择梯度）。结果表明：（1）随着海拔升高,全缘叶绿绒蒿植株性状、花特征及单果结实数显著降低,海拔越高的种群中株高越矮、叶面积越小、花数越少、花越小、单果结实数越低。（2）不同海拔种群中各性状的表型选择存在差异,较低海拔（3 681 m）种群中花数、花大小具有显著的选择差和选择梯度,表现为花越多、花越大的个体雌性适合度越高;海拔较高（4 081 m）的种群中株高、叶面积及花数更容易受到选择,表现为植株越高、叶面积越大、花越多的个体雌性适合度越高;海拔最高（4 452 m）的种群中叶面积与花数的选择梯度接近显著。（3）植物性状分化伴随着海拔的变化而呈现出差异,较低海拔种群中花特征容易受到选择,而较高海拔种群中可能由于传粉者稀少、资源限制等因素使得株高、叶面积更容易受到选择。     

TEMPORAL VARIATION OF FLOWER AND FRUIT SIZE IN RELATION TO SEED YIELD IN CELANDINE POPPY (CHELIDONIUM MAJUS; PAPAVERACEAE)

Ecological and evolutionary studies typically consider variation in single reproductive characters in isolation, without considering how they might be correlated with other reproductive and vegetative characters. In our study, we examined temporal patterns of variation and correlation in flower diameter and fruit length during a reproductive phase in two Massachusetts populations of the herb, Chelidonium majus. We also examined the relationships of such variation to measurements of seed yield components (mean seed weight and number per fruit) and aspects of plant vegetative size. Most of the variation in the sizes of reproductive characters occurred within individual plants, instead of among plants or between populations. Flower and fruit sizes as well as seed number per fruit declined significantly during the season in both populations. Only mean seed size per fruit was relatively stable for individual plants in both populations. Conserving resources by a gradual reduction in the size of reproductive characters over the season may be a strategy for maternal plants to continue seed production. The strong, persistent patterns of correlation between certain characters, such as flower and fruit size, in spite of extensive phenotypic plasticity, was interpreted as indirect evidence for developmental correlation. Furthermore, vegetatively larger plants produced not only more flowers and fruits, but also consistently larger flowers and fruits. The results emphasize that variation in fitness characters, such as seed size and number, should not be viewed in isolation from vegetative characters, flower, and fruit sizes in ecological and evolutionary studies, if the goal is to understand the mechanisms of natural selection in wild populations.     

罗汉果主要性状遗传效应研究

罗汉果近交后代发生明显衰退,花和果变小甚至畸形,种子活力降低,品种间衰退速度不同;杂交F_1后代果实形状、大小、颜色、总苷含量、甜苷Ⅴ含量和雌花柱头生长方式产生严重分离变异,其中果实大小、总苷含量、甜苷Ⅴ含量表现出明显杂种优势;雄性败育系的花粉败育是由遗传决定的,其败育性可通过杂交传递给雌性系产生无籽果实;F17芽变枝条所得雌雄同花两性突变属于遗传变异。     

The role of fungal pathogens in flower size and seed mass variation in three species of Hydrophyllum (Hydrophyllaceae)

Identifying ecological factors that affect seed number and seed size is key to understanding the persistence of large seed mass variation in some plant species. Pathogens may increase seed mass variation by increasing resource demand over the growing season such that late fruits experience higher resource competition than early fruits. We tested whether Fusarium sp. and Rhizoctonia sp., soil fungi that cause wilt, contributed to seasonal decline in flower size, seed number, or seed mass in Hydrophyllum appendiculatum and H. canadense. A third species not infected by these soil fungi, H. virginianum, was studied to determine how seasonal decline in floral traits and seed mass variation varies within this genus. Flower size declined seasonally for all species, but was greatest for H. appendiculatum, a monocarpic biennial with indeterminate inflorescences. Seed number decreased between first and last inflorescences in H. appendiculatum, but not in H. canadense or H. virginianum, perennials with determinate inflorescences. Seed mass varied most in H. appendiculatum and H. canadense (4-20-fold in 50% of individuals) and least in H. virginianum (4-8-fold in >30% of individuals). Fungal infection increased seed mass variation among diseased plants in H. canadense and H. appendiculatum. However, within plants fungal infection only increased seasonal decline in flower size, seed number, and seed mass in H. appendiculatum when flowers received supplemental pollination.     

Phenological variation in fruit characteristics in vertebrate-dispersed plants

Summary We investigated inter-specific variation in fruit characteristics — fruit size, seed number per fruit, seed weight, nutritional content, fruit persistence, and fruit synchronization — in relation to flowering and fruiting phenology in 34 species of fleshy fruited plants. Except for aspects of fruit synchrony and persistence, the results in general were inconsistent with previous suggestions about adaptive variation in phenologically related fruit traits. The main results were as follows: (1) Late flowering, late fruiting, lengthy development time from flower to fruit, and highly persistent fruits constitute a complex of correlated characteristics among the species. (2) Synchronization of fruiting within individuals increased from early ripening fruits to late ripening fruits. Fruiting synchrony was more pronounced in species with a small crop size than in species with a large fruit crop, whereas synchrony was not significantly related to flowering synchronization, nor to life form. (3) Nitrogen and carbohydrate content of fruit pulp did not vary in relation to phenology, whereas lipid content decreased from early to late ripening fruits. (4) No seasonal trends were found for variation in seed size or seed number per fruit. (5) Interactions with flowering phenology and developmental constraints are important in phenological fruiting patterns. Temporal variation in start of fruiting was partly (36%) explained by variation in flowering time. Seed weight variation explained 17% of variation in development time from flower to fruit. (6) Despite constraints from flowering and seed development, some adaptive adjustment in fruiting phenology is likely to be allowed for among the investigated species. Such an adaptive variation in fruiting phenology was suggested by intra-generic comparisons of Prunus and Vaccinium species.     

The role of pollination level on the reproduction of females and hermaphrodites in the gynodioecious plant Gypsophila repens (Caryophyllaceae)

In gynodioecious plant species, females are expected to have more resources available for maturing seeds because pistillate flowers are smaller, do not produce pollen, and are thus less costly that perfect flowers. The potential female advantage arising from more abundant resources is, however, likely to vary depending on whether seed production is limited by resource or pollen availability. Here we experimentally investigated the influence of pollen and resource limitation on female advantage in a gynodioecious species using two levels of pollination. Total seed production of females was always greater than that of hermaphrodites: females produced more flowers and more fruits that contained similar numbers of seeds of similar mass. Under low pollination, female and hermaphrodite plants allocated resources to increased flower production rather than to increased seed size or quality. We did not detect any influence of pollen or resource limitation on female advantage, which remained similar under low (= abundant resources) and full pollination. Outcrossed fruits performed better than selfed fruits when the same plant received both selfed and outcrossed pollen on different flowers. These differences were not greater under high pollination, possibly because resources available for each fruit did not differ between our pollen intensity treatments.