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Mean ( §SE) values of overall fruit set, follicle set per carpel , seed/ovule ratio in follicles and total seed/ovule ratio following autonomous self-pollination (SS), manual self-pollination (HS) and outcross-pollination (HC) in 2003 (open squares) and 2004 (closed squares) at Le Coulet. Treatments with diVerent code letters are signiWcantly diVerent from one another after Dunn's post hoc means comparisons
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Although several factors can limit female fertility in perennial plants, rarely have they been jointly studied in a single species over several years. In this study we experimentally manipulate seed production and simultaneously analyse the potential contribution of pollen limitation, costs of reproduction and plant size to variation in seed output...
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... Paeonia oYcinalis selWng is possible but yields few seeds relative to outcrossing, probably as a result of incomplete self-incompatibility (Fig. 1). In 2003, folli- cle set showed signiWcant variation among treatments: both overall follicle set (H = 25.52, P < 0.001) and folli- cle set per carpel (H = 15.89, P < 0.001) showed signiW- cant diVerences among treatments, with signiWcantly lower values after autonomous self-pollination than on outcrossing, and intermediate values on ...
Citations
... The seeds mature slowly, ripen in late summer, and disperse in autumn [39]. The spatial grouping of seedlings near maternal plants indicates that their dispersal is spatially limited, as confirmed in an investigation conducted in France [40]. The spatial aggregation of wild-growing seedlings of P. officinalis ssp. ...
... The spatial aggregation of wild-growing seedlings of P. officinalis ssp. macrocarpa, their significantly greater abundance down the slope of flowering plants, and a small number of seedlings observed at distances > 1.5 m from flowering individuals all pointed to the conclusion that the species is primarily barochorous [40]. The data also suggest that long-distance dispersal in P. officinalis is extremely rare and that poor seed dispersal may limit colonization of the species at favorable sites [40]. ...
... macrocarpa, their significantly greater abundance down the slope of flowering plants, and a small number of seedlings observed at distances > 1.5 m from flowering individuals all pointed to the conclusion that the species is primarily barochorous [40]. The data also suggest that long-distance dispersal in P. officinalis is extremely rare and that poor seed dispersal may limit colonization of the species at favorable sites [40]. Herbaceous peonies are generally considered self-fertile, meaning that, when isolated, their flowers self-pollinate, and their seeds produce offspring that are a genetic match to the parent plant (for the appearance of herbaceous peony flowers, see the Figure S1 in the supplementary material). ...
Even though peonies are highly valued as ornamental, medicinal, and edible species and
are also considered to be long-lived and relatively disease and pest-resistant, they are becoming rare or endangered in their natural habitats. This could be primarily associated with climate change and unsustainable wild collecting practices. So far, in situ conservation efforts have received little attention. In addition, very little is known about the cultivation of herbaceous peonies, particularly their propagation from seeds. What is known is that their seeds possess double dormancy, often accompanied by a low germination rate, which, together, make the cultivation of herbaceous peonies more difficult. Based on a comprehensive analysis of relevant literature, this paper summarizes, analyzes, and discusses all available studies on the seed traits of herbaceous peonies associated with the effect of seed harvest time on dormancy and seed germination, with a strong focus on dormancy breaking procedures. Improving our understanding of dormancy release modalities (impacts of temperature, moisture, light, hormones, various pre-treatments, etc.) will aid the establishment and management of in situ and ex-situ collections of valuable species of herbaceous peonies and enable further studies for their successful propagation, breeding, and cultivation.
... For example, in groups growing in wetter and cool conditions like CC and in part also SM, seeds may be more prone to damages by the lily beetle (Lilioceris lilii Scopoli, 1763) that prefers shaded, cool and moist areas in mountain habitats (Majka and LeSage 2008). Moreover, the generally moderate seed set may be conditioned by the life-history strategy of L. pomponium; like other long-lived herbaceous perennials, the species may have a strategy of annually limited but inter-annually constant seed production, in which sub-maximal seed production is a part of a size-dependent strategy that maximises lifetime seed production, without compromising adult survival (García and Zamora 2003;Andrieu et al. 2007). ...
Geographical limits of species’ distributions are assumed to be coincident with ecological margins, although this assumption might not always be true. Indeed, harsh environments such as Alpine and Mediterranean ecosystems may favour high phenotypic variability among populations, especially those in peripheral sites. Floral traits are often found to be less variable and less affected by environmental heterogeneity than vegetative traits because variation in the former may have negative effects on fitness. For this reason, it is important to quantify variation in floral traits and plant fecundity in study range limits. The objective of the study is to examine phenotypic variation and differences in reproduction in endemic Lilium pomponium in the Maritime and Ligurian Alps in relation to environmental variation across its distribution range. In this species, marginal climatic populations occur both in the peripheral and central geographical locations of the distribution range; hence, geographical and ecological gradients are not concordant. Floral trait variation is related to local environmental conditions with an array of interactions among resource availability, potential pollen limitation and population size that are differentially related to floral traits. Contrary to the general expectation, all central and peripheral populations had similar, moderate seed production with each group limited by different factors acting on different stages of the life-history strategy. Our results are in line with the idea that general expectations are confirmed only when its assumptions are met and that the differences in pollination environment along an environmental gradient may not be the main determinant of the distribution limit.
... Female parents were emasculated beforehand and then pollinated artificially by dipping the dried pollen into stigmas. Then, pollinated flowers were covered by waxed paper bags [84][85][86] . Hybrid seeds were collected in mid-July after fruits became red, and they were immediately sown in seedbeds or pots. ...
Enlarging the planting area of economic plants, such as the “Southward Planting of Herbaceous Peony” (Paeonia lactiflora. Pall), is significant for improving people’s lives. Peony is globally known as an ornamental because of gorgeous flowers and is mainly cultivated in the temperate regions with relatively cool and dry climates in the Northern Hemisphere. Promoting the landscape application of peony to the lower latitude regions is difficult because of the hot-humid climate. In this study, 29 northern peony cultivars and a unique Chinese southern peony, ‘Hang Baishao’, were introduced to Hangzhou, located in the central subtropics. Annual growth cycles, resistances and dormancy durations were measured, and crossbreeding between the southern and northern peonies was performed for six years, from 2012 to 2017. Based on data collected from the long-running quantitative observation (LQO), a multi-criteria decision making (MCDM) system was established to evaluate the comprehensive planting performance of these 30 cultivars in the central subtropics. ‘Qihua Lushuang’, ‘Hang Baishao’ and ‘Meiju’ were highly recommended, while ‘Zhuguang’ and ‘Qiaoling’ were scarcely recommended for the Hangzhou landscape. This study highlights the dependability and comprehensiveness of integrating the LQO and MCDM approaches for evaluating the introduction performance of ornamental plants.
... Two northern cultivars were emasculated and then pollinated artificially by dipping the stigma into dried pollen or by using a cotton swab to place the pollen onto the stigma. The pollinated whole flowers were immediately covered with waxed paper bags and labeled [23,33,34]. Hybrid seeds were collected in mid-July when they were fully ripe (follicles became red) and immediately sown in a seedbed or in one-gallon pots (five seeds per pot, filled with 7 parts garden soil:2 parts peat:1 part perlite by volume). ...
Expanding the southern range of herbaceous peony (Paeonia lactiflora Pall.) is a meaningful and worthwhile horticultural endeavor in the Northern Hemisphere. However, high temperatures in winter seriously hinder the bud dormancy release and flowering of peony in the more southern areas of subtropical and tropical regions. Resource introduction and hybridization can contribute to creating new cultivars with high adaptability in a warmer winter climate. In this study, three representative cultivars of P. lactiflora were screened for flowering capabilities and their annual growth cycles were observed to provide information needed for hybridization. Among these three cultivars, 'Hang Baishao' is the best adapted cultivar for southern growing regions and is unique in its ability to thrive in southern areas of N 30°00'. Pollen viability of 'Hang Baishao' was 55.60% based on five measuring methods, which makes it an excellent male parent in hybridization. Hybrid plants among these three cultivars grew well, but all of their flower buds aborted. Additionally, the ability of three growth regulators that advance the flowering of 'Hang Baishao' to promote an indoor cultivation strategy for improving peony application as a potted or cut-flower plant was tested. 5-azacytidine could impact the growth of 'Hang Baishao' and induce dwarfism and small flowers but not advance the flowering time. Gibberellin A3 promoted the sprouting and growth significantly, but all plants eventually withered. Chilling at 0-4°C for four weeks and irrigation with 300 mg/L humic acid was the optimal combination used to hasten flowering and ensure flowering quality simultaneously. These results can lay the foundation for future studies on the chilling requirement trait, bud dormancy release and key functional gene exploration of herbaceous peony. Additionally, this study can also provide guidance for expanding the range of economically important plants with the winter dormancy trait to the low-latitude regions.
... Seed production of many species declines towards their northern range limit (Jump and Woodward, 2003), which may be the consequence of either physiological limitations on seed development (Pigott and Huntley, 1981) or a general reduction in plant growth. While smaller plants produce fewer seeds in some species (Andrieu et al., 2007;De Frenne et al., 2011), seed development itself may be limited by low temperature (Dorken and Eckert, 2001;Pigott, 1992), shortened growing season (Ladinig and Wagner, 2007) or photoperiodicity (Griffith and Watson, 2006). In our experiment, the colder Buxton climate severely reduced seed set in B. erecta, and the large proportion of non-viable seeds in the outcrossing treatment suggests that climate also affected seed ripening. ...
Calcareous grasslands are considered as hotspots of plant and invertebrate diversity but little is known about the potential of their main dominants to migrate as a response to climate change. Although it is generally acknowledged that climate warming will allow plant species to expand their ranges northwards and upwards, not all restrictions on dispersal may be climate dependent. We assessed dispersal limitations in Bromopsis erecta and Brachypodium pinnatum, two dominant grasses of calcareous grasslands in Central Europe and southern England. Both species are known to spread rapidly in the absence of disturbance and are thus expected to have major impacts on species diversity and ecosystem functioning of northern calcareous grasslands. Pollination experiments showed that seed production in B. erecta, and we suspect also in B. pinnatum, at the northern range margin is climatically limited, which suggests that the species will be able to produce seeds outside their current distribution under climate warming. Self-incompatibility, on the other hand, is likely to considerably slow northward migration, as isolated founder populations may be unable to set seed, especially since calcareous grasslands are sparse and fragmented. Our results have important practical implications for managers attempting to slow the spread of these potential dominants, and also for those trying to encourage the northward migration of rare self-incompatible species in response to climate change.
... When experiments are performed in multiple sites and/or years, the statistical significance of pollen limitation commonly varies among sites and/or years, indicating that the pollination environment is not constant (Burd 1994). This is particularly apparent from studies of plant species in the Mediterranean region ( Andrieu et al. 2007;Baker et al. 2000;Berjano et al. 2011), where the irregularity of climatic conditions prior to, and during, the flowering period can affect fruit set (Thompson 2005). In our study, we also detected variation in the expression of pollen limitation, with some populations and years showing no evident pollen limitation (e.g. ...
In self-incompatible clonal plants, the spread of individual plants can exacerbate mate limitation to the point that it becomes a serious constraint on long-term population persistence, especially in small, isolated populations. In such species, it may be necessary to introduce new genetic material from other populations to restore seed production, a strategy termed “genetic rescue”. In this study we assess the potential pertinence of such genetic rescue in the clonal perennial plant Convolvulus lineatus L.,
whose populations are often highly reduced in spatial extent and are currently being fragmented by land development projects in Mediterranean France. To do so, we quantify fruit production in a range of populations of different size over four years and perform a series of hand-pollination experiments in natural populations to assess whether fruit set is limited by mate availability. We found that C. lineatus is a self-incompatible species that shows extremely low values of fruit set in natural populations and that a principal cause of this low fruit set is a lack of compatible pollen. This may be primarily due to clonal spread that causes individual populations to be comprised of patches containing one or very few
incompatibility types. In small populations fragmented by human activities and which show an absence of fruit production, we thus argue that genetic rescue represents a promising conservation management strategy to avoid inevitable long-term future population decline. We discuss how best to introduce new genetic material into the study populations.
... Because of their enduring popularity as ornamental and medicinal plants, continual wild collection and habitat loss threaten the existence of endemic populations (Page 2005). Concerns for the conservation of these Paeonia species' remnant populations are prompting research that leads to a greater understanding of their reproductive biology including studies on pollination and breeding systems (Luo et al. 1998;Jing & Zheng 1999;Zhou et al. 1999;Sánchez-Lafuente et al. 1999;Sánchez-Lafuente 2002;Andrieu et al. 2007). J Poll Ecol 11(2) brownii is primarily cross-pollinated, pollen sterility may well be a factor in the quantity and quality of the vector pollen load and the amount of fertile pollen deposited on the receptive stigma ). ...
... Although during the male phase the flowers produce abundant pollen, unlike the Eurasian peonies they do not attract the assemblage of pollen-foraging bee and beetle visitors, as do, for example, the flowers of P. broteroi, P. jishanensis, P. suffruticosis and P. officinalis (Luo et al.1998;Sánchez-Lafuente et al. 1999;Zhou et al. 1999;Andrieu et al. 2007) or even of its closest congener P. californica (Schlising 1976). ...
... Although highly variable over several weeks of sampling, the rate of fertile pollen transferred to the carpels naturally through insect (and autonomous) pollination was generally low (Fig. 2) and may help to explain the low seed set. The number of pollen tubes reaching the style under the hand pollinations was significantly higher than by natural pollination which is in contrast to other Paeonia species, where supplementary pollination did not necessarily increase seed set (Luo et al. 1998;Sánchez-Lafuente et al. 1999;Zhou et al. 1999;Andrieu et al. 2007). Meiotic dysfunction as well as late-acting incompatibility may be expressed when the gametes form a zygote which would account for aborted ovules (Camp & Hubbard 1963). ...
Brown’s peony, Paeonia brownii (Paeoniaceae), is one of only two peony species native to the Western Hemisphere, yet its pollination ecology and breeding system have never been documented. Using flowering individuals of an endemic colony in the Blue Mountains of Oregon, U.S., we investigated the peony’s pollination system and floral function. We also examined pollen/carpel interactions through experimental pollinations aided by fluorescence microscopy. Paeonia brownii appears to be self compatible and mostly protogynous with floral traits of a generalist pollination system. The flowers appear to attract insects by producing abundant floral nectar secreted from lobes of a perigynous disc throughout their 9-15-days of anthesis. The most common pollen vectors were wasp queens (Vespidae), the large flower fly Criorhina caudata (Syrphidae), and females of Lasioglossum spp. (Halictidae), all of which foraged exclusively for nectar. Whether collected from foraging wasps and flies, anthers, or stigmas, about half the pollen grains appeared fertile. The number of ovules per carpel was about 19. Seed set (seeds/ovule) of naturally pollinated flowers was about 20% with about 4 viable seeds per follicle. The number of fertile pollen grains transferred to the stigma under natural conditions was highly variable but generally low, which may have contributed in part to the low rate of seed set. This study raises further questions about the role of pollen sterility, floral nectar and vespid wasps in shaping a pollinator system that is unusual in Paeonia.
... A higher investment in seeds may result in a lower investment in the storage of resources or underground growth. This can affect the probability of plant flowering and fructification for several consecutive years after high reproduction [21]. ...
... Multi-year experiments, best conducted until the end of the plants' life, can make it possible to find out if there is some recovery period after reproduction, identify the optimally efficient period of a study or determine whether there are any differences in cost incurrence among populations [16,20,21]. For instance, an 11-year study on the orchid Cypripedium acaule showed that for this species, at least a four-year experiment is needed to reveal reproductive costs in examined populations; further continuation of the study made it possible to demonstrate differentiation within populations and the ability of a single individual to recover after many years of annual fruit production [20]. ...
We tested a hypothesis based on life history theory that examines reproductive costs incurred by individuals in consecutive years of their life. A multi-year dataset of resource allocation to vegetative and reproductive structures was analysed in Carex secalina — a perennial, monoecious sedge, reproducing only sexually. In a four-year garden experiment, we assessed above-ground biomass at the end of each season and reproductive allocation expressed as the total length of male and female spikes. The study was aimed at determining how size and age of a plant relates to its reproduction, and how the rate of reproduction affects the year-toyear biomass change in Carex secalina. We observed that after each reproductive episode, individuals had significantly smaller sizes and produced a lower number of generative tillers. The total production of reproductive structures decreased significantly with age in all populations. Moreover, the decrease in plant biomass was greater when more reproductive structures were produced in a previous year, which indicates that the plants incur costs of reproduction in terms of above-ground biomass production.
... In the field, we observed whether seeds were damaged or destroyed just prior to follicle dehiscence by gently opening them. However, because in many cases a large part or the whole fruit was predated (e.g. when Roe Deer browsed flowers or young fruits) and the number of seeds per follicle is highly variable in P. officinalis (Andrieu et al., 2007b), it was not possible to exactly count or estimate the number of seeds destroyed. As a consequence, we considered an individual or a stem as predated when it showed at least one damaged seed. ...
... In another study, we showed that ripe seed predation was mainly due to rodents and was higher in woodland, even if remaining at a moderate level (Andrieu and Debussche, 2007). Although peony populations produce only a small annual seed crop (Andrieu et al., 2007b), demographic consequences of seed predation may thus be insignificant because, as in other longlived perennials (e.g. Charron and Gagnon, 1991;Ehrlen et al., 2005;Heppell et al., 2000), the asymptotic growth rate of the peony populations appears to be highly sensitive to survival of adults (elasticity for large vegetative and reproductive plants = 0.50-0.83 in open habitat, depending of the site), but weakly depending on the variation of fecundity parameters (elasticity for fecundity = 0.02-0.16 in open habitats, depending of the site) (Andrieu (2006)). ...
... First, the observed levels of foliage herbivory are too low to cause a significant impact on growth and mortality of the population; specific secondary compounds (Bézanger-Beauquesne et al., 1980) might explain these low levels. Second, the thick tuberized roots developed by Paeonia officinalis, from seedling stage onwards, may buffer the consequences of herbivory; this is consistent with the results of a previous study which showed that a high allocation of resources to seed production has no effect on future survival, growth and flowering in this species (Andrieu et al., 2007b). Third, herbivory has no short term impact and its effects on plant performance are only significant on a long time scale (Hanley and May, 2006). ...
In this study we quantified variability in foliage herbivory and pre-dispersal seed predation and its effects on plant performance and demography in populations of a rare and protected perennial herb, Paeonia officinalis. An individual-based survey was performed during four years in four populations, which contained plants in both open habitat and woodland. We detected marked spatial and temporal variation among and within populations in foliage herbivory (by insects) and pre-dispersal seed predation (by insects, rodents and Roe Deer). Foliage herbivory decreased with plant demographic stages in open habitats, from seedlings to reproductive individuals, but no significant trend was detected in woodland habitats. This may be due to different demographic origin of larger vegetative plants in this habitat. Depending on demographic stage, herbivory was higher in open habitats or not significantly different between habitats. This suggests differences in herbivore abundance in different habitats within sites. Pre-dispersal seed predation remained weak and did not depend on habitat. We did not detect any consequence of foliage herbivory on seedling mortality and individual growth in our study. Our results illustrate the need to investigate plant-herbivore interactions over several years in distinct populations in order to more accurately evaluate herbivore impact on plant population dynamics.
... In July, each dehiscent follicle exposes up to 20 black 7-9-mm-long ovoid seeds. Individuals can produce a small number of seeds on selfing, albeit significantly less than on outcrossing, and a 3-yr comparison of fertility on natural-and supplementarypollinated plants produced no evidence of pollen limitation in the study site (Andrieu et al. 2007). ...
... This is despite the highly variable number of ovules and anthers in P. officinalis flowers, which in other species is associated with gender variation at the flower level (Wright and Barrett 1999;Méndez and Traveset 2003). In the P. officinalis population we studied, smaller flowering plants in 2003 Andrieu et al. 2007). These results provide further evidence for a size-dependent threshold for reproduction (see also Harper 1977;Gross 1981;Hanzawa and Kalisz 1993;Méndez and Obeso 1993). ...
In this study, we quantify how reproduction and allocation to male and female functions vary in relation to plant size during two consecutive but contrasting reproductive seasons in the hermaphroditic perennial herb Paeonia officinalis. Small flowering individuals in 2003 did not flower in 2004; thus, flowering probability is related to size, with an emphasis on survival. In terms of absolute numbers of stamens and ovules, large plants allocated more resources to reproduction than did small plants by the production of additional flowering stems. In contrast, in terms of relative allocation, large plants allocated a similar proportion of resources to reproduction as did small plants. Significant size-dependent gender modification occurred only in the second year of the experiment, when larger plants were more female than small plants. Hand-pollinations performed to minimize external effects on seed set and a severe drought in 2003 may have contributed to sex allocation costs in small plants. Our results suggest that differential expression of between-year reproductive costs in relation to plant size may lead to size-dependent reproduction and be a key feature driving size-dependent gender modification in perennial plants.
