Flowering Phenology Research Articles

Restoration Affects Sexual Reproductive Capacity in a Salt Marsh

Plant sexual reproduction is an important driver of plant community maintenance, dispersal, and recovery from disturbance. Despite this, sexual reproduction in habitats dominated by clonally spreading perennial species, such as salt marshes, is often ignored. Communities dominated by long-lived perennial species can still depend on sexual reproduction for recolonizing large disturbed patches or for establishing in new patches, such as restored sites. We investigated the influence of restoration and elevation on flowering phenology, potential seed and seedling production, and insect flower damage of the dominant salt marsh grass, Spartina alterniflora, in reference and restored marshes in southeastern Louisiana, USA. We additionally tested whether elevation gradients or soil parameters could explain differences in sexual reproduction between sites. We demonstrate that sediment-slurry amendment restoration may not affect flowering phenology or insect flower damage at ecologically relevant levels, but that restoration activity increases sexual reproductive output at the patch scale. Restoration activity affected reproductive dynamics more often than changes in elevation alone. Restoration of subsiding salt marsh habitat by altering the soil environment may increase sexual reproductive capacity of these wetlands.

Floral resource availability of Dicliptera squarrosa (Acanthaceae) and its dependence on hummingbirds for fruit formation in a forest fragment of Central Brazil

Background and aims – Hummingbirds are dependent and specialized on nectar-feeding, and many plants depend upon them for pollination. However, the degree of plant-pollinator interdependence varies greatly among species; thus, information on plant mating systems and availability of resources may help to clarify the dependence of interacting organisms. The goals of this study were to (1) quantify the floral resource available during the flowering of Dicliptera squarrosa Nees for comparison with other co-flowering ornithophilous species, and to (2) determine the importance of floral visitors for the reproductive success of this plant.Methods – Data collection was performed in a forest fragment within the urban perimeter of Catalão, Goiás, from September 2012 to August 2013. We investigated the flowering phenology, floral biology, nectar characteristics, flower visitors and mating systems of D. squarrosa. Additionally, we evaluated the amount of floral resource offered (number of flowers and energy in joules) by co-flowering ornithophilous species within an area of 6000 m2 for comparison with D. squarrosa.Key results – Dicliptera squarrosa presents flowers adapted to pollination by hummingbirds, which act as the sole pollinator group for flowers of this species. Flowering occurs from June to September and is synchronous with five other co-flowering species. During the months between July and September, D. squarrosa is the main food source for hummingbirds in the area, offering more floral resources than all of the other five ornithophilous species together. Plants of this species are self-compatible, but they depend on hummingbirds to transfer pollen; levels of autonomous autogamy were low.Conclusions – We suggest that D. squarrosa is an important species for maintaining hummingbirds in the forest fragment due to its high production of nectar resources. In addition, data on floral biology, flower visitors, and mating systems showed the importance of hummingbirds for reproduction of D. squarrosa, suggesting a mutualistic interaction between plant and hummingbirds.

Seasonal timing in honey bee colonies: phenology shifts affect honey stores and varroa infestation levels.

Increasingly frequent warm periods during winter, which are associated with climate change, may cause mismatches between the colony phenology of the western honey bee, Apis mellifera L., and their floral resources. Warmer winter periods can also affect colony brood rearing activity and consequently the reproduction of the invasive brood parasite Varroa destructor Anderson and Trueman. Until now little is known about the effects of climate change on biotic interactions in such a multitrophic system comprising flowering plants, a pollinator, and its parasite. We performed a reciprocal translocation experiment with honey bee colonies to simulate climate change-induced phenology shifts. Honey bee brood phenology was highly sensitive to environmental conditions in late winter. Colonies in which phenology was experimentally delayed had smaller worker populations in early spring and reduced amounts of stored honey during the following months. During summer, the varroa load in colonies with non-shifted phenology was three times higher than in colonies with delayed phenology. High varroa loads during summer were negatively correlated with worker population growth. Despite a remarkable resilience of colony development to phenology shifts, our results show that mismatches between the phenology of honey bee colonies and flowering plants can affect the build-up of resource stores. Further, an advanced onset of brood rearing activity after hibernation can reinforce the negative impact of the brood parasite V. destructor. We conclude that trade-offs between synchronisation with earlier flower phenology and prolonged brood phases with build-up of varroa populations might constrain the honey bees' capability to adapt to climate warming.

Morphological and physiological features of sweet cherry floral organ affecting the potential fruit crop in relation to the rootstock

The research concerning the evaluation of floral organ attributes affecting the potential fruit crop in relation to the rootstock was performed on sweet cherries cultivars – ‘Burlat’, ‘Kordia’ and ‘Regina’. Potential fruit crop was estimated based on the following parameters: number of flowers, percentage of fruit-set and fruit mass. Moreover, morphological (flower biometrics, number of pollen in anther) and physiological features (flower phenology, viability and germination of pollen, sensitivity of flowers to winter frost damage) were assessed. Type of rootstock affected even several-day differences in the beginning of flowering period in particular cultivars. In the research of sweet cherry flowering, the stigma availability coefficient for pollinating insects (based on the sweet cherry flower biometry) was calculated for the first time. The coefficient indicates that flower’s architecture and the optimal anther position relative to the stigma promotes the most effective collection and transfer of pollen on the insect's body. Sweet cherry flowers differed according to pollen efficiency depending on the type of cultivar and rootstock. ‘Kordia’ cultivar was characterized by a small number of pollen grains and its poor viability. Gisela 5 rootstock was highly rated in terms of potential crop, due to the large number of flowers on spur and high percentage of fruit setting. ‘Regina’ cultivar had higher winter frost resistance compared to 'Kordia'.

Are reproductive traits of dominant species associated with specific resource allocation strategies during forest succession in southern China?

Plant reproductive traits have often evolved to optimize plant fitness under different environmental conditions, and their relationships with vegetative functional traits reflect more general plant reproduction and resource allocation strategies. How those relationships change during succession remains unclear. Here, we investigated the relationships between 8 reproductive traits and 18 functional traits of leaves, stems and whole plants during succession of a subtropical forest. We found that most leaf traits of dominant species were associated with seed/fruit dispersal mode and pollination pattern in the early successional forest, while with flower and fruit phenology in the middle and late successional forests. Plant reproduction traits were associated with specific resource utilization strategies during succession, i.e., plants with acquisitive resource utilization strategies tended to have long-distance fruit dispersal in the early succession, while with conservative resource utilization strategies tended to have early flowering (fruiting) or a long flowering (fruiting) period in the late succession. Our results indicate that acquisitive species may invest less energy and resources on reproduction in early succession, and that the conservative species may invest more energy and resources on reproduction in late succession.

Trails‐as‐transects: phenology monitoring across heterogeneous microclimates in Acadia National Park, Maine

AbstractClimate‐driven shifts in phenology, which are being observed worldwide, affect ecosystem services, trophic interactions, and community composition, presenting challenges to managers in protected areas. Resource management benefits from local, species‐specific phenology information. However, phenology monitoring programs in heterogeneous landscapes typically require serendipitous historical records or many years of contemporary data before trends in phenological responses to changes in climate can be analyzed. Here, we used a trails‐as‐transects approach to rapidly accumulate monitoring data across environmental gradients on three mountains in Acadia National Park, Maine, USA, and compared our results to phenological changes observed in Concord, Massachusetts, USA. In four years of intensive monitoring of transects on three mountains, we found large variability in spring temperatures across the mountains, but consistent patterns of advancing flower and leaf phenology in warmer microclimates. Reduced sampling intensity would have yielded similar results, but a shorter duration would not have revealed these patterns. The plants in Acadia responded to warming spring temperatures by shifting leaf and flower phenology in the same direction (earlier), but at a reduced rate (as measured in d/°C), in comparison with plants in southern New England (e.g., Concord, Massachusetts, USA). Our approach takes advantage of topographical complexity and associated microclimate gradients to substitute for long time series, allowing for rapid assessment of phenological response to climate. Other climate gradients (e.g., urban‐to‐rural, latitudinal, or coastal‐to‐inland) could work similarly. This intensive monitoring over a short time period quickly builds a robust dataset and can inform management decisions regarding future monitoring strategies, including sampling designs for citizen science‐based phenology monitoring programs.

Temperature controls phenology in continuously flowering Protea species of subtropical Africa.

Premise of the StudyHerbarium specimens are increasingly used as records of plant flowering phenology. However, most herbarium‐based studies on plant phenology focus on taxa from temperate regions. Here, we explore flowering phenologic responses to climate in the subtropical plant genus Protea (Proteaceae), an iconic group of plants that flower year‐round and are endemic to subtropical Africa.MethodsWe present a novel, circular sliding window approach to investigate phenological patterns developed for species with year‐round flowering. We employ our method to evaluate the extent to which site‐to‐site and year‐to‐year variation in temperature and precipitation affect flowering dates using a database of 1727 herbarium records of 25 Protea species. We also explore phylogenetic conservatism in flowering phenology.ResultsWe show that herbarium data combined with our sliding window approach successfully captured independently reported flowering phenology patterns (r = 0.93). Both warmer sites and warmer years were associated with earlier flowering of 3–5 days/°C, whereas precipitation variation had no significant effect on flowering phenology. Although species vary widely in phenological responsiveness, responses are phylogenetically conserved, with closely related species tending to shift flowering similarly with increasing temperature.DiscussionOur results point to climate‐responsive phenology for this important plant genus and indicate that the subtropical, aseasonally flowering genus Protea has temperature‐driven flowering responses that are remarkably similar to those of better‐studied northern temperate plant species, suggesting a generality across biomes that has not been described elsewhere.

Hedychiumziroense (Zingiberaceae), a new species of ginger lily from Northeast India.

We describe Hedychiumziroensesp. nov. from Northeast India (NE India) which was discovered during one of our recent botanical explorations in Arunachal Pradesh. We provide detailed morphological comparison of this species with four other Hedychium species (H.griersonianum R.M.Sm., H.ellipticum Buch.-Ham. ex Sm., H.gomezianum Wall. and H.yunnanense Gagnep.), with which it shares some morphological similarities. The new species is characterised by a dense cylindrical spike, pubescent rachis, folded bracts, 2–3 flowers per cincinnus, deeply cleft labellum and a distinctive late monsoonal flowering phenology from August to September.

Comparing ‘Iriet’ and ‘Ettinger’ avocado cultivars as pollinators of ‘Hass’ using SNPs for paternal identification

Avocado (Persea americana M.) exhibits a two-type ‘synchronous dichogamy’ form of flowering that promotes outcrossing. In ‘type A,’ the flower opens in the female phase from morning till noon, then closes and re-opens on the afternoon of the following day in the male phase. In ‘type B,’ the flower opens in the female form on the afternoon of the first day, closes at the end of the day, and re-opens in the male form on the following morning. In both types, the female and male forms may overlap and self-fertilize. Planting an A type and B type cultivar adjacently to each other increases yield in most cases. ‘Hass’ (A type) is the most favorable avocado cultivar worldwide, however, the cultivar that serves as its pollinator varies between regions and countries. In Israel, for more than 30 years, the ‘Ettinger’ cultivar (B type, a seedling of ‘Fuerte’ selected in Israel) is its only pollinator, hence, adding another pollinator for ‘Hass’ should be beneficial. ‘Iriet’ (B type) is an Israeli-bred cultivar and its fruit has a ‘Hass’-like appearance (a marked change in color from green when not ripe to black at full ripe).For accurate comparison between ‘Iriet’ and ‘Ettinger’ as a pollinator of ‘Hass,’ an orchard with the two pollinators was planted and a SNP analysis was developed for the identification of the paternal parents of the ‘Hass’ fruits. In addition, the flowering phenology and honeybee visits were determined. The results suggest that ‘Iriet’ is a good pollinator for ‘Hass’ and could be added alongside ‘Ettinger’ as a pollen donor for ‘Hass’.

Floral Behaviour, Flowering Phenology and Fruit Production of Passion Fruit (Passiflora Species) in East Malaysia

Passiflora species generally known as passion fruit may well be the most fascinating plant of the tropics. This plant is known to be self-incompatible in its native environment and it affects the fruit production. Extend of passion fruit set is highly dependent on effective pollinators such as carpenter bees and honey bees. However, in East Malaysia, there was good fruit sets, although lesser number of pollinators visiting the farm or sometimes absence. It is important therefore, to study the reproduction mechanisms of Passiflora plants, because this factor reflect the quantity of the fruit produced. The present studies aim therefore to evaluate the floral behaviours, reproductive mechanism and fruit production of locally grown Passiflora species. Based on the observations, Passiflora species was classified as “steadystate species” that exhibit constant production of few flowers, each day lasting only one day. All species have the ability to adapt to the local condition where plants continuously grew and produced flowers and fruits all the year around. The flowering and fruiting were not synchronized and showed a marked phenological pattern with species. Good fruit yields were observed throughout the year which was attributed to Passiflora species ability for self-pollination, involving the movement of styles to lead the stigma faced the anthers during flower blooming. This is an important phenomenon in order to reduce the distance between the stigma and anther, aid for pollination and provided reproductive assurance to the species. As P. edulis growing in its native environment is reported to be self-incompatible and have become selfcompatible in the present study; showed that evolution of these features is an important factor for its adaptability and survivability, thus crucial to P. edulis propagation optimally in local conditions.

Determination of floral development stages in ‘Cabernet Sauvignon’ (Vitis viniferaL. cv.): highlighting the manifestation of stamens and pistil primordia with new intermediate stages linking the phenological stages

Despite relatively intensive work on the development of inflorescence primordia during grapevine growth in season one, some informational gaps are present in the flower and floral organ development in the season two. In addition, concurrents events of phenology and formation of flowers and floral parts has not been dealt with. With the aid of digital imaging, this research had three objectives; a) describe the developmental events that take place during and after bud break in the buds and in the individual flowers in terms of differentiation, b) match these events with phenological stages, and c) determine size-related growth of the floral organs. After careful dissecting and examination of the samples under microscopy, taken ever 5-10 days between March 20 and May 10 in 2016, the results indicated that highly esteemed works regarding the reproductive anatomy of grapevines needed some additional stages to fully describe events in the stamen and pistil primordia after the appearance of petal primordia. Five intermediate stages were added to the stages of “formation of flowers”. Differentiation of inflorescence and individual flowers occurred in the second season as the buds swelled in the spring. Stamens and pistil could be seen about 3 weeks later and completed their initial growth in another 3 weeks. Flower primordia was visible on April 1 and showed a more than 9-fold increase over the course of 5 to 6 weeks. flowers increased their width and their length more than 9- and 15-fold, respectively, between stage 8.1 (April 1) and 10.3 (May 10). At first, they were wider than they were longer, but at later stages they grew longitudinally. Reproductive organ primordia were visualized around the time of 2-4 leaves separated on the shoots. Signs of generative parts become apparent in late April. Anthers were the smallest in the flower. Filaments, on the other hand, elongated almost 7-fold in a period of 20 days. Gynoecium growth was the most impressive and total pistil length increased from 52.8 to 162 μm, ovary width from 40.4 to 99.8 μm, and stigma diameter from 9.96 to 44.9 μm in twenty days. By the time the pistil took its final shape, 6-8 leaves grew on the shoot during which inflorescence could also be seen.

Modeling the flowering sensitivity of five accessions of wild soybean (Glycine soja) to temperature and photoperiod, and its latitudinal cline.

The introgression from genetically modified soybean (Glycine max (L)) to wild soybean (Glycine soja Sieb. et Zucc.) could be threat the genetic diversity of wild soybean. Flowering synchrony is essential to the occurrence of outcrossing, but the flowering phenology of wild soybean is less well researched than that of cultivated soybean. We developed models to predict flowering initiation of wild soybean, based on the flowering initiation dates of wild soybean five accessions from different latitudes (31.4°N to 42.6°N) in growth chambers in which temperature and day length varied. Our proposed models predicted the flowering initiation date of wild soybean in the natural habitat well; the averaged difference from observed date in 5 areas was −1.8 days (−8 to +5). In the long day condition, there was a clear latitudinal cline of photoperiodic sensitivity throughout Japan. Accessions in southern part of Japan archipelago required higher temperature even under the short-day conditions and northern accessions were less-sensitive to long-day conditions. Our result showed the possibility of predicting the flowering initiation of wild soybean, corresponding to latitudes.

To pupate or not to pupate: a case study of an obligate pollination mutualism in Glochidion ferdinandi (Phyllanthaceae) and Epicephala colymbetella (Gracillariidae)

Obligate pollination mutualisms have recently been recorded in the Glochidion genus with Epicephala moth associates (leaf-flower and leaf-flower moths). There is limited literature on Australian Glochidion species and their pollinators. Glochidion ferdinandi occurs predominantly across the east coast of Queensland, Australia and has an obligate pollination association with Epicephala colymbetella. Early descriptions of G. ferdinandi describe the encapsulation of the adult moth within the fruit. In the present study, observations and fruit dissections were recorded to analyse the role of symbionts within this mutualism, pollinator life history and the flowering phenology of the host. Our study confirmed this rare behaviour in which E. colymbetella pupated within G. ferdinandi fruit in which adult moths were retained until fruit dehiscence. Fruit dissections identified two other species alongside E. colymbetella, a seed consuming Spilomelinae moth and parasitoid Bracon wasp. Although both moth species were found to reduce the number of surviving ovules in the fruit, E. colymbetella also provided a pollination benefit to G. ferdinandi. Furthermore, the life histories of E. colymbetella and phenology of G. ferdinandi were observed to be highly synchronous, with larvae developing concurrently with ovules after flower fertilisation. Retention of the adult moth in fruit has only previously been recorded in one other Epicephala (lanceolaria).

Overlapping flowering periods among Shorea species and high growth performance of hybrid seedlings promote hybridization and introgression in a tropical rainforest of Singapore

A considerable extent of interspecific hybridization among dominant canopy dipterocarp species was recently found in a tropical rain forest fragment in Singapore. However, information about the fertility of the hybrids and the growth of their successive hybrids remains limited. We studied the flowering phenology of four dipterocarp species in the genus Shorea (S. curtisii, S. leprosula, S. parvifolia, and S. macroptera) and two hybrids (S. curtisii × S. leprosula and S. leprosula × S. parvifolia) and studied the performances of seedlings reproduced from them. We observed that S. macroptera bloomed first, without overlap with congeneric species, followed by the other Shorea species and the two first filial (F1) hybrids. S. curtisii and S. leprosula, the species forming hybrids are most likely to succeed in this forest, completely overlapped with their hybrids. Fruits collected from the hybrids were viable, and these hybrid seedlings showed greater survival and a higher growth rate than those from pure species under greenhouse conditions. They included various cross types such as a backcross with each parent species. These results may imply that successive hybrids and introgression spontaneously occur among Shorea species. It may be important to consider the risk of hybridization for the management of tropical forests, particularly in degraded tropical rainforests where mechanisms of ecological isolation between closely related species might be altered.

Wild Bee Pollen Diets Reveal Patterns of Seasonal Foraging Resources for Honey Bees

Western honey bees (Apis mellifera) are dominant crop pollinators, and access to summer forage is a critical factor influencing colony health in agricultural landscapes. In many temperate agricultural regions, honey bees forage extensively from non-native plants during the summer, but it is unclear whether the use of these species is due to honey bee preference for these plants or is a result of their relative abundance. The foraging choices made by native bees that have evolved with native plants can reveal the seasonal availability of native plant pollens, and so we quantified the pollen collected by 181 wild bee species native to Michigan. Pollen was also trapped from honey bee colonies during the summer to confirm the peak period of non-native pollen collection in this region. Across the state, the generic richness of native pollens collected by wild bees peaked in May before linearly declining into September. Wild social and solitary bees collected a similar proportion of their pollen from non-native plants from April to July, but during August and September social bees collected a significantly greater proportion from non-natives. At a local scale, honey bees collected the majority of their pollen from non-native plants between 4 July and 21 August, with the same trend seen in both social and solitary bees. Across the region, a significantly greater proportion of the solitary bee species that peak during this time are specialists, most of which collect from native plant species that are little utilised by social bees for pollen, such as Dasiphora, Helianthus, Physalis and Vernonia. Our results suggest that Michigan has relatively few native flowering resources during the height of the summer, and that many of those which flower during this time are used primarily by specialised solitary bee species rather than the social bee community, including honey bees. As a result, non-native plant species with a late summer flowering phenology fill a forage gap and thus can contribute to the diet of both honey bees and generalist wild bees during this time, despite the well-documented negative impacts of these species on native plant communities.

Reproductive consequences of variation in flowering phenology in the dry forest tree Enterolobium cyclocarpum in Guanacaste, Costa Rica.

Flowering initiation, duration and magnitude, and degree of flowering synchrony within a population can affect the reproductive fitness of individuals. We examined the flowering phenology within a population of the tropical dry forest Guanacaste tree (Enterolobium cyclocarpum) to gauge the impact of phenological variation among trees on fruit production and progeny vigor. We monitored the flowering phenology of 93 trees weekly during 2005, 2006, and 2007, using a scale based on the percentage of the crown with open flowers. We also monitored fruit production for each tree in 2005, 2006, 2007, and 2008. Finally, we evaluated the relationship between phenological variation and progeny performance. Ten measures of flowering phenology and synchrony among flowering trees, based on the number of weeks when anthesis of the crown exceeded 50%, were used to develop four phenological profiles. These profiles were correlated with significant differences in fruit production and progeny vigor. Trees with flowers in >50% of their crown for at least 2 weeks produced more fruits and more vigorous progeny than trees with other profiles. Trees also tended to produce the same phenological profile among years than predicted by chance. Guanacaste trees vary significantly in the initiation of anthesis, duration and magnitude of flowering, and degree of synchrony among trees. Trees also tend to maintain the same flowering profile among years. Finally, the flowering behavior of E. cyclocarpum leads to significant differences in fruit and seed production, germination, and early progeny growth.

Predicting olive flowering phenology with phenoclimatic models

In plants, day length and temperature are the major climatic factors that affect the transition from a phenological phase to the next one. Non-linear models, such as growing degree hours (GDH), have been successfully used to calculate thermal time required for spring bud burst in deciduous fruit trees. In this experiment, temperature records and blooming dates of olive trees in different years and for 10 different sites in the Italian territory were recorded. Olive booming time was correlated to the amount of (GDH) accumulated from the date of bud rest onset, calculated as the day when the maximum negative chilling units accumulation was reached (UTAH Model), to full bloom. The GDH model was optimised generating 200 random sets of parameters (cardinal temperatures) and calculating for each set the best fit in terms of blooming date forecast. The best bloom prediction model resulted when a base temperature of 5°C, an optimum temperature of 33°C and a critical temperature of 33.1°C were used. Taking into account the rest-to-bloom period, the accuracy of the GDH model in predicting blooming time was high. An accurate early forecast of blooming time was obtained using an olive rest-to-bloom thermal time requirement of about 29.000 GDH.

Morphometrical and biological indicators in definition decorative representatives to the Saintpaulia H. Wendl.

Long-term researches showed that representatives of cultivars of Saintpaulia H. Wendl. are most long flowering plants of family of Gesneriaceae Dumort. in the protected soil of Oles Gonchar Dnepr National University Botanic Garden. The decorativeness of cultivars was determined on morphometric and biological descriptions: to correlation to the diameter of flower with a width and long sheet plate, to the form of flower, double, fringed of edge of petal, and also general proportion of corolla, the phenology of flowering and other. Descriptions of the most perspective cultivars of Saintpaulia getting top marks on the scale of estimation are considered. A brightness, chromaticity, maintenance of these qualities during all life of flower (more than 2 months at some cultivars), beauty and harmoniousness of picture at multicoloured Saintpaulia, was taken into account. Studies and observations were conducted in the stock conservatory of the laboratory of tropical and subtropical plants from 1997 to 2018.We used garden classification of The Special Comity of The African Violet Society of America – AVSA, scale of assessment of economic-biological and decorative features. A complex evaluation of 60 cultivars from the genus Saintpaulia from the laboratory of tropical and subtropical plants of the botanical garden of the DNU was carried out.
 It is educed, that most showily plants look with flowers, having a size of corolla, equal to the width of sheet plate, or less than her no more, than on one centimeter. Most objects driven to this article respond to this request and have the highest productivity of flowering. The evaluation of ornamental properties and prognosis of the succesful introduction of 20 taxsons (the sorts: EK-Boy Bykov, ЕК-Belaya Koroleva, EK-Zhemchujniy Zephyr, Arctic Frost, Blue Dragon, Kilauea et al) have been given. Perspective for cultivation in closed soil species have been selected. Modern varieties for indoors greenbelt setting have been listed.
 The got results served in future for creation of scale of cultivars of Saintpaulia and complex estimation of their decorativeness. All studied cultivars are used in an educational process.

Two decades of evolutionary changes in Brassica rapa in response to fluctuations in precipitation and severe drought.

As climate changes at unprecedented rates, understanding population responses is a major challenge. Resurrection studies can provide crucial insights into the contemporary evolution of species to climate change. We used a seed collection of two Californian populations of the annual plant Brassica rapa made over two decades of dramatic precipitation fluctuations, including increasingly severe droughts. We compared flowering phenology, other drought response traits, and seed production among four generations, grown under drought and control conditions, to test for evolutionary change and to characterize the strength and direction of selection. Postdrought generations flowered earlier, with a reduced stem diameter, and lower water-use efficiency (WUE), while intervening wet seasons reversed these adaptations. There was selection for earlier flowering, which was adaptive, but delayed flowering after wet years resulted in reduced total seed mass, indicating a maladaptive response caused by brief wet periods. Furthermore, evolutionary changes and plastic responses often differed in magnitude between populations and drought periods, suggesting independent adaptive pathways. While B. rapa rapidly evolved a drought escape strategy, plant fitness was reduced in contemporary generations, suggesting that rapid shifts in flowering time may no longer keep up with the increasing severity of drought periods, especially when drought adaptation is slowed by occasional wet seasons.

Pattems and models of flowering of some Gampanulaceae Juss. species

The present work is devoted to the phenology of individual flowering and the construction of structure-dynamic models of this process on its basis. The results of the study of the flowering phenology of Campanula bononiensis, C. sarmatica and Platycodon grandiflorus are presented. The data obtained characterize both the phenological (time and duration of flowering, lifespan of individual flowers) and structural features (degree of branching of the inflorescence, length of floral axes, number of flowers, order of their blooming) that describe the flowering of a monocarpic shoot. Inflorescences of the species are elongated and multiflorous, of the compound type inherent for Campanulaceae, and characterized by a high variability of all structural features. Observation data were processed by standard statistical methods and used to construct stochastic computer models of flowering shoots, while omissions in data were restored by using the maximum likelihood method. Flowering patterns of the species, due to differences in phenological and structural features, have been revealed. It has been shown that flowering curves depend on the synchrony in the flowers blooming on the main (first-order) axis and lateral (second-order) axes. C. bononiensis has one asymmetrical peak with a broadening on the left, achieved with the simultaneous blooming of flowers in the upper and lower parts of the main axis and on lateral axes in the middle part of the inflorescence, where the first-order flowers have already finished blooming (they provided the broadening). Flowering curves for C. sarmatica and P grandiflorus are bimodal, with the first peak being due to the flowers blooming on the main axis and the second one on lateral axes. The constructed models reproduce the patterns of individual flowering well, with natural variability, and can be used to simulate the flowering of a group of individuals (population), for example, in landscape design. In combination with visualization tools, they can be used for augmenting plant phenotyping datasets with rendered images of synthetic plants for the purpose of training neural networks in this field.