Female-biased nectar production in the protandrous, hermaphroditic shrub Salvia hierosolymitana (Lamiaceae)

2011 ◽  
Vol 59 (1) ◽  
pp. 18 ◽  
Author(s):  
Yehoram Leshem ◽  
Tamar Keasar ◽  
Avi Shmida
Keyword(s):  
Vertical Distribution ◽  
Nectar Production ◽  
Short Supply ◽  
Pollination Success ◽  
Female Phase ◽  
Male Phase ◽  
Sterile Pollen ◽  
Germinated Pollen ◽  
Two Populations ◽  
Nectar Availability

Flowering progresses upward along vertical inflorescences in the protandrous dichogamous shrub Salvia hierosolymitana (Boiss.). Flowers’ gender nectar production rates and their vertical distribution were recorded in two populations (northern and central Israel) over 3 years. Female-phase flowers produced significantly more nectar than male-phase flowers and were more abundant at the inflorescences’ base. Thus, nectar availability gradually decreases along inflorescences. Female-biased nectar production can benefit plants by increasing pollinator visits to female-phase flowers, enhancing pollination success when pollen is scarce. In congruence with this hypothesis, the following observations suggest that pollen in S. hierosolymitana may be in short supply: (1) freshly dehisced anthers contained 40% of sterile pollen; (2) pollen counts on female-phase stigmas were low (mean ± s.e. 11.6 ± 1.56); and (3) counts of germinated pollen tubes at the pistils’ base were even lower (5.02 ± 0.54). The nectar gradient along the inflorescence may also be adaptively beneficial in other aspects. Foraging insects that follow this gradient are expected to move from female-phase flowers near the inflorescences’ base, to male-phase flowers closer to the top. Thus, reducing the risk of geitonogamy and promoting outcrossing while moving from male-phase flowers of one individual to female-phase flowers of another.

Nectar secretion pattern, removal effects, and breeding system of Ligaria cuneifolia (Loranthaceae)

1996 ◽  
Vol 74 (12) ◽  
pp. 1996-2001 ◽  
Author(s):  
Guillermo L. Rivera ◽  
Leonardo Galetto ◽  
L. Bernardello
Keyword(s):  
Reproductive Biology ◽  
Breeding System ◽  
Nectar Production ◽  
Female Function ◽  
Flower Nectar ◽  
Flower Age ◽  
Female Phase ◽  
Male Phase ◽  
Pattern Removal ◽  
Flower Phenology

Some aspects of the reproductive biology of Ligaria cuneifolia have been studied, addressing the following questions: (i) Are there temporal differences in the female and male functions? (ii) How do nectar composition, volume, concentration, and amount of sugar vary throughout the flower lifetime? (iii) How does the plant respond to nectar removal? (iv) What is the breeding system of this species? Flowers last 4 days. There is a predominance of the male function in the first days and of the female function in the last days. Chemical composition of nectar varies throughout the flower lifetime; there is a constant decrease in sucrose along with an increase in glucose. Nectar is secreted during nights, and every secretion period is followed by a cessation interval. After the final cessation, a period of active resorption follows. During the mostly male phase of the flower, nectar has more sucrose than hexose, its secretion is discontinuous, and nectar removal reduces the rate of nectar production. During the mostly female phase, nectar has more hexose than sucrose, its secretion ceases, nectar removal does not affect nectar production, and a resorption period is inferred. Tests for spontaneous autogamy and apomixis were negative. Low fruit set is obtained when autogamous, geitonogamous, and xenogamous hand pollinations are performed on flowers less than 2 days old compared with flowers at least 3 days old (0, 15, and 47% versus 19, 37.5, and 89%, respectively). These results indicate the the reproductive system of L. cuneifolia is primarily xenogamous, but reproductive success is related to flower age. Keywords: Loranthaceae, Ligaria, nectar chemistry, breeding system, flower phenology, reproductive biology.

scholarly journals Pollen Germination in Different Genotypes of Gladiolus

1970 ◽  
Vol 11 ◽  
pp. 47-50
Author(s):  
Tul Bahadur Poon ◽  
TM Rao ◽  
C Aswath ◽  
PE Rajasekharan ◽  
DP Kumar
Keyword(s):  
Boric Acid ◽  
Magnesium Sulphate ◽  
Pollen Germination ◽  
Pollen Viability ◽  
Calcium Nitrate ◽  
Potassium Nitrate ◽  
Hybrid Selection ◽  
Fresh Pollen ◽  
Sterile Pollen ◽  
Germinated Pollen

Fresh pollen of 16 promising genotypes of gladiolus was tested for their pollen viability. Modified cellophane method was employed to assess the pollen viability. Pollen germination media consisted of 15% sucrose supplemented with 300 ppm calcium nitrate, 200 ppm magnesium sulphate, 100 ppm potassium nitrate and 100 ppm boric acid. Highly significant variations were observed for percentage of pollen germination, non-germinated pollen and sterile pollen. The highest pollen germination (76.41%) was in genotype Hybrid selection 88-10-22, and did not differ significantly from Gladiolus callianthus (75.41%), Sapna (75.10 %), Hybrid selection 86-32-11, (73.28 %), Kum Kum (69.41%), Poonam (69.22 %), Hybrid selection 87-22-1 (67.87 %), Hybrid selection 87-1-1 (67.61 %), Psittacinus hybrid (64.64%) and Darshan (63.97%). The lowest non- germinated pollen (10.47%) was in genotype Gladiolus callianthus, and insignificantly followed by Hybrid selection 88-10-22 with 18.77 % and Hybrid selection 87-22-1 with 18.95 %. The lowest percentage of sterile pollen was noticed in genotype Sapna (2.82%) followed by Poonam with 4.00 % Hybrid selection 88-10-22 with 4.82% and Hybrid selection 82-11-27 with 5.22%. Key words: Gladiolus; germination; pollen DOI: 10.3126/njst.v11i0.4089Nepal Journal of Science and Technology 11 (2010) 47-50

scholarly journals Flower mites decrease nectar availability in the rain-forest bromeliad Neoregelia johannis

2010 ◽  
Vol 26 (4) ◽  
pp. 373-379 ◽  
Author(s):  
Tadeu J. Guerra ◽  
Gustavo Q. Romero ◽  
Woodruff W. Benson
Keyword(s):  
Rain Forest ◽  
Sugar Content ◽  
Sugar Concentration ◽  
Production Rates ◽  
Nectar Production ◽  
Nectar Volume ◽  
Bombus Morio ◽  
Nectar Rewards ◽  
Flower Mites ◽  
Nectar Availability

Abstract:Nectarivorous flower mites can reduce the volume of nectar available to pollinators. The effects of the flower mite Proctolaelaps sp. on nectar availability in flowers of a melittophilous bromeliad Neoregelia johannis (Bromeliaceae) was evaluated in a coastal rain forest in south-eastern Brazil. In a randomized block experiment utilizing 18 flower pairs, one per bromeliad ramet, pollinators (Bombus morio) and mites were excluded, and then nectar volume, sugar concentration and sugar mass were quantified over the anthesis period. Mites significantly reduced nectar volume early in the morning (6h00–8h00), but not later (10h00–12h00). Mites decreased total volume of nectar available up to 22%. Sugar concentration in nectar was higher earlier in the morning, and decreased between 10h00–12h00. The pronounced consumption of nectar by mites during the period of higher sugar concentration reduced the total amount of sugar available to pollinators by 31%. This is the first study showing that flower mites decrease nectar rewards in a melittophilous plant. Because nectar volume by itself incompletely describes nectar production rates and the effects of nectar removal by flower mites on the availability of sugar, our study highlights the inclusion of sugar content in future studies assessing the effects of thieves on nectar production rates.

Thinking honeyeater: nectar maps for the Northern Territory, Australia

2000 ◽  
Vol 6 (1) ◽  
pp. 61 ◽  
Author(s):  
John C. Z. Woinarski ◽  
Greg Connors ◽  
Don C. Franklin
Keyword(s):  
Northern Territory ◽  
Dry Season ◽  
Spatial And Temporal Variation ◽  
Wet Season ◽  
Nectar Production ◽  
The World ◽  
Eucalypt Forests ◽  
The Times ◽  
Species Specific ◽  
Nectar Availability

We create monthly maps of nectar availability for the 1.4 x 106 km2 jurisdiction of the Northern Territory, Australia. These are based on a combination of vegetation mapping and a series of indices of plant species specific nectar scoring. The maps reveal complex spatial and temporal variation in nectar availability, but most notably a greater nectar resource in the monsoon-influenced north than in the arid south, and a peak in nectar availability in the dry season. The latter is associated with the extensive tropical eucalypt forests (especially those co-dominated by Eucalyptus miniata and E. tetrodonta). In contrast, wet season nectar availability in these forests is limited, but riparian and swampland forests, typically dominated by Melaleuca species, provide rich but spatially restricted nectar resources. The extensive and rich nectar resources available in eucalypt forests in the dry season supplement the diets of many species which are not primarily nectarivorous. This resource helps shape the singularity of northern Australian eucalypt forests relative to other extensive forests elsewhere in the world. Nectarivores remain in the system through a combination of movements across a number of scales, habitat shifting, and diet shifting. The latter is aided by the peaking of invertebrate and fruit resources at the times of minimum nectar production; a shuffling in resource availability brought about by the extreme climatic seasonality.

Pollination of Amorphophallus johnsonii (Araceae) by carrion beetles (Phaeochrous amplus) in a Ghanaian rain forest

1996 ◽  
Vol 12 (3) ◽  
pp. 409-418 ◽  
Author(s):  
Daniel D. N. Beath
Keyword(s):  
Rain Forest ◽  
Rainy Season ◽  
Male Inflorescence ◽  
Large Numbers ◽  
Female Phase ◽  
Male Phase ◽  
Carrion Beetles ◽  
Main Rainy Season

ABSTRACTAmorphophallus johnsonii (N. E. Brown) flowers during April in the main rainy season in Ghana. Anthesis starts at dusk with fluid oozing from the upper spadix accompanied by a strong aminoid odour. Just after dark large numbers of carrion beetles (Phaeochrous amplus) and occasional dung fly species (Hemigymnochaeta unicolor and Paryphodes tigrinus) visit the inflorescences. The beetles become trapped in the lower spathe overnight and remain in the spadix until the following evening. Between 1630 and 1645 h the following day, the anthers produce long threads of sticky pollen. The trapped beetles escape just after dark by crawling up the spadix, past the dehisced anthers and fly away from the spadix tip. Marked beetles were seen to transfer pollen from male phase to female phase inflorescences. Successful fertilisation was only effected if pollen was transferred on the same night from a male inflorescence 30 m or less away. Pollen is psilate and typical of beetle pollinated Araceae. Berries ripen approximately 70 d after fertilization and ripen basisetally in the infructescence.

scholarly journals Male flowers of Aconitum compensate for toxic pollen with increased floral signals and rewards for pollinators

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
A.-L. Jacquemart ◽  
C. Buyens ◽  
M.-F. Hérent ◽  
J. Quetin-Leclercq ◽  
G. Lognay ◽  
...  
Keyword(s):  
Larval Food ◽  
Chemical Defences ◽  
Toxic Nectar ◽  
Pollen Transfer Efficiency ◽  
Aconitum Napellus ◽  
Female Phase ◽  
Male Phase ◽  
Male Flowers ◽  
Nectar Rewards ◽  
Toxic Pollen

Abstract Many plants require animal pollinators for successful reproduction; these plants provide pollinator resources in pollen and nectar (rewards) and attract pollinators by specific cues (signals). In a seeming contradiction, some plants produce toxins such as alkaloids in their pollen and nectar, protecting their resources from ineffective pollinators. We investigated signals and rewards in the toxic, protandrous bee-pollinated plant Aconitum napellus, hypothesizing that male-phase flower reproductive success is pollinator-limited, which should favour higher levels of signals (odours) and rewards (nectar and pollen) compared with female-phase flowers. Furthermore, we expected insect visitors to forage only for nectar, due to the toxicity of pollen. We demonstrated that male-phase flowers emitted more volatile molecules and produced higher volumes of nectar than female-phase flowers. Alkaloids in pollen functioned as chemical defences, and were more diverse and more concentrated compared to the alkaloids in nectar. Visitors actively collected little pollen for larval food but consumed more of the less-toxic nectar. Toxic pollen remaining on the bee bodies promoted pollen transfer efficiency, facilitating pollination.

scholarly journals Linking pollinator efficiency to patterns of pollen limitation: small bees exploit the plant–pollinator mutualism

2018 ◽  
Vol 285 (1880) ◽  
pp. 20180635 ◽  
Author(s):  
Matthew H. Koski ◽  
Jennifer L. Ison ◽  
Ashley Padilla ◽  
Angela Q. Pham ◽  
Laura F. Galloway
Keyword(s):  
Pollen Limitation ◽  
Pollen Deposition ◽  
Pollinator Efficiency ◽  
Flower Visitation ◽  
Female Phase ◽  
Male Phase ◽  
Single Flower ◽  
Floral Visitation ◽  
Low Efficiency ◽  
Plant Pollinator

Seemingly mutualistic relationships can be exploited, in some cases reducing fitness of the exploited species. In plants, the insufficient receipt of pollen limits reproduction. While infrequent pollination commonly underlies pollen limitation (PL), frequent interactions with low-efficiency, exploitative pollinators may also cause PL. In the widespread protandrous herb Campanula americana , visitation by three pollinators explained 63% of the variation in PL among populations spanning the range. Bumblebees and the medium-sized Megachile campanulae enhanced reproductive success, but small solitary bees exacerbated PL. To dissect mechanisms behind these relationships, we scored sex-specific floral visitation, and the contributions of each pollinator to plant fitness using single flower visits. Small bees and M. campanulae overvisited male-phase flowers, but bumblebees frequently visited female-phase flowers. Fewer bumblebee visits were required to saturate seed set compared to other bees. Scaling pollinator efficiency metrics to populations, small bees deplete large amounts of pollen due to highly male-biased flower visitation and infrequent pollen deposition. Thus, small bees reduce plant reproduction by limiting pollen available for transfer by efficient pollinators, and appear to exploit the plant–pollinator mutualism, acting as functional parasites to C. americana . It is therefore unlikely that small bees will compensate for reproductive failure in C. americana when bumblebees are scarce.

scholarly journals Intraspecific Seasonal Variation of Flowering Synchronization in a Heterodichogamous Tree

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1509
Author(s):  
Noemi Tel-Zur ◽  
Tamar Keasar
Keyword(s):  
Genetic Diversity ◽  
Seasonal Variation ◽  
Phase Duration ◽  
Male And Female ◽  
Flowering Synchrony ◽  
Flowering Season ◽  
Hand Pollination ◽  
Female Phase ◽  
Male Phase ◽  
Phase Differences

Heterodichogamous reproduction in plants involves two flowering morphs, reciprocal in their timing of male and female sexual functions. The degree of synchrony in floral sex phase, within and between individuals of each morph, determines the flowers’ potential fertilization partners. Complete within-morph synchrony enables across-morph mating alone, whereas unsynchronized floral sex phases may allow fertilization within a plant individual (geitonogamy) or within a morph. We documented the disruption of flowering synchrony in the heterodichogamous Ziziphus spina-christi towards the end of its seven-month flowering season. This desert tree has self-incompatible, protandrous, short-lived (2-day) flowers that open before dawn (‘Early’ morph) or around noon (‘Late’ morph). We counted flowers in the male and female phase on flowering branches that were sampled monthly during the 2016–2018 flowering seasons. In 2018, we also tagged flowers and followed their sex-phase distributions over two days at the start, middle, and end of the season. The switch to the female phase was delayed at the end-season (November-December), and 74% of the flowers did not develop beyond their male phase. Differences in male-phase duration resulted in asynchrony among flowers within each tree and among trees of both flowering morphs. Consequently, fertilization between trees of the same morph becomes potentially possible during the end-season. In controlled hand-pollination assays, some within-morph fertilizations set fruit. The end-season breakdown of synchronous flowering generates variability within morphs and populations. We suggest that this variability may potentially enable new mating combinations in a population and enhance its genetic diversity.

scholarly journals Does the Rarity of a Flower’s Scent Phenotype in a Deceptive Orchid Explain Its Pollination Success?

2020 ◽  
Vol 11 ◽  
Author(s):  
Herbert Braunschmid ◽  
Stefan Dötterl
Keyword(s):  
Floral Scent ◽  
Dynamic Headspace ◽  
Pollinator Attraction ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Pollination Success ◽  
Cypripedium Calceolus ◽  
Negative Frequency Dependent Selection ◽  
Plant Pollinator ◽  
Two Populations

Floral scent, a key mediator in plant–pollinator interactions, varies not only among plant species, but also within species. In deceptive plants, it is assumed that variation in floral scents and other traits involved in pollinator attraction is maintained by negative frequency-dependent selection, i.e., rare phenotypes are more attractive to pollinators and hence, have a higher fitness than common phenotypes. So far, it is unknown whether the rarity of multivariate and/or continuous floral scent traits influences the pollination success of flowers. Here, we tested in the deceptive orchid Cypripedium calceolus, whether flowers with rarer scent bouquets within a population have a higher chance to getting pollinated than flowers with more common scents. We collected the scent of more than 100 flowers in two populations by dynamic headspace and analyzed the samples by gas chromatography coupled to mass spectrometry (GC/MS). From the same flowers we also recorded whether they set a fruit or not. We introduced rarity measures of uni- and multivariate floral scent traits for single flowers, which allowed us to finally test for frequency-dependent pollination, a prerequisite for negative frequency-dependent selection. Our results do not show rarity has an effect on the likelihood to set fruits in neither of the two populations and in none of the scent characteristics analyzed. Hence, there is no evidence of negative frequency-dependent pollination mediated by the floral scent of C. calceolus. We discuss that our approach to determine rarity of a scent is applicable to any univariate or multivariate (semi)quantitative trait.

scholarly journals Nectar secretion and pollen production in protandrous flowers of Campanula patula L. (Campanulaceae)

2018 ◽  
Vol 71 (1) ◽  
Author(s):  
Bożena Denisow ◽  
Monika Strzałkowska-Abramek ◽  
Małgorzata Wrzesień
Keyword(s):  
Sugar Accumulation ◽  
Reproductive Costs ◽  
Pollen Production ◽  
Nectar Secretion ◽  
Mass Content ◽  
Plastic Response ◽  
Male And Female ◽  
Functional Relationships ◽  
Female Phase ◽  
Male Phase

Nectar secretion was noted both in the male and female floral phases of the protandrous flowers of <em>Campanula patula</em> (Campanulaceae). Female-biased sugar accumulation was evidenced and plasticity in the duration of sexual phases observed. Flowers in the male phase produced twofold less nectar with lower sugar concentrations compared to female-phase flowers. The sugar mass content averaged 0.6 mg ±0.45 <em>SD</em> per flower in the male phase and 1.4 ±0.5 <em>SD</em> per flower in the female phase. The pollen mass averaged 0.16 mg ±0.10 <em>SD</em> per flower. An understanding of the evolution of functional relationships between floral sexes requires consideration of the compensation of the reproductive costs, including the plastic response to interdependent factors, i.e., photosynthesis and growth, the effect of pollinators, pollen robbers, and external environmental forces.

Sign in / Sign up

Export Citation Format

Share Document