scholarly journals Horizontal orientation facilitates pollinator attraction and rain avoidance in radially symmetrical flowers

2021 ◽  
Author(s):  
Taichi Nakata ◽  
Ishii Rin ◽  
Yuki A Yaida ◽  
Atushi Ushimaru
Keyword(s):  
Field Experiments ◽  
Pollen Grains ◽  
Adaptive Significance ◽  
Pollinator Limitation ◽  
Pollinator Attraction ◽  
Pollination Success ◽  
Horizontal Orientation ◽  
Flowering Season ◽  
Germination Experiment ◽  
Female Success

AbstractPremiseFloral angle, such as upward, horizontal, and downward orientation are known to evolve under both biotic and abiotic agents to enhance pollination success in zoophilious plants. Adaptive significance of horizontal orientation in radially symmetrical (actinomorphic) flowers under biotic and abiotic selection pressures were largely unknown, although those in bilaterally symmetrical flowers have been well studied.MethodsUsing experimentally angle changed flowers, we examined the effects of flower angle on pollinator behaviors, pollination success and rain avoidance in a population of insect-pollinated Platycodon grandiflorus. We further investigated the frequency and amount of precipitation in the flowering season and pollen damage by water in this species. Main results: Horizontally oriented flowers received more visitations and pollen grains on the stigma in male and/or female phases than downward and/or upward oriented flowers and avoided pollen damage by rainfall compared to upward oriented flowers. The pollen germination experiment showed that approximately 30% of pollen grains burst in distilled water, thus pollen damage by rainfall was potentially serious in P. garndiflorus.ConclusionIn this study, our field experiments revealed that upward flowers cannot avoid damage from rainfall during the flowering period whereas both upward and downward flowers suffered from pollinator limitation in female success. Thus, horizontal flower orientation is suggested to be adaptive in this insect-pollinated actinomorphic species which blooms in the rainy season.

scholarly journals Why so many flowers? A preliminary assessment of mixed pollination strategy enhancing sexual reproduction of the invasive <i>Acacia longifolia</i> in Portugal

Web Ecology ◽  
2018 ◽  
Vol 18 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Manuela Giovanetti ◽  
Margarida Ramos ◽  
Cristina Máguas
Keyword(s):  
Invasive Plant ◽  
Seed Set ◽  
Pollen Grains ◽  
Striking Difference ◽  
Pollination Syndromes ◽  
Pollination Success ◽  
Relative Contribution ◽  
Acacia Longifolia ◽  
Exclusion Experiments ◽  
Pollination Strategy

Abstract. Acacia longifolia, a native legume from Australia, has been introduced in many European countries and elsewhere, thus becoming one of the most important global invasive species. In Europe, its flowering occurs in a period unsuitable for insect activity: nonetheless it is considered entomophilous. Floral traits of this species are puzzling: brightly coloured and scented as liked by insects, but with abundant staminate small-sized flowers and relatively small pollen grains, as it is common in anemophilous species. Invasion processes are especially favoured when reshaping local ecological networks, thus the interest in understanding pollination syndromes associated with invasive plant species that may facilitate invasiveness. Moreover, a striking difference exists between its massive flowering and relatively poor seed set. We introduced a novel approach: first, we consider the possibility that a part of the pollination success is carried on by wind and, second, we weighted the ethological perspective of the main pollinator. During the flowering season of A. longifolia (February–April 2016), we carried on exclusion experiments to detect the relative contribution of insects and wind. While the exclusion experiments corroborated the need for pollen vectors, we actually recorded a low abundance of insects. The honeybee, known pollinator of acacias, was relatively rare and not always productive in terms of successful visits. While wind contributed to seed set, focal observations confirmed that honeybees transfer pollen when visiting both the inflorescences to collect pollen and the extrafloral nectaries to collect nectar. The mixed pollination strategy of A. longifolia may then be the basis of its success in invading Portugal's windy coasts.

The importance of fruit set, fruit abortion, and pollination success in fruit production of teak (Tectona grandis)

2010 ◽  
Vol 40 (11) ◽  
pp. 2204-2214 ◽  
Author(s):  
E. R. Palupi ◽  
J. N. Owens ◽  
S. Sadjad ◽  
Sudarsono ◽  
D. D. Solihin
Keyword(s):  
Fruit Set ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Tectona Grandis ◽  
Seed Orchard ◽  
Fruit Production ◽  
Time Of Day ◽  
Natural Forests ◽  
Pollination Success ◽  
Fruit Abortion

Teak ( Tectona grandis L.) is believed to have been introduced from India 400–500 years ago and there appear to be no old-growth natural forests. However, Indonesia has many teak plantation forests and 40%–50% of seeds for reforestation come from seed orchards and the remainder from plantations. In both, flower and fruit abortion results in low fruit set and thus seed production. We investigated flower and fruit development in a clonal seed orchard in East Java in 1999 and 2001 using cross- and open-pollinated trees. The rates of abortion using cross-pollinations showed a similar pattern but were lower than for open-pollinations. The highest rate of abortion in cross- and open-pollinations was during pollination and fertilization, ranging 11%–23% and 31%–32%/day, respectively, less during fruit initiation (5%–6% and 6%–8%/day) and the lowest was during fruit maturation (<0.5%/day). Cross-pollinations increased fruit production by 10-fold compared with open-pollinations. About 30% of flowers were pollinated with an average of five pollen grains per stigma in open-pollinations. Pollen viability varied among clones and time of day but was not affected by position of flowers in an inflorescence. We conclude that low pollination success and low pollen viability are major causes for low fruit production in teak and are related to insect pollinators.

The pollination ecology of the late-successional tree, Oroxylum indicum (Bignoniaceae) in Thailand

2008 ◽  
Vol 24 (05) ◽  
pp. 477-484 ◽  
Author(s):  
Tuanjit Srithongchuay ◽  
Sara Bumrungsri ◽  
Ekapong Sripao-raya
Keyword(s):  
Plant Species ◽  
Fruit Set ◽  
Pollen Grains ◽  
Pollen Load ◽  
Pollination Success ◽  
Oroxylum Indicum ◽  
Tropical Plant ◽  
Fruit Bat ◽  
Highly Sensitive ◽  
Multiple Species

Abstract:Although plant species that attract multiple species of pollinators predominate in tropical plant communities, pollination specialists appear to be at a greater advantage in tropical ecosystems in which pollinators are numerous and many plants flower synchronously. The present study determined the breeding system and legitimate pollinators ofOroxylum indicumVent. in Songkhla and Patthalung Provinces, Thailand.Oroxylum indicumexhibits steady-state flowering, with one or two flowers per inflorescence opening each night. Flowers open in the evening and drop off shortly after midnight, while its bilabiate stigma is highly sensitive, and quickly close upon being touched.Oroxylum indicumis self-incompatible. Hand-cross pollination and open pollination yielded the highest pollination success (47.7% and 31.2% respectively, n = 7 trees). About 900 pollen grains are needed for initiating fruit set. It is confirmed that a fruit bat,Eonycteris spelaea, is the legitimate pollinator. Bats are responsible for all pollen load and the pollen load from only one visit is generally sufficient to initiate fruit set. AlthoughEonycteris spelaeais effective, it is an inefficient pollinator. Compared with plant species pollinated by multiple animal species, the likelihood of pollination failure resulting from the decline in populations ofEonycteris spelaeawill be much more intense inOroxylum indicum.

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.

Minimising cold damage during reproductive development among temperate rice genotypes. II. Genotypic variation and flowering traits related to cold tolerance screening

2006 ◽  
Vol 57 (1) ◽  
pp. 89 ◽  
Author(s):  
T. C. Farrell ◽  
K. M. Fox ◽  
R. L. Williams ◽  
S. Fukai ◽  
L. G. Lewin
Keyword(s):  
Low Temperature ◽  
Cold Tolerance ◽  
Field Experiments ◽  
Cold Water ◽  
Genotypic Variation ◽  
Pollen Grains ◽  
Microspore Development ◽  
Spikelet Sterility ◽  
Temperature Conditions ◽  
Anther Length

Low temperature during microspore development increases spikelet sterility and reduces grain yield in rice (Oryza sativa L.). The objectives of this study were to determine genotypic variation in spikelet sterility in the field in response to low temperature and then to examine the use of physio-morphological traits at flowering to screen for cold tolerance. Multiple-sown field experiments were conducted over 4 consecutive years in the rice-growing region of Australia to increase the likelihood of encountering low temperature during microspore development. More than 50 cultivars of various origins were evaluated, with 7 cultivars common to all 4 years. The average minimum temperature for 9 days during microspore development was used as a covariate in the analysis to compare cultivars at a similar temperature. The low-temperature conditions in Year 4 identified cold-tolerant cultivars such as Hayayuki and HSC55 and susceptible cultivars such as Sasanishiki and Doongara. After low temperature conditions, spikelet sterility was negatively correlated with the number of engorged pollen grains, anther length, anther area, anther width, and stigma area. The number of engorged pollen grains and anther length were found to be facultative traits as their relationships with spikelet sterility were identified only after cold water exposure and did not exist under non-stressed conditions.

Functional differentiation in pollination processes between the outer and inner perianths in Iris gracilipes (Iridaceae)

2006 ◽  
Vol 84 (1) ◽  
pp. 164-171 ◽  
Author(s):  
Shin-Ichi Morinaga ◽  
Satoki Sakai
Keyword(s):  
Genetic Correlation ◽  
Seed Production ◽  
Pollen Grains ◽  
Functional Differentiation ◽  
The Other ◽  
Pollination Success ◽  
Other Hand ◽  
Pollen Removal

We examined the functional differentiation in pollination processes between the outer and inner perianths in Iris gracilipes A. Gray flowers. We manipulated the length of the outer and inner perianths and examined the effect on the following: number of pollinator approaches to, and landings on, flowers; pollen removal and deposition during a single pollinator visit; total number of pollen grains removed; and seed production. The outer perianths contributed to the functions of pollinator approach and landing, pollen removal, and seed production, but not to mechanical fitting of pollinators. Since flowers with shortened outer perianths gained less pollination success than control flowers, and since lengthening of outer perianths did not enhance pollination success, the length of the outer perianths might have evolved as an adaptive characteristic. On the other hand, the inner perianths contributed to the functions of pollinator approach and pollen removal but not to pollinator landing, mechanical fitting of pollinators, nor seed production. Since flowers with shortened inner perianths gained pollination success similar to that of control flowers, the adaptive length of the inner perianths may be shorter than what is found in present-day flowers. We propose that genetic correlation between the outer and the inner perianths might prevent shortening of the inner perianths.

scholarly journals Pollen Grain and Hybridization Studies in the Genus Capsicum

2016 ◽  
Vol 8 (1) ◽  
pp. 134-138 ◽  
Author(s):  
Tomi Lois OLATUNJI ◽  
Joseph Akintade MORAKINYO
Keyword(s):  
Success Rate ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Interspecific Crosses ◽  
Putative Hybrid ◽  
Gene Exchange ◽  
Viable Pollen ◽  
Pollination Success ◽  
Capsicum Species

The current study aimed to evaluate the pollen viability of the commonly cultivated varieties of Capsicum species and assessed the potentials for gene exchange among the genotypes through hybridization studies. Capsicum annuum var. abbreviatum, C. annuum var. acuminatum, C. annuum var. grossum and C. frutescens var. baccatum were the species and varieties used in this study. The present findings indicated that the percentage of pollen viability varied in the studied Capsicum genotypes. The highest pollen viability was obtained in C. annuum var. abbreviatum (96.3%), followed by C. annuum var. grossum (95%), and C. annuum var. acuminatum (91.1%). The lowest pollen viability was recorded in C. frutescens var. baccatum (86.2%). The pollen viability was high in most varieties indicating that meiosis is normal, resulting in viable pollen grains. Several intraspecific and interspecific crosses were performed among the Capsicum genotypes and three putative hybrid fruits were produced. Percentage successes obtained in the crosses were low and comparable in both intra and inter-specific crosses. In the entire crosses pattern, pollination success of 10% was recorded for C. frutescens var. baccatum and C. annuum var. acuminatum. Knowing the nature and viability of pollen grains may help in predicting the success rate of hybridization and the successful crosses between C. frutescens var. baccatum and C. annuum var. acuminatum suggest that these two varieties are the closest genetically. 

scholarly journals Sexual ratio and floral biology of the dioecious Neea theifera Oerst. (Nyctaginaceae) in a cerrado rupestre of central Brazil

2011 ◽  
Vol 25 (4) ◽  
pp. 785-792 ◽  
Author(s):  
Felipe Wanderley Amorim ◽  
Clesnan Mendes-Rodrigues ◽  
Pietro Kiyoshi Maruyama ◽  
Paulo Eugênio Oliveira
Keyword(s):  
Resource Allocation ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Reproductive Strategy ◽  
Pollen Viability ◽  
Floral Biology ◽  
Pollinator Limitation ◽  
Dioecious Species ◽  
Male And Female ◽  
Pollination Success

Dioecy is characterized by a complete separation of sexual functions on male and female plants. It has evolved many times in flowering plants and is widespread among distinct Angiosperm families. It is viewed as a reproductive strategy to reduce endogamy, and to promote optimal resource allocation between male and female sexual functions. Neea theifera is a common species in Cerrado, neotropical savannas in Brazil, but information regarding its reproductive biology is still incomplete. In order to investigate how environmental conditions possibly affect this dioecious species, we studied its floral biology, sex ratio and spatial distribution of sexual morphs along a soil-altitudinal gradient. The sex ratio did not significantly deviate from the expected 1:1 ratio. However, flower abundance in the population was significantly biased towards staminate flowers. Female individuals were larger than male individuals and plant size was negatively correlated with altitude, but did not differ between sexual morphs. The population did not show spatial segregation of sexes and male individuals were sexually mature earlier than female ones. Staminate flowers were larger than pistillate flowers and presented high pollen viability. Meliponini bees, small flies and thrips were potential pollinators, but pollination success was very low. Dioecy in N. theifera corroborates many general features of this reproductive strategy, such as woody habit, inconspicuous flowers, pollination by small generalist insects and differential resource allocation between male and female plants. However, reproduction in this species seems to be impaired by pollinator limitation. The results showed that the soil-altitude gradient influenced the growth pattern of the species and may play an important role in its reproductive biology but did not affect dioecy directly.

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