Poor fruit set due to lack of pollinators in Aristolochia manshuriensis (Aristolochiaceae)

Background and aims – Interactions of insects with trap flowers of Aristolochia manshuriensis, a relic woody liana with fragmented natural populations from south-eastern Russia, were studied. Pollination experiments were conducted to identify the causes of the poor fruit set in this plant.Material and methods – The study was carried out at two ex situ sites within the natural range of A. manshuriensis in the suburban zone of the city of Vladivostok (Russia). The floral morphology was examined to verify how it may affect the process of pollination in this species. To test for a probability of self-pollination, randomly selected flowers at the female phase of anthesis (day 1 of limb opening) were hand-pollinated with pollen from the same plant. The daily insect visitation was studied. The pollen limitation coefficient and the number of visitors to the flowers were determined. To identify insects that lay eggs on the flowers, the insects were reared from eggs collected from fallen flowers. Both caught and reared insects were identified.Key results – The floral morphology and the colour pattern of A. manshuriensis are adapted to temporarily trap insects of a certain size. The hand-pollination experiment showed that flowers of this plant are capable of self-pollination by geitonogamy and require a pollinator for successful pollination. The positive value (2.64) for the pollen limitation coefficient indicates a higher fruit set after hand-pollination compared to the control without pollination. The number of visitors to the flowers was low (0.17 visitors per flower per day). Insects from three orders were observed on the flowers: Diptera (up to 90.9%), Coleoptera (8.3%), and Hymenoptera (0.8%). Four species of flies (Scaptomyza pallida, Drosophila transversa (Drosophilidae), Botanophila fugax, and Botanophila sp. 1 (Anthomyiidae)) are capable of transferring up to 2500–4000 pollen grains on their bodies and can be considered as pollinators of A. manshuriensis. Data of the rearing experiment indicate that flies of the families Drosophilidae (S. pallida, D. transversa), Chloropidae (Elachiptera tuberculifera, E. sibirica, and Conioscinella divitis), and Anthomyiidae (B. fugax, B. sp. 1) use A. manshuriensis flowers to lay eggs. Beetles were also collected from the flowers, but they were probably not involved in pollination, because no pollen grains were observed on them during our study.Conclusions – Pollinators of A. manshuriensis include mainly Diptera that lay eggs on the flowers. The poor fruit set (2%) in A. manshuriensis is associated with pollen limitation due to the lack of pollinators, as the number of visitors to flowers was extremely low. This may be due to the fact that the flowers of this species are highly specialized on insects of a certain size for pollination.

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Preferential outcrossing in Banksia ilicifolia (Proteaceae)

Australian Journal of Botany ◽

10.1071/bt04011 ◽

2005 ◽

Vol 53 (2) ◽

pp. 163 ◽

Cited By ~ 15

Author(s):

Bambang Heliyanto ◽

Erik J. Veneklaas ◽

Hans Lambers ◽

Siegfried L. Krauss

Keyword(s):

Breeding System ◽

Fungal Pathogen ◽

Fruit Set ◽

Pollen Limitation ◽

Genetic Load ◽

Open Pollination ◽

Self Pollination ◽

Hand Pollination ◽

Self Compatibility ◽

Non Local

The breeding system of Banksia ilicifolia was assessed by performing controlled hand-pollination manipulations on flowers in a natural population in Perth, Western Australia. The percentage of 2000 flowers per treatment converted to fruits and seeds was assessed across 24 recipient plants following (1) self-pollination, (2) local outcross pollination (same population), (3) non-local outcross pollination (pollen sourced from another population 30 km away), (4) unpollinated but bagged flowers and (5) unpollinated, unbagged flowers (natural pollination). The relative performance of the resulting seeds was assessed by seed weight, germination rates and, in an unplanned component of the study, resistance to a fungal pathogen. The percentage of flowers converted to fruits following self-pollination was low (0.9%), but demonstrated self-compatibility. Fruit set following cross-pollinations (3.6 and 3.3% for non-local and local crosses, respectively) was significantly greater than that following self-pollination, open-pollination (0.4%) and autogamous (0.04%) treatments. Low fruit set for open-pollinated flowers, compared with self- and outcross-pollination treatments, suggests pollen limitation. Pollen tubes were observed in 15 and 20% of upper styles of flowers hand-pollinated with self and local outcross pollen, respectively. Seed germination was dependent on the source of pollen, where fewer selfed seeds germinated (37%) than did both non-local and local outcrossed seeds (83 and 91%, respectively). Selfed seedlings showed poorer survival (33.3%) following fungal attack than both non-local and local outcrossed seeds (69.2 and 68.5%, respectively). Only 13% of selfed seeds survived to be 2-month-old seedlings, compared with 63% for non-local and 57% for local outcrossed seeds. Ultimately, for 2000 flowers hand-pollinated with self pollen, only three seedlings survived to an age of 16 weeks, compared with 37 and 45 seedlings for local-cross and non-local cross treatments on 2000 hand-pollinated flowers, respectively. These results indicate that in this population, B. ilicifolia is self-compatible, but preferentially outcrossing, with strong early acting inbreeding depression. Consequently, the breeding system of B. ilicifolia promotes the maintenance of genetic variation and a high genetic load.

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Occurrence and Prevention of Delayed Autonomous Selfing in Salvia umbratica (Lamiaceae)

Frontiers in Plant Science ◽

10.3389/fpls.2021.635310 ◽

2021 ◽

Vol 12 ◽

Author(s):

Han-Wen Xiao ◽

Yan-Bo Huang ◽

Yu-Hang Chang ◽

Yun Chen ◽

Richard J. Abbott ◽

...

Keyword(s):

Fruit Set ◽

Seed Set ◽

Pollen Limitation ◽

Pollen Grains ◽

Flower Longevity ◽

Plant Resources ◽

Floral Longevity ◽

Hand Pollination ◽

Pollen Vector ◽

Highly Correlated

Delayed autonomous selfing (DAS) provides reproductive assurance under conditions of pollinator and/or pollen-limitation. Few plant species have been investigated to determine if DAS is terminated when a flower is sufficiently pollinated by a pollen vector, thereby saving plant resources for other purposes. We examined this possibility in bumblebee-pollinated Salvia umbratica. We first showed that DAS resulting in high fruit set (100%) and seed set (>80%) per flower occurred in the absence of insect pollinators by means of style recurvature and was completed in 94% of flowers 72 h after they opened. In contrast, in flowers pollinated immediately after opening, DAS was prevented by corollas dropping away before styles recurve toward the upper thecae. We next showed that hand-pollination of flowers immediately after they opened resulted in high fruit set (100%) and seed set (>80%) when 5–10 pollen grains or more were deposited on their stigmas, whereas fruit set and seed set were reduced to 45.00 and 22.50%, respectively, when pollen loads were reduced to 1–3 pollen grains. Finally, we showed that on average single pollinator visits deposited 26 pollen grains on stigmas of flowers that had just opened, which is more than enough to ensure high fruit and seed set. Our results indicate that flower longevity is highly correlated with the pollinator environment and female fitness of S. umbratica, with extended flower longevity allowing DAS to occur being advantageous when pollinators are absent, while reduced floral longevity and prevention of DAS being favored when flowers are pollinated by pollinators. Thus, flower longevity in S. umbratica varies so as to optimize reproductive output and resource efforts, and is dependent on the availability and effectiveness of pollinators to pollinate flowers.

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Breeding System and Tests for Pollen-Limitation in Two Species of Banksia

Australian Journal of Botany ◽

10.1071/bt9900063 ◽

1990 ◽

Vol 38 (1) ◽

pp. 63 ◽

Cited By ~ 9

Author(s):

RL Goldingay ◽

RJ Whelan

Keyword(s):

Breeding System ◽

Reproductive Output ◽

Fruit Set ◽

Pollen Limitation ◽

Floral Display ◽

Cross Pollination ◽

Self Pollination

Three factors that potentially influence fruit set (breeding system, inadequate cross-pollination and variable floral display) were examined for two species of Banksia. Firstly, self-pollination and autogamy treatments failed to produce any fruit in B. spinulosa and produced very few fruit in B. paludosa. This suggests that cross pollen is required to produce the level of fruit set observed in the field. Secondly, when plants were given abundant cross pollen, fruit set was not altered in B. spinulosa but was in B. paludosa. Although the number of follicles per inflorescence was was not different for open- pollinated (control) and manipulated B. paludosa inflorescences, the latter produced twice the proportion of inflorescences with follicles produced by control plants and twice the total number of follicles per plant. Thirdly, larger floral display in open-pollinated B. spinulosa plants was associated with a greater production of fruit. However, larger floral display was not associated with a greater reproductive output in B. paludosa, and we suggest that recurrent pollen-limitation in this species may be responsible for this result.

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Fruit Set in Avocado: Pollen Limitation, Pollen Load Size, and Selective Fruit Abortion

Agronomy ◽

10.3390/agronomy11081603 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1603

Author(s):

María L. Alcaraz ◽

José I. Hormaza

Keyword(s):

Fruit Set ◽

Pollen Limitation ◽

Pollen Grains ◽

Endosperm Development ◽

Pollen Deposition ◽

Woody Perennial ◽

Flowering Season ◽

Fruit Abortion ◽

Load Size ◽

Competition For Resources

Avocado is a woody perennial fruit crop originating in Central America and Mexico domesticated and cultivated in the Americas since pre-Columbian times, currently cultivated in subtropical, tropical, and Mediterranean climates worldwide, with increasing importance in international trade. Avocado shows an exuberant flower production that, however, results in a very low fruit set reflected in a massive abscission of flowers and fruitlets. Several factors are involved in this behavior, and, in this work, we have focused on pollination limitation. The results obtained show that pollen deposition takes place at the female and male stages during the avocado flowering season and that the percentage of flowers with pollen on the stigma varies along the flowering season, probably due to changes in temperature that affect not only the floral behavior but also pollinator activity. However, no embryo or endosperm development took place when pollination occurred during the male flowering phase. Thus, the low number of pollen grains landing on the stigmas of female stage flowers observed under natural pollination conditions might not be enough to ensure a good yield. The production of an excess of flowers and subsequent flower drop of most of the flowers provides the opportunity of a selective fruitlet drop depending on the genotype of the embryo since fruits derived from outcrossing showed higher chances of reaching maturity. Moreover, an important competition for resources occurs among developing fruits and new vegetative growth, conferring importance to the time of flower fertilization for effective fruit set.

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Self pollination in peach

International Journal of Horticultural Science ◽

10.31421/ijhs/5/3-4/49 ◽

1999 ◽

Vol 5 (3-4) ◽

Author(s):

Z. Szabó ◽

J. Nyéki

Keyword(s):

Seasonal Variation ◽

Fruit Set ◽

The Self ◽

Male Sterile ◽

Proper Sense ◽

Fruit Species ◽

Self Pollination ◽

Hand Pollination ◽

The Usa

The peach is though considered to be a self fertile fruit species, also some self sterile and male sterile varieties have been registered. The latter type seems to be frequently met in Asian varieties, whereas in the USA and Europe, J. H. Hale and Flaminia are grown. The purpose of the present study was the assessment of fertility relations of peaches and nectarines grown in Hungary. The authors studied, since 1974, more than 100 different peach and nectarine varieties as for fertility relations, especially their autogamous or geitonogamous fruit set on isolated, i.e. bagged flowers at bud stage, then set free after blooming finished. Isolated flowers of some varieties were also self pollinated, artificially. According to the results the varieties have been assigned to four alternative groups. Self sterile varieties in the proper sense have not been found, but partial self sterility (less than 10% fruit set), self fertility (10 to 20% fruit set) and high self fertility (more than 20% fruit set on selfed flovters) was generally met. The majority of the varieties belonged to the last two groups, nevertheless. the rate of fruit set displayed seasonal variation, the maximum was in one case 89.9%. The purposeful self (hand)pollination of the isolated flowers increased fruit set, substantially. Varieties rated as partially self-sterile are J. H. Hale and Fuzador (the former being partially male sterile too). Although in some years and some varieties, fruit set legged below 10% but according to the means the majority of nectarines are assigned to the self fertile category whereas most peach varieties, either for fresh consumption or industrial types, were highly self fertile.

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Addition of Forchlorfenuron to Spray Pollination Media Increases Fruit Set in ‘Hosui’ Japanese Pear

HortTechnology ◽

10.21273/horttech.26.2.185 ◽

2016 ◽

Vol 26 (2) ◽

pp. 185-190

Author(s):

Daisuke Sakamoto ◽

Shinnosuke Kusaba ◽

Yuri Nakamura

Keyword(s):

Fruit Set ◽

Germination Rate ◽

Pollen Grains ◽

Fruit Production ◽

Fruit Shape ◽

Japanese Pear ◽

Pyrus Pyrifolia ◽

High Germination ◽

Hand Pollination ◽

Acceptable Method

The effects on fruit set of adding forchlorfenuron (CPPU) to media in which pollen grains were suspended and used for spray pollination was investigated in ‘Hosui’ japanese pear (Pyrus pyrifolia). The percentages of fruit set after spray pollination were lower than those after hand pollination; however, media with 2 or 10 mg·L−1 CPPU used for spray pollination resulted in greater percentages of fruit set than media without CPPU. The media with CPPU also resulted in higher levels of pollen germination compared with the medium without CPPU; however, the number of seeds per fruit with CPPU treatment tended to be almost the same or less than for fruit without CPPU treatment. From these results, the higher levels of fruit set by CPPU might not be due to the high germination rate of the pollen grains but due to the induction of partial parthenocarpic properties. The medium with 10 mg·L−1 CPPU gave the highest levels of fruit set, but the fruit had abnormally thickened and enlarged calyxes, and the fruit shape tended to be deformed at ≈21 days after flowering. In addition, all of the harvested fruit were calyx-perpetual fruit in which the calyx remains until harvest time. Fruit treated with 2 mg·L−1 CPPU also yielded calyx-perpetual fruit with high frequency, but the fruit had normal calyxes and the fruit shape tended to be more normal. Thus, we conducted experiments focusing on the medium containing 2 mg·L−1 CPPU. Although the results were variable from year to year, more than 70% of hand-pollinated flowers set fruit during the 3-year study; this level of fruit production is sufficient for practical use. Thus, spray pollination using a medium with 2 mg·L−1 CPPU is an acceptable method for pollinating ‘Hosui’ japanese pear.

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On the reproductive biology of Salacia fruticosa Wall. ex M.A. Lawson - an endemic medicinal plant of the Western Ghats, india

Journal of Threatened Taxa ◽

10.11609/jott.3069.10.15.13002-13005 ◽

2018 ◽

Vol 10 (15) ◽

pp. 13002-13005

Author(s):

K. Subin ◽

P. A. Jose ◽

T. V. Sarath

Keyword(s):

Reproductive Biology ◽

Fruit Set ◽

Pollen Viability ◽

Pollen Grains ◽

Seedling Bank ◽

The Poor ◽

Short Period ◽

Poor Seed ◽

Endemic Medicinal Plant ◽

The Western Ghats

Salacia fruticosa Wall. ex M.A. Lawson, an endemic species was studied for the reproductive biology as this species showed reduced fruit set and natural regeneration. The stigma-anther proximity, an extremely low number of pollen grains, a short period of pollen viability, a sparse incidence of pollinators, protandrous and facultative autogamous nature of the flowers and a low percent in fruit set were identified as biological constraints for the species. The incidence of seed pest was added to the poor seed and seedling bank and accelerated rarity process of the species.

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Determination of Blooming, Pollen and Fruit Set Characteristics in Punica granatum

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha47411216 ◽

2019 ◽

Vol 47 (4) ◽

pp. 1258-1263

Author(s):

Deniz AKSOY ◽

Zeynel DALKILIC

Keyword(s):

Fruit Set ◽

Pollen Viability ◽

Pollen Grains ◽

Punica Granatum ◽

Digital Object Identifier ◽

Self Pollination ◽

Beginning Of Flowering ◽

Male Flowers ◽

In The Beginning

The objective of this study was to investigate flowering, pollen, and fruit set characteristics of locally registered pomegranate cultivars between two consecutive years. ‘Dr. Ercan 35’, ‘Efenar 35’, ‘Kamilbey 35’, and ‘Tezeren 35’ cultivars have been developed by cross-breeding programs. Open-, cross-, and self-pollination studies were performed with these cultivars using three trees in each replicate in the field. Number of anthers per flower, number of pollen grains per anther, viability, and germination tests were conducted in the laboratory. Fruit set ratio of self-pollinated combinations were lower than open-pollination. The fruit set ratio from self-pollination was obtained from ‘Dr. Ercan’ (60.3%), ‘Efenar 35’ (62.4%), ‘Kamilbey 35’ (50.5%), and ‘Tezeren 35’ (25.2%). The highest fruit set ratio (49.7%) was obtained from ‘Kamilbey 35’ × ‘Dr. Ercan 35’ combination. The highest number of characteristics was as follows: ‘Tezeren 35’ (402 anthers/hermaphrodite flowers), ‘Kamilbey 35’ (8550 pollen/anther, male flowers in the beginning of flowering), ‘Efenar 35’ (84.7% pollen viability, hermaphrodite flowers), ‘Kamilbey 35’ (71.2%, pollen germination, hermaphrodite flowers). In conclusion, at least one, two or more, pollinator cultivars are necessary for commercial plantations using with these recently released pomegranate cultivars. ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

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Pollination and seed production in five boreal species of Vaccnium and Andromeda (Ericaceae)

Canadian Journal of Botany ◽

10.1139/b96-165 ◽

1996 ◽

Vol 74 (9) ◽

pp. 1363-1368 ◽

Cited By ~ 24

Author(s):

Heléne Fröborg

Keyword(s):

Seed Production ◽

Fruit Set ◽

Seed Set ◽

Coniferous Forest ◽

Natural Habitats ◽

Vaccinium Uliginosum ◽

Self Pollination ◽

Hand Pollination ◽

Understory Shrubs ◽

Fruit And Seed Set

Using experimental manipulations, I examined if pollen quality affected fruit and seed production in five ericaceous understory shrubs in a coniferous forest in central Sweden. Flowers of Vaccinium myrtillus L., Vaccinium uliginosum L., Vaccinium vitis-idaea L., Vaccinium oxycoccos Gil., and Andromeda polifolia L. were (treatment 1) open-pollinated, (treatment 2) bagged without further treatment, (treatment 3) bagged and self-pollinated, (treatment 4) cross-pollinated with pollen from neighbouring plants, or (treatment 5) supplied with pollen from distant plants. Finally, flowers were (treatment 6) open-pollinated with a supply of extra pollen of distant origin. To investigate pollen or resource limitations to fruit and seed production, V. vitis-idaea was subjected to partial flower removal followed by open- and hand-pollination. Fruit and seed set were estimated for each treatment. The main conclusion is that natural levels of outcrossing are sufficiently high for full seed production and that the availability of pollen is not limiting in natural habitats. There were significant reductions in fruit and seed set after self-pollination in V. myrtillus. Fruit set was reduced in V. vitis-idaea, and V. uliginosum failed to set fruit after self-pollination. Self-pollination caused a decreased seed set in A. polifolia. There was no significant variation across treatments in V. oxycoccos. Since fruits tend to develop regardless of seed number, resources are likely to limit seed production in species with costly fruits. Keywords: self-fertility, pollination, Vaccinium, fruit set, seed set.

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Facultative autogamy in Cyrtopodium polyphyllum (Orchidaceae) through a rain-assisted pollination mechanism

Australian Journal of Botany ◽

10.1071/bt07135 ◽

2008 ◽

Vol 56 (4) ◽

pp. 363 ◽

Cited By ~ 9

Author(s):

Ludmila Mickeliunas Pansarin ◽

Emerson Ricardo Pansarin ◽

Marlies Sazima

Keyword(s):

Fruit Set ◽

Floral Morphology ◽

Natural Habitat ◽

South American ◽

Stigmatic Surface ◽

Self Pollination ◽

Eastern Brazil ◽

Viscous Drop ◽

Plant Families ◽

Rainy Days

Cyrtopodium includes ~42 species, among which is Cyrtopodium polyphyllum (Vell.) Pabst ex F. Barros that occurs in a rainforest in south-eastern Brazil. Its non-rewarding flowers, which attract Centridini bees by deceit, are rain-assisted self-pollinated, a phenomenon rarely found in orchids and other plant families. In addition, self-pollination has never been reported in Cyrtopodiinae and data on the pollination of South American orchids are scarce. Flowers were observed at different times of the day, on both sunny and rainy days, to record floral morphology, visitors and the effects of rainfall on flowers. On rainy days, water accumulates on the stigma and dissolves the adhesive substance of the stigmatic surface. A viscous drop thus forms, which contacts the pollinarium. When evaporation makes the viscous drop shrink, the drop moves the pollinarium with the anther onto the stigmatic surface and promotes self-pollination. Fruit set in natural habitat was low, with 2.4% at one study site, where a similar value (2.2%) was recorded in flowers self-pollinated by rain. In C. polyphyllum, facultative self-pollination assisted by rain is thus an important strategy that guarantees fruit set when pollinator’s visits are scarce, which is common in species pollinated by deceit.

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