Effects of parentage, prior fruit set and pollen load on fruit and seed production in Campanula americana L

Richardson, Thomas E.; Stephenson, Andrew G.

doi:10.1007/bf00323783

Cited by 54 publications

(56 citation statements)

References 38 publications

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“…In this species, the fruit set is significantly higher, but the weight of a single fruit and single seed is significantly lower in plants where flowers were removed compared with those without flower removal in control plants. Based on the findings that seed weight is positively correlated with its progeny vigor (Richardson and Stephenson, 1991), our results provide support for the "selective abortion hypothesis".…”

Section: Ecological and Evolutionary Implications Of Pollen And Resousupporting

confidence: 74%

Pollen and resource limitations to lifetime seed production in a wild population of the endangered plant Disanthus cercidifolius var. longipes H. T. Chang (Hamamelidaceae)

Ping

Xiao²,

et al. 2007

Front. Biol. China

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Disanthus cercidifolius Maxim. var. longipes H. T. Chang, a plant species that only occurs in a few counties in Hunan, Jiangxi and Zhejiang Provinces and with a relatively small number of individuals, is ranked as a second Class endangered species for conservation in China. We have studied the effect of pollen and resources available to female reproduction, and the reproductive mechanism of "excess flowers with low fruit set" in Disanthus cercidifolius Maxim. var. longipes H. T. Chang was discussed. Results are as follows:Pollen from different sources has significant effects on fruit set and seed set of Disanthus cercidifolius Maxim. var. longipes H. T. Chang. The pollen source rather than pollen numbers significantly affected reproduction of this species. In wild populations, producing one fruit needs about 54.8 flowers, and one satiation seed needs about 6.60 flowers or 83.19 ovules.After fertilizing, which was propitious to flower development, the abortion rate of flower buds was decreasing, but the flowering rate was increasing. The fruit set and seed set was also significantly increasing, while abortion rate of fruit was significantly decreasing. With the increasing percentages of cutting leaves, the fruit set decreased, but the abortion rate of fruit shows no significant differentiation among treatments. After cutting branches that were puny, broken and insectinfested branches, the flower number seemed to be decreasing, but the fruit set and seed set all increased significantly. After removing some flowers, the fruit set was calculated with respect to the number of flowers remaining after the treatment increased with increasing of percentages of flower removal, whereas fruit set calculated with respect to the initial number of flowers remained constant, and the mean weights of per fruit and per seed all decreased significantly.Sufficient spatial or temporal heterogeneities in nutrient levels might allow limitation of seed set by resources and pollen in a natural population, while supplying resources may indirectly affect pollination by increasing attraction of the flowers to pollinators. There were very low fruit and seed sets in natural populations of Disanthus cercidifolius Maxim. var. longipes H. T. Chang. Different factors may have interacted to effect a low fruit set. A joint adoption of the "selection abortion hypothesis", "ovary reserve hypothesis" and "male function hypothesis" seems to be the most likely explanation for the reproductive strategy of "excess flowers with few fruit sets" in Disanthus cercidifolius Maxim. var. longipes H. T. Chang.

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Section: Ecological and Evolutionary Implications Of Pollen And Resousupporting

confidence: 74%

Pollen and resource limitations to lifetime seed production in a wild population of the endangered plant Disanthus cercidifolius var. longipes H. T. Chang (Hamamelidaceae)

Ping

Xiao²,

et al. 2007

Front. Biol. China

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“…Many authors conclude that selective forces operate which lessen the interference of a plant's own pollen with its stigma(s) (Lloyd and Yates 1982;Richards 1986;Richardson and Stephenson 1991). In secondary pollen presenting taxa, a number of adaptations exist which reduce inter-sexual interference caused by the reduced herkogamy and which consequentially promote xenogamy.…”

Section: Reproductive Advantage Gained Tlzrough Secorzdary Pollen Prementioning

confidence: 97%

Secondary Pollen Presentation in Angiosperms and Its Biological Significance

Howell¹,

Slater²,

Knox³

1993

Aust. J. Bot.

107

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Secondary pollen presentation is the developmental relocation of pollen from the anthers onto another floral organ which then functions as the pollen presenting organ for pollination. Nine different types have been identified in sixteen angiosperm families according to which organ is used for presentation, whether the pollen is exposed or concealed within a structure and how pollen is loaded onto the presenting surface: (1) Enveloping bloom presenters (Araceae); (2) Perianth presenters with exposed pollen presentation (Epacridaceae); (3) Androecial presenters (Santalaceae); (4) Terminal stylar presenters with passive pollen placement and concealed stigmas (Rubiaceae and Proteaceae); (5) Terminal stylar presenters with passive pollen placement and sub-terminal stigmas (Marantaceae and Polygalaceae); (6) Terminal stylar presenters with active pollen placement (Asteraceae, Calyceraceae and Lobeliaceae); (7) Sub-terminal stylar presenters (Campanulaceae, Cannaceae, Fabaceae and Myrtaceae); (8) Exposed stigmatic presenters (Rubiaceae); (9) Indusial stigmatic presenters (Goodeniaceae and Brunoniaceae). Secondary pollen presentation occurs in three monocotyledon and thirteen dicotyledon families. The presentation types appear to have been independently derived indicating that secondary pollen presentation is a character with a selective advantage.In all but the enveloping bloom type of secondary pollen presentation, developmental relocation of pollen requires simultaneous, introrse anther dehiscence and a close association of the presenting organ to the anthers prior to anthesis.The various secondary pollen presentation systems may be modified to promote xenogamy or autogamy and this can even change during anthesis. Most plants which have secondary pollen presentation, display reduced herkogamy within the flower to facilitate pollination. Increased risk of self-pollination due to this may be overcome through dichogamy, herkogamy within inflorescences, dry stigmas, self-incompatibility systems and passive or active control over pollinator behaviour. Enhanced male function of the flowers of secondary pollen presenting plants is also evident through extension of the male phase by the protection, controlled release and precise placement and receipt of pollen. Plants displaying secondary pollen presentation are almost always protandrous.

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“…Seeds contained in each of the fruits collected were counted under a stereoscope. Given that a number of reproductive attributes, such as seed number and mass or flower and fruit abortion have been found to change over the course of the reproductive season (Stephenson 1981;Richardson and Stephenson 1991;Galloway 2002), counting and collection of fruits were carried out right after the end of the flowering period for each population.…”

Section: Data Collectionmentioning

confidence: 99%

Reproductive attributes of Campanula populations from Mt Olympos, Greece

Blionis

Vokou

2005

Plant Ecol

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We studied five reproductive attributes (fruit production and volume, seed content and weight, and seed germination) of different populations of Campanula species occurring along the elevation gradient of Mt Olympos, the highest mountain of Greece (2917 m), in order to examine whether and how they change with elevation, and if there are trade-offs among them. We also studied flower and fruit (reproductive) losses and population features in order to estimate whether there might be a threat to the survival of Campanula species on Mt Olympos. The genus is represented by nine species, ranging from cosmopolitan to stenoendemic. All species were found non-autogamous, and hence they depend on pollinators for their sexual reproduction. At the genus level, there is a trade-off between seed content per fruit and seed weight. At the species level, this is manifested only for C. glomerata, which produces the heaviest seeds, far exceeding all other species, and for C. spatulata, represented on Mt Olympos by two elevation distinct subspecies. Changes of the reproductive attributes are not continuous all along the elevation gradient at the genus level nor are they monotonic at the species level. Nevertheless, upland Campanula populations ( ‡1500 m) produce fewer fruits per individual, containing fewer but heavier seeds than lowland populations. This indicates a transition from 'r' to 'K' strategies, from low to high elevations, respectively. The patterns of change of reproductive attributes indicate prevalence of phylogenetic over environmental constraints. Laboratory tests showed that for many populations germinability is high at 15°C, but there are both inter-and intraspecific differences regarding temperature optima. Ecotypic variation among populations of the same species at different elevations was evident; populations from higher elevations had lower optima and vice versa. Reproductive losses, ranging from zero to over 90%, occurred mainly at the stage of fruit maturation; grazing by sheep and goats was the usual cause. Though such losses might affect the short-lived species (the annual C. sparsa and the biennial C. lingulata), which depend entirely on fruit maturation and seed dispersal for their reproduction, there does not seem to be a serious threat to the survival of Campanula species on the mountain.

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Effects of parentage, prior fruit set and pollen load on fruit and seed production in Campanula americana L

Cited by 54 publications

References 38 publications

Pollen and resource limitations to lifetime seed production in a wild population of the endangered plant Disanthus cercidifolius var. longipes H. T. Chang (Hamamelidaceae)

Pollen and resource limitations to lifetime seed production in a wild population of the endangered plant Disanthus cercidifolius var. longipes H. T. Chang (Hamamelidaceae)

Secondary Pollen Presentation in Angiosperms and Its Biological Significance

Reproductive attributes of Campanula populations from Mt Olympos, Greece

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