Factors affecting reproductive success in three entomophilous orchid species in Hungary

Abstract

The reproductive success of orchids is traditionally estimated by determining the fruit-set of individuals. Here, we investigated both the fruit and the seed production of three orchid species and the factors that may affect individual fruit-set, like pollination strategy, individual traits or the annual amount of precipitation. The species [Dactylorhiza sambucina (L.) Soó, Dactylorhiza majalis (Rchb.) P. F. Hunt & Summerhayes and Platanthera bifolia (L.) L. C. M. Richard] were studied in three consecutive years (2010)(2011)(2012) in the Bükk Mountains, Hungary. All three species were proved to be non-autogamous by a bagging experiment. Data analyses showed significant differences between seed numbers but not between fruit-sets of species. There was no statistical difference in individual reproductive success between wet and dry years, however, the effect of the annual amount of precipitation is significant on the population level. Comparison of published fruit-set data revealed accordance with our results in P. bifolia, but not in D. sambucina and D. majalis. We assume that the surprisingly high fruit-set values of the two Dactylorhiza species may be due to the fact that the pollination crisis reported from Western European countries is not an actual problem in the Bükk Mountains, Hungary.

No Evidence for Historical Declines in Pollination Success in Hungarian Orchids

“…pollination crisis has not occured in Hungary, at least until the end of the 20th century. Our results are in accordance with a recent paper of E. Vojtkó et al (2015) who also reported relatively high recent reproduction success of two deceit pollinated Dactylorhiza species in comparison to Western European data.…”

Management affects the pollinator abundance but not the reproductive success of butterfly orchids

“…Our research showed that the fruit set of P. bifolia and P. chlorantha did not differ in the study years. In all study years, the fruit sets of both species were in the range of fruit sets reported by other authors (Kindlmann and Jersáková 2006;Maad 2000;Maad and Alexandersson 2004;Nilsson 1983;Vojtkó et al 2015). The similarity in fruit set between the plant species with a contrastingly different number of pollinator species shows again that pollinator species richness does not seem to affect the reproductive success of butterfly orchids and in fact pollinator abundance may be of key importance, as several authors have shown in other plant species (Amorim et al 2014;Lowenstein et al 2015;Petanidou et al 2013).…”

“…Fruit set (the proportion of flowers which have developed into fruits) of P. bifolia and P. chlorantha varies to a great extent between years and populations (Kindlmann and Jersáková 2006;Maad 2000;Maad and Alexandersson 2004;Nilsson 1983;Vojtkó et al 2015) and is generally pollinator limited (Maad and Alexandersson 2004). While Mróz (2006) found no difference in fruit set between managed meadows and unmanaged road verges, Nakahama et al (2016) detected a negative effect of mowing during July-September on fruit set.…”

Analyses of sexual reproductive traits in Dactylorhiza majalis: a case study from East Germany

“…Since the mean fruitset of deceptive orchids was found to be only 27.7 % (Neiland and Wilcock 1998), whereas we registered in mean from 31.1 % to 69.3 %, it is unlikely that our studied D. majalis populations suffered from limited services of the pollinator insects. Moreover, we found no significant positive correlation between the numbers of flowers and fruits as has been described by Vojtko et al (2015) for D. majalis. The reason might be the fact that several flowering plants or their seeds disappeared in the nature before the fruit-assessment took placea phenomenon which can likely be explained by plant poaching.…”

“…III) The reduced embryo viabilitya trait likely attributable to possible inbreedingis also known to be an intrinsic genetic burden of allotetraploids hybrids under the condition of heterogeneic chromosomal recombination as pointed out at the start of the discussion. IV) Selfing, an extreme form of inbreeding, is unlikely due to the specific blossom morphology of D. majalis (Schoenichen 1940, experimentally shown by Vojtko et al 2015) and pollinaria bending (discussed in Ostrowiecka et al 2019). V) An elevated level of gene flow, counteracting possible inbreeding, will be expected with regard to the fact that the embryo is embedded into a surrounding scaffold of collapsed cork-like cells.…”