Lanzino M, Palermo A M, Pellegrino G
Department of Biology, Ecology and Earth Sciences, University of Calabria, Cosenza, Italy.
Plant Biol (Stuttg). 2023 Apr;25(3):396-402. doi: 10.1111/plb.13505. Epub 2023 Feb 20.
Inflorescence display size and flower position on the inflorescence play important roles in plant reproduction, in the formation of fruits and are primarily linked to pollinator behaviour. We used three orchids to determine how visitation rates and choice of pollinator depend on number and position of the flowers along the inflorescence. We measured reproductive success in (1) natural conditions, (2) hand-pollination experiments and (3) an experimental design, by modifying composition of inflorescences in populations of two deceptive orchids, Orchis anthropophora and O. italica, and one rewarding orchid, Anacamptis coriophora subsp. fragrans. There were no differences in natural fruit production in relation to flower position on the inflorescence (i.e. upper versus lower part), suggesting no preference of pollinators for different parts of the inflorescence. Hand-pollination experiments highlighted low pollen limitation in A. coriophora subsp. fragrans but high limitation in O. italica and O. anthropophora. Reproductive success of deceptive orchids in experimental plots decreased significantly when flowers on the upper half of the inflorescence were removed leading to reduced floral display, while reproductive success of the nectariferous species did not differ significantly. Our data highlight that in the examined orchids there is no clear relationship between fruit formation and flower position along inflorescences. Thus we can affirm that, for orchids, the entire inflorescence plays a dominant role in insect attraction but the part of the flower spike does not influence the choice of the insect. This implies that all flowers have the same possibility of receiving visits from pollinators, and therefore each flower has the same opportunity to set fruit.
花序展示大小以及花在花序上的位置在植物繁殖、果实形成过程中起着重要作用，并且主要与传粉者行为相关。我们使用了三种兰花来确定访花率和传粉者的选择如何取决于沿花序的花朵数量和位置。我们通过修改两种欺骗性兰花（意大利红门兰和拟兰）以及一种有报酬的兰花（香花红门兰亚种）种群中花序的组成，在（1）自然条件下、（2）人工授粉实验和（3）一种实验设计中测量了繁殖成功率。在自然条件下，果实产量与花序上花的位置（即上部与下部）无关，这表明传粉者对花序的不同部分没有偏好。人工授粉实验突出显示，香花红门兰亚种的花粉限制较低，而意大利红门兰和拟兰的花粉限制较高。当去除花序上半部分的花导致花序展示减少时，实验地块中欺骗性兰花的繁殖成功率显著下降，而有花蜜的物种的繁殖成功率没有显著差异。我们的数据表明，在所研究的兰花中，果实形成与沿花序的花的位置之间没有明确的关系。因此我们可以肯定，对于兰花来说，整个花序在吸引昆虫方面起主导作用，但花穗的部分并不影响昆虫的选择。这意味着所有的花都有相同的可能性接受传粉者的访问，因此每朵花都有相同的机会结果。
