2019 Update: Pollen addition and exclusion

Supplemental pollen — pollen that an Echinacea head might not otherwise receive—could increase a plant’s fitness. But does this extra pollination lead to a tradeoff in survival or flowering consistency? Since 2012, we have been manipulating the amount of pollen Echinacea plants receive – either no pollen, or lots of pollen – and recording how this affects their fitness and survival. In 2012 and 2013 we identified flowering E. angustifolia plants in experimental plot 1 and randomly assigned one of two treatments to each: pollen addition or pollen exclusion. The team bagged the heads of all plants and hand-pollinated the addition treatment, and did not manipulate the exclusion plants further. Plants receive the same treatment across years.

In summer 2018, 14 of the 26 plants alive in the pollen addition and exclusion experiment flowered, producing a total of 25 heads. This year none of those plants flowered. Of the original 38 plants in this experiment, 12 of the exclusion plants and 14 of the pollen addition plants are still alive. No plants died between 2018 and 2019. This year’s data were unique among the eight years of data collected, because not a single plant in the experiment produced even a single head. The dramatic decrease in flowering rates this year may help or hinder us in analyzing this data set and providing answers to this eight-year question.

Tris did not find significant demographic differences between plants which received pollen exclusion, addition or open pollination treatments.

Start year: 2012

Location: exPt1

Physical specimens: We harvested no specimens this year

Data collected: Plants survival and measurements were recorded as part of our annual surveys in P1 and can be found with the rest of the P1 data in the R package EchinaceaLab.

Michael presented a poster on the polLim experiment at MEEC 2019, which you can find here

Tris also presented a poster on polLim at MEEC 2019, which you can find here

You can find more information about the pollen addition and exclusion experiment and links to previous flog posts regarding this experiment at the background page for the experiment.


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