Updated July 5, 2018:
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Investigating the Feasibility of Artificial Pollination as a Herbicide-Resistant Weed Management Tool
Michael J. Christoffers
Department of Plant Sciences, North Dakota State University
The problem of herbicide-resistant weeds in soybean production is well documented, and it is important that soybean growers have diverse tools to fight herbicide resistance. Artificial pollination is when pollen is purposefully applied to plants in order to supplement pollination that is occurring naturally. Using artificial pollination, the introduction of pollen from normal, herbicide-susceptible plants into resistant weed populations might help reduce the frequency of herbicide resistance. To speed reversion back to herbicide susceptibility, introduced pollen might even carry genes for new biological pest management strategies, such as gene drives. However, artificial pollination is poorly studied in weeds.
We performed artificial pollination experiments using a small birdsrape mustard plant that is often used for laboratory experiments in the plant sciences. Pollen from birdsrape mustard with purple stems was suspended in a solution that is known to keep pollen alive, and then the solution was sprayed onto the flowers of birdsrape mustard with green stems. We grew the resulting seed and checked for purple-stemmed plants, which would have indicated successful artificial pollination. We did not observe any purple-stemmed plants when pollen was sprayed, and only observed successful but inconsistent artificial pollination when flowers were dipped into the pollen-containing solution or dusted with dry pollen. This indicates that achieving artificial pollination using a pollen spray is difficult, and that dry pollen applications might have more potential.
If artificial pollination methods were improved and used in the field, herbicide-resistant waterhemp would be a likely target weed. We studied the ability of waterhemp pollen to be kept alive during storage at room temperature, in the refrigerator, and in the freezer. We found that waterhemp pollen remained alive for up to 2 weeks in all conditions, but died when stored at room temperature for at least 4 weeks. Pollen kept in the refrigerator or freezer for 4 weeks remained alive. These results suggest that waterhemp pollen to be used for artificial pollination could be stored for at least a month in a refrigerator or freezer prior to use. However, this result needs to be confirmed on a larger scale.
Our results show both the difficulty and potential of artificial pollination. Further development of this potential tool for herbicide-resistant weed management is needed before this and other new technologies are useful in the field, and currently recommended herbicide-resistant weed management practices remain the most important strategies for soybean producers.