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Controlling Palmer amaranth reproduction using the sterile pollen technique

Controlling Palmer amaranth reproduction using the sterile pollen technique

This method helps reduce weed seed production

By Diego Flammini
Staff Writer

Researchers have found a way to manage weed seed production in weeds like Palmer amaranth.

A team led by Dr. Mohsen Mesgaran, an assistant professor of plant sciences at the University of California Davis, discovered that sterilizing pollen from Palmer amaranth helps reduce the number of weed seeds produced in future weeds.

“The pollen is sterilized using ionizing radiation,” Dr. Mesgaran told “But we are not killing the pollen. It’s still alive so it can germinate on a female plant, but the regenerative cell that fertilizes the weed is dead.”

A common example of ionizing radiation is X-rays.

A similar tactic is used with mosquitoes.

Male mosquitoes are sterilized then released back into nature. They mate with females, but the females don’t reproduce, thus helping control the population.

Dr. Mesgaran’s team conducted its initial research in a greenhouse.

The researchers collected pollen from the male plants and sterilized it in a lab.

They found that 300 units of ionizing radiation (Gy) is the optimal dose to sterilize the pollen. Too high of a dose would kill the pollen and too low of a dose doesn’t provide the proper sterilization.

For context, a chest X-ray produces about 0.0001 Gy of ionizing radiation.

Dr. Mesgaran’s team then used a drone to apply the sterilized pollen to the female plants using baby powder and/or wheat flour to help weigh the pollen down to ensure proper fertilization.

The results showed this process has the potential to reduce weed seed production in Palmer amaranth by up to 80 percent.

One Palmer amaranth plant can produce up to 250,000 seeds, the USDA says.

Using sterilized pollen could bring that number down to about 200,000 seeds.

“In some cases, nothing was produced,” Dr. Mesgaran said.

One of the challenges the weed presents, however, is how prolific it grows.

Palmer amaranth will continue to produce new branches and flowers, so multiple applications could be necessary, he said.

The next step in the research process is to test the sterilized pollen in a crop field either elsewhere in the state or another location where Palmer amaranth is present.

Another part of the research could see the development of a genotype where the weed is bred to produce sterile pollen, Dr. Mesgaran said.

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