Detecting soil-surface ozone early can help prevent damage to grapes and apples

Date:
September 8, 2020
Source:
University of Massachusetts Amherst
Summary:
Farmers and fruit growers report that climate change is leading to
increased ozone concentrations on the soil surface in their fields
and orchards, which can cause irreversible plant damage, reduce crop
yields and threaten the food supply. A ne method of vapor-depositing
conducting polymer 'tattoos' on plant leaves can accurately detect
and measure such ozone damage, even at low exposure levels.



FULL STORY ========================================================================== Farmers and fruit growers are reporting that climate change is leading
to increased ozone concentrations on the soil surface in their fields
and orchards -- an exposure that can cause irreversible plant damage,
reduce crop yields and threaten the food supply, say materials chemists
led by Trisha Andrew at the University of Massachusetts Amherst.


========================================================================== Writing in Science Advances, co-first authors Jae Joon Kim and Ruolan Fan
show that the Andrew lab's method of vapor-depositing conducting polymer "tattoos" on plant leaves can allow growers to accurately detect and
measure such ozone damage, even at low exposure levels. Their resilient
polymer tattoos placed on the leaves allow for "frequent and long-term monitoring of cellular ozone damage in economically important crops such
as grapes and apples," Andrew says.

They write, "We selected grapes (Vitis vinifera L.) as our model
plant because the fruit yield and fruit quality of grapevines decrease significantly upon exposure to ground level ozone, leading to significant economic losses." Ground-level ozone can be produced by the interaction between the nitrates in fertilizer and the sun, for example.

UMass Amherst viniculturist Elsa Petit, who advised the chemistry
team, says the sensor tattoo could be especially useful to the grape
industry. "With climate change, ozone will increase and this new sensor
might be extremely useful to help farmers act before the damage is
recognizable by eye," she says.

Ground-level ozone can be mitigated by early detection and treating the
soil surface with charcoal or zeolite powders.

As Andrew explains, her lab, funded by the National Science Foundation,
adapted the electrode vapor-deposition method they had developed earlier
to coat fabrics for medical sensing devices for a new use -- on living
plants. The conducting polymer film, poly(3,4-ethylenedioxytiophene),
PEDOT, is just 1 micron thick so it lets sunlight in and does not hurt
leaves. Non-metal, carbon-based polymers that act as conducting electrodes
are increasingly used in soft materials design since they were invented
in the 1970s, she adds.

"Ours acts like a temporary tattoo on a human," Andrew says. "It doesn't
wash away and the polymer's electrical properties don't degrade,
even over a long time. We have some tattooed plants in a greenhouse
on campus and a year later they are still growing fine, putting out
roots and leaves as normal." To test for early ozone damage, she and colleagues use a hand-held impedance spectrometer adapted from human
medical practice. When it touches the electrode tattoo, a read-out
reports the electrical resistance vs frequency relationship.

This voltage value changes in the presence of various factors, including oxidative damage from ozone.

Andrew says, "You get a wave-form image; a software program fits the
wave so we can extract certain tissue parameters. We can recognize
patterns for different kinds of damage. It's consistent and remarkably accurate. If you use it on the same plant over a year, as long as
the plant is healthy the signal doesn't really change over that time."
"The problem scientifically is that visual ozone damage looks exactly the
same as if you watered the plant too little or it got too much sun. This project became intellectually interesting to us when we looked at the
ozone signature of our read-outs and it was very different from drought
or UV damage. Ozone produces a unique change in the high-frequency
electrical impedance and phase signals of leaves." The scientists hope
their invention could be used by farmers and fruit growers who could
place a few "reporter plants" among crops to periodically monitor soil
ozone levels. "It gives you a picture of what is going on in your soil,"
Andrew suggests. "You can be alerted if the fertilizer level is wrong,
for example. This can happen, especially with food crops that need a
lot of sun and fertilizer to produce, like melons, grapes and orchard
fruits. Some plants are very sensitive to it."

========================================================================== Story Source: Materials provided by
University_of_Massachusetts_Amherst. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Jae Joon Kim, Ruolan Fan, Linden K. Allison, Trisha
L. Andrew. On-site
identification of ozone damage in fruiting plants using
vapor-deposited conducting polymer tattoos. Science Advances,
2020; 6 (36): eabc3296 DOI: 10.1126/sciadv.abc3296 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200908131032.htm

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