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  • From: Lawrence London <lfljvenaura@gmail.com>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: [permaculture] Corn Variety Grabs Fertilizer from the Air - Scientific American
  • Date: Fri, 10 Aug 2018 14:25:17 -0400

Corn Variety Grabs Fertilizer from the Air - Scientific American
https://www.scientificamerican.com/podcast/episode/corn-variety-grabs-fertilizer-from-the-air/

Biology
60-Second Science
Corn Variety Grabs Fertilizer from the Air

- By Christopher Intagliata on August 7, 2018

A variety of corn from Oaxaca, Mexico, has aerial roots that harbor
nitrogen-fixing bacteria, allowing the corn to suck nitrogen straight from
the air. Christopher Intagliata reports.
Full Transcript
<https://www.scientificamerican.com/podcast/episode/corn-variety-grabs-fertilizer-from-the-air/#>

Plants need three things to grow: air, water and nutrients. Farmers usually
take care of the last bit by fertilizing their fields. But now scientists
have found a type of corn that seems to thrive on air and water alone.

"This has been sort of the holy grail, you know, if only I could grow corn
and not put 200 pounds of nitrogen on it." Allen Van Deynze is a plant
breeder at the University of California, Davis, and part of a team that
analyzed this one corn’s unusual ability.

The corn variety hails from Oaxaca, Mexico, where it typically grows in
nitrogen-poor soils. Nitrogen is needed for proteins, DNA and the
chlorophyll that let plants perform photosynthesis. But the Oaxacan corn
does well despite the bad soil, and with little or no fertilization.

The plants pull off this trick via thick, red, aerial roots that protrude
from its stem—above the ground—that ooze out a clear goo packed with
sugars. That slime is the perfect habitat for nitrogen-fixing bacteria: a
sugar-rich, oxygen-poor environment where the microbes transform nitrogen
gas into a soluble form the corn plant can use. It’s an above-ground
version of the nitrogen-fixation you might usually think of as happening in
the underground roots of legumes, like peas and beans.

The researchers demonstrated the corn plants’ talent by exposing them to
labeled isotopes of nitrogen. And they were able to track the movement of
the distinctly identifiable nitrogen atoms from the air, to the root, and
into the plant. This pathway allows the corn to obtain up to 80 percent of
its nitrogen straight out of the air. The details are in the journal *PLOS
Biology*. [Allen Van Deynze et al., Nitrogen fixation in a landrace of
maize is supported by a mucilage-associated diazotrophic microbiota
<https://doi.org/10.1371/journal.pbio.2006352>]

Van Deynze says early plant breeders may have inadvertently got rid of
corn’s nitrogen-fixing proficiency long ago. "When early man made some
selections for bigger ears, higher yield, perhaps they lost this ability
along the way. And we have the opportunity perhaps to bring it back."

—Christopher Intagliata

[*The above text is a transcript of this podcast.*]




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