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"Seed the Day" by: Matthew Holm (Research/Penn
State, Vol. 17, no. 1 (March, 1996))
On his porch, surrounded by plants and blooms from around
the world, Norm Deno tells me how, when he retired from his
chemistry professorship about 15 years ago, he went down to
the library to see what had been written about his lifelong
hobby, seed germination. He felt -- as he says, like Darwin
at the Galapagos -- that everyone in the field had somehow
gotten it completely and utterly wrong. "My only choice,"
he says, "was to do the whole field over.
"The problem all plants have, that most botanists have
overlooked," he says -- and he's tested more than 6000
species of plants -- "is keeping the seeds from
germinating." My first reaction is that this energetic,
eccentric, 70-something man has his statement backwards.
But then I look at his yard and see the ease with which
the wildflowers have devoured the land, staring lawn-care in
the face and laughing. Deno's yard is a testament to many
things -- the beauty of nature, the haziness between the
terms weed and flower -- but especially to the need for a
plant to disperse its seeds. "You don't want the seeds to
start growing in the follicle," Norm says, and I can see his
point -- it would be rather embarrassing (if not fatal) for
seeds to germinate before they're off the branch. Plus, he
adds, they need to wait for the right growing conditions
once they hit the ground.
Deno's approach to seed germination -- the one that
turns the field on its head -- is that seeds have chemical
inhibitors to prevent germination. No seed can grow until
these blocks have been destroyed by things like temperature
changes, moisture, and sunlight. These conditions combine
in nearly infinite ways, making each plant's germination
needs different. Of course, when you know what the proper
conditions are, you can break down the barriers relatively
quickly and easily -- this is why you can plant Burpee seeds
straight from the envelope (where they have waited in dry
storage for several months) and have sprouts in a few weeks,
and why you can "force" a crocus to bloom in February by
keeping the bulb in your cool, dark garage and then moving
it to a sunlit windowsill.
To test his inhibitor theory and catalogue the
germination patterns of thousands of seeds, Deno employed
some of the most powerful tools of modern science: a small,
brown, dormitory-style refrigerator, moist paper towels, and
polyethylene sandwich bags. His mighty home lab sports a 6-foot long workbench, a row of unfinished plywood shelves,
some fluorescent lamps, and miscellaneous fly-fishing tackle
-- a far cry from the gas chromatographs, mass
spectrometers, ultraviolet and infrared lights of his
chemistry days at Penn State, but it's all he needed to
redefine thought about seed germination.
In less than two years, his self-published, 242-page
book (printed by Kinko's Copy Center, no less), Seed
Germination Theory and Practice, has sold more than 8,000
copies without any advertising whatsoever -- Simon and
Schuster, eat your heart out. Norm gets boxloads of mail
every day, from people asking him to try out some
interesting seeds, solve a tricky germination problem in
South Africa, or send them his book. "For $20, I'll get it
to you anywhere in the world, postage-paid," he grins.
Deno unashamedly acknowledges his success in the field,
accrediting it to good science. "One of the biggest
mistakes experimenters made in the past," says Deno, "was
not controlling for the fungi in the soil," -- hence the
moist paper towels and plastic bags, which make for a
sterile, controlled environment. The fungi are significant
because they, too, can break down the chemical inhibitors.
Deno tells of a cactus that will only germinate in the
presence of a fungal chemical called a gibberellin
(gibberellins, of which only 3 of 70 known types appear to
affect plants, are not well understood). "Here you have
this tiny seed, with a tiny speck of a root, in the middle
of this huge, dry desert," he says -- if the seeds germinate
just anywhere, they'll surely die and the parent cactus will
be left with no offspring. "What it needs, then, is a
pocket of moist leaf mold," says Deno. "It drifts around
and will only germinate when exposed to that gibberellin,
produced in that pocket of mold, where it can get a start."
This ingenious twist of natural selection demonstrates
just one of the six main ways that inhibitors are destroyed.
Along with the gibberellins go exposure to sunlight, dry
storage (this works for most seeds, including all of our
grains), moist storage at 70 degrees F, moist storage at 40
degrees F, and the puncturing of the seed coat.
This last method -- removing a physical rather than
chemical block -- is the least common, used by only 5% of
all species. But Deno, of course, has some of these seeds
as well -- he picks a Kentucky Coffee Tree seed pod off the
ground (his yard is littered with vegetation in various
states of growth and death, including a spectacular 150
different species in bloom -- just today) and tears it open,
exposing the smooth, dark, walnut-sized seeds that lie in a
sticky, sickly yellow paste.
"Raccoons carry these pods away, then eat the sweet
stuff inside," Norm says, offering me a taste. I dab my
fingertip in the goo, then touch it to my tongue, where the
initially sweet flavor soon fades into a persistent
sourness. As Norm warns, "Not too much -- I think it's got
toxins," I'm reminded of underripe banana.
As the raccoons take their treat home, they also
disperse the seeds. The seeds themselves, which look like
they would require a few good hours with a hammer and a
tungsten-carbide drill to open, won't germinate until heat
expansion and contraction finally crack the shell in another
5 to 10 years. "They can be viable for over 150 years,"
says Deno.
Dropping the seed and leaving it to its decades-long
journey, he ambles along the winding, rocky path through his
sloping backyard. Common and endangered plants vie for soil
and sunlight in a manner that would make a conservationist
cringe. "I went to a Sierra Club meeting," Deno says,
shaking his head. "Once." At the meeting, he recalls, the
club members spoke for five minutes about the disappearance
of the lady slipper orchid, then spoke for 45 minutes about
the need to plant trees.
"Reforestation is the single worst thing for a lady
slipper like the Queen's lady slipper or the small white
lady slipper," says Deno. "Encroaching trees rob the orchids
of the sunlight they require." Under a large power line
junction in Ohio, where every spring the earth is
intentionally burned free of brush and weeds, the white lady
slipper still covers acres. The snow orchis grows in the
Bennett bogs in New Jersey, Deno notes, because farmers mow
the marsh in June, allowing sun to reach the plant's ground-hugging rosettes. A rare gentian in Centre County is found
only along the roadside where the road crews mow. "Many rare
species of flowers exist only because of man's
interference," Deno says. "Without this, some of them would
probably be on their way out."
Deno's approach to conservation is realistic -- not
everyone can be responsible for saving all species
simultaneously. He waves at a patch of dry brown foliage
where he has killed some flowers with Roundup, saying, "My
wife and I encourage a species to grow some years, then cut
it back other years." In his garden, everything gets its
fair turn. "If you want to preserve a species, then I think
you need to set aside an area and just concentrate on that
one alone," he says. I am reminded of the hundreds of
thousands of seeds he has worked on and the hundred or so
more that await preparation later today as he tells me, "You
just have to take things one at a time."
Norman Deno, Ph.D., is professor emeritus of chemistry in the Eberly College of Science,
139 Le Nor Dr., State College, PA 16801; 814-238-8770. Matthew Holm is a
former writing intern at Research/Penn State.
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