Urbana, Illinois
March 16, 2009
By crossing maize plants adapted
to the tropics with lines used as parents of popular Midwestern
corn hybrids, researchers at the
University of Illinois have developed a new type of plant
with the potential to yield three crops and use less nitrogen.
Sugar corn can be harvested for the grain, the sugar inside the
stalk, and for biomass to produce energy.
Crop scientist Fred Below and plant geneticist Stephen Moose
wanted to develop a corn plant that would produce competitive
amounts of biomass while using less nitrogen.
“Nitrogen is a big cost for farmers and there are environmental
issues, so we wanted to be able to reduce the nitrogen needed,
while increasing the biomass,” Moose said.
Moose and Below recognized that there is a lot of interest in
growing switchgrass and miscanthus as alternative fuel sources,
but more research needs to be done to make it a viable crop
choice for Midwest farmers who are currently growing corn.
“If you’re going to grow miscanthus for biomass, we thought,
well, what about corn?” Moose said. “We found that the amount of
nitrogen needed for efficient biomass production is a lot less
than growing it as a grain crop. So, you can get more tons per
acre of total biomass with less nitrogen by growing these kinds
of lines.”
Moose explained that these tropical temperate hybrids have
delayed flowering and greatly reduced seed set, yet still
accumulate a lot of carbon—sugar basically – and no where to go
with it because it has been programmed to put it in the ear.
“So, a key thing about what we did is that we crossed the
tropical line with a line that would be grown here – a popular
U.S. kind of line. What we’ve done is we’re bringing together
the benefits of more than 50 years of intensive breeding for
higher grain yields in temperate environments with the delayed
flowering effects from the tropical lines, which gives these new
varieties the biomass potential – it’s got the best of both.”
Moose said that when you grow these lines in this temperate
climate, they have reduced seeds so you get lower yield of
grain. But if you go total biomass – the total amount of mass
produced per acre, it’s much higher than you would get with a
grain crop.
The yields of this new corn, even under low nitrogen, beat the
record for switchgrass yields in the Midwest.
“These plants are massive. They have big stalks, and unlike
normal corn where stalks become hollow as they supply the grain
with nutrients, these corn stalks are all filled up inside with
sugar. Our initial observations on small plots during the past
few years were promising. So, in 2008 we expanded the size and
locations of our tests for yield of corn grain, sugar and
biomass – so that we would have better data for comparison.”
Some varieties of sugar corn have been tested at Illinois
research stations in DeKalb and in Dixon Springs and there were
big differences. “In the north, the flowering and the maturity
suppressed even more. And in the south, it’s less, so you get a
lot more grain. They were actually pretty good grain hybrids in
Dixon Springs. The days are warmer and slightly shorter there,
so it had less of this suppressing seed effect,” Moose said.
Moose concedes that if grain is what you want, sugar corn isn’t
the answer. The grain yield from sugar corn might make a
suitable livestock feed. “What’s happened over the years in
selection for higher grain yield, we’ve worked toward making a
plant that’s all grain and produced on a single ear relatively
high on the plant so that the combine can easily get it off. But
it takes a lot of energy for the plant to make the grain and it
actually isn’t as efficient in the big scheme --- but obviously,
if grain is what you want then that’s what’s done.”
The advantages of sugar corn are the high biomass and the
sugar-filled stalk. “Initially, we noticed the high biomass and
the sugar increase. The idea is that this corn could be like a
temperate sugar cane – that can be grown in non-tropical
environments, like the U.S. Corn Belt. So you could grow this as
an annual crop and harvest it for its sugar and biomass just
like they do in Brazil for sugar cane.”
“If biomass is what you want, then this corn might be better
than the corn we currently grow because it needs less nitrogen
and it accumulates sugar. If you harvest at the right time, it’s
almost like harvesting sugar cane – the amount of sugar in the
stalk is like sugar cane.” They calculated that there is six
times the amount of sugar in the stalk of this newly developed
corn and could produce about 200 gallons of ethanol per acre.
The problem right now is: where’s a market for it?
In Brazil, they grow sugar cane to make ethanol and burn the
rest for electricity. “There are at least two companies in the
United States that are interested in Brazil’s sugar cane model
and want to build plants that co-generate ethanol and
electricity,” Moose said. “They’re looking at sweet sorghum as
their source material and this corn is very much like sweet
sorghum.
“But with sugar corn, we could even make a Bt, a Round-up ready
version of it. Biotech traits are not yet available for sorghum,
and total biomass is probably not as high, because they were
developed for the molasses, not the biomass.”
Funding for this project was provided by the University of
Illinois and the National Science Foundation. |
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