By John Brien, CCA,
AgriGold regional agronomist
From planting until pollination a corn grower is concerned about building their corn factory. The corn factories foundation is
corn roots, the stalks are the walls and the leaves are the machines that run the entire factory. The goal is to build the best, most
efficient factory possible and then turn it on line at pollination. The factory needs to be built to produce enough sugars to maximize
kernel development and grain fill. Currently our factories have been built and are running at full steam, the question now is can
our corn factories run too fast?
What is meant by a corn factory running too fast? At a car factory there is a pace of operation that maximizes production, too
slow and the company will eventually run out of money, too fast and the machines may breakdown or more likely the quality of
the product is sub par. Just like the car factory, a corn factory has a pace that maximizes grain production. Typically the factory
needs 60 days from pollination to black layer to produce a crop. If it takes 90 days to produce a crop, frost will prematurely kill
the crop and the quality will be poor. Likewise if the factory takes only 45 days to produce a crop, the yield of the crop will be sub par.
The driving force that keeps the corn factory running is heat units or growing degree units (GDU’s). GDU’s are accumulated
daily and the rate of accumulation determines how fast or how slow a corn crop grows. Last year the GDU accumulation was
slower than normal and the grain fill period was extended. The extended grain fill period resulted in high corn yields, but the
grain carried too much moisture for most growers. The 2010 growing season is a complete opposite and our GDU accumulation
is happening rather quickly.
What is undesirable about a rapid accumulation of GDU’s for a corn factories ability to produce grain? The rapid accumulation
of GDU’s has two negative effects on our corn factory. The first negative impact is the loss of sugar due to dark respiration.
Corn plants build sugars during the day through photosynthesis and then use some of those sugars at night for dark respiration.
The oversimplified process of dark respiration is the process of “burning” sugars for cell growth and maintenance at night.
Therefore take the amount of sugars produced during the day and subtract what sugars are used at night and what is left is used
by the corn plant to produce grain. Warm nightly temperatures over 70° greatly speeds up dark respiration and causes the excessive
burning of sugars that could have been used to produce grain. With less
available sugars can lead to less than desirable yield production.
The second negative impact of a rapid accumulation of GDU’s is the
shortening of the normal grain fill period. Instead of accumulating 20 to
22 GDU’s per day in a normal year, in 2010 the GDU accumulation has
been between 25 and 30 GDU’s per day. The massive difference in GDU
accumulation potentially could shorten the grain fill period from 60 days to
40 days. With potentially 20 less days to capture sunlight and produce sugars,
the kernels will not have enough time to maximize fill. The kernel count will
be high, but the individual kernel weight will be less, thus equating to a lower
yield potential had the corn plant had the additional 20 days to fill the kernels.
Currently the corn factories are running at full capacity and working
overtime. The final product is yet to be determined, but due to the speed
the factory is running, the gauges are telling us our product will not reach
its full potential.