Selecting corn hybrids has become a daunting task. The selection of top-notch genetics has been made even more complicated due to the myriad of traits that accompany these newer genetics.
There's a lot on the line. Consider that just within various university yield trials, the difference between the top-performing hybrids and those that don't fare as well can be considerable. At the University of Wisconsin, corn yield variance in trials has been as much as 70 bu. Ohio State's trials showed a 60-bu. difference top to bottom, and the University of Illinois yield variance was up to 50 bu.
“In most of our yield trials, we are on better-than-average fields, and in recent years we have had high yields in the 250-bu. range,” says Emerson Nafziger, Extension agronomist at the University of Illinois. “That means that most of the hybrids yield well. Still, the differences from top to bottom can be striking.”
Experts caution that simply looking at yield data, or even selected yield data, when selecting hybrids can be a risky proposition. “Somewhere in the selection process, hybrids entered into university trials have performed well,” says Peter Thomison, professor of horticulture and crop science at Ohio State University. “Truth is, hybrids react differently depending on the growing environment, which makes hybrid testing so difficult. A hybrid that's exhibited outstanding performance at one location in one year may be at the bottom of the trial data the next year.”
And further complicating the selection process is the short life a hybrid may have in field trials. “Our recommendations have always been to look at hybrid performance over at least a three-year period,” Thomison says. “But in our trials, we have less than 20% in the trials for more than one year, and only 3% have been in the trials for three years. The half-life of a hybrid isn't that long, and if you wait for multiple years of data to compare, that hybrid may not be available.”
Nafziger says that lack of multiple-year comparisons is evident in the published results. “As you look down the data, there are a lot of blanks in the two-year and three-year averages,” he says.
MULTIPLE-YEAR DATA help identify how a hybrid performs under multiple environments. “That's the real value in yield trials,” Nafziger says. “But since most aren't entered for more than one year, we plant them in several locations within each year to show how hybrids consistently perform.”
A hybrid that performs well under stressful growing conditions may not necessarily perform the best under optimal conditions. And those top-yielders under ideal growing conditions may fall flat if conditions don't cooperate.
But Nafziger cautions that university trials also have some limitations. “There is no way that our 12 trial sites can reproduce all the variability producers face in Illinois,” he says. “We repeat the tests, and the more data we have of a hybrid performance gives us more confidence to know how that hybrid will perform.”
Caution is warranted here, as well. “The difference between a single hybrid's performance at one location and its performance at another is due to environmental effects and random variability,” Nafziger says. “Add to that the fact that the genetics will perform differently in each environmental condition.”
“THE PRIMARY SOURCE of data for hybrid selection must come from an unbiased source,” says Roger Elmore, Extension corn agronomist at Iowa State University. That's not to say that other data shouldn't be excluded, “but private trials should not be the only source of information used. The strength of university trial results is that they compare hybrid performance over several sites.”
And seed companies have a vested interest in ensuring their hybrids perform. “One thing our trial data doesn't do is give a farmer individual attention,” Nafziger says. “Our trials are a come one, come all, and farmers can see how hybrids perform against each other. But seed company representatives will know more about an individual hybrid than these trial results will ever show.”
That includes knowing which hybrids are best for specific growing conditions on the farm. “There really aren't many bad hybrids out there, but some may not do well in certain conditions,” Nafziger says. “There's always the potential for an outstanding hybrid not to perform well, and for one location that isn't unusual.”
Meshing various data will help smooth out the variables and give a clearer picture of exactly how that hybrid will perform. “We can't predict next year's growing environment,” Nafziger says. “But having data from more than one location, even if locations are many miles apart, does a better job of predicting future hybrid performance than a single location.”
HYBRIDS PERFORM differently based on geography, soils and environmental stresses throughout the growing season. “So it's imperative to choose hybrids based on their consistency of performance,” Thomison says. While transgenic traits have become the norm in a seed company product catalog, yield variation still occurs in these high-priced hybrids. “Our tests have shown that while stacked trait hybrids can have the highest yields in our trials, they also can have the lowest,” Thomison says. “Several conventional hybrids have produced yields that weren't significantly different from top-yielding transgenic hybrids.” However, he notes that less than 10% of the hybrid trial entries in Ohio were conventional hybrids.
“Choosing a hybrid just because it has the latest traits does not ensure high yields,” Thomison says. “Those genetics still need to be put in the right environment.”
The bottom line: No seed company can survive selling bad hybrids. “The seed industry is highly competitive, and competition for market share has never been more intense,” Nafziger says. “So companies want to put the best products out there. It's up to producers to select which hybrids will work on their farm.”
THE HYBRID SELECTION PROCESS
With bushels on the line, and more choices than ever, hybrid selection can be a daunting task. Peter Thomison offers these steps:
Match maturity ratings with geography. Short- or mid-season hybrids may be a better choice than full-season hybrids, especially when you factor in expensive drying costs.
Look for consistent yields across a number of locations. Today's hybrids can perform very well in perfect conditions, but evaluating how hybrids perform in a variety of conditions can point you to more hybrids that are more stable if Mother Nature doesn't cooperate.
Good stands mean standability. If you're drying in the field, look to hybrids with a low stalk-lodging percentage.
Disease resistance. Different hybrids react differently to disease pressure. Ask questions on how your hybrid selections have reacted to various disease pressures.
Data, data, data. The more data available, the better you can see how a hybrid performs year-in and year-out. Choosing a hybrid based on one location, or one data set, can be a dangerous proposition.