If you plant three versions of the same hybrid side-by-side, two versions each containing different traits and the parent version, can you pick them apart? The answer after looking at 60 hybrids in the Farm Progress Corn Illustrated plots seems to be yes. There are obvious similarities, but there can be basic differences too.
Jim Facemire, Edinburgh, cooperator of the plot, helped Dave Nanda, Corn Illustrated consultant and president of Bird Hybrids,
A rating of a 1 meant near perfect, with higher numbers meaning less performance. Basically, Facemire was analyzing "Would I want to try this on my acres?" On more than one occasion, they encountered different versions of the same hybrid, planted side-by-side. Often the rating ended up the same, but not always. Facemire and Bechman, who combined to do the actual ratings, didn't know the background of the hybrids, other than maturity in days ratings, when they announced their ratings. Nanda simply recorded the ratings assigned.
There were instances where one version would receive a '3' and another a '4' for example. Once they knew the hybrids were similar, Facemire and Bechman looked for visual differences as well as similarities. In one case, the most obvious difference was leaf width. One hybrid obviously put on wider leaves than the other, even though base genetics were the same, and they shared everything except a certain trait.
Or do they? That's the point, Nanda says- when genes are introduced, it's not a 'cut and splice' in one gene operation. Other genes come along, for better or worse. Sometimes it doesn't matter, but sometimes genes may come along that confer qualities not as good as the original.
"That's why backcrossing several times after inserting genes or making crosses is so important," Nanda stresses. "It's not something easily explained unless you understand genetics. But what it amounts to is that most things happening within a plant, especially related to yield, are not one-gene traits. When you introduce a new trait, several genes go along, not one. It takes backcrossing selection to remove the 'junk' that came along.
Nanda contends that's why new introductions sometimes get off to a rocky start the first year. The other factor, of course, is that a new trait may only be introduced in limited genetics the first year or so. As time goes along, breeders are able to work it into a wider array of products, perhaps some with better yield potential, or products that work well over a broader area of the country.
Take-home message form the hybrid comparison portion of the Corn Illustrated plots is that two hybrids, one with a trait and one not, otherwise supposedly the same, still aren't necessarily identical.