Selecting the right pressures to apply during breeding can result in seed varieties that resist insects and drought, that find their own nutrients, and that outcompete weeds and cover crops
Conventional corn — by which I mean corn that is not genetically modified — is the future of corn production. It can be grown anywhere without restriction. No one questions the health and safety of its consumption. And anyone can breed their own.
The beauty of independent breeding programs is that each is a little different. If you gave different breeding programs the same starting material, the resulting commercial inbreds developed after a decade or so would all be different — each with its own unique traits (by “traits,” I simply mean “characteristics” — not GMO traits).
Those traits in the final inbred or hybrid depend on the selection pressure that the breeder uses. If you grow your breeding material in a place with a lot of disease pressure and only keep seed from plants that are disease-free, you will have disease-resistant plants in future generations — provided 1) you have plants that survive (you can kill them all by doing this) and 2) it’s a trait that is heritable (able to be passed on into future generations).
Insect Tolerance
Native insect tolerance does exist in corn. Breeding for native insect tolerance is where we started with our own breeding program.
We do our insect breeding work in Puerto Rico, where insects are plentiful and temperate-climate corn is a tasty snack. It takes approximately 90 days to grow a temperate corn crop in Puerto Rico, and in that time we budget spraying for insects 21 times. We do not take three-day weekends because you can lose a crop in three days.
Image 1 shows a no-spray nursery where we were evaluating different lines for insect tolerance. The tall one on the left has more insect tolerance than the one on the right, where the growing points are eaten. Beginning this kind of work is not for the faint of heart.
The first nurseries where we tried this were very ugly (Image 2). Once you get through it, though, you can find some really good corn with higher levels of insect tolerance. The descendants of these surviving plants are in commercial hybrids in our lineup today, and they carry that insect tolerance.
Native insect tolerance in corn involves several different modes of action. One is physical non-preference — the corn plant is so uncomfortable, due to the numerous hairy trichomes, that the insects move on to other plants. Another method we have seen is increased sugar content. A little bit of feeding on the plant can cause the sugar levels in the plant to spike, and the insects move on because they do not like the increased sugar.
Feeding on the plant that triggers a response within the plant (e.g., increased sugar or other metabolites) is quite common with native tolerances. The plants do not go into more aggressive protection mode until they have a reason to. This is an efficient way of operating that is advantageous to the plant: energy is not spent on protection from insects until it is needed. I don’t put on insect repellent until I get bitten a few times, either.
Drought Tolerance
Stress does not exist in a vacuum. When we breed for drought tolerance, we also incorporate heat tolerance and insect tolerance, because we do this work in Puerto Rico. We also have drought and dry weather sometimes in our Olivia, Minnesota, nurseries, and we select for it there, too. However, we get more consistent pressure in Puerto Rico. We do not ignore that, instead using those tougher conditions to our advantage to breed tougher corn.
In PR, all our corn nurseries are grown with drip irrigation. This makes it easy to control the amount of water we apply to a crop. Usually we water until there is uniform emergence; after that, we vary when and how much water we apply per field so that we do not inadvertently select for plants that can only tolerate water stress at a particular point in their lifecycle.
Image 3 shows a recent drought-selection nursery with intentional insect damage. Image 4 shows the seed harvested from the four 400-foot-long rows with tassel bags on the left in Image 3. Ouch. But that’s forward progress!
When you limit water in a system where most of your fertilizer is applied through the irrigation, you also reduce the amount of fertilizer applied to your crop. If you do this in a research field, you can make selections for plants that are more efficient with the nutrients they have — or you can select for those that get the nutrients they need via soil biology.
Biological Boost
A key part in developing multi-stress-tolerant corn is not using anti-microbial seed treatment during development. Whether we are planting into cold soils, insect-prone soils, corn-on-corn soils, wet soils, or any other condition, we do not use seed treatment during the development process. Our development nurseries never get seed treatment. Our hybrid development trials only get seed treatment at the end; the first four levels of hybrid testing are all untreated seed. This kind of development leads to healthier seed that is better able to fend off any pathogens in the soil.
Development work with untreated seed also encourages the plant to work with existing beneficial microbes. I am not too proud to say this was an accidental discovery. When we started testing biologicals and growing trials in regenerative/biologically active fields, we noticed that the hybrids we developed responded a little bit differently than hybrids developed in a more industry standard way. They tended to be a lot more biology friendly.
When the literature started being published about aerial corn roots that appeared to be working with microbes, we understood what was going on.
Cover Crop Friendliness
The groundcover in Image 5 is not an intentional cover crop. Those are weeds.
If in a corn field you select plants that can grow through weed pressure, do you think that those same plants (or their progeny) would be well-suited for growing alongside a cover crop? Our data is saying so.
Besides just the weeds, we have found farmers who grow cover crops who are willing to let us grow yield trials on their farm, so we have been able to make hybrid selections now in actual cover crop scenarios. We also just rented a new farm where we plan to put in cover crops ourselves so we can do multi-year trials in the same area.
Breeding Works
Can conventional, non-GMO corn solve all our problems? No, it cannot. However, I do think that conventional can do a lot more than most people give it credit for.
We (myself included!) have been under the influence of one heck of a marketing campaign for 30-plus years now when it comes to GMO corn (and GMO crops in general). Back in the ’90s, I was writing papers about how genetic engineering could be so beneficial to the world because of everything it could do. Most of that has not come to pass. We have not fed the world with GMO crops.
Too many people harbor the unconscious assumptions that conventional corn cannot yield as much as GMO corn and that conventional corn cannot handle different situations — some of which the GMO traits do not even claim to help with.
“If conventional corn doesn’t yield less, why is there a premium?” (Because consumers want it).
“I’m not growing conventional corn if I can’t get a premium.” (Why? Is glyphosate controlling all your weeds like it used to? Why are your CRW numbers so high if you have been growing only GMO-traited corn, and your neighbors do, too?).
I want to encourage the conversation to change. When you hear “conventional corn” or “non-GMO corn,” what is the first thing you think of? Why? What are your biases? We all have them.
I found more of mine this spring when our new second- and third-breeding-cycle hybrids had some stellar emergence in some cold, wet ground (better than some of those $350+ bags of seed). Should it have surprised me? No; we breed for this stuff. We look for it on purpose. We beat the tar out of our corn so that our customers don’t have to worry about these conditions.
But what did I do when I saw it in the field? I called my dad with what has become our code phrase over the years: “Hey, guess what?!? Breeding works!”
Raechel Baumgartner is the general manager of Baumgartner Agricultural Science & Service, LLC (BASS) in Danube, Minnesota. Her background is in research and plant breeding.
