When farmers today want to plant their crop fields, they buy seeds. Was this always the case? Why do they buy seeds? Is there something special about the seeds they buy? Let’s walk through it together!
Historical Seed Sources
Let’s go way back to the beginning. Farming began as a practice in the Neolithic Era when people started collecting seeds from plants they were gathering, and purposefully put them in specific areas. This kept people more grounded in one location, and made their food supply more controllable. This process of harvesting what you need to use and then setting aside extra to plant the next year became common for centuries. Some people still do this today! Have you ever kept a couple extra potatoes from the bottom of your potato bag to plant in your garden in the spring? You have, too!
When collecting seed from crops was the main practice, farmers would keep seeds from specific crops that did well. A good example of this is corn. The native crop, teosinte, had extremely small ears with very tough and difficult-to-use kernels. Indigenous folks in teosinte’s native region slowly and purposefully kept (selected) seeds from teosinte that were from desirable plants that offered improved traits such as larger ears and easier-to-use kernels. This process of artificial selection brought us early corn!
The Hybridization Boom
In the 20th century, a new phenomenon was starting to be harnessed in the world of crops: hybrid vigor. This concept basically means that when you take two varieties of one species and breed them together, the offspring performs better than either parent would suggest. For example, if you crossbreed a breed of dog that commonly has joint issues with a breed of dog that commonly has breathing issues, the offspring may be larger and healthier than both parents. The same concept works with livestock and crops!
Here in Iowa, one of the pioneers of this concept was Henry A. Wallace. He went on to found a hybrid corn seed company that eventually became Pioneer Hi-Bred, now Corteva Agriscience.
Second Generation Hybrid Crops
Ok, so hybrid crops became more commonplace because they outperformed other open-pollinated varieties that folks were collecting from their own farm. But then why didn’t the farmers keep the seeds from the first year hybrid crop yield? Unfortunately, it doesn’t quite work like that.
What makes hybrid crops so interesting is that they’re so uniform. We know what parent A and parent B are, so we know what their offspring will be. But when the first generation open-pollinates itself, the offspring are much less uniform. It’s not that the seeds won’t grow or that the plants are sterile, it’s more that you have lost that initial hybrid vigor of breeding two different varieties together. In a crop field, this could look like corn plants of many different heights or different abilities to fight off disease. The crop field could simply end up less uniform.
The chart to the right can help illustrate this. The first generation (F1) has a predictable genetic makeup (genotype) as well as predictable physical characteristics (phenotype). However, if it were to self-pollinate, its offspring (F2 generation) would be much less predictable due to the variety in its genetic background.
Does Genetic Engineering Have Anything To Do With This?
Yes and no.
Genetic engineering isn’t a term that’s really regulated, but you could call it the scientific intervention of a plant on a DNA level instead of at the plant level (like with cross-breeding). There have been different ways that this can be done, but essentially a plant breeder will be able to isolate a gene that is either good or bad for a plant and add, delete, or shut off the expression of that gene.
Having the ability to change specific genes can increase the development of a plant’s trait. For example, if there is one specific variety of corn that has poor yield, but is more drought resistant, scientists can identify and isolate that trait to incorporate into a variety that has better performance. This leads to a better-performing crop with improved drought resistance and none of the negative attributes from the parent plant.
Now, if a parent crop has engineered traits, its offspring will have those same traits. However, many engineered traits in crop seeds are copyrighted material, making it illegal to use without permission. These technologies, the research involved, and even down to the time it takes to go through regulations, is a very lengthy and expensive process. For that reason, legally, if using genetically engineered crops, you do need to purchase new seed each year.
But in addition to that, most, if not all, crop seed varieties that are genetically engineered (GE) are also hybrid, meaning that even if the offspring does have the GE trait, it wouldn’t perform as uniformly as the initial seed once did.
So, in short, GE traits would be passed down to future generations, but those traits must be used with permission, and also that offspring wouldn’t perform as desired anyway.
Is this true for all crops?
Partially yes, partially no!
The rules for GE crop seed would hold true to all GE crop seeds (unless the patent was forfeited to be used for humanitarian needs, like golden rice). However, there is a pretty limited amount of GE crops on the market right now. Farmers that produce corn, soybeans, and cotton will likely purchase hybrid, GE crop seed each year.
However, with the new boom of cover crops, more farmers are keeping seed from their last year’s cover crops to seed the field next year. When farmers do this, they will often call the seed bin-run. Cover crops in Iowa might be plants like rye. The goal of this rye crop isn’t necessarily to have the best rye crop or the most uniform rye crop, it’s to protect the soil. So, saving money by keeping some seed back can make sense for some producers!
What other questions do you have about seed?
-Chrissy
Iowa Agriculture Literacy 