How Many Ears?

How many ears will you find on a stalk of corn?

The question seems simple enough. Often times, cartoon drawings of corn plants show bountiful plants with six or eight or more ears of corn – one with every leaf. But the reality is much different. How many ears of corn on a single stalk? The short answer is….one.

But as Paul Harvey would say…and now, the rest of the story.

How many ears on a single stalk of corn? It depends! Corn or maize is a grass and like other grass species it has the possibility of producing tillers (stems that grow after the initial parent shoot grows from the seed) or branches. In the case of corn, the branch is called the shank which is a small stalk-like structure that grows out from a leaf node. Leaf nodes in the middle of the stalk have the potential of growing these shanks. It is from this shank that an ear of corn will grow.

One factor that will influence ear production is population density. Over the last half century, farmers have been able to plant corn plants closer and closer together. This allows for more total production and more bushels of corn per acre to be harvested. As the plant’s genes interact with its environment the plant will respond. More light, water, and nutrients will produce more branching. In high density populations (like in a typical cornfield) light doesn’t get all the way down and so there is less branching. The plant can dedicate all of its resources to producing one really good ear of corn rather than wasting water and nutrients on producing multiple, less viable ears. The corn plant’s main goal in life is reproduction and it wants to give its seeds the best chance of survival. One ear of corn with 600-800 seeds is better than two ears with only 200-300 seeds.

In modern cornfields in the U.S., farmers may plant 30 inch rows with 30 to 35 thousand seeds per acre resulting in that many individual plants. Some farmers are planting 12 inch rows with as many as 60,000 plants per acre! Soil and available nutrients have to be able to support that many plants, and each farm and each field is different. Corn varieties that farmers use today have been selected and bred for high densities, meaning that they can tolerate high populations and usually only produce one ear per plant.

But in the right conditions things could change. If those high density varieties of corn (or any other cultivar of corn) are spaced out with low competition, plenty of sunlight, water, and nutrients, they could branch more and produce more ears of corn. Often times, farmers will see more ears at the edges of fields because the end rows have more sunlight and more space. But the second ear will not usually be as good of quality. The primary nutrient that is a limiting factor for overall growth and ear development is nitrogen.

Sometimes farmers can increase the population of corn planted and actually decrease the number of ears. Some plants would be barren and not produce an ear. If the farmer is growing the corn as stover (stem and leaf materials) to feed to livestock as chopped silage, there is no need to produce a large ear.

Of course with all of this, we are primarily talking about field corn (also called dent corn). Field corn accounts for 99% of the corn grown in Iowa. Field corn can be used for human food (tortilla chips, cornbread, etc.), animal food (both ground corn and fresh silage), and fuel production (ethanol and corn oil biodiesel).

Sweet corn, the kind that we enjoy fresh off the cob in the summer, is sometimes considered a low-value crop when compared to other vegetables. This is because it takes up valuable room – a lot of room – in a garden and only produces one ear per plant. Sweet corn can take up to 3 square feet of space. If you harvest a cucumber from the garden, more will grow and you can get multiple harvests. But if you pick an ear of corn, the plant is done producing. Sweet corn may produce two or sometimes three ears per plant because there is wider spacing and less competition. Early maturing sweet corn varieties may still only have one ear. Later maturing sweet corn varieties might have multiple ears.

So, don’t believe those cartoon drawings! Corn usually only has one ear per stalk.

And now you know the rest of the story.

-Will

 

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