Corn School: How short plants impact yield

PRIDE Seeds agronomist Matt Chapple.

Why are corn hybrids that typically reach eight and nine feet tall coming up as much as two feet short? It’s a question many Ontario growers are asking this year as the crop pushes through grain fill.

On this episode of the RealAgriculture Corn School, PRIDE Seeds agronomist Matt Chapple digs into the “short corn” question, assesses the yield potential of these vertically challenged plants and looks at what growers can learn from a stressful growing year.

Chapple says a number of factors conspired to reduce plant stature. He notes that the 2022 crop actually got off to a fast start with much of the crop being planted early and emerging within five to seven days. Fast-growing plants then quickly transitioned from living off radical root reserves to nodal roots. It’s at this point that plants in many fields started to hit roadblocks. At V3 and V4, when the plants were putting down nodal roots, many started to encounter restrictions related to poor fall harvest conditions that contributed to tough soil, tillage layers and compaction. “That’s when we started to see that wave of variability in the crop,” says Chapple.

That was followed by extremely dry conditions and moisture stress across much of the province. That combination typically sends the plant into defensive mode and it no longer focuses on growing to its maximum vegetative potential, says Chapple. “It’s roped up, looking a little grey and it slows down the whole factory.” When that happens, the result is a smaller plant that’s not as efficient in intercepting sunlight and maximizing photosynthetic potential as more sunlight hits the ground.

Chapple, however, points out that “plant height is not indicative of our full yield potential. Short corn does not necessarily mean that you are going to have a crop failure.” As usual, plants need adequate moisture at pollination and silking and good conditions through the grain fill period to produce yield. “For the most part, there are some very good kernel counts on some six foot tall corn out there. Kernel counts that will get us to at least an average crop.” (Story continues after the video.)

In the video, Chapple notes shorter corn should withstand tough fall conditions and provide good standability through harvest.

Short plants can also teach growers a few things about their management systems. At the PRIDE Seeds Education Centre at Pain Court, Ont., Chapple compared the same hybrid in two different management systems — corn on corn versus rotated ground. He notes that the plants in the rotated ground were almost two feet taller.

“It really speaks to the need for crop rotation, managing residue and most importantly, good soil health,” he says. “If we can give the crop a great early start with good soil health we can weather the storm, reduce the days under stress… and we can maximize our yield in spite of moisture challenges.”

Click here for more Corn School episodes.

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