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Poor Corn Kernel Set
The number of kernels on an ear of corn is important for total grain yield per acre. An ear that’s totally filled out with perfect rows has benefitted from good growing conditions and successful pollination. But sometimes you end up with more cob than kernels.
Bob Nielsen is an agronomy professor at Purdue University. He says there are several reasons why this happens, but severe drought is probably the most common culprit. Each silk represents a kernel of corn and requires a lot of moisture to grow up and out of the husk for pollination.
"Under severe drought stress that elongation of the silks can sometimes be delayed or occasionally even stopped altogether to the point where they may be delayed in their elongation so long, that by the time they do finally come out, all of the pollen’s already been shed from the tassel," says Nielsen. "So, there’s no pollen left to be captured by the silks and then you don’t get any kernels developing."
On the other side of the spectrum, an extended period of cloudy, rainy weather can result in a less-than-full ear of corn because it messes with photosynthesis.
"It can affect those newly-fertilized ovules because if the plant becomes terribly short on the sugars and the carbohydrate that are formed by photosynthesis, basically that can cause almost immediate abortion of newly-developing kernels," he says. "So, sometimes we’ll see some poor kernel set if there’s been upwards of a week of cloudy weather during pollination."