Below you will find a good read on estimating yield potential in corn from Rome Ethredge (UGA Interim Grains Agronomist)
Estimating Yield Potential of Corn
“There are ways to estimate what your corn will make, but they are rough estimates due to many factors. I remember one year a grower asked me to tell him which of 2 corn hybrids would yield more that were side by side in his field. I took a quick look and one hybrid had longer ears. I incorrectly said that hybrid will be much better, look at that ear length.
At season’s end they both yielded the same. Why? The other corn had more rows around it and heavier weight per kernel. Also remember the corn is far from made at the dough stage so yield from that point out can be affected by stresses, mainly moisture stress and disease progression.
Yield estimating plans are mostly based on the number of kernels you have per acre. We have to be late enough in the season, dough stage, R4, so that we know the number is set. Kernels are pollinated and no more abortion on the tip.
Basically you are counting the kernels per acre. To do that you have to know the number of ears per acre and kernels per ear. You may say, Oh I planted 34,000 seeds so lets go with that, no that won’t work, not that many plants even came up . You can’t even go on early season plant population due to the fact that all plants don’t produce ears. Got to count ears per area now in several parts of the field for better accuracy.”
Here’s a link to LSU’s yield estimation plan as a reference.
Estimating Yield Potential of Corn LSU