While guest lecturing to a class of high school ag students, I showed them two ears of corn. One was longer and narrower in girth, but had 18 rows of kernels on the ear. The other was bigger in girth but only had 14 rows of kernels on the ear.
Some eyes glazed over when I tried to explain why number of kernels in a bushel matter – OK, a lot of eyes glazed over. But when I ended my talk and asked for questions, one young student asked a question I couldn't answer. That's because it's been debated for decades, and likely will be debated for decades more. It's one of those questions where the answer will likely begin with "it depends."
"So do you want more kernels on an ear which are smaller, or a fewer number of kernels where the kernels are bigger?" the student asked.
Corn Illustrated (1/13): Calculate seed cost when figuring seeding rates for corn
Sound simple enough, right? The two ears I showed them were from side-by-side, replicated plots. The hybrid with the fewer number of rows – only 14, and slightly fewer kernels per row, yielded 40 bushels fewer per acre than the ear representing corn with 18 rows of kernels per ear and a couple more kernels per row, right?
Wrong! The results were nearly dead even. In fact the hybrid with fewer rows of kernels per row yielded a few bushels more per acre, but the difference wasn't significant. Walking the plots I thought a 40-bushel per acre edge to the hybrid with more rows of kernels per ear might be conservative; maybe it would be more like 60 more bushels per acre bushels.
The answer becomes clearer in this case when you broke the two ears in half. The kernels on the ear with fewer rows per ear were nearly twice as deep as the kernels on the ear with more rows per ear. The kernels on the ear with fewer rows tended to be flats, medium flats, and the kernels on the ear with more rows tended to be rounds, small rounds.
Corn Illustrated (1/6): Think through 2015 corn hybrid purchases carefully
So do you want ears with more, smaller kernels per ear or ears with fewer but larger kernels per ear to get the most yield per acre?
In all my wisdom, this was my answer to the young man: "It depends!"