Ear Size Determination in Corn
Bob Nielsen, Extension Corn Specialist, Department
of Agronomy, Purdue University
Row number and kernel number per row are two of several yield
corn. Typically, from 750 to 1000 ovules (potential kernels) develop
ear shoot. The number of kernel rows multiplied by the number of
row determines total kernel number per ear. Actual (harvestable)
number per ear averages between 400 and 600. For a 16-row ear,
per row is equal to about five bushels per acre (for average populations).
Like so many other processes in the corn plant, kernel row number
determination on an ear proceeds in an acropetal fashion (from
base to tip).
Kernel row number determination of the uppermost ear begins shortly
the ear shoot is initiated (V5 to V6) and is thought to be complete
Kernel rows first initiate as "ridges" of
cells that eventually
differentiate into pairs of rows. Thus, row number on ears of corn
even unless some sort of stress disrupts the developmental process.
number is often difficult to visualize in tiny ears dissected from
younger than about the 12-leaf stage.
The potential number of kernels per row is complete by at least
maybe as early as V12. Kernel number (ear length) is strongly affected
environmental stresses. This means that potential ear length will
dramatically from year to year as growing conditions vary. Severe
greatly reduce potential kernel number per row. Conversely, excellent
growing conditions can encourage unusually high potential kernel
For more information on ear size determination, see my lengthier
the Web at http://www.kingcorn.org/news/timeless/EarSize.html.
Click image to enlarge
Ear shoot at Node #6 on a V6 corn plant
Upper ear shoots and tassel dissected from a V9 corn plant
Tip of uppermost ear shoot dissected from a V14 corn plant