We are all hoping for more rain soon, so hopefully we won't have to worry about the impact of drought stress on corn in the V6 stage! But in case you are wondering...
Drought stress at the V6 stage has the biggest impact on the number of kernel rows. The number of kernels in each row can also be affected by drought as early as V5, and can be impacted through pollination and grain fill. Corn hybrids have a typical size and shape that is determined by genetics, but environmental factors like drought can have a significant impact on ear development resulting in potential yield losses.
Stephen D. Strachan, Ph.D., DuPont Research Scientist, has written an excellent article, Corn Grain Yield in Relation to Stress During Ear Development. Strachan summarizes the following impacts:
"In general, ear responses to environmental stress factors at specific times of the corn life cycle include:
· A reduction in the number of kernel rows around the ear if substantial stress occurs at or just before ear initiation (approximately V7).
· A reduction in the number of kernels along the length of the ear or a shorter ear if substantial environmental stress occurs from the late vegetative phase until just before pollination.
· A portion of the cob that may be barren if substantial environmental stress occurs during pollination.
· A portion of the cob that shows either very small kernels or kernel dieback if substantial environmental stress occurs during grain fill."
The good news is that rain later in the season can help compensate for early drought if it comes ahead of pollination and grain fill.
Fingers crossed for a good soaking rain ahead!