This is the time you can set a yardstick out and corn will grow about an inch every day for several days. Dave Nanda says plant breeders call it the grand growth phase. Nanda is director of genetics and technology for Seed Consultants, Inc., and a plant breeder with 50 years of experience.
The Crop Watch '13 field is no exception. It is hitting V7 and will soon be at the V8 stage this week. That means that seven and soon eight leaves with leaf collars are fully exposed. It also means the growing point is now above ground. It would be subject to hail damage and not regrow at this point if the growing point was destroyed. However, so far so good – some timely rain but no major storm damage at the site.
The corn plant is making important decisions at this time in the growth cycle, including how many rows of kernels to put on per ear. The number of rows of kernels, always in pairs, is primarily controlled by genetics, but can be influenced by the environment. In 2012, most plants dropped two to four rows per ear due to stressful conditions. As Nanda says, the plants are trying to procreate, and want to produce viable kernels, not just a bunch of "runts" with less chance to reproduce. As far as the corn plant knows, you're going to replant the seed.
Ironically, the number of rows per ear in any given field or hybrid experiencing the same environmental conditions is fairly uniform. If the hybrid normally has 16 rows of kernels around the ear, but suffers dry conditions, it will likely drop to 14. There may be a few 12s and 16s, but the majority make the same decision: drop one pair and go with 14.
If moisture remains available, it would seem likely that plats in the crop watch field would try to put on the maximum number of rows that the genetics of the hybrid allows.
Stay tuned for more updates.