Corn that was suffering in dry areas of Indiana and other states, especially Indiana eastward, rebounded and greened up again once rains came. The effect is even more noticeable where timely rains have continued to fall. But if fields only got an inch or less from planting to mid-June or later and were into the 10-to-12 leaf stage by the time relief came, how much was yield already hurt?
It's a question Extension educators and agronomists are asking, but one to which they yet don't have an answer. When it's time to figure yield estimates by late August or so, number of rows around the ear may be the tell-tale sign of how much the early dry weather impacted yield potential.
Why? Because there are about five times when corn plants make crucial determinations during the season that wind up going a long way toward deciding final yield, notes Dave Nanda, consultant for the Farm Progress Corn Illustrated plots and president of Bird Hybrids, Tiffin, Ohio. One of those comes around the V6 stage, more or less. That's when plants decide what diameter ear they should put on.
If plants look around and say, hey, conditions are good and I can make lots of babies, explains Nanda in his own unique style, then they're likely to put on an ear with as many rows of kernels as that hybrid's genetics allows. There are typically differences in genetics tied to the normal number of rows per ear in a typical year for any one hybrid.
But if the plants are stressed, especially by lack of moisture, they may say 'Gee, I don't think I can support as many children, so I will make a smaller ear to take care of what I can produce,' Nanda continues. "The plant's goals is to produce as many babies as it can. But it wants to make sure it produces some. The main goal for corn plants is to provide as many babies (kernels) as possible for next year."
At least that's Nanda's belief. It's not to put more grain in your combine tank and more money in your pocket, although the two sometimes wind up going hand in hand. It's all about reproducing and surviving.
Once the ear diameter is set, if conditions improve, as they did this year in many places, plants can compensate somewhat by deciding to make a longer ear at the second key junction. Later, the plant can also decide kernel depth.
"There are several checkpoints for adjustment along the way, but once number of rows of kernels per ear is set, you're not going to change that factor," Nanda explains.
The first ear pulled out of the field Nanda visited the other day in a relatively hard-hit drought stress area had only 14 rows of kernels. Typically, 16 rows would be more common for the hybrid.
"That type of thing will really show up in yield estimations shortly, taken in the field," Nanda says.