John Werries has experienced the kind of summer this year that brings to mind the old saying: “You can almost hear the corn growing.” Row after row of towering corn has tasseled and creamy silks wait for the half-million or more grains of pollen that will shower from each plant over the coming weeks.
“That’s 16 around,” Werries said, counting the baby blisters on a cob pulled from a field near Chapin, Ill., last week. Slightly more than an inch of rain fell on his field Monday night, and so far, night temperatures have been perfect for the beginning of pollination.
University of Illinois crop physiologist Fred Below told DTN there’s more truth than fiction to the old adage. One really can hear corn grow. “On very still nights you can hear a popping or cracking noise,” said Below. “It occurs around the V15 growth stage and what you hear is the cell walls of the stalk expanding. Mostly I believe it is the tracheids (the specialized water-conducting tissues of the xylex), which are expanding.”
Below noted that this period of rapid growth also makes the crop susceptible to green snap. “The stalk if rapidly expanding is not yet fully lignified.” Some hybrids are more susceptible to green snap than others, so growers are encouraged to take note of those that might have experienced problems this year. Patches of green snap have been reported throughout the Midwest after strong winds last week. Below said a rare ‘double derecho’ cut a wide swath through the Midwest last week and caused some green snap in his research plots.
Ohio State University agronomist Peter Thomison noted in a recent news release that corn has exploded in growth during the past two weeks in that state. He reported that under favorable growing conditions, corn plants can grow nearly 3 inches per day between V8 (the eight-leaf collar stage) and V15.
Variation in corn maturity abounds across the Corn Belt this year, depending on planting date and drainage. Hail damage has required replanting in some areas. However, corn tends to mature in predictable growth stages that provide good clues to how the crop is faring.
Thomison reminded growers that ear shoot initiation is completed and the tassel is initiated on the top of the growing point as early as the V4/V5 stage. Kernel row numbers per ear may be established as early as V8 (Nielsen, 2007). Kernel row numbers are usually less affected by environmental conditions than by genetic background. Corn hybrids characterized by “girthy” ears exhibit more kernel rows (about 18 or 20 rows) than hybrids with long tapering ears (about 14 or 16 rows).
Determination of kernels per row (ear length) is usually complete by V15 stage and maybe as early as V12 (Nielsen, 2007). Unlike kernel rows per ear, kernels per row can be strongly influenced by environmental conditions. Kernels per row (ear length) can be adversely affected by stress (usually drought) in the two weeks prior to pollination.
“Many of our late-planted corn fields experiencing excess soil moisture have not yet reached these critical stages,” Thomison wrote. “For most of these fields, loss of kernels per row on developing ears may be minimal and impact on potential yield limited. However, if N losses associated with ponding are substantial, they may result in N deficiencies that can lead to kernel abortion during early grain-fill stages and premature plant senescence.”