So, those 2-eared plants along edge of field die first, resulting in stalk rot. How about back in the field, where bordered 2-ear plants are rare, is early death of the plant associated with kernel number? An associate of mine, Eduardo Teyssandier, and I set out to compare prematurely dead plants with adjacent live plants in September 1976. We randomly sampled variety display plots of many companies across 5 Midwest states. All plants examined were bordered by others, and those with leaf damage or stalks broken from corn borer were noted but excluded from the study. Forty hybrids were included, 112 pairs of plants studied. The ones with rotted stalks averaged 561.9 kernels whereas the healthy adjacent plants averaged 459 kernels. Repetition of the study in 1978 with 30 hybrids and 65 comparisons showed 647.5 kernels on dead stalks and 586.8 kernels on live ones. Differences were statistically significant at the 99.9% level. Dead plants had 10-14% more kernels than live ones and yet the genetically identical plants were only a few inches from each other. Also, in 1978, seven commercial hybrids were hand planted at density of 26100 plants per acre and at 34800 P/A to compare dead versus live adjacent plants. In each case the dead plants had more kernels than adjacent live plants, although two hybrids had no dead plants when planted at the lower density.
It should be noted that these were commercial hybrids in the 70’s basically selected for performance at about 30% less density than is common in 2015. They would be called flex ear types in today’s corn lingo. Also it should be noted that all comparisons were made with adjacent plants within a variety and comparisons were not made between hybrids.
So, plants that show early death symptoms have more kernels than adjacent genetically identical plants. Also known is that pith cells of early death plants are depleted of sugar and senesce and that root rot precedes stalk rot. What is the connection with these facts and the occurrence of stalk rot? How do breeders select for less stalk rot if genetically identical plants do not behave the same?
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About Corn Journal
The purpose of this blog is to share perspectives of the biology of corn, its seed and diseases in a mix of technical and not so technical terms with all who are interested in this major crop. With more technical references to any of the topics easily available on the web with a search of key words, the blog will rarely cite references but will attempt to be accurate. Comments are welcome but will be screened before publishing. Comments and questions directed to the author by emails are encouraged.