The kernel used as grain is the product of the hybrid plant between a male and female parent. It is bred for maximum production of carbohydrate from conversion of solar energy. Genetic contribution of both of the inbred parents is utilized by the grower to maximize the grain yield. Use of the kernel as a seed has different genetics and handling requirements. Maximizing seed yields requires experience to match timing of silking of female inbred with pollen distribution of male inbred. Amount of male pollen can be limiting with some male parents. Membrane deterioration, critical to mitochondria function in the seed embryo, can begin if the moisture levels remain high for prolonged time, a character that varies among seed parent inbreds. Consequently, seed is usually harvested before normal black layer and dried quickly to at least 13.5% moisture. Whereas high germination quality is not of much significance with kernels used as grain they are highly significant with use as seeds. Not only is seed dried with minimal heat addition, and lots of air movement, the harvest at high moisture requires harvests by ears, gentle handling within the facility becomes essential.
Damage to the kernels whether in the field prior to harvest or within the facility after harvest, genetic factors also become significant. Inbreds differ in vulnerability to these factors. Some of this vulnerability involves pericarp structure features of the female parent. Disease resistance of the female parent can be a factor also. Inbreds are intended to be homozygous to assure repeatability but this also allows unexpected homozygous recessive genes for susceptibility to a race of a pathogen such as that of Races of Helminthosporium carbonum(Bipolaris zeicola) that can cause premature death of the female plants as well as infection of the kernels. Use of T-cytoplasm corn for sterile female plants was associated with defective mitochondria membranes, allowing a toxin produced by race t of Helminthosporium maydis(Bipolaris maydis). Although the hybrid seed embryo is a product of the genetics of both parents, some cellular organelles such as mitochondria originate only from the female inbred.
Dual use of the corn kernel as a grain and as a seed requires effort by different specialists, the grain farmer and the team of seed experts.
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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.