The kernel as a seed
The corn kernel is a fruit with one giant seed. We humans mostly bred and selected this grain for its use as a food source, increasing the endosperm size with carbohydrates. Selecting for desirable seed traits has been at least somewhat secondary to the grain production. On the other hand, uniform and reliable field emergence is a major contributor to corn grain production in modern corn hybrids. This is dependent on the science and experience of seed producers.
Much of the propensity for high germination is dependent upon the female seed parent. Pericarp, being totally part of the female plant, affects rate of moisture loss during drying, vulnerability to physical damage from handling of the seed and susceptibility to ear molds. Mitochondria genetics are totally inherited from the female parent. Much of the damage from rapid, cold imbibition of water at the initial stage of germination involves the mitochondrial membranes.
Maize kernels handled as grain need to be stored at 15% moisture to avoid mold. Modern hybrids are usually allowed to dry in the field well beyond the 30-32% moisture level that black layer forms and completion of movement of carbohydrates to the kernel. It is usually most economic to allow drying in the field before finishing with artificially drying.
Most maize seed begin losing germination capacity if left in the field during those final days of slow drying in the field. Studies have shown that greater germination percentages are retained if seed is harvested in the 35-40% moisture level and then is quickly dried with lots of air and less than 100°F. Retaining the higher moisture level for some time initiates metabolism in the embryo, essentially an artificial aging process. Seed dried to about 12% moisture is considered optimum of storage and retention of high germination rates.
Producing and retaining high germination is the result of research of each hybrid parent’s vulnerability as well as experience with weather and facility. Drought damage during grain fill, rain delaying harvest, drying at too high temperature and not enough air, rough handling during processing and adding too much water during seed treatment can contribute to below standard germination. One can write a manual for production of seed corn but ultimately it takes some experience to apply the science. Like most agriculture.
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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.