Corn seed duality
The large Cottonwood (Populus deltoides) tree close to our home covers our neighbors and our lawns, and fields with seed in late spring. A white oak (Quercus alba) tree produces huge volumes of acorns to be carried away by chipmunks and squirrels. Walnuts are buried by squirrels in late fall. A white paper birch (Betula papyrifera) covers a nearby deck with seed during the summer. Most flowering plant species have survived by spending reproductive energy in producing tremendous numbers of seeds, allowing a few to be positioned where they can germinate and established the next generation of the species. This strategy is not foreign to any one attempting to control weeds in a corn field- or a garden. Plant species have evolved many variants of this basic method leading to the wonderful plant variability, but this is not always advantageous to those of us interested in growing food.
Humans attempt to manipulate seed selection to not only propagate the species but also utilize the seed for their use. The original Teosinte species, from which corn was derived, had a hard case and very little endosperm for starch storage. People selected for softer outer case and much more starch storage in the endosperm. A more floury and softer endosperm became associated with a reduction in germination percentages, perhaps because of vulnerability to mechanical damage or perhaps faster imbibition damaging membranes.
As corn culture moved to different geographies and selected for different food uses, seed functionality was affected as well. Corn seed breeders have the basic objectives of selecting genetics for use of the kernel, field performance of the hybrid and high germination percentage. It is good that corn has a very large number of genes to manipulate but also there are many physiological and structural aspects to corn seed germination.
Whereas wild plant species mostly have developed reproduction strategies emphasizing large numbers of seeds to be widely distributed with a small probability of successfully producing the next generation, we have the dual objective of producing seed for our uses as well as a high probability of reproduction. Selection for both of these characters requires a lot of human effort
Comments are closed.
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.