Late season dynamics in corn
As the sugars in the corn plant move to developing kernels, each individual plant differs in number of kernels and supply of stored sugars as well as daily differences in photosynthesis. Shading of leaves by adjacent plants differs especially if distance between plants differs or if leaf pathogens differ. Water and mineral differences also could differ with soil differences. Although genetics may be the same, small environmental differences can affect total photosynthesis even between adjacent plants in a corn field.
Transportation of sugars to the ear is largely affected by number of ovules pollinated and genetics of the hybrid. After the first 10 days after pollination, there is a constant and consistent pull of sugars to the kernels. This is daily, regardless of daily variation of photosynthesis caused by cloudy and dark days. Sugars are transported from storage in stalk tissue if not available from leaves.
Sugars in the stalk are also used to supply energy for root cell metabolism. Root tissue started deteriorating shortly after pollination, but the speed of that deterioration is at least partly determined by sugar supplied from above ground sources. Metabolism of root cells is essential for resisting invasion by fungi in the soil. Plugging of the vascular system by these fungi interferes with the water intake from the soil and transport in the xylem to the stem and leaves.
Meanwhile, transpiration of water through leaf stomates continues at a rate determined by usual dynamics, hot dry days requiring more water transported from roots to keep the leaves turgid. Furthermore, water is the solvent for the sugars to be moved from the leaf cytoplasm to and in the phloem to the developing kernels.
Water in the stalk also contributes to the stalk strength, especially by keeping the pith cells swollen and adjacent to the outer rind cells, essentially keeping the stalk with the physical strength of a rod.
A lot of things are happening in each corn plant that we can’t see but each of these plants is essentially on its own, as dictated by its genetics and environment.
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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.