Harvest of corn for grain depends upon the stalk strength to maintain upright plants. Environment and genetics were major factors influencing the ability of the plants to be upright at harvest time.
Photosynthesis supplied the carbohydrates deposited as the strong lignin, cellulose and hemicellulose components of the outer rind cells. These molecules not only provide physical strength but are difficult for digestion by invading microbes. Factors influencing photosynthesis during the season affect the supply of carbs for formation of these complex carbohydrates. Plant density affects the light intensity per plant. Leaf disease can detract from carb production. Minerals influence affect photosynthesis and construction of these complex carbohydrate molecules in the outer rind of the corn stalk.
Net production and distribution of carbohydrates in the corn plant influences the stalk strength not only by effecting the deposition in the outer rind but also by maintaining the connection of the pith tissue to the rind. Monocotyledon plants like corn differ from dicotyledons in the distribution of the vascular bundles. Xylem cells, with their solid outer walls of lignin are organized in the center of the dicot plant such as the wood of a tree. Xylem cells in monocots are in separate vascular bundles scattered among weak-walled parenchyma cells in the center of the stem. Parenchyma cells in a corn stalk are living cells that become temporary sugar storage cells. Pith contributes to the stalk strength only when it is physically connected to the rind. If the plant wilts before completion of grain fill, dehydration of these cells results in withdrawal from the rind tissue, not only reducing a rod to a tube, but reducing the strength contribution of the vascular tissue.
Genetics effects photosynthesis, formation of complex molecules in the rind tissue and maintenance of pith tissue’s connection to the rind. Environments influence photosynthesis. Harvest time allows us to observe how these factors were in action for this season.
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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.