Competition for carbohydrates between kernels in developing ear and plant metabolism sites especially in the roots of a corn plant is established 10 days after pollination. This is a battle being fought individually by each plant in a corn field, as each plant can have slightly different environmental factors influencing its ability to produce carbohydrates and different numbers of kernels.
Net supply of carbs is influenced by environments, like light intensity, in which the rate of photosynthesis drops directly with less light. Cloudy days result in lass carbs produced. Leaf disease, reducing photosynthesis due to less leaf area, as does shade from adjacent plants. We have selected genetics programed to move carbs to non-photosynthesizing tissue like the roots with excess stored in stalk. During the grain fill time of the corn plant, newly produced carbs are transported to the kernels as well as those stored in the stalk pith tissue. The draw to kernels is constant, influenced by genetics and minerals, regardless of daily photosynthesis factors. Competition between kernel development and root cell metabolism for carbohydrates reserves stored in the stalk tissue becomes more intense if daily photosynthesis is reduced during the 40-day period of maximum draw by developing kernels.
Energy supplied by the carbohydrates pulled to the root tissue is used in its cells’ metabolism for normal function including producing the compounds needed to ward off the multiple organisms in the soil attempting to devour the root tissue. Defense of the living, functioning root tissue is essential to the rest of the corn plant, as the minerals and water absorbed by roots and transferred upwards are essential to function.
It is a battle essentially between roots and kernels for carbs that is fought by each individual plant in a corn plant especially between day 10 and day 50 after pollination. If carb supply is not sufficient to meet both needs, kernels win the race. The roots degenerate prematurely and are unable to supply the water to leaves to match the loss of leaf water due to transpiration. As a result, the plant wilts. Kernels’ win is temporary, as the wilted plant no longer can transport carbs to kernels.
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.