Corn germination physiology
Successful emergence from the soil is dependent upon the physiological events after imbibition of the seed. Imbibition allowed activation of enzymes needed for the following metabolic processes but temperatures influence the speed of those steps. Important initial enzymatic activity is dissolving the starch in the endosperm into water soluble glucose. These molecules are absorbed in the scutellum where sucrose is formed and then moved into the root and shoot cells of the embryo. The carbohydrate is transformed in the mitochondria to form the ATP energy utilized for cell elongation, mitochondria reproduction, more enzyme creation, more starch digestion and a continuation of the cycle as the radical pushes through the pericarp.
Cellular respiration is an obvious key to these processes. The multiple steps ultimately moves electrons from oxygen and glucose molecules ultimately capturing the energy that holds the atoms to the respective molecules to a new molecule called adenosine triphosphate (ATP). Ultimately the process results in creation of CO2 and H2O molecules as well as the ATP. All of this activity is occurring in the mitochondria on membranes that are essentially electron transport systems. Thus, mitochondrial membrane damage during imbibition, with ageing or during stress while developing in the seed field can have a great effect on the germination process.
Cell elongation continues as the hypocotyl surrounding the apical meristem pushes upward (geotropism), still using the energy stored in the endosperm. Once the leaf tissue reaches the surface, chloroplasts turn green and photosynthesis turns on production of new carbohydrates, significance of the endosperm is reduced.
Adequate water, oxygen and heat are needed for corn germination processes to succeed. It is to credit of grower’s agronomic practices and seed producers that usually all happens within expectations.
A good summary of the physiology can be found here:
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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.