Corn seed respiration
Aerobic respiration is the process in which oxygen molecules are utilized in breaking loose the stored chemical energy of carbohydrates into the biological usable energy chemical of ATP (adenosine triphosphate). This series of chemical reactions is called the citric acid cycle or Krebs cycle. Oxygen is absorbed in the cycle ultimately ending in the bi-products of CO2 and H2O.
This activity occurs in the mitochondria of cells on their membranes. This process is common to all aerobic organisms, like us and corn seeds. It is ultimate process in which we and corn seeds obtain the energy for all biological functions. Maize seed stored at low internal moisture levels have low respiration rates but, upon imbibition and adequate heat, the Krebs cycle rate dramatically increases. This can be evaluated by measuring O2 uptake and CO2 discharge in controlled environments.
A research paper published in 1967 (Plant Physiol. 42, 1071-1076) compared the O2 uptake levels during first hours after imbibition and first days of seed germination. After comparing seed at different levels of damage from storage conditions, the research indicated that the initial oxygen uptake was related to eventual metabolism of the germinating seed 3-5 days later.
I interpret this and later studies to indicate that seed germination success is dependent upon mitochondrial membrane integrity, especially during imbibition. Individual cells include large numbers of mitochondria, and the embryo includes large numbers of cells, it seems reasonable that those individual seed that germinate slowly have some percentage of damaged mitochondria. Respiration rates on intact mitochondrial membranes are affected by heat energy, allowing the ATP to assist in membrane repair. Corn seed respiration rates increase with temperatures above 50°F as reflected in warm and cold germination tests.
Imbibition occurs at any temperature, but respiration activity is dependent upon mitochondrial membrane integrity and sufficient oxygen and heat energy to provide the ATP for all other cellular functions involved in seed germination.
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.