Dry corn seed are alive and breathing. Respiration in the seed, like in the rest of us, occurs in the mitochondria of the cell. The process of breaking down sugar provides the energy for creation of enzymes needed to maintain membrane structures in the seed that will be needed when germination begins.
Membrane deterioration increases as the temperature and moisture increase. These interactions of storage temperature and moistures have been shown to have a drastic affect on eventual germination percent of stored seed. Even size of root and shoot length of the seedlings is reduced if the seed was stored under conditions of higher humidity and temperatures.
Membranes not only surround individual cells but also the main sites of activities in cell organelles. Enzyme activity along these are the sites of protein production in ribosomes, transfer of proteins and other products are often done via cellular membranes. Much of this activity is guided by DNA within the cell nucleus, its integrity and activity affected by the nuclear membrane. Because natural breakdown of membranes increases with temperature and moisture, the need for higher respiration rate increases when seed is stored under poor environments. Seed stored at 9% moisture content and 10°C (50°F) retained nearly 100% germination for 4 years whereas the same lot of seed stored at 15% moisture content and uncontrolled temperatures as high as 38°C (100°F) had o% germinations. Reducing the seed moisture percent to 11% even under the warm conditions increased the percent germination to 90% (Plant Physiol. (1967) 42, 1071-1076). Many seed studies and experiences since then have verified the principle that drying seed and storing under low temperatures are essential to maintaining eventual high percentage germination of corn seed.
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.