The biological entity that we call a corn seed is more complex than it appears. Each seed of each hybrid may appear to be identical upon first glance, but a closer study reveals external differences in terms of size and shape and, perhaps, external damage. Each seed within a container may have been produced by pollination by the same male parent onto the silk of the same female parent. They may have identical genetics. But position on the ear in the production field may reflect slight differences in environmental exposures ranging from pathogens in the seed production field to handling during seed harvest, drying, shelling and bagging. Seed treatment application, including the important drying process, may not be equal for each seed. Potentials for variation continue as the seed is distributed to growers with varying storage conditions.
Internal biology of each seed can be affected in each step. Even a dry non-germinating environment, the critical cellular membranes are vulnerable to damage that only becomes exposed when imbibition allows cell activity.
Moisture is needed for germination but too much water, especially in some soils, can suppress availability of oxygen needed for cellular respiration. Membrane function is essential to all cellular activity. RNA produced with enzymatic activity in the cell nucleus is transmitted through the nuclear membrane to the membrane intense ribosome. Among these enzymes are those that split the starch molecules in the endosperm in to glucose molecules that are moved to the mitochondria. The membranes in mitochondria become the site in which enzymes utilize oxygen, water and glucose to produce the energy source known as ATP, that provides energy for other cell functions including the elongation and duplication of cells for seed germination.
Once planted, the seed engages many field environment variables that potentially could interfere with normal germination and emergence from the soil surface. Temperature and moisture extremes, absorption of damaging chemicals, pathogens, insects and soil hardness can be factors interfering with normal emergence from the soil.
Everyone involved in corn seed attempts to limit the risks of poor field emergence. Genetics of the hybrid, especially of the seed parent, are selected for reduced vulnerability to seed damage. Seed production methods are adjusted to limit physical damage to the seed. Growers use tillage and planting methods to provide best soil environments for the seed. In most cases all these efforts come together with a good uniform emergence in the field. Uncontrollable weather can be involved when all the efforts have failed. Surely production of a biological entity like a corn crop is more complicated than production of inanimate things.
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.