Farmers devote a large amount of their time to making the decisions necessary to plant a crop each year. Steady temperature, sunshine and the “right” amount of moisture combine to create an environment that is nearly perfect for corn emergence — at least that’s what we planned for. However, most years Mother Nature has the final say for potential crop yields. Spring is a time of unsettled weather patterns with wild temperature swings that can be challenging for corn seed trying to emerge (Figure 1).
Let’s look at the challenging scenario when cold soil temperatures affect developing corn seed. First, the seed needs three conditions to begin the germination process:
Once these conditions exist, the enzymatic activity of germination begins. Under normal conditions, most corn seeds require about 90-120 growing degree Units (GDU) to emerge. To accumulate GDUs the seed bed temperature must exceed 50° F, and the young plant is completely dependent upon the environment (sun, solar aspect, air temperature, moisture, etc.) to emerge. The more prolonged this process of accumulation becomes, the greater the chance for problems to occur. Corn can tolerate cold, dry soils longer than cold, saturated soils. Excess moisture within the first 24-48 hours after planting and prior to the kernel imbibing 30%-35%, moisture content can greatly reduce potential stands by drowning the seed. Widely fluctuating temperatures that drop below 50° F can cause corn seedling problems. Seedlings may start growing toward the surface when temperatures are above 50° F but shut down and, in some instances, start growing down (it’s warmer deeper in the soil profile because the air temperature has cooled the ground near the soil surface), causing the seedlings to “corkscrew” underground (Figure 2). Too many cycles of turning on and shutting down of the enzymatic process of germination can cause the seedling to weaken to the point that it no longer turns on in warmer temperatures and becomes too weak to emerge, resulting in decay (Figure 3).
Cold soil temperatures can affect emergence, stand and final yield. Choosing a planting date that follows at least a 50° F seedbed temperature with a warming weather trend forecast is one of the best ways to get your corn field off to a good start. Channel® corn products have a vigor rating that helps identify which products can best handle the stress associated with early planting. Your Channel Seedsman can help you determine the most effective planting order for the Channel products on your farm this spring.
Licht, M., Abendroth, L.J., Elmore, R.W., Boyer, M.J., and Marlay, K. 2011. Corn growth and development. PMR1009. Iowa State University.
Frost and cold temperature damage to small corn. 2016. Agronomy Advice. Channel.com. http://www.channel.com/agronomics/Documents/AgronomicContentPDF/FrostandColdTemperatureDamagetoSmallCorn.pdf