Corn Roots and Plant Growth: VE to V3

BY Dairyland Seed Agronomy Team

As our growing season is progressing, depending on planting dates, we have corn that is either just germinating or is soon approaching 3-4 leaf, or V3 to V4 stage. As discussed in previous Dairyland Seed Agronomy Updates, it takes roughly 100-150 Growing Degree Units (GDUs) for the coleoptile to emerge from the soil.

Plant / Leaf Stage	Growth Stage	GDUs
Germination		10 to 20
Radicle Root Emergence		30 to 40
Coleoptile Emergence Seed		50 to 60
Seminal Root Emergence		60 to 70
Coleoptile Emergence Soil	VE	100 to 150
First collar on emerged leaf	V1	150 to 190
Collar on second Leaf	V2	190 to 220
Collar on third leaf	V3	280 to 310

Prior to the coleoptile emerging the soil surface and starting between 60-70 GDUs, the seminal root system will start to emerge from the seed and almost immediately start taking in water and nutrients for the plant to continue to grow. I normally think of the seminal root to be three individual roots much like fingers on a hand when you signal the number three. The seminal root system and the radicle will anchor the plant and act as the main root system for the plant until VE (shoot/spike coleoptile emergence) and will continue to grow until V3 (three collared corn).

Shortly after the coleoptile emerges (VE) from the soil, the first set of nodal roots starts to emerge from the plant. By V6 (collar on sixth leaf), with additional sets of nodal root growth, will become the main supplier of water and nutrients to the plant.

At V1 or collar on first emerged leaf, the plant is starting to utilize energy from the sun and is photosynthesizing but is still relying on the energy of the seed to help grow. The root system on a V1 plant is normally 3 to 5 inches wide and 2 to 4 inches deep. As the corn plant continues to grow and reaches V2 (as the plant in the photograph shown below is very close to V2), the root system is 5 to 8 inches wide and 4 to 6 inches deep. In general, roots (except the radicle) tend to grow out of the plant at a 25 to 30° angle from the horizon. Compaction and water availability impact that as well. The radicle can grow in any direction but reacts to gravity (gravitropism or geotropism) and eventually orients itself downward in its growth pattern.

Once a corn plant reaches the V3 (collar on third leaf) growth stage, the plant is relying less on the energy of the seed and more on the leaves and the root system for its energy source. Cloudy and cool weather at this stage can cause plants to yellow up to a “Ghostbusters” yellow green slime type of color. I have always thought that a frost or two at this stage can cause more plant stand loss then earlier stages due to: 1) having more leaf tissue present which can shrivel up from the frost damage; and 2) running out of energy from the seed and subsequentially not having leaf tissue to photosynthesize and give energy to the plant.

I have always thought of the V2-V3 growth stage as the “Pre-Teenage Years” and the V5-R1 stage as the “Teenage Years”. The V5-R1 stage is also called the Grand Uptake period which, much like a teenager, the plant is taking in a tremendous amount of energy (water, nutrients and sunlight) to put on growth. If you are applying additional nutrients (either applying V2-V3 or the “Pre-Teenage” growth stage) allows those nutrients more time to get into the plant as the plant enters V5 and later growth stage.

More on corn growth stages to follow in subsequent Agronomy Updates.