Understanding corn seedling emergence, development
April 20, 2019
Corn is one of the most efficient agricultural plants. It is a fantastic factory for using the resources supplied by nature. The grower who understands the development of the plant can profit by selecting the right hybrids, fertilization and cultural practices, as well as timely disease and insect control.
The date of planting is very important for achieving high yields. Many farmers want to plant corn before the middle of May, but Mother Nature decides when planting occurs. Maximizing the use of solar energy makes sugars and starches and increases chances of higher yields.
It is also important to know the early stages of development because establishing good plant stands is so critical. Unlike soybeans, corn does not develop more branches and compensate for big gaps. So, planting the appropriate number of seeds is required to have the desired population stands that meet yield goals, soil type, fertility and water availability.
Knowing the growth stages of the corn plants allows for field operation planning. Most hybrids produce 18 to 22 leaves based on their relative maturity. To measure the stage of maturity of corn crops, the most commonly used method is the “collar” method in which the number of leaves with collars. Developed when the leaf partially unclasps the stem, a leaf-collar is the light colored band at the base of the leaf. It includes the first emerging round-tipped leaf. The first sign of corn emergence is the appearance of a tip that breaks through the ground, called the “coleoptile”. It pierces through the ground like a spear and starts to elongate.
One hundred to 120 Growing Degree Days are needed from planting to seedling emergence. The growing point is one to one-and-a-half inches below the ground. This stage is called the “VE” stage. The growing point stays below ground for three to four weeks and is protected from frost or insects on the surface. The root system, called radical and seminal roots, develop to supply water and nutrients to the young, fast-emerging seedling. The secondary roots, known as nodal roots, get started at this stage and grow from the nodes below the ground. Four nodes develop below the ground. The first node above the ground is generally the fifth node.