[Crop Note] current corn stage (16 June 2023) at Champaign in IL, USA
Since joining a research team at the University of Illinois Urbana-Champaign, I first visited a cornfield. It had been 15 years since I last worked in a Midwest cornfield in Iowa. The visit brought back memories of my time in the U.S., especially in 2007. The current growth stage of corn in Illinois is between V6 and V7.
Current growing stage of corn is between V6 and V7.
Corn is a monocotyledonous plant. In other words, it has one cotyledon or seed leaf. Therefore, the first leaf that emerges will be one. It is called the VE. Additionally, the first leaf has a rounded shape.
In that case, since the corn in the picture above has a total of 4 leaves, would it be referred to as V4? In the growth stages of corn, the “V” classification is not solely based on the number of leaves but rather on the presence of a collar. The collar represents a structure with the following shape.
The growth stages of corn can be classified as follows. Furthermore, the differentiation in the V stages is always based on the presence of a collar.
VE (Emergence) - Collar not visible.
V1 (First leaf) - Collar visible on the first leaf.
V2 (Second leaf) - Collar visible on the second leaf.
V3 (Third leaf) - Collar visible on the third leaf.
V4 (Fourth leaf) - Collar visible on the fourth leaf.
V5 (Fifth leaf) - Collar visible on the fifth leaf.
Please note that the number of leaves alone does not determine the V stage; it is the presence of the collar that serves as the criterion.
As the V stage increases, stem elongation in corn also increases. Starting from V6, stem elongation and the development of adventitious roots (nodal roots) begin in earnest, while the lower leaves gradually tear and disappear. If the lower leaves disappear, it becomes difficult to determine the current V stage of the nutritional growth phase.
One of the methods to distinguish growth stages is by applying color-coded lacquer spray to the V5 leaf. This allows for the differentiation of the current Vn growth stage based on the V5 leaf, even if the lower leaves have disappeared.
However, if color-based differentiation is not possible, there is another way to determine the V growth stage. The first node formed just above the root is typically V5. Subsequently, the node that appears most prominently above the root is typically N6. By examining which node the lowest leaf is connected to, if it is near the root, it can be considered as V5, and if it is connected to a node one level above the root, it can be considered as V6. Generally, leaves from V1 to V4 wither and disappear over time, so the first visible leaf around V10 would be either V5 or V6.
For example, in the picture below, we can identify the V5 leaf by observing the first node formed just above the root, which is typically associated with the V5 stage.
