Published on Wednesday, April 17, 2019
CLICK HERE FOR A DOWNLOADABLE VERSION OF THIS AGRONOMY TALK UPDATE
A soybean seed has two distinct parts: the cotyledons and the embryo. The two cotyledons are the main food storage structure, which supply food during emergence and for the seven to ten days after emergence through the V1 growth stage.
The embryo itself is comprised of three parts.
The hypocotyl arch is a large structure that is relative to seed size, utilizing considerable seed energy to push through the soil. Therefore, compaction or crusting is a serious threat to soybean emergence.
Soon after exposure to sunlight, the cotyledons and other plant parts develop chlorophyll and turn green. The cotyledons drop after the seedling can support itself, approximately seven to ten days after the VE growth stage. After reaching the V1 growth stage (first trifoliate leaf), photosynthesis by the developing leaves is adequate for the plant to sustain itself.
The first two leaves are unifoliate, positioned opposite each other at the same node. All subsequent leaves are trifoliate and are positioned on alternate sides of the stem, one at each node. A plant achieves a new V stage (new trifoliate) every five to seven days through V5, and every three to five days between V5 and R5.
Nitrogen-fixing nodules begin to form at the V2 growth stage, and most are concentrated at the planting depth. Nodules are sensitive to moisture, pH, and temperature, among other factors. Planting too deep or too shallow may expose the nodules to suboptimal conditions.
The following practices can help you ensure you’re reaching your top-yield potential:
Author: Denny Cobb
Categories: Agronomy, Agronomy Talk
Tags: soybeans, soybean growth, cotyledons, embryo, soybean growth stages