Soybean Growth & Development

Corn and Soybean Production October 02, 2008|Print

Soybean Growth Stages

The following descriptions of soybean growth stages are taken from the Iowa State University publication "Soybean Growth and Development" (PM 1945). You may use the information from this Web page for educational use. Please credit the source with our name and URL: Soybean Extension and Research Program, Department of Agronomy, Iowa State University (www.soybeanmanagement.info). You can also obtain a print copy of this 29-page, full-color publication by visiting the Web site of the Iowa State University Extension Distribution Center or by calling (515) 294-5247.

Using soybean growth stages to maximize yield

Management strategies for improving soybean yield are most effective when you are able to identify the growth stage in which potential yield is affected. For example, the effects of fertilization, frost or hail, moisture stress, plant diseases, and pesticide application on yield will be determined by the growth stage in which these events occur.


How to Identify Growth Stages

The system of soybean growth stages divides plant development into vegetative (V) and reproductive (R) stages. The vegetative stages are numbered according to how many fully developed trifoliate leaves are present. The R stages begin at flowering and include pod development, seed development, and plant maturation.

The stages can overlap. When determining the growth stage of your crop, consider that a growth stage begins when 50 percent or more of the plants are in or beyond that stage.


Vegetative Stages

VE Emergence - cotyledons have been pulled through the soil surface

VC Unrolled unifoliolate leaves - unfolding of the unifoliolate leaves

V1 First trifoliolate - one set of unfolded trifoliolate leaves

V2 Second trifoliolate - two sets of unfolded trifoliolate leaves

V4 Fourth trifoliolate - four unfolded trifoliolate leaves

V(n) nth trifoliolate - V stages continue with the unfolding of trifoliolate leaves. The final number of trifoliolates depends on the soybean variety and the environmental conditions.

Reproductive Stages

R1 Beginning flowering - plants have at least one flower on any node

R2 Full flowering - there is an open flower at one of the two uppermost nodes

R3 Beginning pod - pods are 3/16-inch (5 mm) at one of the four uppermost nodes

R4 Full pod - pods are 3/4-inch (2 cm) at one of the four uppermost nodes

R5 Beginning seed - seed is 1/8-inch long (3 mm) long in the pod at one of the four uppermost nodes on the main stem

R6 Full seed - pod containing a green seed that fills the pod capacity at one of the four uppermost nodes on the main stem

R7 Beginning maturity - one normal pod on the main stem has reached it's mature pod color

R8 Full maturity - 95 percent of the pods have reached their full mature color

For more information on this or other topics related to soybean production, contact your state extension specialist or your local extension educator/agent.

The following is the link to the soybean extension specialists: state extension soybean specialist.