Soybean Growth Stages

Encyclopedia Article

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 (http://extension.agron.iastate.edu/soybean/).

You can also obtain a print copy of this 29-page, full color publication by visiting the website of the Iowa State University Extension Distribution Center, or by calling them at (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 reproductive (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% or more of the plants are in or beyond that stage.

Note: Click on the thumbnail image to view a larger version of the photo

Vegetative Stages
Thumbnail of soybean emergence stage

VE

Emergence - cotyledons have been pulled through the soil surface

Thumbnail of soybean unrolled unfoliolate leaf stage

VC

Unrolled unifoliolate leaves - unfolding of the unifoliolate leaves

Thumbnail of soybean at one set of unfolded trifoliolate leaves

V1

 

First trifoliolate - one set of unfolded trifoliolate leaves

Thumbnail of soybean at two sets of unfolded trifoliolate leaves

V2

Second trifoliolate - two sets of unfolded trifoliolate leaves

Thumbnail of soybean at four 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 trifoliolate's depends on the soybean variety and the environmental conditions

Reproductive Stages

Thumbnail of flowering soybean

R1

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

Thumbnail of soybean full flowering stage

R2

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

Thumbnail of soybean pods

R3

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

Thumbnail of full soybean pods

R4

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

Thumbnail of soybean beginning seed

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

Thumbnail of soybean full seed

R6

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

Thumbnail of soybean beginning maturity

R7

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

Thumbnail of soybean at full maturity

R8

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

SU Extension publication Soybean Growth and Development (PM 1945)
View a slideshow of soybean growth and development
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Category: 
Origin: 
Soybean Extension and Research Program
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