Michigan State University Extension
Michigan Soybean Information - 00000010
11/16/00

Soybean Growth & Development - Reproductive (R) Stages

List of files and visuals associated with this text.

The reproductive period begins at the time of first bloom
and ends at maturity. It is divided into four phases:

- Flowering (R1 and R2)

- Pod development (R3 and R4)

- Seed growth (R5 and R6)

- Seed/plant maturation (R7 and R8)

The main stem is again used for describing the
reproductive stages. A specific description of each stage
is as follows.

R1 Stage (Vis. 8)

R1-First bloom-an open flower at any node on the main
stem.

R2 Stage (Vis. 9)

R2-Full bloom-an open flower at one of the two uppermost
nodes on the main stem with a fully developed leaf.

R3 Stage (Vis. 10)

R3-Beginning pod growth-pod 5 mm (3/16 inch) long at one
of the four uppermost nodes on the main stem with a fully
developed leaf.

R4 Stage (Vis. 11)

R4-Full pod elongation-pod 2 cm (3/4 inch) long at one of
the four uppermost nodes on the main stem with a fully
developed leaf.

R5 Stage

R5-Beginning seed growth-seed 3 mm (1/8 inch) long in a
pod at one of the four uppermost nodes on the main stem
with a fully developed leaf (period of rapid seed
development).

R6 Stage (Vis. 12)

R6-Full seed-pod containing green seed that fill the pod
cavity at one of the four uppermost nodes on the main
stem with a fully developed leaf (seed reaches maximum
size).

R7 Stage

R7-Beginning maturity-seed in one or more pods are
physiologically mature. One or more pods have reached
mature pod color (e.g. tan).

R8 Stage

R8-Full maturity-95% f the pods have reached mature pod
color.

This system accurately identifies the existing soybean
growth stage of any plant and is applicable to varieties
with determinate and indeterminate growth traits. A
similar V or R growth stage for an entire field of
soybeans may be assigned when 50% or more of the plants
have reached or exceeded the most advanced growth stage.


Visuals associated with this text.

Visual title - Visual size Visual title - Visual size
Reproductive Stages - R1 - 26K Reproductive Stages - R3 - 39K
Reproductive Stages - R4 - 32K Reproductive Stages - R6 - 17K
Reproductive Stages - R2 - 13K
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