Soybeans: Growth Stages

Excerpt from 2002 edition of Agronomy Guide for Field Crops (Chapter 4)

Order 2009 editon of OMAFRA Publication 811: Agronomy Guide for Field Crops

Table of Contents

1. Vegetative Growth Stages in Soybean - Table 4-12
2. Vegetative Growth Stages in Soybean - Table 4-12 (continued)
3. Reproductive Growth Stages in Soybean - Table 4-13 (Part 1)
4. Reproductive Growth Stages in Soybean - Table 4-13 (Part 2)
5. Reproductive Growth Stages in Soybean - Table 4-13 (Part 3)
6. Reproductive Growth Stages in Soybean - Table 4-13 (Part 4)
7. Updates on Soybeans: Growth Stages
8. Related links...

Table 4-12. Vegetative Growth Stages in Soybean

(Not all V stages are presented here.)

Stage Abbreviated1	VE	VC	V1
Stage Title	Emergence	Cotyledon	First Node
Trifoliate Leaves	0	0	1
Days to Achieve Stage2	10	5	~ 5 days/fully expanded trifoliate leaf
Range in Days3	5-15	3-10	3-10
Notes	Seedlings emerge from soil. Emergence can be hindered by soil crusting.	Hypocotyl straightens, and cotyledons unfold. Unifoliate leaves open. Growing point is above soil surface. Frost can kill the plant. Stem severed below the cotyledons will kill the plant.	First fully developed trifoliate leaf unfolds at first node. Start of critical weed-free period.

¹V refers to the vegetative stages of soybean development. Vn = number of nodes on the main stem with fully developed leaves beginning with the unifoliate node. A fully developed leaf is defined as one that has a leaf above it (at the next node) with an unrolled leaf.
²An estimate of the number of days required to move from one stage to the next.
³Range is an estimate of days within a specific stage of development an dis influenced by planting date, maturity rating and climatic conditions and can vary considerably within and between seasons.

Table 4-12. Vegetative Growth Stages in Soybean (continued)

(Not all V stages are presented here.)

Stage Abbreviated1	V3	V5	Vn
Stage Title	Third Node	Fifth Node	Node n
Trifoliate Leaves	3	5	n
Days to Achieve Stage2	~ 5 days/fully expanded trifoliate leaf	~ 5 days/fully expanded trifoliate leaf	~3 days/trifoliate leaf (V6-Vn)
Range in Days3	3-10	3-10	2-6
Notes	Trifoliate leaves at 3 nodes. End of critical weed-free period. Nitrogen fixation begins at a slow rate.	Trifoliate leaves at 5 nodes. 50% leaf loss has little impact on final yield. Early maturity soybeans reach R1 at approx. V4.	No. of nodes to develope is function of maturity rating, planting date, climatic conditions.

¹V refers to the vegetative stages of soybean development. Vn = number of nodes on the main stem with fully developed leaves beginning with the unifoliate node. A fully developed leaf is defined as one that has a leaf above it (at the next node) with an unrolled leaf.

²An estimate of the number of days required to move from one stage to the next.

³Range is an estimate of days within a specific stage of development and is influenced by planting date, maturity rating and climatic conditions and can vary considerably within and between seasons.

Table 4-13. Reproductive Growth Stages in Soybean (Part 1)

When evaluating a field of soybeans, each vegetative (V) or reproductive (R) stage is reached when 50% or more of the plants are at or beyond that stage.

	R1 - Beginning Bloom	R2 - Full Bloom
R. Stage1	One open flower visible from any node on stem.	Open flowers at highest nodes of main stem.
Coinciding V Stage2	V4-V7	V5-V10
Days to Achieve Stage3	3	8
Range of Days4	1-10	3-15
Target Event	Flowering	Flowering
Notes	Triggered by changing day length and temperature. Flowering begins near node 5 (V4) and moves up and down the stem. Root growth rates increase. Extreme heat (i.e., over 32°C) can reduce growth, flowering and pod development.	50% height and dry weight accumulation. Stress does not usually reduce yield. Nitrogen fixation increasing rapidly.

¹R refers to the various reproductive stages of soybean development.
²In Ontario, where the majority of soybeans grown are indeterminate in habit, vegetative and reproductive stages of developent overlap for much of the plant's development.
³An estimate of the number of days required to move from one stage to the next.
⁴Range is an estimate of days within a specific stage of development and is influenced by planting date, maturity rating and climatic conditions, and can vary considerably within and between seasons.

Table 4-13. Reproductive Growth Stages in Soybean (Part 2)

	R3 - Beginning Pod	R4 - Full Pod
R. Stage1	Short pods visible at upper nodes of main stem with fully developed leaves.	Pods 2 cm (.75 in.) long at upper nodes of main stem.
Coinciding V Stage2	V8-V13	V11-V16
Days to Achieve Stage3	10	10
Range of Days4	4-22	6-25
Target Event	Pod Development	Pod Development
Notes	Look for 2-3 seeds per pod. Flowering peaks.	Stress occurring between R4-R6 can result in significant yield loss.

¹R refers to the various reproductive stages of soybean development.
²In Ontario, where the majority of soybeans grown are indeterminate in habit, vegetative and reproductive stages of developent overlap for much of the plant's development.
³An estimate of the number of days required to move from one stage to the next.
⁴Range is an estimate of days within a specific stage of development and is influenced by planting date, maturity rating and climatic conditions, and can vary considerably within and between seasons.

Table 4-13. Reproductive Growth Stages in Soybean (Part 3)

	R5 - Beginning Seed	R6 - Full Seed
R. Stage1	Seed .3 cm long within upper pods.	Seeds within pods fill cavity in the upper pods.
Coinciding V Stage2	V14-V19	V17-V21
Days to Achieve Stage3	14	27
Range of Days4	10-22	20-40
Target Event	Seed Development	Seed Development
Notes	Flowering completed except for some branches. Plant reaches max. height, nodes and leaf area. Nitrogen fixation rates reach max. and begin to decline. Rapid nutrient uptake and redistribution to pods.	Pods reaching full length. Root growth slows substantially. Above-ground dry weight accumulation shows. Rapid leaf yellowing begins. Leaves in lower canopy begin to fall.

¹R refers to the various reproductive stages of soybean development.
²In Ontario, where the majority of soybeans grown are indeterminate in habit, vegetative and reproductive stages of developent overlap for much of the plant's development.
³An estimate of the number of days required to move from one stage to the next.
⁴Range is an estimate of days within a specific stage of development and is influenced by planting date, maturity rating and climatic conditions, and can vary considerably within and between seasons.

Table 4-13. Reproductive Growth Stages in Soybean (Part 4)

	R7 - Beginning Maturity	R8 - Full Maturity
R. Stage1	One major pod has changed to brown colour on the main stem.	95% of pods have changed to brown colour.
Coinciding V Stage2	-	-
Days to Achieve Stage3	7	-
Range of Days4	1-30	-
Target Event	Plant Maturity	Plant Maturity
Notes	Moisture begins to decline in seeds. Physiological maturity reached, maximum dry weight. Seed moisture is about 60%.	Harvest moisture reached in 1-2 weeks after R8.

¹R refers to the various reproductive stages of soybean development.
²In Ontario, where the majority of soybeans grown are indeterminate in habit, vegetative and reproductive stages of developent overlap for much of the plant's development.
³An estimate of the number of days required to move from one stage to the next.
⁴Range is an estimate of days within a specific stage of development and is influenced by planting date, maturity rating and climatic conditions, and can vary considerably within and between seasons.

Updates on Soybeans: Growth Stages

No updates available at this time.

Related links...

• Soybeans