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Soybeans: Growth Stages

Author: OMAFRA Staff
Creation Date: 01 March 2002
Last Reviewed: 01 March 2002
Agronomy Guide > Pub 811: Soybeans > Growth Stages
Excerpt from Agronomy Guide for Field Crops (Chapter 4)
Order 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.)
  Emergence Cotyledon First Node
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.

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

    (Not all V stages are presented here.)
      Third Node Fifth Node Node n
    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.

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    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.
      Beginning Bloom Full Bloom
      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.

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

      Beginning Pod Full Pod
      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.

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

      Beginning Seed Full Seed
      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.

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

      Beginning Maturity Full Maturity
      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.

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    Updates on Soybeans: Growth Stages

    No updates available at this time.

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    Related links...

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