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Also known as soyabean, soybean is a notable species of legume that is native to East Asia. It’s grown chiefly for its edible bean and various uses. You can use soybean to make other products like tofu, soy milk, and even soy flour.
Soybeans are packed with numerous nutrients; they are mostly consumed because it is filled with nutrients. And like every other legume, there are different soybeans growth stages, with vegetative and reproductive being the most notable stages.
The vegetative stage includes the emergence of the flowering process, while the reproductive stage includes the flowering process through the maturation stage.
These growth stages require different attention, and in this post, we will learn more about the different growing stages of soybean.
Soybeans Growth Stages
Generally, soybeans emerge the best if you plant them at most 2 inches into the soil. For the best result, you should use light soil so it would be easy for the seed to emerge through the ground’s surface.
When it is time for germination, the hypocotyl helps push the cotyledons through the soil to the surface. At this point, the plant can develop leaves with stored energy in the plant.
First, the leaves that are the first to develop are the unifoliate leaves. In subsequent times you will notice some leaves form above the cotyledons.
See Also: Different Tomato Plant Growth Stages
Soybean Vegetative Stages
This is the period of growth between the germination and flowering process. It is during this vegetative stage that plants carry out the process of photosynthesis.
Furthermore, the plant can conserve enough energy or resources that the plant will leverage for its production and flowering.
In soybean’s growth stages, the vegetative phase will include;
- VE- The emergence stage
- VC- The cotyledon stage
- V1- First trifoliolate
- V2- Second trifoliolate
- V3- Third trifoliolate
- V(n) nth trifoliolate
- V6- Flowering stage
Once you have completed this stage, you will notice that from the V1 to Vn stages, the leaves are now trifoliolate and produced singularly on different nodes.
1. VE- (emergence)
Plant emergence occurs within 10 to 18 days of planting, depending on soil temperature, moisture, variety, and depth. In this period, the primary root begins to sprout lateral seeds. Additionally, root hairs emerge, providing the plant with nutrient and water absorption functions.
The taproot will continue growing so that side roots can reach the center of a 30- inch row within five to six weeks. Ultimately, soybean roots typically go to a depth of 2 to 3 bases, with the utmost origins in the upper 6 to 12 elevation of soil.
You would have to plant the soybeans 1 to 1½ inches deep. However, now it is no longer deeper than 2 inches. The soybean frequently has to push via crusted soil, and deeper planting can restrict the viability of seed and very last stand number.
For the successful growth of your soybean, you can introduce some fertilizers. Fertilizers will encourage the early development of your plant and help the seed yield quickly.
Note: soybeans are more sensitive to salt than corn and most legumes. So be careful to avoid adding fertilizer directly to the plant, mainly when it contains nitrogen.
Try exposing your plant to indirect sunlight; remember, it requires enough energy to do well.
2. VC- cotyledon stages
At this stage, the unifoliate leaves are expected to be fully expanded. During this stage, the cotyledons supply the young plant’s the required nutrients.
This should last for about seven to ten days. If for any reason, you get to lose one cotyledon, it will not have a significant impact on the plant’s growth rate.
Nonetheless, losing both cotyledons will only affect the yielding rate by 10%, yet after some time, the plant should be able to sustain itself. The plant will always transit to other stages.
3. First trifoliolate V1
This stage is said to be at its peak when the first trifoliolate fully emerges and opens. The upper leaf node above the unifoliate leaves defines the V stage of the plant.
When determining the V stages, the trifoliolate on branches is not counted; only the trifoliolate off the main stem is used in the count.
4. Second node V2
In addition to their unifoliolate nodes, trifoliolate leaves have unfolded leaflets, and the plants grow between 6 and 8 inches tall. Root nodules are just beginning to fix nitrogen from bacteria.
They are located within 10 inches of the soil surface, and each nodule contains millions of bacteria.
Nodules that are red or pink inside are active in nitrogen fixation, but those that are white, brown, or green are probably parasitic on the plant. It uses the nitrogen produced by bacteria and the nitrogen applied to the soil.
Having too much soil nitrogen will cause the plant to use the soil nitrogen first, causing modulation to be delayed and reducing the number and size of nodules. The top 6 inches of soil are developing rapidly for lateral roots.
5. Third trifoliolate V3-V5
At this stage, the soybean plants should have grown between 7 to 9 inches tall, possessing three nodes above the unifoliolate node at V3.
At this point, the branches on the plant may increase in broader row spacings.
Expect that the bud in the plant will form flower clusters at this stage. At this stage, the number of nodes the plant needs is already fully established.
Provided one axillary bud remains intact, soybeans will grow and branch profusely even though the stem apex (main growing point) dominates. Soybeans can produce new branches and leave even after hail destroys almost all above-ground foliage.
The plant, however, dies if it is broken off below the cotyledonary node since it does not have any axillary buds below it.
6. Sixth node
At this stage, six nodes on a soybean plant have trifoliolate leaves that have fully unfolded and expanded by this point.
New stages unfold quickly, every 2 to 3 days. Even if 50% of the leaves are lost at this stage, the plant may still be able to recover; 3% of the yield will be affected.
The soybean growth stages have gone past the vegetative stages; it will now transition to the reproductive stage.
Soybean Reproductive Stage
Although the reproductive stages comprise eight stages, for easy reference, it is grouped into
- The R1 and R2 are the flowering stages
- The R3 and R4 are the pod development stage
- The R5 and R6 are the seed development stage
- The R7 and R8 are the plant maturation stage
Let’s delve into this second part of the soybean growth stages
1. Beginning flowering R1
Each node of the plant has at least one flower. The soybean plant starts flowering from the third to the sixth node on the stem, depending on its vegetative stage.
This flower initiation continues up and down the plant. Branches eventually also bloom. The flowering will begin from the base to the tip of each raceme, so the basal pods are always the most mature.
2. Full bloom R2
At this stage, the soybean has already accumulated some features a mature plant should have. The soybean must have accumulated dry weight and nutrients by 25% and obtained 50% of the adult height. You will even notice a flower in one of the two nodes of the main stem.
Be aware of the rapid accumulation of nitrogen, Phosphorus, potassium, and other dry matter; they will keep happening even through the 6th stage of the reproductive stage.
Flowers will continue to form and might become notable during R5; defoliation at this stage would reduce the soybean yield.
3. Beginning pod R3
This is the length where you will notice pods grow at the four nodes of the plant, and it should be between 3/16 inches. At this stage, the soybean requires all the strength to grow well. If for any reason, the plant experiences stress, it will affect the yielding of the plant.
However, leaving the plant in a favorable condition will contribute to the plant’s growth and pod formation.
4. Full pod R4
At this stage, the plant would experience the complete growth formation of the pod on the plant.
This is considered a critical stage for soybean growth because any mistake can reduce yield. Furthermore, the seed will begin to develop even at this stage.
So, you must pay attention to the plant.
5. Beginning seed R5
The soybean needs all the nutrients to supply the part of the plant with everything it needs to thrive. The plant might lose leaves at this stage, but the yield would be affected depending on the amount lost. If the plant loses 100% of its leaves, it will affect the outcome by 80%.
Additional stress can also affect pod development and seed formation. So you can try to avoid things that would stress the soybean plant.
6. Full seed R5
They are also referred to as the green bean stage or the beginning of the bean growth. Do expect the development of the bean at this stage too.
The plant initiates this stage by forming a pod containing a green seed in one of its four top nodes. Three to six trifoliolate leaves will fall from the plant’s lowest nodes before they begin yellowing. At about R6.5, root growth is complete.
7. Beginning maturity R7
On the main stem, one normal pod obtains its mature color (brown or tan). At this stage, dry matter begins to peak in seeds and pods. This is visible when all the green material has been removed (they become yellow). Leaf yellowing and loss start at this time.
When seeds are physiologically mature, they contain about 35% moisture, so stress at this stage or later has minimal effect on yield unless the pods are crushed, or the seeds are broken.
In addition, lodged plants may decrease actual yield (reduced light interception) and harvested yield (harvest losses). A mild frost does not threaten the crop at this stage.
8. Full maturity R8
Generally, 95% of the soybean pods on the soybean plant have reached their mature color. The soybeans must be dried for 5 to 10 days after getting to this stage to be less than 15% moisture or harvest moisture.
In this case of warm and dry weather, soybeans will quickly lose moisture, so harvesting them on time will prevent losses.
Why is it Important to Know Your Plant Growth Stages?
For plants to grow, develop and produce mind-blowing results, there are always some processes they go through, and this should conform with environmental factors and, of course, a genuine effort from the gardener.
More than that, the growth stages affect the plant’s forms, hence the need to know the soybean growth stages. So you know the things to put in place to get an optimal result.
So, it is easier for farmers or even gardeners with the first experience knowing the plant growth stages. It will, in turn, affect the plant’s growth positively.
The farmer must know the seedbed preparation, variety selection, the planting depth required, the condition to leave the plant in at every stage, and pest management.
It seems uneasy growing soybeans, especially having many soybean growth stages.
However, knowing the growth stages of your plant would grant you the chance to understand it and the growth stages it is likely to go through every season.
Soybean is an excellent product primarily planted by many regions, and you, too, can make this a dream come true.
Ensure you offer the plant the safest and most favorable condition, and it will reward your effort with blooms and mature seeds.