The cotton seed is the first control point in the crop. What happens to it within the industry determines the plant density, initial plant health, and a large part of the risk of replanting.
To be sold in Brazil, it must be threshed and meet the germination and purity standards set forth in MAPA Normative Instruction 45. Next come neutralization and industrial processing.
This guide outlines what changes at each of these stages and how to assess the quality of the batch arriving at the farm.
What defines a high-quality cotton seed?
The quality of cotton seed is assessed through laboratory tests and recorded on the analysis report that accompanies each lot.
For categories C1, C2, S1, and S2, MAPANormative Instruction 45 establishes a minimum germination rate of 75% and a minimum physical purity of 98%.
For basic seeds, the minimum germination standard varies, reaching 70 percent depending on the category.
Germination indicates how many seeds are able to develop into normal seedlings under conditions considered ideal in a laboratory setting.
Vigor, on the other hand, shows how a seed lot may respond when faced with less favorable conditions during emergence. A seed lot may have germination rates within the standard range and still exhibit lower vigor.
Therefore, evaluating only the germination percentage does not provide a complete picture of the batch's potential.
Laboratory tests follow methods standardized by the Rules for Seed Analysis.
When analyzing cotton seed germination, different temperature regimens may be used, depending on the method employed.
To compare lots, it is important to verify that the vigor tests were conducted using the same method.
A combined analysis of germination, vigor, and purity helps reduce the risk of selecting a lot that is unsuitable for the planting window.
Debridement and neutralization: What happens before treatment?
After ginning, the cotton seed is covered with linter, a layer of short fibers that remains attached to its surface.
Cotton seed hulling involves removing this layer before the seeds are sold.
Delinting improves the flow of the seeds and facilitates their passage through the seeder’s distribution mechanisms. The law also stipulates that cotton seed sold on the market must be delinted.
There are various methods for performing this operation, including chemical and mechanical processes.
In the chemical method, the seed is passed through a solution capable of removing the linter and must then be washed and neutralized. Neutralization is important because residues from the process may remain on the seed’s surface.
In the mechanical flame-stripping process, the linter is removed using burners, without the use of acid. The choice of method depends on the available infrastructure, the production system, and the characteristics of the processing.
Once the cotton seed has been ginned, neutralized, and dried, it is ready for the next stages of processing.
Cotton Seed Treatment: Fungicides, Insecticides, and Coating
Cotton seed treatment protects the crop during the period between planting and seedling emergence.
Fungicides are used to protect against diseases that can harm seedlings during this early stage, such as ramulose.
Among the problems associated with the outbreak are tree collapse and diseases caused by various species of fungi.
Insecticides can also be used to protect crops from certain early-season pests. When selecting products, technical recommendations, the area’s history, and the characteristics of the plot should be taken into account.
The treatment must provide uniform coverage so that all seeds receive the intended protection.
Improper application may result in some seeds receiving an insufficient amount of the product. Therefore, the equipment used and the operational settings also affect the outcome.
According to a survey cited by Embrapa, the cost of treatment represents a small portion of the total cost of the crop. However, a failure to emerge may require replanting and significantly increase operating costs.
Film coating: polymer and drying powder
After the protective coatings comes the film. The film coating creates a layer around the seed that holds the treatment in place.
The process uses two combined seed treatments. LabFix® polymers improve adhesion and abrasion resistance.
LabSec® drying powders accelerate drying and improve seed flow within the planter.
In practice, this combination helps preserve the treatment during application, transport, and seeding.
Plantability: What effect does it have on the stand?
Plantability refers to the ability of cotton seeds to pass through the metering system and be distributed evenly.
Improper distribution can increase the incidence of failures and duplicate seeds in the row.
Gaps are areas without plants, while clusters contain more than one plant in the same spot.
Every failure means one fewer plant per meter. Every duplicate plant competes for light and water at the same point along the line.
Smooth, dry, and uniform seeds reduce both problems. That is why the film and drying powder are no longer considered a finish but have become part of the treatment.
How should treated seed be stored and transported?
Storage begins immediately after processing and affects the preservation of the batch's physiological quality.
Water content is one of the key factors in preserving cotton seeds during the storage period.
Under conditions where temperature and humidity are not controlled, it is recommended to avoid prolonged storage periods.
In a controlled environment, studies by Embrapa indicate that batches can remain viable for longer periods.
The warehouse must be well-ventilated, protected from direct light, and free of damp spots.
Packages must also be kept off the floor to minimize contact with moisture.
Excessive stacking can impede air circulation and lead to unsuitable storage conditions.
During transport, friction also warrants attention because it can remove part of the applied film.
If sowing is delayed, a new germination test helps verify the condition of the batch before the operation.
How to Sow: Spacing, Density, and Planting Care
Once prepared, the cotton seed needs to be exposed to the right conditions to germinate and form a uniform stand.
The seeding depth should take into account soil type, available moisture, and field characteristics. The distribution must also adhere to the spacing guidelines established for the cropping system used in cotton farming in Brazil.
In conventional farming, the spacing between rows is usually greater than in high-density systems.
In high-density systems, the spacing between rows is reduced and the plant population is adjusted.
The choice of seeding density should take into account the cultivar, growing conditions, soil fertility, and water availability. The seeder should be adjusted before entering the field to ensure proper distribution and seeding depth.
Monitoring the setup allows you to quickly identify any issues that could compromise the booth.
The planting season must also comply with the phytosanitary regulations established for each growing region.
Therefore, planning must take into account plot quality, soil conditions, climate, and machine settings.
FAQ – Frequently Asked Questions About Cotton Seeds
What is the minimum germination rate for cotton seeds?
MAP Normative Instruction 45 requires a 75% germination rate and 98% physical purity for categories C1, C2, S1, and S2. For basic seed, the minimum germination rate is 70%. These values are listed in the lot analysis report. Low vigor, even with an approved germination rate, still compromises field stand.
What is cotton seed dehusking?
Dehulling is the removal of the lint, the fuzz that remains on the seed’s surface after shelling. It can be done chemically, using sulfuric acid followed by washing and neutralization, or mechanically by flambing. Without this step, the seed does not flow well through the metering device and carries more inoculum into the soil.
Why does the seed need to be neutralized after chemical delinting?
This is because the acid residue is not completely removed by washing alone. The sulfate that remains on the surface acts as a weak binder and reduces sprouting during storage. In a UFPel study, batches stored for ten months without neutralization showed poorer physiological performance than those neutralized with sodium hydroxide. The traditional neutralizing agent used in the industry is calcium carbonate.
Is it worth treating cotton seeds?
Yes, and the math is straightforward. A study by Embrapa Agropecuária Oeste estimated that the treatment accounts for 0.17% of the cost per hectare of cotton, compared to 4.07% for replanting in the conventional system and 5.13% in no-till farming. The figures are from 2002, but the ratio still explains the decision.
What diseases does seed treatment control in cotton?
The primary target is seedling damping-off, caused by Rhizoctonia solani and seed-borne Colletotrichum species, including the agent that causes ramulose. The technical recommendation is to combine a systemic fungicide with a protective fungicide, because this combination broadens the spectrum of control beyond what a single product can achieve.
What is film coating on cotton seeds?
It involves applying a film to the pre-treated seed. The coating uses a polymer to improve adhesion and abrasion resistance, and a drying agent to speed up drying and improve flow. The result is less loss of pesticide during transport and more uniform seeding along the row.
How long can cotton seeds be stored?
It depends on storage conditions. In a warehouse without temperature and humidity control, the practical recommendation is not to exceed eight months, with a moisture content of around 10%. In a dry storage chamber, Embrapa reports that viability is preserved for up to twelve months. In any scenario, repeat the germination test if sowing is delayed.
How much seed is lost during cotton processing?
The industry estimate is for a 20% to 25% loss in mass along the processing line, from the lint-covered seed to the graded seed. The yield varies depending on the cultivar, the ginning method, and the stringency of the grading process, and is factored into the industry’s cost per bag calculation.
Well-prepared seed, more predictable crop
Much of what determines the quality of the crop happens before the cotton seed even reaches the farm.
Proper de-linting, complete neutralization, treatment applied using the right equipment, and a film that holds the product in place until it reaches the groove: these are four industrial steps, not four on-site decisions.
For those who process seeds, that's where the profit margin lies. For buyers, it's what distinguishes two lots with the same germination label.
Laborsan Agro develops polymers, drying powders, and binding agents for each of these stages.
