What you need to know about seed quality

Vigor and germination are just two of the fundamental concepts surrounding this topic.

16.03.2022 | 10:46 (UTC -3)
Gilberto Medeiros, Agricultural Engineer and Marketing Manager at Fertiláqua
Gilberto Medeiros, Agricultural Engineer and Marketing Manager at Fertiláqua

The success of soybean farming depends on several factors, but without a doubt, one of the most important is the use of high quality seeds. The use of high-quality seeds allows access to genetic advances with performance guarantees and technologies that adapt to different regions, conditions that ensure greater productivity.

Seed quality can be understood as the set of characteristics, attributes, indices or components that determine the value of seeds for sowing and their performance in field conditions. You see, this type of seed has attributes of genetic, physical, physiological and health qualities, attributes that guarantee high agronomic performance.

Let's therefore understand each of the main concepts involving seed quality and other issues that you should know about the subject: 

How to assess Seed Quality?

The quality of a batch of seeds is evaluated by four attributes, as presented below:

1. Physical quality

Physical quality is nothing more than the physical purity of the seed lot. The objective is to have the purest possible seeds of the species in the batch. In this analysis, characteristics related to the structure, composition, shape, weight, size, integrity and appearance of the seeds are evaluated. The seed sample is separated into three fractions: pure seeds, seeds from other plants (such as weeds, for example) and inert materials (soil, plant pieces, insects and other impurities).

2. Genetic quality

Genetic quality is related to intrinsic factors that define physiological and biochemical characteristics, and interact with external factors that include the physical and biotic environments. You must have detailed descriptions of the materials, with their possible variations, and know the main techniques used to distinguish and identify cultivars. We can cite as examples resistance to pests and diseases, crop cycle and field performance (productivity).

3. Sanitary quality

This is an attribute related to the presence of a pathogenic agent or pathogen, causing disease, which is transmitted by the seed such as loss of quality in storage, transmission of pathogens, stand establishment, seed treatment, etc. Therefore, the detection and identification of microorganisms before sowing are essential for making decisions such as disposal or treatment to control microorganisms.

 4. Physiological quality

This quality is related to the attributes of seed metabolism and all the processes that occur within its cells. Its action is mainly determined by the environment where the seed is formed and by handling during the harvesting, processing and storage phases.

The inevitable loss of quality indicates the need to correctly assess the physiological potential of the seeds before their use. To achieve this, it is important to make use of information obtained in the laboratory, which allows the physiological potential of the samples examined to be compared. This measure avoids problems and difficulties in establishing and managing plants in the field.

In summary, we can say that a physiological attribute is one that measures the ability of seeds to have good plant emergence in the field and the level of physiological quality of the seed is evaluated through two fundamental parameters: viability and vigor. 

Seed Quality Control

Quality control must be established by a seed analysis laboratory, where various tests will be applied to evaluate the viability and vigor of a batch of seeds, before their implementation in the field. Tests must be fast, reliable and complementary. The recommendation is to carry out more than one test for each batch of seeds to compare the results and, in this way, make them more reliable and accurate. This action speeds up decision-making regarding batch management.

This control is carried out through seed testing and analysis at various stages of the process and aims to verify, monitor and check quality. The main ones are: field (harvest), process (processing, seed treatment, storage) and ready batches. However, to choose the appropriate test, it is necessary to consider extremely important issues.

Let's first analyze the difference in concepts between germination and vigor: germination is the set of phenomena that occur in the seed to give rise to a new plant (transformation of the embryo into a seedling). Vigor is those properties of seeds that determine their potential for rapid and uniform emergence and the development of normal seedlings under a wide range of environmental conditions. 

Seed Vigor

Seed vigor is one of the parameters evaluated to attest seed quality. There are several concepts for seed vigor, but in general, they are all linked to seed deterioration. It can be said, simply, that vigor represents the speed of emergence and uniformity of seedling emergence. Deterioration can be understood as the loss of the seed's ability to produce a normal seedling, that is, the greater the seed's vigor, the less its deterioration and vice versa. 

Bearing in mind that the germination test attests to the percentage of seeds in a batch capable of germinating and producing normal seedlings under optimal conditions for the germination process, we can say that the germination test alone is not the best parameter to determine the choice of a batch of seeds. This is because, in the field, the environmental conditions offered are not always the best for the process of germination and emergence of seedlings. Therefore, knowing seed vigor can help in choosing the lot to be used for sowing, reducing initial losses due to uneven plant stands. Furthermore, this knowledge helps define storage times and strategies, serves as a parameter for evaluating seed quality and as a sales strategy (monitoring seed deterioration). 

At field level, it is important to choose seeds with higher emergence and vigor values, which reduces productivity losses resulting from poor plant establishment - remembering that seed vigor is inversely proportional to seed deterioration, i.e., seeds with greater vigor present less deterioration and possibly greater speed and uniformity of germination.

The issue of vigor in seeds is increasingly on the agenda among the seed production sector and farmers. However, there is a lack of better technical mastery of the concepts and parameters related to seed technology, capable of providing better use of the information generated by vigor tests, which are: cold test, accelerated aging test, electrical conductivity test and tetrazolium test. .

Viability and vigor tests

Viability is measured mainly by the germination test and seeks to determine the maximum germination capacity of the seeds, offering the most favorable conditions possible.

Vigor represents more subtle aspects of physiological quality not revealed by the germination test, but rather determined under favorable conditions or by measuring the decline of some biochemical or physiological function. Through vigor tests it is possible to identify differences in the physiological quality of batches that have similar germination power.  

Seeds with low vigor deteriorate and become completely unviable faster than those with high vigor. A seed whose morphological and physiological structures have suffered some type of deterioration during storage does not have the capacity to restore damaged tissues and have the energy to allow embryo growth to resume and form a plant capable of developing in the field. 

Factors that affect Seed Quality

The seed is a living organ, which we need to take care of in order to preserve the quality obtained in the field.

The factors that influence seed quality can occur during the field production phase, harvesting operation, drying, processing, storage, transportation and sowing. Therefore, quality control must be established that encompasses analysis and certification of the seed with the aim of guaranteeing the genetic purity of the cultivars and, thus, guaranteeing the farmer a pure batch with high vigor, capable of establishing a uniform stand in the field.

This all explains the importance of rigorous quality control of seeds before reaching the end customer. It is also important to remember that the seed field, or part of it, will only be harvested if it meets the legally established minimum quality standards.

Seeds of Truth Program: proven quality

The Sementes de Verdade Program is a partnership between Fertiláqua and seed companies that seek excellence in the seed production process. The program aims to meet the growing demand for seeds with proven potential and quality. To this end, Fertiláqua analyzes, identifies and recognizes, with the Sementes de Verdade Seal, the lots that meet the quality standards established by the program and, in this way, offers greater efficiency to rural producers.

The Seeds of Truth Program involves some extremely important rules and characteristics, such as:

Seed analyses: carried out at the Fertiláqua Seed Analysis Laboratory – LAS. Its main objective is to analyze, identify and generate detailed information about the performance potential of seeds.

Logistics with refrigerated trucks: aims to preserve seed viability through specific temperature and humidity control.

Traceability: action carried out through QR CODE with access to detailed information about the origin and quality of approved lots.

Seed storage and conservation system: For this purpose, appropriate containers are used (dry and cold environment) to preserve the quality of the seeds.

Quality approval classes in two categories: GOLD and SILVER

GOLD: In the Gold category, lots must reach a minimum germination rate of 95%, of which 70% of the lot must be in the very high and high vigor classes. Furthermore, they must present a minimum of 90% vigor through the accelerated aging test.

SILVER: In the Silver category, lots must reach a minimum germination rate of 90%, of which 60% of the lot must be in the very high and high vigor classes. Furthermore, they must present a minimum of 85% vigor according to the accelerated aging test.

 Learn more at: https://sementesdeverdade.com/

By Gilberto Medeiros, Agricultural Engineer and Marketing Manager at Fertiláqua

Mosaic Biosciences March 2024