Seed analysis laboratory

Edição XXI | 02 - Mar . 2017

Maria de Fátima Zorato - fatima@mfzorato.com.br

    Our world lives in constant evolution and it is part of the agricultural complex. More than 10,000 years ago, farmers are the agents of the agrarian base construction  in which we live and in which the seed analysis laboratory has been inserted since the 19th century.

    The processes of the agricultural revolution are many. In Brazil, in particular, soybeans have become the flagship of agriculture, and several states have become viable through the seed, which has provided gains throughout the chain, including contributing positively to the trade balance, with significant volumes of export.

    Soyabean represents the basic and indispensable input in the productive system, acting in the agricultural market as the protagonist of the technological innovations. It has encapsulated the linkage of genetic information and chemical products, generating productivity to the Brazilian agriculture, which increasingly becomes more competitive in the world scenario. Therefore, it is a living organism that carries the full potential that can be translated into product, be it in grain, considered as commodity, destined to the industry to obtain oil, bran and other derivatives, or be it in a seed, considered as intellectual property , which connects to the aggregate technologies and restarts the cycle. That is, the seed represents at the same time the culmination of the activities of a plant generation and the beginning of a new generation.

    When a crop is driven for seed production, the complexities are much larger and take on new dimensions. Strategy, planning and management gain significant importance due to strong climatic influences throughout the period that the crop is subject, since agriculture acts as an industry without a roof.
    In recent times, with all the blessing carried by breeding programs and seed treatments, its quality has become a preponderant requirement in obtaining the maximum yield of the cultivars, either by the intrinsic and extrinsic factors, as well as, the genetic, physical, physiological and sanitary conditions.

The seed laboratory
    As known, the quality of the seed originates in the field, however, its analysis is done in the laboratory, which has its processes, procedures and costs, its plans, strategies and results. Well-trained and skilled analyst working well representative samples make up the key piece of quality assurance. However, this actor is a member of one of the parts of the production system gear, which comprises the agricultural part (origin), the industrial part (seed processing unit), storage until the moment of distribution (shipment) to the destination of sowing and the post-sale (commercial) and in the service of quality assurance, in situation of complaints by the clients. Therefore, it is necessary the interaction and good communication among all the actors involved in the process and, above all, to maintain the effectiveness of the whole greater than the sum of the parties efficiency.


Natural seed coat rupture shown by the tetrazolium test


    In the changing and complex agricultural system, the fact remains that the seed laboratories still remain in the nineteenth century when it refers to the results of the official analysis, ie the issue of the Seed Analysis Certificate (SAC) which regulates the seed production. Or rather, since the remarkable professor Dr. Friedrich Nobbe (1830-1922) created, in April, 1869, in Thorandt, Saxony, Germany, the first laboratory, initiating scientific seed analysis , aiming at a more food production insurance, in our country there was no change in practically anything, except for many internal quality controls, walking parallel to the SAC.

The seed evolution 
    But let’s reason. The seed inverted its degree of complexity. About a hundred years ago, it was simpler and more understandable; Currently, it is a complex product, more difficult to understand, more elaborate. What were the circumstances for this exchange of orders? Responding to this question, several information are found, however, we can infer that the twentieth century was considered the milestone of the evolution of the plant production mother, the seed.
    Punctuating the changes that occurred, Dr. James C. Delouche summarized in the best way the trajectory of this relevant input. It addresses two fundamental discoveries: the first, the laws and forms of inheritance, which propitiated the production of varieties and hybrids, with desirable characteristics from the natural variability of the species; and the second, the structure and properties of DNA that it identified, revealing the basic units and inheritance mechanisms that converged to molecular biology and the consequent development of recombinant genetics, and later biotechnology, inducing high technology.
    Biotechnology, the genome, and chemistry are being worked out in cooperation to have greater innovative power in a universe where only human competence is the limit. In this context, the seeds of different plant species constitute great agents of a true technological package of genetic engineering and the assisted selection of molecular markers. So, we begin to understand why the seeds have become complex, demanding, and valued. The processes have become more sophisticated, and this is due to the implementation of laws and standards that served as directives, especially the Law of Plant Protection, tied to the responsibility of intellectual property, the Patent Law and the Law of Biosafety, in addition to other policies related to the expansion and development of the agricultural system, mainly impacting the seed industry.

Greenish soybean seed


    Other circumstances corroborated the mutation of simplicity to the complexity of the seeds, in particular globalization, information technology (computers), and the communication system, which, in a significant way, caused the world to shrink, allowing science and technology advances diffusion, very fast.  
    The seed cradle, agriculture, added quality and transformed lives through modernization in all its processes: in the field, with better adaptation and use of the land potential, which reflects in greater productivity; in equipment, planters, harvesters, sprayers, industrial seed treatment, dryers more suitable for seeds, cold contributing to quality preservation; in agrochemicals, fungicides, polymers, dyes, insecticides, nematicides, inoculants; in the market, agribusiness and marketing was included; and, finally, the man in the field and all those involved in the activity, through training, courses, improvements, which supported the transformations of technologies and established the success and greatness of food production, as well as production of alternative sources of industrial energy. 



Natural damaged, wrinkled and mechanical damage seed


Seed analysis
    With regard to seed analyzes, is there a follow-up of these events in the same proportion? Yes and no. This issue has an order of greater difficulty because the methods directly influence the results.
    The seed production chain involves, among other sectors, the laboratory, whose main objective is to generate detailed information about the performance potential of the seeds by means of specialized and standardized tests to identify problems and their possible causes. Seed analysis represents the technical methodologies that must be standardized, be practical, with high degree of precision and uniformity, used to evaluate the quality and identity of a seed sample.
    In this sense, one of the major driving forces in recent times to ensure the qualification and validation of a laboratory was the implementation of standards for accreditation based on the NBR ISO / IEC 17025 standard, a quality management system applied to provide reliable results to the seed chain, at a time when agribusiness requires more and more optimized and fast processes. 
    Therefore, the need for a more integrated laboratory support was provided, aiming at technical support to improve quality and possible corrections of failures in the seed production process. With this imposition, the already existing procedures were being improved and, taking into account the demand for incorporation of tests, mainly of vigor, for large crops as well as for oil, forage, forestry, to support production and decision making on seed quality . Among the tests, all of them being worked for the different plant species according to their peculiarities. We can mention some examples, such as: tetrazolium, accelerated aging, controlled deterioration, electrical conductivity, seedling and root length, speed of germination index, seedling vigor, cold test, low temperature test, seedbed emergence, (whether sowing in sand or soil) and, recently, following the dynamism of the market, many state-of-the-art laboratories keep pace with change, applying computerized techniques for specific testing procedures, such as computer image analysis. In addition, many already run routine testing through a computerized system, which corroborates for time-maximization and the development of a more reliable database and the interface with producers - a traceability that can be accessed anywhere in the world at real time.

    Regarding the tests that determine seed vigor, as previously mentioned, most are still being used only for internal quality control of the companies; however, a growing number of seed producers are requesting vigor tests, the results of which are placed in the SAC with the methodology used (which is permitted by law in Brazil). The International Seed Testing Association (ISTA), which edits the international rules for seed analysis, already has five tests described with its proper procedures, namely: accelerated aging, tetrazolium, controlled deterioration, electrical conductivity and emergence. Evaluating, diagnosing and recommending procedures
    Contextualizing, for the soybean crop is worth the reflection that many laboratories are not yet interacting in a necessary and required way these days. Technical information and data interpretation are the driving force and are decisive for more assertive decisions when working with high technology cultivars. Not only that, but the sum of circumstances that the productive environment has allowed. Among the main ones, the earlier cycle, since, as a rule, production takes place under non-advantageous environmental conditions. The habit of indeterminate growth, which generates different maturity periods and causes a strong variation in the individual quality of the seeds within the same plant.


Soybean seed with purple-stained seed coat


    Field detereration, in the different soybean producing regions in Brazil, has been contributory to leave considerable scars when associated with the intrinsic characteristics of the cultivars, that is, what is in the bundle of each genotype. Among them, if only the physiological potential (vigor and viability) occurs, if water deficit and, especially, high temperatures occur in certain primordial phases for the quality formation, the seed production that retain chlorophyll in the cotyledons can be produced and leave the greenish seeds, a fact that does not favor its longevity; formation of wrinkles spread on the cotyledons, which makes this type of seed with greater problem of water absorption to initiate the physiological processes, besides causing very bad visual appearance; deterioration of internal cells in the center of the cotyledons, although the external side is not visualized; and also the very rapid dehydration of the seeds, which makes it difficult to reorganize the membrane system at the time of water imbibition to start the germination process, and also leave seeds with internal cellular cracks in the cotyledons due to drying too fast. 
    On the other hand, if the climate is instability, with high relative humidity of the air, with precipitation at the end of the cycle, after physiological maturity, when the seeds are disconnected from the mother plant, many losses are observed from the field until the end of storage. Because at this stage the deterioration process begins, and this is inexorable and irreversible. The most damaging to production are the deterioration due to humidity, which progresses significantly over the conservation period, even after cooling and stored in air conditioned environments, depending on how the deterioration began; The formation of seeds with purple-stained seed coat caused by the fungus Cercospora kikushii, an end-of-cycle disease. 
    What about abnormals? A few years ago, some strange seeds were detected in some seed lots. However, nowadays, it is occurring more intensely, in any cultivar and indifferent to production place. The entanglement of cotyledon pieces and, normally, a deleterious effect on parts of the embryonic axis, with duplicity of hypocotyl-radicle axis. There is no technical explanation for this damage, which has been posed as mechanical damage because it has no categorization for it. Result of some product application?
    In this same line has appeared a strange configuration in the plumules, also indifferent to the genotype and place. There is a curvature of the plumule (almost intersecting) and, at the seedbed emergence, there has sometimes been a difficulty to the formation and development of the main leaf, when it had the plumule of this nature. It is worrisome, because this type of damage has often gone unnoticed, since only a few laboratories have the practice of opening the cotyledons when evaluating the seedlings  in the germination test. 
    Another, at least unusual, effect is the opening of the cotyledons in dry seeds in an area opposite the embryonic axis. When only some seeds are detected Another, at least unusual, effect is the opening of the cotyledons in dry seeds in an area opposite the embryonic axis. When only some seeds are detected in the population of the lot, they mean problems in almost all tests.
    There are some thoughts about it, but nothing concrete. The problem has already been seen in fields that have experienced rain at maturity. A very strong rhetoric is that the seeds with a very high water content, when undergoing abrupt drying, would remain with the inner part still with much water - even the surface drying very fast, thus causing the opening of the cotyledons 
    Nowadays, with soybeans being a “technological chip”, we have the following: we are in the 21th century however delivering to the client  only the certificate with germination data that is performed under optimal conditions of environment (water, Light, temperature, oxygen) and, in the evaluation, a concept contained in the Rules for Seed Analysis is obeyed, where it is prescribed that germination in the laboratory is the emergence and development of the essential structures of the embryo, demonstrating its aptitude to produce a normal plant under favorable field conditions. Thus, in the laboratory, seedlings of two centimeters, are considered as normals. There is no standard categorizing the size that will give rise to a seedling with more aptitude. The deception of quality, in my view lies in this picture.

Seed vigor effect


    As it is not analyzed individuals, but the population of individuals of a lot, which today can represent up to thirty tons of soybean seeds, this whole can germinate above the standard (80%) or even greater value, but considered inadequate before abiotic conditions already mentioned, with smaller, weaker, unstructured seedlings.
    Actions are performed before sowing. Real cocktails of products are being used in order to protect the seeds, aiming at the best performance of plants in search of high productivities. That lot whose seeds are weaker but that the germination is above the national standard will be totally dependent on the optimal soil and climatic conditions for its expression. Therefore, vigor, which comprises seedlings with their strongest, most developed structures, responding with rapid emergence, uniform under more stressful conditions, is at the mercy of the concept of germination and is worked internally in almost all the seed companies of the country. 
    Well, in view of the facts described, when the sum of the defects occurs, associated with known physiological damages such as mechanical damage, deterioration due to humidity and insect damage, the consequences are devastating, especially in the analysis results. At this time, there is a need for a professional seed Actions are performed before sowing. Real cocktails of products are being used in order to protect the seeds, aiming at the best performance of plants in search of high productivities. That lot whose seeds are weaker but that the germination is above the national standard will be totally dependent on the optimal soil and climatic conditions for its expression. Therefore, vigor, which comprises seedlings with their strongest, most developed structures, responding with rapid emergence, uniform under more stressful conditions, is at the mercy of the concept of germination and is worked internally in almost all the seed companies of the country. 

    Well, in view of the facts described, when the sum of the defects occurs, associated with known physiological damages such as mechanical damage, deterioration due to humidity and insect damage, the consequences are devastating, especially in the analysis results. At this time, there is a need for a professional seed specialist within the laboratory, taking care to  establish data connection to understand and make them understand the reason for fluctuations within the test and between tests and know how to guide the germination test, with its troubles. 
    Often there is no need to re do testing, because the physical analysis of a lot explains its data. It is necessary to have a better understanding of the contemporary seed and its package of situations related to the climate. There is no longer the seed of the past. The technological seed requires more technical knowledge and interpretation.
    We need a consensual cohesion that the communication process has become imperative in the production of contemporary soybean seeds. We must be disruptive and act in a way that has fewer losses in every way. The prodigious epic shows us that the path has always been one of evolution and transformation. And why not in the seed analysis certificate? We will evaluate the seed, diagnose the possible causes of its poor performance and recommend possible correction alternatives. Knowledge exists for this. 

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