Seed treatment is used as an important tool in crop management and is a reality, as it helps maintain seed quality and prevents losses caused by diseases and insects. The use of seed treatment is an important practice for reducing pathogens that infest and infect seeds, in addition to protecting against pathogens that survive in the soil when sowing is carried out (HENNING 2005). In seed treatment, several products can be used, such as agrochemicals (fungicides and insecticides), biological products, inoculants, stimulants and micronutrients (MENTEN & MORAES 2010).
New technologies, combined with the use of improved seeds and appropriate management are used to increase crop productivity (FREZATO et al., 2021). The use of biostimulants is highlighted, as these are natural or synthetic substances that can be applied to seeds, plants and soil and cause changes in vital and structural processes, in order to increase the productivity and quality of seeds and/or grains (ÁVILA et al., 2008).
According to Castro et al., (2019), biostimulants are natural substances or microorganisms that improve nutritional efficiency, responses to abiotic stresses, productivity and quality of crops, regardless of their nutrient content; or products that contain active components or biological agents that act on plants to improve their performance, free from bioregulators and agricultural pesticides. Such as algae extracts, humic and fulvic acids and amino acids (ESAYAMA et al., 2022).
According to the Ministry of Agriculture, Livestock and Supply (MAPA, 2020), a biostimulant is a product that contains a natural substance with different compositions, concentrations and proportions, which can be applied directly to plants, seeds and soil, with the purpose of increasing production, improving seed quality, stimulating root development, favoring the hormonal balance of the plant and faster and more uniform germination, interfering in plant development, stimulating cell division, differentiation and elongation, including processes and technologies derived from the biostimulant.
In order to increase productivity, strategies aim at better development through the use of products such as bioregulators and biostimulants that favor the expression of the genetic potential of plants through changes in vital and structural processes, promote hormonal balance and stimulate the development of the root system (VIEIRA; CASTRO, 2003). Many of these products increase the absorption of water and nutrients by plants, as well as their resistance to water stress and the residual effects of herbicides in the soil, leading to their increasing use in agriculture (VASCONCELOS, 2007).
Biostimulants have been used in agriculture to improve several agronomic characteristics of commercial crops (ANJOS et al., 2017). It can be used in seed treatment and/or foliar spraying. Positive results have been observed in several crops, such as beans, soybeans, corn, among others (RAMOS et al., 2015). According to Abrantes (2008), the biostimulant promoted an increase in the vigor of bean seeds, increasing the percentage of strong seedlings (seedling vigor classification).
Amino acids
Amino acids are organic molecules formed by atoms of C (carbon), H (hydrogen), N (nitrogen) and O (oxygen) linked together. Any amino acid has a carboxyl group (COOH) and an amine group (NH2) linked to a C atom. An H atom and a radical (R) are also linked to this same C. The radical represents an organic radical, different in each existing amino acid molecule. Each variation in the number or sequence of amino acids produces different proteins and, thus, there is a great variety of proteins (TAIZ and ZEIGER, 2017; ESAYAMA, 2022).
Amino acids can perform different functions in plants, and can act as stress-reducing agents, sources of N and hormone precursors (CELEDONIO et al., 2020). The application of amino acids in plants is also used to improve the growth and nutritional level of plants, making them more tolerant to disease damage (EL-GHMRY et al., 2009).
An amino acid of importance for cellular metabolism is L-glutamic acid, which presents a significant diversity of biological functions, acting as a central molecule in the metabolism of higher plants (FORDE and LEA 2007), being a precursor of chlorophyll synthesis in leaves (YARONSKAYA et al., 2006), in addition to the regulatory function of carbon and nitrogen metabolism (ROBINSON et al., 1991).
Skopelitis et al. (2006) observed that plants of Nicotiana tabacum L. and Vitis vinifera L. exposed to saline stress conditions, induced by NaCl, showed induction in the synthesis of glutamate dehydrogenase (GD), a precursor enzyme of glutamate. The authors verified that GD may be a stress-responsive enzyme, as it exhibits thermal stability, the ability to act in the detoxification of ammonia and the production of a new glutamate molecule (DE CARVALHO et al., 2013).
Glutamate is also a precursor of arginine and ornithine, which in turn act in the synthesis of polyamines, which can act on plants, minimizing stress conditions (RHODS et al., 1986; FORDE and LEA, 2007; LEA et al., 2007). Ferreira et al. (2002) also highlighted the importance of the amino acids glutamine and glutamate, which serve to translocate organic nitrogen from sources to sinks, acting in the vital processes that control plant growth and development and have marked effects on phytomass and final crop productivity.
Rathore et al. (2009) found that seaweed extract, applied via foliar application, provided greater seed productivity of Glycine max (L.) Merr. Amin et al. (2011), in turn, also obtained an increase in the quantity and quality of Allium cepa L. bulbs with foliar application of putrescine and the amino acid glutamine.
Micronutrients
Micronutrients are chemical elements essential for plant growth and are required in very small quantities (MORTVEDT, 2001). Although the participation of micronutrients is small, the lack of any of them can result in significant production losses (BARBOSA FILHO et al., 2002). Micronutrients can be applied directly to the soil, through conventional fertilization, or through fertigation, in the aerial part of the plants, through foliar fertilization, or seed treatment (CHENG, 1985).
The symbiosis between bacteria collectively called rhizobia with legumes is characterized as one of the N-fixing systems.2 most efficient currently known. Efficiently nodulated legumes present concentrations of molybdenum (Mo) in the nodules that are up to ten times higher than those found in the leaves. In conditions of Mo deficiency, it tends to accumulate only in the nodules, to the detriment of other parts of the plant (PATE, 1977). The participation of Mo as a cofactor in the enzymes nitrogenase, nitrate reductase and sulfide oxidase is closely related to the transport of electrons during biochemical reactions (SFREDO & DE OLIVEIRA,2010).
Cobalt (Co) is a nutrient absorbed by roots as Co2+, considered mobile in the phloem. However, when applied via foliar application, it is partially mobile. Co is essential for N fixation2, as it participates in the synthesis of cobamide and leghemoglobin in the nodules. Therefore, Co deficiency can cause nitrogen deficiency in soybeans, due to low N fixation.2. Its deficiency causes total chlorosis, followed by necrosis in older leaves, due to nitrogen deficiency (SFREDO & DE OLIVEIRA,2010).
Growth regulators
Growth regulators have been associated with micronutrients in seed treatment, seeking to stimulate germination and improve plant establishment in the field (SILVA et al., 2008). These products increase the capacity for water and nutrient absorption, as well as resistance to water stress, allowing better plant development in suboptimal conditions (VASCONCELOS, 2006; CASTRO et al., 2008).
Biostimulants can be used as a strategy to minimize the effects of uneven seeding (KLAHOLD et al., 2006). CASTRO & VIEIRA (2001) defined biostimulant as a mixture of plant growth regulators, or of one or more plant regulators with other compounds of a different biochemical nature (amino acids, nutrients, vitamins, etc.). These products favor the expression of the genetic potential of plants through changes in vital and structural processes, promoting hormonal balance and stimulating the development of the root system (CASTRO & VIEIRA, 2001; SILVA et al., 2008).
Santos & Vieira (2005) analyzed doses of a biostimulant product, composed of cytokinin, indolebutyric acid and gibberellic acid, applied via seed, observing an increase in the percentage of seedling emergence. Gossypium hirsutum L., as well as in leaf area, height and initial growth of seedlings, with the gain being proportional to the increase in the dose of the biostimulant.
After explaining how biostimulants work, let's talk about ILSA products – which are not direct biostimulants but act nutritionally on plants – which can contribute to increased productivity when used in the initial stages of production, whether in seed treatment or foliar applications.
First, let's talk about ILSAMIN Radix, which is a liquid fertilizer based on GELAMIN®, used in seed treatment that represents a natural source of fast-absorbing AMINO ACIDS, which has both nutritional and stimulating action on the physiological processes of plants and can be used together with seed treatment and aims to provide amino acids, humic substances and tryptophan (auxin precursor) in order to promote greater rooting and greater use of nutrients.
Another product that enhances plant development, especially in legumes, is ILSAMIN is a mixed mineral fertilizer based on enzymatically hydrolyzed proteins (GELAMIN), which represents a natural source of rapidly absorbed amino acids combined with mineral sources of molybdenum (Mo) and cobalt (Co) for foliar application. Its use is recommended for soybean crops via foliar application at the V4 stage with the aim of enhancing the biological nitrogen fixation process, acting both on the development of fixing bacteria and on the transformation of atmospheric nitrogen into forms assimilable by plants.
Mo is essential for soybeans, as it participates in the nitrogenase enzyme, synthesized by bacteria during the process of biological nitrogen fixation (BNF) by symbiosis, in which microorganisms infect the roots of soybeans, forming nodules, the interior of which contains an enzyme complex, called nitrogenase, providing ammonia (NH3) to the plant, which in turn synthesizes the nitrogen compounds necessary for its survival (ALBINO; CAMPO, 2001).
Co is responsible for the enzymatic activation of dehydratases, mutases, phosphorylases and transferases, constituting an essential element in the N fixation process.2 by bacteria of the genus Rhizobium present in the nodules of leguminous plants (ZIBIANI et al., 2023). The production of vitamin B12 is also limited in plants without a sufficient supply of Co, and the fixation of atmospheric nitrogen is reduced (RAIJ, 1991; MARSCHNER, 1995).
For Zibiani, 2023, foliar application, applied 40 days after planting cobalt and molybdenum via foliar in the appropriate treatments in soybeans at vegetative stage 5, demonstrated better results in the soybean production components, mainly in the characteristics: number of seeds per pod, number of seeds per plant and number of pods per plant.
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Authors
Agr Eng. Dr. Angélica Schmitz Heinzen
Agricultural Eng. Msc. Carolina Custodio Pinto
Agricultural Eng. Msc. Thiago Stella de Freitas
