Biostimulants in farming: necessity, types, and application

What are biostimulants? 

Despite the lack of a single legislative definition worldwide (particularly in the EU and the US), plant biostimulants can be characterized based on the decision of the European Council of the Agricultural Sector.

Plant biostimulants are substances and/or microorganisms that, when applied to plants or the rhizosphere, stimulate natural processes to:

• improve nutrient uptake.
• increase the effectiveness of nutrients.
• increase tolerance to abiotic stress.
• improve crop quality.

Biostimulants are not plant protection products. They increase the vitality of plants without directly preventing diseases or pests. They also promote nutrition, condition the rhizosphere, and enhance the activity of soil microflora.

Need for application:

Abiotic stresses are caused by changes in the sowing environment. Climatic changes such as drought, high temperatures, frost, wind, and hail affect plant sensitivity:

• reduced evaporation
• lower photosynthetic activity
• impact on crop components

These abiotic symptoms lead to reduced yields.

Biostimulants are used to influence the physiological processes of plants, accelerate photosynthesis, increase nutrient efficiency, and improve abiotic resistance. This allows for better realization of the genetic potential of plants and improves the quality of agricultural products. It is possible that biostimulants also affect growth processes, but this is not their main purpose.

Modern agricultural experts believe that the high genetic potential of modern varieties and hybrids of agricultural crops can only be realized by introducing additional stimulating substances into technological processes.

Types of biostimulants

Today, there are several groups of plant biostimulants that are used for root nutrition, improving the absorption of elements, and reducing the negative impact of stress factors on the plant organism.

Microbial preparations.

This group includes biostimulants containing live bacteria and fungi, as well as preparations containing inactivated microorganisms and/or their metabolites. Microbial biostimulants stimulate the release of organic acids by the root system of plants, thereby dissolving hard-to-reach soil substances and making nutrients more accessible to the plant. They also stimulate nitrogen fixation.

Amino acids and protein hydrolysates.

These are mixtures of peptides and amino acids obtained by enzymatic and/or chemical hydrolysis of proteins of animal or plant origin. Amino acid biostimulants stimulate carbon and nitrogen metabolism, increase their assimilation, and regulate the enzymes of the photosynthetic cycle. The use of certain amino acids reduces the negative impact of free radicals, which helps to alleviate environmental stress on plants.

Humic and fulvic acids.

The source of these compounds is mineral deposits (leonardite) or natural humic organic substances such as peat, compost, and vermicompost. Such biostimulants increase the availability of phosphorus and some other nutrients to the plant, activate the transport of most ions and metabolites through the cell membrane. Humic substances also exhibit auxin, cytokinin, and gibberellin-like activity, thereby stimulating root system development.

Seaweed extracts.

These preparations contain polysaccharides, phytohormones, amino acids, and certain nutrients (micro- and macroelements) that were originally found in the “donor” brown algae Laminaria digitata, Ecklonia maxima, Fucus vesiculosus, Ascophyllum nodosum, etc. Biostimulants from algae extracts often have a hormone-like effect on plant organisms, stimulate the root system, normalize transpiration, and help increase cell membrane strength, which reduces the plant’s sensitivity to stressful weather factors.

Microelements.

Microelements such as Cu, Co, Se, and Si have the properties of biologically active substances and can be used as biostimulants that enhance enzyme activity, stimulate phytohormone synthesis, and affect thermoregulation and transpiration in plants. With certain limitations, phosphites, which can exhibit stimulating properties and fungicidal action, can also be included in the class of these biologically active substances.

Phytohormones.

Preparations containing plant hormones are obtained by fermentation of plant raw materials or are synthetic. There are not many such biostimulants on the world market at present. Separately, it is worth noting a stimulator based on brassinosteroids, which helps to realize the maximum genetic potential of a crop. This class of phytohormones induces cell division and stimulates vegetative growth of plants. It has been established that in low concentrations, brassinosteroids not only affect the processes of plant growth and development, but also increase their resistance to various stress factors, including drought, sudden temperature fluctuations, and pesticide damage.

Biostimulants contain organic substances that can improve plants’ access to nitrogen in the soil and even in the air. Today, the world’s largest companies—manufacturers of plant protection products—are already interested in the production and use of biostimulants. They are gradually entering this market, and where there is market expansion, there is also abuse. Probably all farmers have heard about “holy water,” which you just need to sprinkle on the field to get unprecedented yields, and “miracle pills” for all problems. After all, such miracles are offered by some unscrupulous manufacturers and sellers. Counterfeit products have long been commonplace in the plant protection products market. Similarly, in the biostimulant segment, there are many untested products with unproven effectiveness that are positioned as extremely useful.

When choosing such products for your technology, you need to consider several important points:

• The availability of publicly accessible research results on the performance and effectiveness of the biostimulant. These should be long-term results, not only from laboratory tests, but also from practical tests in real farms.
• A clear explanation of how the biostimulant works, without vague phrases such as “increases yield by … percent” or “stimulates and influences, makes things better than they were.”
• The experience of farmers who have already used the product on their fields and have achieved certain results.
• An assessment from scientists who study the work of biostimulants.

Collecting this information, of course, takes some time, but it is better to spend a little time searching for a biostimulant that really works than to spend money on “holy water.”

The possibilities for applying biostimulants to plants are quite varied.

In order for the effect of using microfertilizers and biostimulants to be noticeable, a complete analysis of both the site and the water must be carried out. First of all, an agronomist needs to understand what microelements the plant needs and in what doses to provide them, in what soils the plant grows and what fertilization will be more effective, what hardness and quality of water is used for irrigation, and adjust all this for proper development.

Most plants yield about 10-15% of their potential, and stress is one of the main causes of crop loss. Plant biostimulants are derivatives of various natural substances that activate natural biological processes and help crops cope with stress and reach their maximum genetic potential in terms of yield and quality. And while no one had heard of them a few years ago, this market is now growing rapidly in agriculture, increasing by 12-15% per year.