Biostimulants may be defined as activators of biological reactions which may modify plant metabolism in such a way that it becomes better adapted to its environment. The wide range of effects on plant metabolism is reflected in a wide range of bioactive compounds described so far in scientific literature. Biostimulants are mostly natural products, some of which are able to improve crop resistance to disease and other environmental stress and thereby improve growth.

Biostimulants may be foliar applied or applied to the root system. Biostimulants are not fertilizers, pesticides, fungicides or herbicides. Biostimulants can result in better root systems, more efficient chlorophyll, stress reduction, quicker recovery from injury, and faster germination and establishment. The beneficial effect of biostimulants may be due to the presence of natural growth regulators like cytokinins, gibberellins or auxins.

Biostimulants may also be defined as activators of biological reactions which may modify plant metabolism in such a way that it becomes better adapted to environment factors negatively affecting growth and quality.

Types of Biostimulants

Presently, the following main bioactive compounds or classes have been recognized as having biostimulant characteristics:

• Seaweed extracts
• Plant extracts
• Amino acids
• Oligosaccharides
• Salicylic acid
• Silicates
• Others

How do Biostimulants work?

Phytohormonal Effect:
The balance of the various hormones within a plant is a complex interaction that controls its overall growth and development. Thus, materials (like phytohormones in seaweed or other plant extracts) that alter the hormonal status of a plant can exert large influences over its growth and health.

Antioxidant Effect:
Biostimulants may help plants develop higher plant antioxidant activity. Antioxidants are another group of plant chemicals linked to the action of biostimulant. Apparently, some biostimulants promote antioxidant production capable of counteracting the damaging effects of oxidation in plant tissues. Research over the past decade has shown that various environmental stresses, such as drought, heat, ultraviolet light and the use of herbicides, damage plants by causing production of free radicals or reactive oxygen molecules. These molecules are strong oxidizing agents and damage lipids, proteins and DNA inside cells.

Antioxidants are metabolites and enzymes that neutralize or remove free radicals and thereby protect plant cells from damage. Antioxidants include substances such as vitamin E and beta-carotene, water-soluble materials such as vitamin C and glutathione, and various enzymes. Frequently, several antioxidants work together to suppress free-radical toxicity.

Amino Acids are building blocks for proteins and enzymes. Some free amino acids, such as proline,  improve osmotic adjustment and water-stress tolerance of plants. Amino acids have been shown to stimulate biochemical and enzymatic processes in the plant. Amino acids are also optimal chelating agents for cationic micronutrients.

Salicylic Acid, has been shown to improve plant resistance to disease and environmental stress.