What Are Biostimulants and How Do They Work?

The global biostimulant market is worth around $3.14 billion, with a projected tendency of steady growth that’s expected to hit a $6.69 billion mark in 2029. The main driver of this growth will be the search for cleaner, greener, and more efficient solutions for crop protection and enhancement.

But why and how are the biostimulants valuable for this search? In order to understand this, let’s try to take a more detailed look into what biostimulants are and how they work.

What are biostimulants?

There’s no single, widely-accepted definition of a biostimulant. To put it in the simplest possible terms, it’s a biological or biologically derived compound that is used to increase the health or quality of the crops in an organic way. The U.S. Department of Agriculture used this definition of biostimulants in their Farm Bill from 2018:

“A substance or micro-organism that, when applied to seeds, plants, or the rhizosphere, stimulates natural processes to enhance or benefit nutrient uptake, nutrient efficiency, tolerance to abiotic stress, or crop quality and yield.”

How do biostimulants work?

Have in mind that biostimulants are different from classic fertilizers, pesticides, or supplements that directly supply the plant with nutrients. Biostimulants don’t have such a straightforward effect on the crops, but they rather improve their metabolism and support their natural development.

So biostimulants don’t directly feed the plant, they just affect its vital processes or its environment in a way that’ll help it make better use of nutrients and boost its defense system. In an era where agricultural pollution poses a critical threat to the environment, the development of green, bio-based enhancement products will be absolutely crucial.

The effects of biostimulants

Biostimulants can have a large number of positive effects on  the crops, and these can be divided into three main categories:

1. Improving the absorption of nutrients

First of all, biostimulants can increase the nutrient-use efficiency of crops. This is done in a number of different ways, for instance by affecting the root of the plant. Biostimulants can influence root growth, root architecture, and root diameter, boosting the absorption of nutrients.

Also, they can affect the plant’s water holding capacity as well as induce beneficial microbial activity that helps with nutrient availability in the rhizosphere.  

2. Reducing the effects of abiotic stress

Biostimulants also have a positive influence on the plant’s ability to endure different types of environmental stress. These include drought, heat, cold, and other extreme weather conditions, as well as some other factors such as salinity and heavy metal contamination.

Obviously, the very fact that biostimulants are able to structurally change a plant to boost nutrient uptake means that they can make a plant more resistant to abiotic stress. But they can also improve plant-defense responses in general by helping the plant to accumulate different proteins and other compounds that will make them less vulnerable. Finally, some biostimulants such as silicon can boost the immobilization of toxic materials in the soil and in the plant.

3. Improving the plants’ overall health and quality

At last, by improving all these functions and making the crops more tolerant to various kinds of abiotic stress, you’re improving their general strength and immunity in a completely natural way.

Keep in mind that you don’t use biostimulants to treat the plant, but to act preventively, and improve its systemic resistance, appearance, growth, and health in the long run.

Types of biostimulants

There are numerous kinds of biostimulants, and they’re generally categorized based on the material they’re derived from. Here are some of the most widespread types of stimulants:

  • Humic substances  – these substances include humic and fulvic acids, and they naturally occur in the soil as a result of a breakdown of organic materials
  • Protein hydrolysates – these are a mixture of amino acids and soluble peptides. They are produced by a hydrolysis of organic residue.
  • Seaweed extracts – extracts of seaweed can be powder or liquid substances produced by different extraction methods. The nutrients and hormones from seaweed can boost the plants’ growth as well as their defense system.
  • Chitosan – this biopolymer is most commonly derived from the shells of crustaceans and insects, and they also naturally occur in fungal cell walls. Chitosan can be beneficial in many ways, most notably helping the plant’s anti-pathogen defense.
  • Beneficial microbes – these include a wide range of fungi and bacteria, which can, for instance, extend the plant’s root system, improve phosphorous uptake, or produce plant-growth hormones.
  • Inorganic compounds – some minerals, such as silicon, cobalt, or selenium can also improve plant growth, resistance, and quality.

Final remarks

Biostimulants can be very valuable for the future of agriculture as they offer a natural way to enhance the crops’ growth and quality without making any damage to the plant or to the soil or to the environment in general.

Just have in mind that they’re not almighty as well. We still don’t understand the exact mechanisms used by some of them, while others have so far been proved to be efficient only in controlled surroundings. Their effects can vary for different species and can depend on weather conditions or other local factors.

So if you’re thinking of using biostimulants for your plants, just make sure you have all these parameters in mind and try to optimize their use based on what’s best for a particular species in its specific surroundings.