Patrick Du Jardin on biostimulants: "They are defined by their function and not by their nutrients"

The academic from the University of Liege, Belgium, participated in the International Expert program on Blueberry Irrigation and Nutrition, organized by Blueberries Consulting together with the University of Almería.

With the talk, "Plant biostimulants, innovation for sustainable crop production", the prominent academic Patrick Du Jardin, professor of plant biology and researcher in plant physiology and nutrition, became part of the group of prominent teachers to participate in the program " International Expert in Irrigation and Nutrition in Blueberries: conventional production and cultivation without soil”.

The doctor of sciences and full professor at the University of Liege in Belgium, was part of the team that helped define what biostimulants are in the latest agricultural regulation of the European Union. His expertise was demonstrated during the talk by conducting an exhaustive bibliographical review of existing research on this supply. 

Biostimulants, what are they and what innovation do they represent?

Du Jardin explained that although there are variations in the definition of a biostimulant, the different versions tend to agree on three characteristics: they are not fertilizers, they are not phytosanitary products, and their definition is based on their function. 

"The biostimulation of a plant is a type of physiological effect that improves the growth and quality of plants," said the teacher, beginning the review of different publications on the subject.

The first use of the word biostimulant in the academic world occurred in a paper published by Ricardo Russo and Graeme Berlyn of Yale University, where they recommended its use for sustainable or low-resource agriculture. 

Zhang and Schmidt, from Virginia Polytechnic University, define biostimulants as materials that promote plant growth. In addition, they are again differentiated from fertilizers by explaining that biostimulants have an effect that is not due to nutrients, so they have an action in small doses. Instead, fertilizers must be used in higher amounts to deliver nutrients to the plant.

According to the definition of the European Union, biostimulants have the goal of improving one or more of the following characteristics of the plant rhizosphere: nutrition efficiency, tolerance to abiotic stress, quality traits and availability of nutrients confined in the soil or rhizosphere. If a product can improve one or more of these characteristics, then it can be declared as a biostimulant in the European Union market.

Offer of biostimulants

The most found on the market are: seaweed extracts, hydrolyzed proteins, humic and fulvic acids. However, the supply of biostimulants from plant extracts, fermentation products, industrial waste, microorganisms, advanced technologies, among others, is growing.

The functions to which biostimulants can be directed, within the characteristics that define them, are as diverse as the forms of treatment. They can be applied, for example, via fertigation to plants, crops and soil; it can be used as a seed coating or fertilizer, and on a wide range of crops. 

The inconsistency of the performance in the field with respect to the laboratory has been one of the greatest limitations to the investigation of the application of biostimulants in agriculture and horticulture.

One of the problems is that when a biostimulant is used, it is not always clear what the expected benefit is. “We must understand biostimulants as a new way of changing the genetic expression of a gene that controls a plant trait. Therefore, if we want to make these biostimulants work more efficiently, we must be clear about the expected results of their use," said Du Jardin.

Innovations to increase the efficient use of nitrogen

Precision agriculture, the use of slow and controlled release fertilizers, in addition to stabilized fertilizers, are some of the options that help optimize the use that the plant gives to nitrogen.

To obtain the same effect, biostimulants modify the physiology of the plant. An example is rhizobia, which "will be able to open new roots so that nitrogen enters the plant," explained Du Jardin. 

The agronomic way of measuring the efficient use of nitrogen is a product between the effectiveness of nitrogen uptake, that is, what is absorbed by the plant given the amount applied, and the efficiency of nitrogen use.

We can review how to control the different variables on which the efficiency of nitrogen use depends. However, Patrick Du Jardin stated that there is a “bottleneck problem”: although the scientific community understands the ability of biostimulants to manipulate the genome of a plant, there are difficulties in dissecting plant development into the different traits that they can be exchanged for biostimulants.

“As the genes make the genome, the phenomena make the phenomenon. The difficulty is that dissecting the phenomenon into the different phenos is a complicated task that we must do, because this will help us to better define how biostimulants act on the plant," Du Jardin asserted.

Increased tolerance to abiotic stress

Biostimulants can significantly increase crop yields against problems that cause plant stress, such as drought or salinity.

"This is where biostimulants are most interesting, because they contribute to high yields together with pesticides and fertilizers, being considered not as substitutes for biocontrol, but as incremental technology," said the plant biology professor. 

Biostimulants can help prepare a plant to face a stress episode, help it during the episode, and then contribute to its recovery after the event.

Concluding his talk, Patrick Du Jardin emphasizes the existing scientific interest in biostimulants, and how this will boost the offer in the market. However, in his opinion, three challenges must first be overcome.

The first is scientific, understanding the mechanisms of action of biostimulants, their interaction with the plant and other environments, in order to eliminate the differences between laboratory and field experimental results.

In addition, it indicates that technical difficulties must be overcome, to deliver the appropriate indications for the management of farmers. And finally, create a consistent regulation worldwide, based on science, to facilitate access to biostimulants in different markets. 

More information on innovations and scientific advances that can contribute to the efficiency of high-value crops, such as blueberries, will be exhibited at the International Blueberries Seminars 2023. For more information about these meetings, write to or WhatsApp +56 9 3469 3871.

Catalina Pérez Ruiz - Blueberries Consulting

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