High temperatures, late frosts, unseasonal rains, and drought are some of the most visible effects of climate change. This scenario has led to increased use of biostimulants in fruit production, especially in blueberries, due to their ability to increase crop resilience to abiotic stress—such as drought, heat, and salinity—strengthen plants’ natural defenses, improve water and nutrient use efficiency, and enhance photosynthesis and yield.
In conversation with Blueberries News, Thomas Fichet, Doctor of Biotechnology at the Polytechnic University of Valencia and lecturer in the Department of Agricultural Production at the Faculty of Agronomy of the University of Chile, explained that biostimulation corresponds to “a stimulus of organic origin that generates greater growth and development of the plant, either at the cellular level or in a particular organ. What we seek with biostimulation is to promote more efficient growth using organic products.”
The specialist was emphatic in pointing out that, when the objective is to biostimulate the roots, the application must be made directly on them. “A foliar application can generate biostimulation in the aerial part—branches, leaves, or fruits—but it does not translate into an effect at the root level, or very little. Therefore, these products must be applied via irrigation to generate an effective stimulus in the roots,” he explained.
Regarding the types of biostimulants available, Fichet explained that there is a wide range, including seaweed extracts. “Some of the most evaluated and widely used are based on Ascophyllum nodosum and Ecklonia maxima, which have a solid track record and scientific backing. There are other more recent products from markets such as India and China that have yet to undergo extensive scientific or field trials,” he noted.
He also mentioned other types of organic extracts such as aquatic plants from Amazonian rivers, by-products from the fishing or meat industry, and organic plant compounds such as fulvic and humic acids, which can also be applied via irrigation.
Currently, there is also talk of second-generation biostimulants, which refer to products whose “active” compounds are generally more limited to a single molecule. In this case, we are talking about: polyphenols, glutamic acid, glycine betaine, peptides, etc.
Root growth and development
According to the expert, one of the main effects of biostimulation takes place at the root level. “What interests us is generating root growth that covers a larger surface area. This allows the plant to be better nourished and absorb water more efficiently. We are talking about root multiplication through cell division, growth in length, and greater branching, which translates into a more robust root system,” he added.
He also explained that strengthening the roots promotes the production of compounds that are transported to the aerial parts of the plant, such as plant hormones and other organic compounds, generating positive effects on tolerance to abiotic stress caused by high temperatures, cold, light radiation, or salinity.
Fichet pointed out that some first-generation biostimulants contain sugars and amino acids associated with stress tolerance, which are absorbed by the roots and transported via xylem to the aerial parts of the plant. “This translates into increased photosynthesis, improved growth and fruit size, better organoleptic characteristics, and more uniform color,” he said.
He also explained that these products help reduce oxidative stress. “They generate enzymes that neutralize free radicals, transforming them into water, which reduces the damage caused by salt, water, or heat stress. They also have a positive influence on stomatal opening, improving the plant’s physiological conditions.”
Mistakes and best practices in biostimulant application
One of the most common mistakes made by producers is underdosing, i.e., applying doses lower than those recommended. “This is usually for economic reasons, as these products are expensive. However, to be effective, they must be applied at the appropriate frequency, ideally every 15 days or monthly,” explained Fichet.
The expert compared its effect to homeopathy in humans: “To keep the defense mechanisms active, they must be stimulated continuously. If you stop applying the product, the mechanisms are deactivated and the plant becomes susceptible again.”
Although some biostimulants have shown some curative effect when applied after a stress event, Fichet pointed out that the best results are obtained with preventive applications. “Just as there is a nutritional program, there should also be a program for applying biostimulants throughout the season.”
The specialist concluded that biostimulation is a growing trend in modern agriculture. “It’s not just a fad. Consumers will increasingly demand more sustainable and natural products. In addition, the adverse conditions associated with climate change will force us to use these products not only as a cure, but as a permanent practice in production systems.”
