Plant Biostimulants:
Definition, Concept, Highlights
Based on a literature review, a plant biostimulant is defined by its agricultural/horticultural function. Biostimulants enhance nutrition efficiency, abiotic stress tolerance, and crop quality. Bio stimulants contribute to sustainable, high-output, low-input crop productions. There is a need for a legal and harmonized definition of “biostimulant.”
Abstract
A plant biostimulant is any substance or microorganism applied to plants with the aim to enhance nutrition efficiency, abiotic stress tolerance and/or crop quality traits, regardless of its nutrients content. By extension, commercial products containing mixtures of such substances and/or microorganisms are designated as biostimulants.
The definition of Biostimulant proposed by this article is supported by arguments related to scientific knowledge about the nature of, modes of action, and effects of biostimulants on crops and horticultural plants. Furthermore, the proposed definition aims at contributing to the acceptance of biostimulants by future regulations, especially in the EU, drawing the lines between biostimulants and fertilizers, pesticides, or biocontrol agents. Many biostimulants improve nutrition and they do so regardless of their nutritional contents.
Biofertilizers, which we propose as a subcategory of biostimulants, increase the efficiency of nutrient use and open new routes of nutrient acquisition by plants. In this sense, microbial biostimulants include mycorrhizal and non-mycorrhizal fungi, bacterial endosymbionts (like Rhizobium) and Plant Growth-Promoting Rhizobacteria. Thus, microorganisms applied to plants can have a dual function of biocontrol agent and of biostimulant, and the claimed agricultural effect will be instrumental in their regulatory categorization.
The present review gives an overview of the definition and concept of plant Biostimulant as well as the main categories. This paper will also briefly describe the legal and regulatory status of biostimulants, with a focus on the EU and the USA, and outlines the drivers, opportunities, and challenges of their market development.
—Science Direct website Scientia Hortculturea Vol 196 11/15 p3-14 by Elsevier
Plant Biostimulant Act of 2025: (Senate)
Main Benefits
- Increasing organic matter content.
- Reducing atmospheric volatilization.
- Promotion of nutrient management practices.
- Limiting or eliminating runoff and leaching of soil and nutrients (such as nitrogen and phosphorus) into groundwater and other water sources.
- Restoring beneficial bioactivity and healthy nutrients to the soil.
- Aiding with carbon sequestration, nutrient use efficiency, and other climate-related benefits.
- Supporting innovative approaches to improving agricultural sustainability which includes the adoption of performance-based outcome standards and criteria.
The submission of the Plant Biostimulant Act of 2025 indicates that Agriculture as an industry is moving in this direction.
Section 3A of the Plant Biostimulant Act of 2025 amends the Federal Insecticide, Fungicide & Rodenticide Act of 2023
This section provides for the exclusion of plant biostimulants.
The following content is from the Federal Insecticide, Fungicide, & Rodenticide Act of 2023:
The term plant biostimulant means a substance, microorganism, or mixture thereof, that, when applied to seeds, plants, the rhizosphere, soil, or other growth media, act to support a plant’s natural processes independently of the nutrient content of that substance, microorganism, or mixture thereof, and that thereby improves:
1) nutrient availability, uptake, or use efficiency
2) tolerance to abiotic stress and
3) consequent growth, development, quality, or yield
Additionally, the term “Vitamin Hormone Product” means a product consisting of a mixture of plant hormones, plant nutrients, inoculants, or soil amendments.
Plant biostimulants are like probiotics or vitamins for plants. They stimulate plant natural processes to increase growth and optimize plant health, thereby reducing abiotic stress such as heat, salinity, floods, and drought. Plant biostimulants can provide environmental benefits by improving soil health, enhancing fertilizer efficiency, and reducing greenhouse gas emissions. The California Department of Food and Agriculture is a leader in the development of guidelines used to register plant biostimulant products and the University of California, Davis has pioneered research on the efficacy of plant biostimulants for increasing drought resiliency in tomatoes, among other areas.
Press Release for the Plant Biostimulant Act of 2025 sponsored by Senators Padilla and Marshall
Additional Information:
Plant Biostimulants: Definition, Concept, Main Categories & Regulation
Patrick du Jardin, University of Liége, Belgium
Published Sciencedirect.com, November 2015
Biostimulant Activity of Phosphite in Horticulture
Fernando C. Goméz-Merino, Libia I. Trejo-Téllez
Colegio de Postgraduados, Mexico
Published on Scientia Horticulturae, November 2015