Biostimulants are substances applied to plants or soils to enhance crop vigor, yields, quality, and stress tolerance. Unlike fertilizers that provide essential nutrients, biostimulants work by stimulating natural processes and enhancing nutrient uptake and use efficiency.
Biostimulants can be derived from various organic materials including seaweed extracts, plant extracts, microbial inoculants, humic and fulvic acids, chitin and amino acids. They influence plant physiology through diverse mechanisms:
- Hormonal effects: Biostimulants like seaweed extracts contain plant hormones like auxins, cytokinins and gibberellins that regulate growth and development.
- Stress tolerance: Many biostimulants boost abiotic stress tolerance against drought, salinity, heat and cold stress by inducing antioxidant production, osmotic adjustments and other protective compounds.
- Root growth promotion: Biostimulants enhance root growth and architecture, improving access to water and nutrients. Microbial biostimulants also facilitate nutrient mobilization in the rhizosphere.
- Cell metabolism modulation: Biostimulants improve photosynthetic efficiency, nitrogen assimilation, enzyme activity and other metabolic processes resulting in increased vigor.
- Biocontrol: Microbial biostimulants can induce systemic resistance against diseases and pests by priming plant immune responses.
Unlike synthetic fertilizers and pesticides, most biostimulants work through natural mechanisms to enhance the plant’s overall physiology for improved productivity and resilience. They complement conventional crop inputs by boosting the efficacy and decreasing environmental impacts.
Benefits of Using Biostimulants
Biostimulants offer a wide range of benefits that make them highly valuable in agriculture and horticulture. Some of the key advantages of using biostimulants include:
Increased Yields
One of the most notable effects of biostimulants is their ability to increase crop yields. By enhancing plant growth, metabolism, and development, biostimulants can improve productivity and lead to higher yields per acre. Studies have shown yield increases ranging from 5-30% depending on the crop and biostimulant used. The yield boosts are especially significant under suboptimal or stressful conditions.
Enhanced Quality
In addition to increasing yields, biostimulants can also improve the quality and nutritional value of produce. They help plants properly ripen, leading to higher brix levels, better coloration, extended shelf-life, and enhanced sensory properties. Biostimulants promote the synthesis of secondary metabolites which boost nutritional content.
Improved Stress Tolerance
Plants treated with biostimulants have greater tolerance to abiotic stresses such as drought, extreme temperatures, salinity, and heavy metals. Biostimulants mitigate the impacts of stress at physiological and cellular levels. This allows plants to maintain growth and productivity even under suboptimal conditions.
More Efficient Nutrient Use
Biostimulants enhance the plant’s ability to take up and utilize nutrients from fertilizers. They improve nutrient use efficiency, allowing growers to potentially reduce fertilizer inputs. Biostimulants also mobilize nutrients already present in the soil, further optimizing nutrient availability.
Stimulation of Natural Processes
Rather than supplying nutrients directly, most biostimulants work by stimulating natural growth and defense processes in plants. This stimulation occurs through enhanced enzyme activity, gene expression, and molecular signaling pathways. The result is better plant performance driven by biological processes.
Major Categories of Biostimulants
Biostimulants can be grouped into several major categories based on their source and composition:
Seaweed Extracts
Seaweed extracts contain polysaccharides, macro- and micro-nutrients, plant hormones, and other bioactive compounds that can improve plant growth, yield, fruit quality, and tolerance to abiotic stress. Major seaweed species used as biostimulants include Ascophyllum, Laminaria, and Sargassum.
Humic and Fulvic Acids
Humic substances like humic and fulvic acids are major components of soil organic matter. They stimulate nutrient uptake, soil microbial activity, and root growth. Humic acids are derived from sources like peat, leonardite, and lignite.
Amino Acids
Amino acid biostimulants contain free amino acids or short peptides that enhance plant growth and development. They can be produced via chemical synthesis or hydrolysis of natural proteins.
Chitin Derivatives
Chitin and chitosan polymers found in crustacean shells and fungal cell walls exhibit biostimulant properties like plant defense activation and enhanced germination.
Beneficial Microbes
Microbial biostimulants introduce beneficial bacteria or fungi to the plant or soil. These microbes promote nutrient mobilization, stress tolerance, soil health, and plant growth through various mechanisms.
Other Natural Extracts
Biostimulants may also be derived from plant materials like fruits, vegetables, herbs, tree extracts, and plant cell cultures. These contain bioactive compounds that elicit beneficial plant responses.
Biostimulant Mechanisms of Action
Biostimulants enhance plant growth through several key mechanisms of action in the plant and soil. These include:
Hormonal Effects
Many biostimulants contain plant hormones or hormone-like compounds that regulate plant growth and development. These can stimulate processes like cell division, flowering, fruit set, and root growth. For example, biostimulants containing auxins, cytokinins, gibberellins, or brassinosteroids modulate plant hormone levels.
Antioxidant Activity
Some biostimulants boost plants’ antioxidant capacity, helping them overcome oxidative stress. Compounds like polyphenols, carotenoids, and amino acids act as antioxidants in plants. This protects cells from damage and supports overall plant health.
Improved Nutrition
Biostimulants can improve nutrient use efficiency, uptake, transport, and assimilation in plants. This provides optimal nutrition for growth and helps plants overcome nutrient deficiencies. Acid-based biostimulants, in particular, increase availability of soil nutrients.
Modulation of Stress Response
Biostimulants mediate plant responses to abiotic stresses like drought, salinity, extreme temperatures, and heavy metals. They regulate stress tolerance pathways and expression of stress-related genes. This enhances the plant’s ability to withstand and recover from environmental stresses.
Soil Conditioning Effects
Some biostimulants have direct effects on soil properties and processes. They can alter soil pH, increase water holding capacity, enhance microbial activity, and stimulate nutrient cycling. This creates a healthier soil environment for plant growth.
Biostimulant Applications in Agriculture
Biostimulants are applied in various ways to provide benefits at key stages of plant growth and development. Understanding proper application methods, timing, and rates is essential for optimizing crop responses. Some of the main agricultural applications of biostimulants include:
Foliar Sprays
Foliar sprays involve applying diluted biostimulant solutions directly to the leaves and stems of plants. This allows the active compounds to be quickly absorbed and transported to sites of action within the plant. Foliar sprays are commonly used to provide biostimulant benefits during the vegetative growth stage, flowering, and fruit development. The timing of foliar sprays depends on the crop and purpose, but they are often applied at 7-14 day intervals or during periods of abiotic stress. Spray volumes and product concentrations should be optimized to ensure sufficient coverage without causing leaf burn.
Seed Treatments
Treating seeds with biostimulant formulations prior to planting helps stimulate early root and shoot growth. This gives seedlings an improved start, enhancing vigor, uniformity, and overcoming environmental stresses. Seed priming and coating techniques allow biostimulants to be effectively delivered to seeds. Microbial biostimulants may also be used to inoculate seeds with beneficial microbes.
Soil Applications
Applying biostimulants directly to the soil can stimulate root growth, nutrient uptake, and soil biological activity. Soil drenching, in-furrow applications at planting, and chemigation through irrigation are common techniques. The timing depends on the purpose, for example early season soil treatments promote root growth while later applications may enhance fruit quality. Application rates are tailored to soil conditions and desired effects.
Application Rates and Timing
Recommended biostimulant application rates vary based on the product, crop, growth stage, and application method. Following manufacturer guidelines ensures optimal results. Multiple applications are often needed to achieve season-long benefits. Proper timing matched to crop development cycles and stress periods is also critical for maximizing the performance of biostimulant applications. With the right rates and timing, biostimulants can boost yields, quality, and stress resilience in agricultural crops.
Regulation and Safety Considerations
The regulation of biostimulants varies significantly across different countries and regions. In the European Union, biostimulants fall under the EU Fertilising Products Regulation which provides a harmonized framework for placing biostimulants on the EU market. Companies must submit scientific dossiers demonstrating product safety and efficacy to receive CE marking. The EU has a positive list of approved biostimulant ingredients.
Safety studies and risk assessments are a critical part of biostimulant regulation. Manufacturers must evaluate the risks associated with biostimulant use, including toxicity, environmental impact, and effects on non-target organisms. Studies typically assess acute toxicity, genotoxicity, reproductive toxicity, and ecotoxicity. As biostimulants are designed to enhance plant growth, there are generally low risks if products are used as intended.
Most biostimulants are considered low risk for the environment. Many are derived from natural materials like seaweed or plant extracts. However, some biostimulants contain metals like copper which can accumulate in soils. Proper application rates and avoiding environmentally sensitive areas can mitigate potential impacts. Understanding the environmental fate of biostimulant ingredients is an active area of research.
Overall, clear and consistent regulations based on scientific risk assessments ensure biostimulant safety for farmers, consumers, and the environment. Safety should remain a priority as the biostimulant market continues expanding globally.
Global Biostimulant Market Trends
The global biostimulant market has been experiencing rapid growth in recent years, driven by rising demand for sustainable agriculture solutions. The market is projected to reach $4.47 billion by 2028, expanding at a CAGR of 11.5% from 2021 to 2028 according to one estimate.
Several factors are fueling the adoption of biostimulants worldwide:
- Need to enhance crop yields to feed a growing global population
- Reducing the use of synthetic fertilizers and pesticides
- Mitigating abiotic stress effects of climate change on crops
- Regulatory support for sustainable agricultural practices
Europe is currently the largest regional biostimulant market, accounting for over 40% of global revenue. However, the Asia Pacific market is expected to expand at the fastest CAGR during the forecast period. Rising populations, food security concerns, and large agricultural economies like China and India are driving demand in Asia.
The Americas are also an important market, led by the U.S., Argentina and Brazil. Government subsidies and promotion of sustainable agriculture in these countries is propelling biostimulant adoption.
Key global biostimulant companies include BASF, UPL Ltd., Valagro, Italpollina, Koppert Biological Systems, Isagro, and Marrone Bio Innovations. Major product categories are humic acids, seaweed extracts, microbial inoculants, amino acids, and microbial metabolites. Continued innovation and new product development are creating opportunities for these players.
The biostimulant market outlook remains very promising, as the need for sustainable solutions to enhance productivity and crop resilience intensifies globally. Key industry participants are ramping up production capacities and making strategic acquisitions to capitalize on this high-growth market.
Challenges and Limitations
While biostimulants offer many potential benefits, there are some challenges and limitations to be aware of:
Variability in Product Quality
One key issue is the variability in quality and efficacy between different biostimulant products. Since the industry is still emerging, quality control standards are still developing. Some products may not contain the listed ingredients at effective concentrations or may be missing key information on the label. More transparency and regulation is needed to ensure product quality and performance claims.
Insufficient Field Testing
Many biostimulant products lack rigorous field testing to validate their effectiveness under real farming conditions. Efficacy often varies depending on the crop, environment, application method, and other factors. More on-farm trials and demonstrations are needed to evaluate products and build farmer confidence.
Knowledge Gaps on Mode of Action
The mechanisms of action behind many biostimulants are not fully understood scientifically. While some modes of action have been characterized, there are still knowledge gaps about how certain biostimulants influence plant physiological processes at the molecular level. More research is needed to elucidate biostimulant modes of action.
High Costs Limiting Adoption
The high cost of some biostimulant products can limit their adoption, especially for smallholder farmers with limited resources. Bringing down costs through increased production, enhanced formulations, and market competition will be key to improving biostimulant accessibility and uptake. Financial incentives and education on return on investment can further drive adoption.
Current Research Areas
There are several key areas of focus in biostimulant research:
Elucidating mechanisms
Researchers are working to better understand the precise modes of action and biological mechanisms by which biostimulants influence plant physiology and development. This involves studying their effects at the molecular, biochemical, and physiological levels using advanced techniques like transcriptomics and metabolomics. A clearer picture of biostimulant mechanisms will enable more targeted product development and application.
New product development
Ongoing research aims to identify, characterize, and develop novel biostimulant products from natural sources like seaweed, plant extracts, and microbial fermentation. Screening a wide diversity of organisms and compounds can uncover new biostimulant candidates. Researchers also work to optimize extraction, purification, and formulation methods to improve product quality and stability.
Application optimization
Field trials and greenhouse studies explore how biostimulant application methods, timing, rates, and combinations with other inputs like fertilizers can be fine-tuned for maximum benefit. Factors evaluated include crop species, growth stage, production system, and environmental conditions. This helps refine real-world usage recommendations.
Combinations with other technologies
There is great interest in integrating biostimulants with other advanced agricultural technologies like precision farming tools, genetically modified crops, and integrated pest management. Researchers are investigating synergistic effects and compatibility to provide complete agronomic solutions.
Future Outlook
The future holds great promise for biostimulants to play an expanding role in global agriculture. Key trends and innovations shaping the future outlook include:
Reducing Dependence on Agrochemicals
Biostimulants present an opportunity to reduce reliance on synthetic fertilizers and pesticides. As sustainable agriculture gains momentum, biostimulants can offer a natural way to enhance crop productivity and resilience without excessive agrochemical use. Their compatibility with organic systems makes them well-suited for low-input farming approaches.
Integration into Sustainable Agriculture
Biostimulants align well with principles of sustainable agriculture, such as soil health, biodiversity, and ecosystem balance. Their ability to reduce environmental impact while maintaining yields can support sustainability goals. Biostimulants are expected to be increasingly incorporated into sustainable cropping systems and integrated pest management programs.
Precision Application Technologies
Emerging precision agriculture technologies, such as variable rate application, targeted spraying, and smart release formulations, can enable more efficient use of biostimulants. These innovations allow biostimulant application to be tailored to specific plants, fields, or environmental conditions for optimized results.
Commercial Potential and Innovations
The biostimulant market has significant room for growth as awareness and adoption expand globally. Advances in biotechnology and natural product research are unlocking new biostimulant sources and modes of action. Novel product innovations and application methods can open up new commercial opportunities in this dynamic sector.