Introduction to Biostimulants

In today’s agricultural sector, the use of biostimulants has become a key strategy for improving the productivity and sustainability of crops. In particular, olive trees, which are an essential component of Mediterranean agriculture, can benefit greatly from these solutions. In this article, we will compare biostimulants that have proven effective in improving olive harvests, focusing on their characteristics, applications, and results.

Types of Biostimulants for Olive

Biostimulants can be classified into several categories based on their origin and mechanism of action. Below are the main types used in olive cultivation:

1. Algal Extracts

Algal extracts are known for their ability to improve plant resistance to stress and stimulate growth. These products contain plant hormones and bioactive compounds that favor root development and nutrient absorption. Studies have shown that algae, such as Ascophyllum nodosum, can increase the activity of antioxidant enzymes in plants, resulting in better tolerance to adverse conditions such as drought or salinity. A study conducted by the University of Cádiz found that olive trees treated with algal extracts showed a 40% increase in superoxide dismutase enzyme activity, translating to a greater defense capacity against oxidative stress.

1.1 Biochemical Mechanisms

Algal extracts act through several biochemical mechanisms. On one hand, they stimulate the synthesis of phytohormones such as auxins and cytokinins, which regulate cell growth and division. This not only promotes a more robust root development but also enhances the formation of shoots and flowers. Additionally, the polysaccharides present in algal extracts can improve water retention in the soil, which is vital in arid regions. These extracts have also been shown to induce the production of secondary metabolites that act as natural defenses, providing a quicker response to pathogens.

1.2 Applications of Algal Extracts in the Field

In practical applications, algal extracts can be applied in liquid form through drip irrigation or spraying. For example, in a trial conducted in an olive plantation in the Almería region, algal extract was applied at the beginning of flowering and during fruit development, resulting in an 18% increase in olive size and a 25% increase in total production. This result was attributed to improved water regulation and increased photosynthetic activity.

2. Amino Acids

Amino acids are essential components in protein synthesis and can help plants recover from abiotic stress. Their application in olives can result in better fruit formation and higher quality harvests. Research has shown that foliar application of amino acids can increase chlorophyll concentration in leaves, enhancing photosynthesis and, consequently, fruit production. A specific study found that using amino acids in olives increased the fruit set rate by 15% under water stress conditions. Additionally, the application of specific amino acids like proline has been shown to improve salt stress tolerance, allowing for more robust growth under unfavorable conditions.

2.1 Applications in Abiotic Stress

The application of amino acids can be especially useful in situations of abiotic stress, such as droughts or high temperatures. In a trial conducted in 2025, it was observed that applying amino acids to olives during a heatwave resulted in a 25% increase in olive production compared to untreated controls. This is because amino acids act as osmoprotectants, helping plants maintain cellular homeostasis and regulate stomatal opening, thereby reducing water loss. Furthermore, it has been shown that applying amino acids like arginine can enhance ethylene synthesis, which favors fruit set and maturation.

2.2 Examples of Amino Acid Application

In a project carried out in Seville, amino acids were applied to olives during the flowering phase and again during fruit filling. This resulted in a 20% increase in fruit weight and an improvement in olive quality, translating to olive oil with 10% more phenolic compounds. The application was carried out at a concentration of 3 L/ha every 14 days, facilitating a better response in plant growth and development.

3. Beneficial Microorganisms

Biostimulants based on microorganisms, such as bacteria and fungi, improve soil health and promote nutrient assimilation. These products can increase the resilience of olive trees against diseases and pests. For example, the fungus Trichoderma harzianum has proven effective in the biological control of soil pathogens and can increase the availability of nutrients such as phosphorus, which is crucial for olive growth. A trial conducted in 2025 indicated that olive trees treated with microorganisms showed a 30% increase in olive production compared to untreated controls. Additionally, inoculation with Azospirillum brasilense has resulted in a 20% increase in nitrogen fixation, contributing to better vegetative development and greater fruit production.

3.1 Synergy between Microorganisms

The combination of different microorganisms can result in synergistic effects. A study conducted in 2026 showed that the combined application of Trichoderma and Azospirillum not only improved nutrient availability but also increased the resistance of olive trees to foliar diseases by 30%. This synergy is due to Trichoderma improving nutrient absorption and Azospirillum increasing nitrogen fixation, creating an optimal environment for root growth. Furthermore, it has been observed that applying products containing mycorrhizae along with these bacteria can increase root colonization by 50%, which in turn improves water and nutrient absorption, especially in soils with low fertility.

3.2 Examples of Microorganism Application

In an estate in Málaga, a trial was conducted where mixtures of Trichoderma harzianum and Azospirillum brasilense were applied during an olive growth cycle. The application was made at two times: at the beginning of spring and mid-summer. The results showed a 40% increase in olive production compared to the control. Additionally, an improvement in soil health was recorded, with a 35% increase in microbial activity, contributing to better soil structure and greater moisture retention.

4. Bioactive Compounds

Bioactive compounds, such as phenols and flavonoids, have antioxidant properties that can improve the quality of olive oil and plant resistance. Their use has been associated with an increase in the production of beneficial compounds in fruits. A study conducted by the University of Córdoba found that olive trees treated with phenol-rich extracts showed a 25% increase in the phenolic content of the oil, which not only improves quality but also its stability against oxidation. Additionally, it has been observed that flavonoids can induce the synthesis of defense compounds in plants, increasing their resistance to diseases such as olive tuberculosis, caused by Phytophthora.

4.1 Benefits for Oil Quality

The application of bioactive compounds not only improves production quantity but also positively impacts the quality of olive oil. An analysis from 2026 demonstrated that olive trees treated with biostimulants containing bioactive compounds showed an improvement in the sensory profile of the oil, enhancing its aroma and flavor, which translated to a healthier and higher-value oil. This is critical, as high-quality olive oils can fetch higher prices due to their health benefits and greater stability. Additionally, it has been shown that treatment with phenolic compounds can reduce the formation of undesirable volatile compounds during storage, prolonging the oil’s shelf life.

4.2 Examples of Bioactive Compound Application

In a trial conducted in an olive plantation in Córdoba, bioactive compound extracts were applied throughout the growing season. The results showed that the phenolic content of the olive oil increased by 30%, in addition to improving its aromatic and sensory profile. This translated into a 15% increase in the market sale value of the oil, demonstrating that the quality of the final product can be significantly improved through the use of specific biostimulants.

Effectiveness Comparison

In this section, we will analyze various studies and trials conducted with different biostimulants in olive crops. The selection of products is based on their availability in the market and the scientific evidence regarding their effectiveness.

Study 1: Algal Extract vs. Amino Acids

A comparative trial conducted in 2026 in Andalusia showed that the use of algal extracts significantly improved harvest yield compared to treatment with amino acids. Olive trees treated with algae showed a 15% increase in production, while amino acids achieved a 10% improvement. Additionally, it was observed that olive trees treated with algal extract had greater resistance to foliar diseases, suggesting a positive effect on the overall health of the plant. This study also highlighted that the application of algae in combination with amino acids resulted in a synergistic effect, achieving a 25% increase in production compared to individual treatments.

Study 2: Beneficial Microorganisms in Acidic Soils

In another study, the application of biostimulants with microorganisms was evaluated in acidic soils, typical in some regions of Spain. The results indicated that products with microorganisms improved nutrient availability, resulting in 20% more olive production compared to conventional treatments. Microorganisms also contributed to the decomposition of organic matter, improving soil structure and facilitating root development. In particular, it was observed that the application of Bacillus subtilis promoted phosphorus solubilization, increasing its availability by 30% compared to untreated controls. This increase in phosphorus availability translates into better root development and increased fruit production, highlighting the importance of soil microbiology in sustainable agriculture.

Study 3: Bioactive Compounds and Oil Quality

An analysis from 2026 demonstrated that olive trees treated with biostimulants containing bioactive compounds showed an improvement in the quality of olive oil, increasing its phenolic content and reducing oxidation. This translated into a healthier and higher-value oil. Market studies showed that olive oils with high phenolic content can fetch higher prices due to their health benefits and greater stability. Additionally, it was observed that the use of bioactive compound extracts not only increased oil quality but also improved the resistance of olive trees to pathogens, reducing the incidence of diseases by 15% during the harvest season. This highlights the relevance of integrating bioactive compounds into olive management practices.

Practical Applications

The implementation of biostimulants in olive cultivation requires proper planning. It is recommended to follow application guidelines to maximize benefits:

• Application Timing: The application of biostimulants should be done at critical moments, such as the beginning of flowering and during fruit development. For example, a study has shown that applying algal extracts just before flowering can increase the fruit set rate by 20%. Additionally, application during the fruit growth phase can enhance the size and quality of olives, achieving an 18% increase in fruit weight compared to untreated ones.
• Dose and Frequency: It is essential to follow recommendations regarding dose and frequency of application to avoid adverse effects on the crop. For example, excessive application of amino acids can lead to excessive vegetative growth at the expense of fruit production. A recent study suggests that the optimal dose of amino acids should be maintained between 2 and 4 L/ha, applied every 15 days during the growth cycle to maximize production. It has also been observed that the application of microorganisms can be more effective when done during stress moments, allowing plants to benefit from their action under adverse conditions.
• Combination of Products: Combining different types of biostimulants can enhance their effects, provided that a prior compatibility study is conducted. Research has shown that combining algal extracts and amino acids can result in a synergistic increase in fruit production, achieving improvements of up to 25% compared to the individual use of each product. For example, in a trial conducted on a farm in Córdoba, the combination of both biostimulants resulted in a 22% increase in harvest yield, as well as a 15% improvement in the phenolic content of the oil.

Practical Example of Field Application

On an olive farm located in Jaén, a biostimulant program was implemented that included algal extracts and beneficial microorganisms. The biostimulants were applied at two key moments: at the beginning of flowering and during the fruit growth phase. The results were surprising, with a 30% increase in olive production and a notable improvement in oil quality, which increased its phenolic content by 15%. This combination not only improved yield but also allowed the farm to position itself better in the market, achieving a higher value for its high-quality olive oil. Additionally, a reduction in pest incidence was observed, allowing for a 25% decrease in pesticide use, contributing to more sustainable agriculture. This practical case demonstrates the effectiveness of biostimulants in optimizing yield and quality in olive cultivation.

Example of Implementation with Microorganisms

In another farm located in Granada, a trial was conducted with Bacillus subtilis and Trichoderma harzianum. The application of these microorganisms was carried out at the time of planting and then repeated halfway through the growth cycle. The results showed a 35% increase in olive production and a notable improvement in disease resistance, reducing the incidence of Verticillium dahliae by 40%. This approach not only resulted in higher production but also improved soil health and microbial biodiversity, creating a more balanced ecosystem that favors olive growth. The implementation of these microorganisms also allowed for improved nutrient activity in the soil, favoring the availability of essential elements such as nitrogen and phosphorus, which resulted in more vigorous plant growth and higher quality harvests.

Conclusions and Recommendations

The comparison of biostimulants demonstrates that these products are effective tools for improving olive harvests. The choice of the appropriate biostimulant will depend on the specific conditions of each crop and the goals of the farmer. It is recommended to conduct field tests before adopting a product on a widespread basis. Additionally, it is essential to consider factors such as soil type, climatic conditions, and the overall state of the olive trees to maximize the benefits derived from their use. The integration of biostimulants into agricultural practices not only improves yield but also contributes to the sustainability of the crop and the production of high-quality food. Collaboration with agronomists and biostimulant experts is suggested to design personalized strategies that optimize the application and use of these products on each farm.

For more information on biostimulants and their application in olives, do not hesitate to contact us. Our team of experts is ready to advise you on improving your crops.

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