Phytohormone and Biostimulant Profiling

Phytohormone and biostimulant profiling involves the measurement of plant signalling compounds and bioactive molecules that influence plant growth, development, and stress response.
These compounds are present at very low concentrations but have significant biological effects. Accurate profiling is therefore essential for understanding product performance, validating formulations, and supporting agricultural applications.
Phytohormones regulate plant physiological processes, while biostimulants include a broader group of compounds that enhance plant growth, nutrient uptake, and resilience to environmental stress.

The concentration and balance of phytohormones directly affect plant growth and development. Small changes in these compounds can significantly influence rooting, flowering, yield, and stress tolerance.
In agricultural and biostimulant applications, analysis is used to:
‣ Verify active ingredients in products
‣ Support product development and formulation
‣ Monitor consistency between batches
‣ Evaluate plant response to treatments
‣ Ensure quality and efficacy of biostimulants
Because these compounds are active at very low levels, accurate and sensitive analytical methods are required.

The following compounds are commonly measured to assess plant growth regulation and biostimulant activity:
Auxins, cytokinins, and gibberellic acid (GA3) form the core group of classical plant hormones responsible for growth regulation. In addition, specific compounds such as indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) are key auxins involved in root development and plant elongation.
Cytokinin compounds such as kinetin are associated with cell division, shoot development, and delayed senescence. Gibberellic acid (GA3) plays a central role in stem elongation, seed germination, and flowering processes.
Salicylic acid is involved in plant defence mechanisms and systemic resistance, particularly under stress conditions.
In addition to phytohormones, several phenolic and flavonoid compounds are included in profiling due to their biostimulant properties. These include quercetin, hesperidin, and resveratrol, which are associated with antioxidant activity, stress tolerance, and plant signalling pathways.

Auxins, particularly indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA), are primarily responsible for cell elongation and root initiation. They play a critical role in early plant development and are widely used in rooting formulations.
Cytokinins, including kinetin, regulate cell division and influence shoot growth and branching. They also delay leaf senescence and support nutrient mobilisation.
Gibberellic acid (GA3) promotes stem elongation, seed germination, and flowering. It is particularly important in crop development and yield optimisation.
Salicylic acid functions as a signalling molecule in plant defence, activating responses to biotic and abiotic stress.

Biostimulant compounds such as quercetin, hesperidin, and resveratrol contribute to plant health through antioxidant activity and modulation of plant signalling pathways.
These compounds may enhance plant tolerance to environmental stress, including drought, temperature fluctuations, and oxidative stress. Their presence in formulations is often associated with improved plant resilience and performance.

Phytohormones and biostimulant compounds are typically present at trace levels and may be unstable or prone to degradation.
Analytical challenges include:
‣ Low concentration levels requiring high sensitivity
‣ Complex sample matrices such as plant extracts and formulations
‣ Potential interference from co-extracted compounds
‣ Stability during sample preparation and storage
Careful extraction and sample preparation are critical to ensure accurate quantification.

Phytohormones and biostimulants are analysed using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). This technique provides the sensitivity and selectivity required to detect multiple compounds at low concentrations within complex matrices.
LC-MS/MS allows for:
‣ Simultaneous quantification of multiple analytes
‣ High sensitivity for trace-level compounds
‣ Selective detection in complex plant and formulation matrices
‣ Reliable and reproducible results