Dualex

Measure Plant Nitrogen and Chlorophyll Instantly, Without Damaging the Leaf

Dualex delivers fast, non-destructive readings of chlorophyll and flavonols for accurate insight into plant nutrition and physiology, trusted in both field and research environments.

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About Dualex

Thanks to its patented optical technology, Dualex provides precise, repeatable measurements of chlorophyll and flavonols directly on the leaf, in seconds and without destructive sampling.

It helps you quantify nitrogen balance, monitor plant health, and optimize crop management or research outcomes with confidence.

  • Non-destructive, in site measurements
  • Instant data on chlorophyll and flavonols
  • Proven correlation with laboratory analysis
  • Reliable indicator of nitrogen balance (NBI®)
  • Lightweight, portable, and easy to use
  • Consistent performance in both field and controlled environments

Accurate measurement of chlorophyll and flavonols

Chlorophyll plays a vital role in photosynthesis and plant development. Dualex measures chlorophyll by analyzing the light transmitted through the leaf at specific wavelengths. The chlorophyll content is given as an absolute value in µg/cm².

With a single measurement, Dualex captures not only chlorophyll content but also provides indices for flavonols.

Flavonols are mainly synthesized after light exposure. As a consequence, they are a good indicator of plant-light interaction history.

Flavonols belong to the polyphenol group, known for their various health benefits. These compounds have antioxidant properties that help reduce cell damage and inflammation. Flavonols are associated with improved cardiovascular health and have the potential to reduce the risk of neurodegenerative diseases like Alzheimer’s. 

Dualex measures flavonols by analyzing their screening on chlorophyll fluorescence. A smart measuring system uses different light wavelengths to excite the chlorophyll, measure its fluorescence and then calculate the results. Flavonols are given in relative absorbance.

How it works?

No destructive sampling. No waiting for lab results. Just instant, accurate data where it matters most.

Clip Dualex onto the leaf. The sensor emits controlled light pulses to capture chlorophyll and flavonol responses.
Results appear instantly.
Connect your Dualex to Computer to store and analyse data even further.
Clip Dualex onto the leaf. The sensor emits controlled light pulses to capture chlorophyll and flavonol responses.
Results appear instantly.
Connect your Dualex to Computer to store and analyse data even further.

Want to learn more?
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NBI®: Nitrogen balanced index

Chlorophyll is often used as an indicator of plant nitrogen status. However, several years of research and experimentation showed that polyphenols, specifically flavonols, are also good indicators of nitrogen status of plants.

The NBI® (Nitrogen Balance Index) combines chlorophyll and flavonols into a single, more precise result. It’s a plant nitrogen status indicator directly correlated with massic nitrogen content. The NBI® is less sensitive to variations of environmental conditions than chlorophyll (leaf age, leaf thickness…).

This dual-parameter approach provides a more stable and representative indicator than single-variable methods, supporting better analysis and more informed decisions.

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    FAQ

    1. How does Dualex differ from SPAD or other chlorophyll meters?

    Unlike single-wavelength SPAD meters (which give a relative index), Dualex combines chlorophyll screening with fluorescence/transmittance at multiple wavelengths to separately estimate chlorophyll per area and epidermal polyphenols. This gives earlier detection of nitrogen status and stress (flavonols rise before chlorophyll falls) and reduces saturation issues at high chlorophyll. For many research applications Dualex provides complementary information to SPAD rather than a simple replacement.

    2. Can Dualex be used to estimate leaf nitrogen or crop N status? How accurate is it?

    Yes. Dualex outputs (Chl and NBI®) are widely used as proxies for leaf N and can improve early diagnosis of N deficiency. Accuracy improves when Dualex readings are calibrated against tissue N analyses for the crop/variety and sampling protocol is standardized (same leaf position, time of day, replicate count). For best scientific use, report the calibration method, leaf area sampled and number of replicates.

    3. What are best practices for taking Dualex measurements (sampling protocol)?

    Use the same leaf position and leaf developmental stage (e.g., fully expanded 3rd leaf), measure at consistent time of day (avoid direct midday extremes), take multiple replicates per plot/plant (≥10–20 points for field surveys depending on variability), avoid damaged/wet leaves, and record metadata (species, phenological stage, light conditions). Clean optical surfaces regularly and follow manufacturer calibration/maintenance. Report units and averaging method in publications.

    4. Which crops and research questions is Dualex best suited to? Any limitations?

    Dualex is widely used in crops (maize, wheat, rice, vineyards, vegetables), model plants and forestry research for nutrient diagnostics, UV/oxidative stress, phenotyping, and early stress detection. Limitations: it’s a point sensor (time-consuming for large area surveys unless coupled with sampling design), results are leaf-type dependent (need calibration across different leaf anatomies), and values should be interpreted relative to species/variety baselines. For large-scale mapping, combine Dualex with remote sensing or higher throughput sampling.