Disease, Damage, and Drought: Impacts on Photosynthesis



  • How does photosynthesis and other measurements change in diseased, damaged, and otherwise unhappy plants?

  • What diseases impact photosynthesis, and how do they do it?

  • Is it possible to identify the onset of diseases (especially non-visible diseases like root rots) using photosynthesis measurements?


The goal of this project is to survey of ‘unhappy’ plants and comparison to similar ‘happy’ plants to identify the ways in which photosynthesis changes based on different types of disease, drought, and damage. By collecting information from many environments across the world, we may be able to develop early predictors of these stresses and better understand how plants adjust and defend themselves.


NOTE: Make sure NOT to measure holes or tears directly - if there are physical holes measure right next to the hole, not on top of it. Ideally, each measurement should be on a slightly different part of the leaf, or different leaves all together.

  1. Measure a diseased plant or leaf 5 times.
  2. Measure a healthy leaf 5 times on the same plant, or a plant of the same species nearby.

You'll also need to know roughly what has damaged the leaf. Here are some examples:


Viruses, bacterial, and fungal- including root rots not visible on foliage



Insects and pest animals



Frost, drought, heat, wind, and flooding



Gonstruction, human, and other physical



Leaf Photosynthesis MultispeQ V1.0


Measures many photosynthesis-related parameters in <15 seconds, including:

  • Chlorophll Fluorescence: Phi2, PhiNPQ, PhiNO, NPQt, qL, LEF
  • Relative Chlorophyll: SPAD
  • Proton Motive Force: ECSt, vH+, gH+
  • Absorbance at: 450, 535, 605, 650, 730, 850, 880, and 940nm.
  • Leaf Thickness (in mm), angle, and cardinal direction
  • Leaf Temperature and differential from ambient temperature
  • Environmental conditions: PAR and ambient temperature/pressure/humidity


Leaf Photosynthesis MultispeQ V1.0 is the classic and by far the most utilized PhotosynQ Protocol.

This protocol delivers a wide range of plant photosynthetic parameters, a full list can be found here

If you want to see the exact calculations for each parameter, please see the associated macro called "Leaf Photosynthesis MultispeQ V1.0".

There are two publications about the MultispeQ Beta device covering many of parameters and their comparisons to commercial instruments. While the beta was an older model device, the calculations and comparisons are still true for this protocol and V1.0 device. You can find them at the Royal Society for Open Science, and Plant, Cell & Environmental Journal.

The Leaf Photosynthesis protocol collects many different measurements from a leaf as quickly as possib...


  1. Plant Type (Multiple Choice with images)
  2. Plant Height (Multiple Choice)
  3. Optional: Genus and Species (lowercase) (Short Answer)
  4. Leaf Condition (Multiple Choice with images)
  5. Optional: Disease or Pest Name (Short Answer)
  6. Leaf Location (Multiple Choice)
  7. Leaf Image (Take a Picture)
  8. Leaf Number (Use Auto Increment) (Multiple Choice)



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By Greg Austic, over 1 year ago
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