By Paul Davis from Hansatech about measuring the health of trees and plants via their photosynthesis activity.

1. Bringing Research Indoors
The Applied Use of Chlorophyll Fluorescence Analysis for Monitoring Indoor Landscapes
Paul Davis
Research & Development Officer

3. • How can current plant science research trends be applied to
indoor landscaping?
• Used widely in precision agriculture for many years
• Principles are the same but different timescales

4. What is Photosynthesis?
The process by which green
plants use sunlight to
synthesize nutrients from
carbon dioxide and water

5. What do Plants Need to Photosynthesize?
• Light
• CO2
• Water
CO2 + Water O2 + Sugars
Light
=
Chlorophyll

6. Light energy
from the sun
Photosynthesis
• Plant draws water from the roots
• Leaves take in CO2
• Chlorophyll harvests energy from
sunlight
• Light energy splits H2O molecule
into O2 and 2 hydrogen ions
• O2 released into the atmosphere
• CO2 and Hydrogen ions converted
to sugars
• Sugars used for plant growth.
CO2
O2
Water
Sugars

7. Light energy
from the sun
Photosynthesis
• No system is entirely perfect
• Leaf absorbs more energy that it
can use
• Energy that is surplus to
requirement must be dissipated to
avoid damaging the leaf structure.
CO2
O2
Water
Sugars

8. Light energy
from the sun
Photosynthesis
Chlorophyll
Fluorescence
Chlorophyll Fluorescence
• Biological process that
exists in all photosynthetic
organisms
• Used to dissipate excess
energy that cannot be used
for photosynthesis
• A re-emission of far-red
light energy from within the
leaf
• It is NOT reflected light.

9. Light energy
from the sun
Photosynthesis
Chlorophyll
Fluorescence
• Biotic or abiotic stress
factors may inhibit
photosynthesis
• Results in a reduction in
photosynthetic output
• Inversely proportional rise
in chlorophyll fluorescence.
STRESS
Chlorophyll Fluorescence

10. • Far-red light energy
• Just outside of the spectral
response of our eyes.
Chlorophyll Fluorescence

11. How do we Measure Chlorophyll Fluorescence?
• Not a new technique
• First discovered in 1931 by Dr. Hans W.
Kautsky at the University of Heidelberg
in Germany
Advances in technology have allowed
increasingly advanced instrumentation to
be developed from this in the 1970’s....

12. Through to the Handy PEA and Pocket PEA;
the current crop of research fluorescence
systems.
Each system consists of:
• Leaf dark-adaptation clips
• High-intensity LED light source
• Fast-response chlorophyll
fluorescence detector.
How do we Measure Chlorophyll Fluorescence?

13. Arborcheck system for arboricultural
professionals
• Takes 20 readings from a single
tree (10 x fluorescence, 10 x
chlorophyll content)
• Compares data to species-specific
benchmark values for trees in
optimum condition
• Presents results in a easy to
interpret visual format.
How do we Measure Chlorophyll Fluorescence?

14. From a Healthy Leaf:
• Signal starts at a base level of
fluorescence where all light energy
receptors in the leaf are open
• Rises rapidly (approx. 0.5s) through a
series of phases representing energy
moving through electron transport
chains
• Reaches a maximum level when all light
receptors are closed i.e. no further light
energy can be used and maximum
energy dissipation occurs
When a dark-adapted leaf is suddenly
illuminated with a bright light:

15. From a Healthy Leaf:
• Leaf in the dark
• all light acceptors open

16. From a Healthy Leaf:
• Leaf illuminated
• Some light acceptors
closed
• Baseline chlorophyll
fluorescence

17. From a Healthy Leaf:
• Illumination continues
• More light acceptors
closed
• Fluorescence intensity
rises

18. From a Healthy Leaf:
• Illumination continues
• More light acceptors
closed
• Fluorescence intensity
rises

19. From a Healthy Leaf:
• Illumination continues
• All light acceptors
closed
• Fluorescence intensity
reaches maximum

20. From a Healthy Leaf:
During this poly-phasic rise, various
measured and calculated parameters are
defined:
• Fo : Base level fluorescence
• Fm: Maximum level fluorescence
• Fv: Variable fluorescence (Fm – Fo)
• Area over the fluorescence trace
• OJIP – inflection points where energy
moves between electron transport chains
• Fv/Fm: Maximum light use efficiency
• Over 50 individual measured and
calculated parameters offered in
research devices.

21. How is this Helpful?
• Measurements taken from 2 different
samples
• Red trace – Mature English Oak
• Blue Trace - Elysia viridis

22. How is this Helpful?
• All healthy photosynthetic material
exhibits same characteristic traits during
measurement
• Allows chlorophyll fluorescence to be
used as an indicator of plant health
regardless of species.
O
J
I
P

23. Visual Changes in the Signal

24. Visual Changes in the Signal

25. Visual Changes in the Signal
Heat stress

26. Changes in Measured/Calculated Parameters
Correlation of chlorophyll fluorescence Vs survival of young trees (>2.0m)

27. Changes in Measured/Calculated Parameters
Increases in plant vitality following appropriate fertilisation

28. Early Detection of Stress
Chlorophyll fluorescence
can detect stress BEFORE
any visible symptoms are
apparent.

29. photosynthesis <> >
cell growth > wall/protein synthesis >
protochlorophyll formation >
nitrate reductase > ABA accumulation >
respiration > proline & sugar accumulation >
cell leakage > >
death.
What Happens to a Plant Under Stress?
leaf stomatal closure
necrosis

30. Stress
Type
Chlorophyll
Fluorescence
Leaf
Necrosis
Waterlogging 4-8d 10-28d
Drought 8h 4d
Chilling 6-12h 6-18d
Salinity 2h 3-4d
Freezing 0h 1-3d
h =hours, d =days
Chlorophyll Fluorescence vs. Visible Symptoms
in Young Trees

31. Early Detection of Stress: Brief Case Study
• Avenue of 18 Lime trees
• Visually in good health… however…
• Fluorescence results showed that the
Fv/Fm for all trees was between 2 and 10
standard deviations below the value
expected for a healthy Lime tree
• The cause…

32. Early Detection of Stress: Brief Case Study
• Poor nursery practice (tree too deep in root ball)
• Poor planting
• Too deep
• Root ball wire not cut
• Compacted soil
• Herbicide overspray by gardener.

33. Early Detection of Stress: Brief Case Study
• Chlorophyll fluorescence was effective in
detecting a significant decline in vitality
prior to any visible symptoms
• Allowed remedial work to be prescribed
• Clear grass to drip line
• Airspade decompaction of soil
• Soil amendments (biochar)
• Mulch
• Repeat fluorescence test following
year…

34. Early Detection of Stress: Brief Case Study

35. Having a Plan
• A newly project requires a certain degree of flexibility in the plans
throughout all stages of development/construction
• Important when/if unforeseen circumstances occur
• What if the selected plants are already in poor health prior to
planting?
• What if the people trusted to follow the plan make mistakes?
• Once the development is finished, can we simply hand
responsibility of the welfare of the plants to the customer?
• Could fluorescence analysis help to avoid problems associated with
plant health?

36. “Everyone has a plan
until they get punched
in the face”
- Mike Tyson
Having a Plan

37. The Plan
• King’s Cross Square, London
• Part of a £550 million regeneration
of the King’s Cross area.

38. The Launch – September 2013

39. The Punch in the Face
2019

40. Hindsight – a Wonderful Thing!
• Chlorophyll fluorescence analysis is
demonstrably effective in detecting pre-visual
loss of vitality
• As part of routine monitoring, fluorescence
analysis could have identified problems soon
after planting
• Simple remedial action to prevent further decline
could have been prescribed
• Public perception?
• Financial implications?
• Legal cases to answer?
• Should routine, post-planting monitoring have
been part of the original plan?

41. • Routine monitoring as part of an ongoing maintenance plan
• Selection of quality planting stock
• QC/biosecurity monitoring for nurseries
• Early detection of problems caused by pests and diseases
• Monitoring effects of maintenance/pruning
• Checking vitality following damage
• Tracking changes following remedial action
How else can Fluorescence be Used?

42. Which Tree is Under Stress?

43. Which Tree is Under Stress?

44. Final Thoughts…
A very simple, cost-effective method of getting detailed
“under-the-hood” information
Can provide early warnings for decline in vitality and
presence of stress in plants
Can validate visual assessment with empirical data
Directs your line of questioning
Helps you to understand that……

45. Thank You for Listening!!
Things aren’t always
what they seem!