July 2024 - 8

LIGHTING RESEARCH
The biofeedback system measures chlorophyll fluorescence parameters and the data is sent to a datalogger. LED light levels needed
are calculated and provided based on the target values which will then affect the newly measured chlorophyll fluorescence. The
biofeedback logic will allow an increase in LED light levels when measured ETR is lower than a target ETR or when measured
ΦPSII is higher than a target ΦPSII.
such as temperature and humidity, are reflected when
determining supplemental light levels.
THE PROCESS
Two trials were tested to evaluate the biofeedback
system's applicability. The biofeedback system was
installed in a climate control chamber with dimmable
LED lighting.
During the first experiment, a wide range of ETR and
ΦPSII target values were maintained for a single day
using lettuce and cucumber plants. The chlorophyll
fluorescence parameters were monitored every 15
minutes, and the LED light levels were adjusted
whenever the current ETR and ΦPSII differed from the
target values.
The objectives of the second experiment were to
test if the biofeedback system can be used throughout
the growing cycle and to find out which level of target
ETR is optimal for growing lettuce in terms of yield and
energy efficiency.
RESULTS
From the first experiment, we could confirm that the
biofeedback system precisely maintained the specific
level of photosynthetic capability (either ETR or ΦPSII)
constantly, and also adjusted the LED light levels
according to the target values.
Lettuce and cucumber plants showed slightly different
levels of LED light because there is a crop-specific
difference in photosynthetic efficiency. The second
experiment showed that lettuce plants acclimated to
the new light conditions and increased photosynthetic
efficiency over time. Also, the high target ETR produced
greater biomass with a higher growth rate but required
high electrical use at the same time leading to low
energy efficiency.
In summary, the biofeedback system could
successfully maintain specific levels of physiological
response as we designed, and the system adjusted
LED light levels considering environmental factors,
crop-specific response and acclimation process. Optimal
target ETR can be determined based on the grower's
objectives such as crop yield, electrical energy use and
growth cycle.
WHAT'S NEXT?
Ultimately, the biofeedback system is
expected to perform a distinctive role in
optimizing the energy efficiency of supplemental light
in greenhouses. There are fluctuating environmental
8
JULY 2024 GPNMAG.COM
FEBRUARY 2024 GPNMAG.COM

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July 2024

Table of Contents for the Digital Edition of July 2024

Table of Contents
Editor's Report | Summertime decisions
Lighting Research | Supplemental lighting strategies
Technology | Transforming with automation
CAST 2024 | Remarkable releases for 2025
CEA | The importance of canopy ventilation
Climate Control | Enhancing greenhouse management
Special Advertising Section | Grower's Guide: Professional Growing Media and Biologicals
Variety Information | New take on smooth hydrangeas
Big Grower | Hydroponic farming
Product Showcase
Plant Health | Setting ground rules
Forty Under 40 Perspectives | Turning a lifelong education into a business
Culture Report | Grama grass
Technically Speaking | Why crops don't flower (on time)
Product Marketplace
Industry News/Events
Classifieds/Ad Index
July 2024 - 1
July 2024 - 2
July 2024 - Table of Contents
July 2024 - Editor's Report | Summertime decisions
July 2024 - 5
July 2024 - Lighting Research | Supplemental lighting strategies
July 2024 - 7
July 2024 - 8
July 2024 - 9
July 2024 - 10
July 2024 - 11
July 2024 - Technology | Transforming with automation
July 2024 - 13
July 2024 - 14
July 2024 - 15
July 2024 - CAST 2024 | Remarkable releases for 2025
July 2024 - 17
July 2024 - 18
July 2024 - 19
July 2024 - 20
July 2024 - 21
July 2024 - 22
July 2024 - 23
July 2024 - 24
July 2024 - 25
July 2024 - 26
July 2024 - 27
July 2024 - CEA | The importance of canopy ventilation
July 2024 - 29
July 2024 - 30
July 2024 - 31
July 2024 - 32
July 2024 - 33
July 2024 - Climate Control | Enhancing greenhouse management
July 2024 - Special Advertising Section | Grower's Guide: Professional Growing Media and Biologicals
July 2024 - A2
July 2024 - A3
July 2024 - A4
July 2024 - A5
July 2024 - A6
July 2024 - A7
July 2024 - A8
July 2024 - A9
July 2024 - A10
July 2024 - A11
July 2024 - A12
July 2024 - A13
July 2024 - A14
July 2024 - A15
July 2024 - A16
July 2024 - Variety Information | New take on smooth hydrangeas
July 2024 - 36
July 2024 - 37
July 2024 - 38
July 2024 - 39
July 2024 - 40
July 2024 - Big Grower | Hydroponic farming
July 2024 - 42
July 2024 - 43
July 2024 - 44
July 2024 - 45
July 2024 - 46
July 2024 - Product Showcase
July 2024 - Plant Health | Setting ground rules
July 2024 - 49
July 2024 - 50
July 2024 - 51
July 2024 - Forty Under 40 Perspectives | Turning a lifelong education into a business
July 2024 - 53
July 2024 - Culture Report | Grama grass
July 2024 - 55
July 2024 - 56
July 2024 - 57
July 2024 - Technically Speaking | Why crops don't flower (on time)
July 2024 - 59
July 2024 - Product Marketplace
July 2024 - 61
July 2024 - 62
July 2024 - 63
July 2024 - 64
July 2024 - Industry News/Events
July 2024 - Classifieds/Ad Index
July 2024 - 67
July 2024 - 68
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