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1
Applications of supplemental LED pp pplighting in vegetable propagation
Chieri Kubota and Ricardo Hernández
The University of Arizona
SCRI LED Stakeholders Meeting (6/24/2014)
UA LED Research Objectives
1. To conduct research necessary for vegetable propagators to adopt LED lighting technologypropagators to adopt LED lighting technology– Light quality requirement for LED lighting
– Side‐by‐side comparison with the conventional HID lighting
– Testing new fixture designs and application methods
2. To explore new LED applications beneficial to p ppvegetable propagators– Low intensity applications of red and far‐red LEDs for controlling plant morphology
– Pulsed lighting
University of Arizona 2014, Not for Publication
2
Phase I: Supplemental LED B:R photon flux ratios for vegetable transplants
• ObjectiveT t diff t l t l LED Bl R d h t– Test different supplemental LED Blue:Red photon flux ratios for growth and development of vegetable transplants.
• Hypothesis
– Vegetable seedlings respond different to B:R PF ratios under different solar DLI conditions.
Phase I: Materials & Methods
Testing different RED:BLUE ratios providing 55 μmol m‐2 s‐1 for 18 hours = 3.54 molm‐2 d‐1 of supplemental LED light.
100%
4%
96%
16%
84%
N
NO SUPPLEMENTAL
LIGHT
treatment treatment treatment control
Blue = 455 nm, Red = 661 nm
96% 84%
Tested under different DLIs• Controlling sun radiation by deploying different shade
cloths.
University of Arizona 2014, Not for Publication
3
Phase I: Materials & Methods
DRY MASS RESPONSE
Effects of supplemental LED light
Phase I: Results
Similar results for
0.45 0.5
0.55 0.6 0.65 0.7
ry m
ass (g)
DRY MASS RESPONSE
control LED supplement
P < 0.000126%
increase
P < 0.0001
48%
Similar results for Tomato ‘Komeett’, and Pepper ‘Fascinato’
0.2 0.25 0.3 0.35 0.4
High DLI Low DLI
Shoot dr
SOLAR DAILY LIGHT INTEGRAL
48% increase
Hernández, R., Kubota, C. (2014)
University of Arizona 2014, Not for Publication
4
CUCUMBER LEAF AREA RESPONSE High DLI
Effects of LED B:R PF ratios
Phase I: Results
Leaf area reduction 13%
0.017
0.018
0.019
0.02
0.021
0.022
area/plant (m
2 )
CUCUMBER LEAF AREA RESPONSE High DLI
Low DLI
P = 0.2138
reduction: 13%
Dry mass reduction: 12%
0.014
0.015
0.016
0 2 4 6 8 10 12 14 16 18
Leaf
Percent of blue light
P = 0.0163
Hernández, R., Kubota, C. (2014)
Conclusion Phase I
• LED supplemental lighting increased plant growth even under high DLI conditions.under high DLI conditions.
• 100% red supplemental LED lighting is preferred at the current LED efficiencies.
• Responses to LED light quality vary under different solar DLI.
• Responses to LED light quality are species specific.
University of Arizona 2014, Not for Publication
5
Phase II
• Objective
– Quantify plant responses of vegetable transplants grown side‐by‐side under LED and HPS supplemental lighting
– Compared electrical efficiencies between HPS and LED supplemental lighting
Materials & methods: treatments
Testing different lighting technologies providing 60 μmol m‐2 s‐1
for 18 hours = 3.9 molm‐2 d‐1 of supplemental light.pp g
100% 100%100%
TreatmentRed‐LED
TreatmentBlue‐LED
Treatment 600W HPS
53%42%
5%
Blue = 443 nm peakRed = 632 nm peak
42%
University of Arizona 2014, Not for Publication
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Phase III: Materials & methods
Phase III: Results
Cucumber ‘Cumlaude’
P < 0.0001
22% 22%
Similar results for tomato
A
BB
for tomato‘Komeett’
Hernández, R., Kubota, C. In press
University of Arizona 2014, Not for Publication
7
Phase III Results: morphology
P < 0.0001
38%
100% blue HPS 100% red
Hernández, R., Kubota, C. In press
Phase III: Discussion
Tomato and cucumber plants had higher dry mass under the HPS treatment than the LED treatments.under the HPS treatment than the LED treatments.
Air T measured directly under the leaf was 1 ºC higher in
Higher leaf T in HPS than LED
Air T measured directly under the leaf was 1 C higher in the HPS treatment
University of Arizona 2014, Not for Publication
8
Phase III: energy consumption
66 % more66 % more
Greenhouse Engineering R. Aldrich
Aeral Power Consumption (W m‐2) Fixture Growing Efficiency (g kWh‐1)
Phase III: energy consumption
Lamp type and ballast
Input power (W)
Fixture efficiency (µmol·J-1)
Fixture photon emission rate (PER,
µmol·s-1)
UF MF Effective photons (EP,
µmol·s-1)
Number of fixtures per
hectare
Areal power consumption
(W·m-2)
Fixture growing
efficiency (g·kWh-1)
Blue-LEDs 43x 1.9 y 81.2z 1.00u 0.85u 69 8258 35 3.3 600W HPS 656 1.6 w 1075z 0.90v 0.90v 871 655 43 3.5 Red-LEDs 22x 1.7 y 37z 1.00u 0.85u 31 18124 39 3.0
z Values provided by the manufacturer. y Values provided by Nelson and Bugbee (2013) for red-LED (655 nm) and blue-LED (455 nm).
Fixture Growing Efficiency (g kWh )
p y g ( ) ( ) ( )x Calculated using fixture photon emission rate and fixture efficiency. Input power does not include fixture controller and cooling system. w Calculated using fixture photon emission rate and measured input power. v Reported for HPS lamps by Aldrich and Bartok (1994). u UF is a high value due to the directional nature of the emitted light, MF is 0.85 since LED lamp life is defined as the time to reach 70% of initial output and LED light output almost linearly declines over time (EERE, 2009).
Hernández, R., Kubota, C. unpublished (a)
University of Arizona 2014, Not for Publication
9
Phase II: Energy Consumption Conclusion
• At the current technology state, supplemental HPS lighting is more efficient than supplemental LED lighting as over‐head lighting for the production of tomato and vegetable transplants.
Phase II: Leaf Curling Index in bell peppers
University of Arizona 2014, Not for Publication
10
Greenhouse pepper varieties
Phase II: Leaf Curling Index
• Viper• PP0710• Orangela• Fascinato
Phase II: Leaf Curling Index
Supplemental Blue Supplemental HPS Supplemental red
Hernández, R., Kubota, C. unpublished (b)
University of Arizona 2014, Not for Publication
11
Phase III: R:B photon flux ratio sole‐source LEDs
ObjectivesObjectivesEvaluate LED technology for the production of vegetable transplants.
Find the optimal B:R Photon flux ratio for theFind the optimal B:R Photon flux ratio for the production of vegetable transplants using LEDs.
Phase III: Materials & Methods
Testing different RED:BLUE ratios providing 100 μmol m‐2 s‐1 for 18 hours = 6.48 molm‐2 d‐1 DLI.
• 0B‐100R• 10B‐90R• 20B‐28G‐52R
• 30B‐70R• 50B‐50R• 75B‐25R• 100B‐0R
Growing temperature: 25 ˚CCO2 concentration: Maintained at ambientRH: 40‐70%
University of Arizona 2014, Not for Publication
12
Phase III: Materials & Methods
Phase III: Cucumber R:B ratio Results
Percent blue
University of Arizona 2014, Not for Publication
13
Phase III: Cucumber R:B ratio Results
P<0.0001
Hernández, R., Kubota, C. unpublished (c)
Phase III: Cucumber R:B ratio Results
P<0.0001
Hernández, R., Kubota, C. unpublished (c)
University of Arizona 2014, Not for Publication
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Phase III: Cucumber R:B ratio Results
P<0.0001
Hernández, R., Kubota, C. unpublished (c)
Phase III: Tomato R:B ratio Results
P<0.0001
Hernández, R., Kubota, C. unpublished (d)
University of Arizona 2014, Not for Publication
15
Si l l f
Chlorophylls
(McCree, 1972; Sager et al.,1988)
Single leaf
Si l l f
Canopy (LAI =3)
Chloroplast
http://en.wikipedia.org
Single leaf
(Paradiso et al., 2011)
Light quality effect on plant growth can be photosynthetic or
photomorphogenic.
Plant growth rate = Leaf photosynthetic ratep y
x Leaf area
University of Arizona 2014, Not for Publication