Light-emitting-diode (LED) lighting for greenhouse tomato production

115 Pages·2013·6.36 MB·English

by  Paul Deram

Light-emitting-diode (LED) lighting for greenhouse tomato
production

Paul Deram
Under the supervision of Dr. Mark Lefsrud
Department of Bioresource Engineering
Macdonald Campus
McGill University, Montréal
January, 2013

A thesis submitted to McGill University in partial fulfillment of the
requirements of the degree of Master of Science.

©Paul Deram 2013
ABSTRACT

The cost of artificial lighting is a major expense in the greenhouse production
industry, especially during the winter where supplemental lighting is required to
maintain production. Current technology uses broad spectrum high pressure
sodium lamps (HPS), which, despite being excellent luminous sources, are not the
most efficient light source for plant production. Specific light frequencies have
been shown to impact photosynthesis more directly than others (especially in the
red and blue ranges); focusing on specific wavelengths, light-emitting diodes
(LEDs) could diminish lighting costs due to their high efficiency and lower
operating temperatures. LEDs can be selected to target the wavelengths absorbed
by plants, enabling the growers to customize the wavelengths of light required to
maximize production and limit wavelengths that do not significantly impact plant
growth. The primary purpose of this experiment was to test tomato plants
(Solanum lycopersicum), in a research greenhouse using a full factorial design
-2 -1 -2 -1
with three light intensities (High: 135 µmol m s , Medium: 115 µmol m s and
-2 -1
Low: 100 µmol m s ) at three red to blue ratio levels (5:1, 10:1 and 19:1)
compared to 100% HPS, and a control (no supplemental lighting). The exact
wavelengths chosen were 449 nm for the blue and 661 nm for the red. Secondary
treatments were also tested using 100% red light supplied from the top, 100% red
light supplied from the bottom, a 50%:50% LED:HPS and a replicate of the 10:1
ratio with High light intensity. The experiment was replicated over two different
seasons (Summer-Fall 2011 and Winter-Spring 2011-2012). During the
experiment, the highest biomass production (excluding fruit) occurred with the
19:1 ratio (red to blue), with increasing intensity resulting in more growth,
whereas a higher fruit production was obtained using the 5:1 ratio. The highest
marketable fruit production (fruit over 90 g, Savoura internal standard) was the
50%:50% LED:HPS, followed by 5:1 High and 19:1 High. From this research,
LEDs have been shown to be superior in fruit production over HPS alone, and
LEDs can improve tomato fruit production with HPS and have the ability to
become the dominant supplemental greenhouse lighting system.
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RÉSUMÉ
Le coût de l'éclairage artificiel est une dépense importante dans le secteur de la
production en serre, surtout en hiver lorsqu’un éclairage supplémentaire est
nécessaire pour maintenir le niveau de production. La technologie actuelle utilise
des lampes à haute pression de sodium (HPS), qui en dépit d'être d'excellentes
sources lumineuses, ne sont pas les sources lumineuses les plus efficaces pour la
production végétale. Certaines fréquences spécifiques de lumière ont montré avoir
un impact plus direct sur la photosynthèse que d'autres (en particulier dans les
gammes de rouge et de bleu); en mettant l'accent sur certaines longueurs d’onde,
les diodes électroluminescentes (LED) pourraient diminuer les coûts d'éclairage,
en raison du rendement élevé et des températures plus basses de ce type de lampe.
Les LED peuvent cibler les principales fréquences de lumière mieux absorbées
par les plantes, ce qui permettrait aux producteurs de créer une lumière aux
longueurs d'onde adaptées à la production optimale des plantes. Le principal
objectif de cette expérience était de tester les lampes sur des plants de tomate
(Solanum lycopersicum) dans une serre de recherche en utilisant un plan factoriel
-2 -1
complet avec trois intensités lumineuses (Haute: 135 μmol m s , Moyenne: 115
-2 -1 -2 -1
μmol m s et Basse: 100 μmol m s ) et trois proportions de rouge et bleu (5:1,
10:1 et19: 1), et comparer leur performance à celle de 100% HPS, et d’un contrôle
(pas d'éclairage supplémentaire). Les longueurs d'onde choisies sont 449 nm
(bleu) et 661 nm (rouge). Certains traitements secondaires ont également été
testés, dont 100% rouge (éclairage par le haut ou le bas), un 50%:50% LED:HPS
et une reproduction du 10:1 à haute intensité. L'expérience a été menée au cours
de deux saisons différentes (été-automne et hiver-printemps). La production
végétative la plus importante s'est produite avec le rapport 19:1 (rouge : bleu). La
production de fruits était la plus élevé avec le rapport 5:1. La production en fruits
commercialisables la plus importante (fruits de 90 g et plus : étalon interne de
Savoura) a été pour le 50%:50% LED:HPS, suivi du 5:1 et 19:1 à haute intensité.
Les LED se sont montrés supérieures aux HPS quant à la production de tomates.

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ACKNOWLEDGEMENTS

This thesis is the result of the input of numerous parties. First of all, I would like
to thank the company, General Electric Lighting Solutions Canada (Nabil Jacques
Salem, Jean-François Richard) for proposing the research project, and committing
to the research with funding and development of the LED array prototypes.
I would also like to thank my supervisor: Dr. Mark Lefsrud for providing me
with much needed support throughout the duration of this research project, as well
as opening up his laboratory for me to conduct my research, and for sharing his
personal expertise in the domain of LED lighting for plant research.
I would like to thank Dr. Valérie Orsat, for her always kind and encouraging
advice, as well as for all the help given as part of my advisory committee for the
sake of this project.
To Savoura in Portneuf, QC (David Brault and Claire Boivin), I extend my thanks
for their knowledge in tomato growing and care techniques which was
instrumental in the completion of this research, as well as for teaching me how to
work efficiently and in a timely fashion in a greenhouse operation.
To any others who helped me during the greenhouse experiments, for answering
my questions, for advice on methodology or even for their friendship, thank you
all (Alejandro Jaul, Nicholas Matlashewski, Allison Busgang, Michael Schwalb,
Julie Gagné, Anil Patel, Yvan Gariépy and many others).
Finally, I would like to thank my family, friends and my wonderful fiancée, for all
their moral support, and for making their unseen presence known and felt.
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TABLE OF CONTENTS
ABSTRACT ............................................................................................................. 2
RÉSUMÉ ................................................................................................................. 3
ACKNOWLEDGEMENTS ..................................................................................... 4
TABLE OF CONTENTS ......................................................................................... 5
LIST OF TABLES ................................................................................................... 8
LIST OF FIGURES ................................................................................................. 9
LIST OF EQUATIONS ......................................................................................... 11
ABBREVIATIONS ............................................................................................... 12
1. INTRODUCTION .......................................................................................... 13
2. HYPOTHESIS AND OBJECTIVE ................................................................ 15
3. LITERATURE REVIEW ............................................................................... 16
3.1. Tomato and Greenhouses ............................................................................ 16
3.2. Photosynthesis ............................................................................................. 17
3.3. Lighting Systems: ........................................................................................ 20
3.4. LEDs in Plant Research:.............................................................................. 23
3.5. Effects of Different Wavelengths ................................................................ 24
3.6. Effect of Intensity ........................................................................................ 27
4. MATERIALS AND METHODS ................................................................... 29
4.1. Plant Care .................................................................................................... 29
4.2. Experimental Setup ..................................................................................... 31
4.2.1. Greenhouse Setup ................................................................................. 31
4.2.1. LED Setup ............................................................................................ 34
4.3. Instrumentation ............................................................................................ 36
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4.4. Statistical Analysis ...................................................................................... 39
5. RESULTS ....................................................................................................... 41
5.1. Fruit ............................................................................................................. 41
5.1.1. Marketable Fruit Number ..................................................................... 41
5.1.2. Marketable Fruit Mass .......................................................................... 42
5.1.3. Total Fruit Number ............................................................................... 44
5.1.4. Total Fruit Mass .................................................................................... 45
5.1.5. Average Fruit Mass............................................................................... 47
5.2. Vegetative Biomass ..................................................................................... 49
5.2.1. Fresh Mass ............................................................................................ 49
5.2.2. Dry Mass ............................................................................................... 50
5.2.3. Dry to Fresh Biomass Ratio .................................................................. 52
5.2.4. Fruit and Flower Counts ....................................................................... 53
5.3. Fruit to Biomass Ratio ................................................................................. 55
5.4. Environmental Data ..................................................................................... 57
5.4.1. Temperature .......................................................................................... 57
5.4.2. Relative Humidity ................................................................................. 57
5.4.3. Light Sensor Map ................................................................................. 58
6. DISCUSSION ................................................................................................. 60
6.1. Ratios chosen ............................................................................................... 60
6.2. Fruit ............................................................................................................. 61
6.2.1. Marketable Fruit ................................................................................... 61
6.2.2. Total Fruit ............................................................................................. 63
6.3. Vegetative Biomass ..................................................................................... 64
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6.4. HPS to LED comparison ............................................................................. 66
6.5. Top versus Bottom Lighting Systems ......................................................... 66
6.6. Light Measurement Techniques .................................................................. 67
6.7. Production Issues ......................................................................................... 71
6.7.1. First Run: .............................................................................................. 72
6.7.2. Second Run: .......................................................................................... 74
6.8. Observations for future research ................................................................. 76
7. CONCLUSIONS ............................................................................................ 81
8. REFERENCES ............................................................................................... 83
APPENDIX A: Formatted Data ............................................................................. 89
APPENDIX B: Statistical Data (Box Plots) .......................................................... 94
APPENDIX C: Raw Data .................................................................................... 101
APPENDIX D: Weather and Lighting Data ........................................................ 110

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LIST OF TABLES
Table 1: Greenhouse section placement ............................................................... 31
Table 2: Treatment list and description.................................................................. 35
Table 3: End of first run and start of second run light map data............................ 38
Table 4: Fruit and flower count summary .............................................................. 54
Table C1: Total fruit data ..................................................................................... 101
Table C2: Red fruit data ....................................................................................... 103
Table C3: Marketable fruit data (> 90 grams) ..................................................... 104
Table C4: Biomass data ....................................................................................... 105
Table C5: Fruit and flower count data ................................................................. 108
Table D1: Temperature data during the second run ............................................. 110
Table D2: Temperature data during the first run ................................................. 111
Table D3: End of second run light map data ....................................................... 112
Table D4: Initial light map data ........................................................................... 113
Table D5: Summary of initial light map data ...................................................... 114
Table D6: GE spectroradiometer data .................................................................. 115

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LIST OF FIGURES
Figure 1: PAR curves based on absorbed light and direct photosynthesis
measurement .......................................................................................................... 18
Figure 2: Cross sectional view of an LED lamp as well as a conventional LED .. 20
Figure 3: Spectral distribution of LEDs versus a dysprosium lamp ...................... 21
Figure 4: High pressure sodium spectrum ............................................................. 22
Figure 5: Diagram of the greenhouse used in the experiment ............................... 32
Figure 6: Light and plant setup for each section .................................................... 36
Figure 7: Total number of marketable fruit per light treatment ............................. 42
Figure 8: Total marketable fruit mass per light treatment ..................................... 43
Figure 9: Total number of fruit per light treatment ................................................ 44
Figure 10: Total fruit mass per light treatment ...................................................... 46
Figure 11: Fruit mass average per light treatment ................................................. 47
Figure 12: Fruit mass average for fruit over 90 g per light treatment .................... 48
Figure 13: Wet mass of plant biomass (excluding fruit) per light treatment ......... 50
Figure 14: Dry mass of plant biomass (excluding fruit) per light treatment ......... 51
Figure 15: Dry to fresh biomass ratio .................................................................... 52
Figure 16: Total fruit mass to plant biomass ratio ................................................. 55
Figure 17: Marketable fruit to plant biomass ratio ................................................ 56
Figure 18: Light direction from the LED arrays .................................................... 68
Figure 19: Typical angular response of the LI-193 ............................................... 70
Figure 20: Two examples of viable clusters turning into secondary stems ........... 77
Figure 21: Leaf burn .............................................................................................. 78
Figure 22: Powdery mildew ................................................................................... 79
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Figure A1: Total marketable fruit for the second run for the tomato plants .......... 89
Figure A2: Total marketable fruit for the first run for the tomato plants.............. .89
Figure A3: Total mass of marketable fruit for the second run ............................... 90
Figure A4: Total mass of marketable fruit for the first run ................................... 90
Figure A5: Total fruit count during the second run ............................................... 91
Figure A6: Total fruit count during the first run .................................................... 91
Figure A7: Total fruit mass during the second run ................................................ 92
Figure A8: Total fruit mass during the first run ..................................................... 92
Figure A9: Total plant fresh biomass (excluding fruit) for the second run ........... 93
Figure A10: Total plant fresh biomass (excluding fruit) for the first run .............. 93
Figure A11: Total plant dried biomass (excluding fruit) for the second run ......... 94
Figure A12: Total plant dried biomass (excluding fruit) for the first run .............. 94
Figure B1: Total number of marketable fruit per plant for the 120 day harvest .... 95
Figure B2: Total marketable fruit mass per plant, for the 120 day harvests .......... 96
Figure B3: Total number of fruit per plant, for the 120 day harvests .................... 96
Figure B4: Total mass of fruit per plant, for the 120 day harvests ........................ 97
Figure B5: Total fresh biomass per plant for the 120 day harvests ....................... 97
Figure B6: Total dry biomass per plant for the 120 day harvests .......................... 98
Figure B7: Ratio of dry to fresh biomass production ............................................ 98
Figure B8: Ratio of fruit mass to fresh biomass for the 120 day data ................... 99
Figure B9: Ratio of marketable fruit mass to fresh biomass for the 120 day ........ 99
Figure B10: Total number of red fruit per plant, for the 120 day experiment ..... 100

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