Controlled environment agriculture - enhancing productivity for long term space exploration
Michael StasiakMichael Dixon
Bernie Grodzinski
Controlled EnvironmentSystems Research Facility
University of GuelphGuelph, Ontario
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ACKNOWLEDGEMENTS We wish to thank Thomas Graham, Evangelos Leonardos, George Lin, Nan McKay, L.G. Phillips, and Rodger Tschanz for planting, maintenance, and harvesting of the soybeans, and Jamie Lawson for his untiring technical support and unparalleled ability to fix stuff. Research is supported by grants and contributions from the Natural Sciences and Engineering Research Council of Canada, the Ontario Ministry of Agriculture, Food, and Rural Affairs, the Centre for Research in Earth and Space Technology, L.W. Anderson Software Consultant, Hutchins International Ltd., Allied Signal Aerospace Canada Ltd., Genetron Systems Ltd., Constant Temperature Control Ltd., and the University of Guelph.
ABSTRACT In future space travel and colonization, plants and other biological systems are expected to function as an integral part of life support, providing food, potable water, and oxygen. The technical achievements that have enabled the Canadian greenhouse industry to readily grow plants during the winter are directly applicable to advanced life support (ALS) systems research. In dense plant canopies, shaded leaves represent considerable unused photosynthetic capacity which can be exploited to improve production in closed environments. By coupling Fusion Systems Solar 1000 microwave powered lights to 100 mm diameter glass tubes lined with 3M Optical Lighting Film, energy equivalent to about 420 µmol m-2 s-1 PAR was delivered to the inner canopy of a developing soybean (Glycine max L. Merr. cv. Secord) crop. When overhead illumination of 400 - 1200 µmol. m-2 s-1 PAR was supplemented with inner canopy illumination, net carbon exchange rates (NCER) were increased by 23 to 87%. With inner canopy lighting, carbon assimilation, water and oxygen production, and ethylene evolution into the closed environment were increased during leaf canopy development.
PLANTS AS LIFE SUPPORT
COCO22OO22
FoodFood
WasteWaste HH22OO
Pure HPure H22OO
Plants can provide:• food• air revitalization• potable water• waste processing
nnCOCO22 + + 2n2nHH22O + O + lightlight ➡➡ (CH (CH22O)O)nn + + nnOO22 + H + H22OO
Food Oxygen Carbon dioxide uptakeWater
• >$50,000 per kg
• 70 kg person requires● 0.5 - 0.6 kg food● 0.75 - 1.0 kg oxygen● 3 kg water
● re-supply from Earth makes long-term space missions not economically viable
● Solution? Advanced Life Support systems utilizing plants and microbes
Light from overhead results in typical canopy architecture
• mutual shading• competition for light
• decreased irradiation and productivity in lower canopy
• senescence
• thus light is a limiting factor in dense plant canopies and shaded leaves represent lost photosynthetic capacity
• productivity can be enhanced by adding light to the inner canopy
materials required for life support are supplied from Earth
OBJECTIVES• investigate potential value of inner canopy irradiation • evaluate short-term net carbon exchange rates• assess long-term water, O2, and carbon accumulation • monitor ethylene accumulation
In dense plant canopies there is:
CONTROLLED ENVIRONMENT CHAMBERS
Inner canopy lighting system
Blower
Blower
External Reservoir
295 cm
InternalReservoirPressure
compensation
GrowingTrays
Inner canopy lighting
Bulb Bulb rotatorrotator
MagnetroMagnetronn
BulBulbb
Radio frequency Radio frequency screenscreen
Microwave lamp 3M Optical Lighting Film
SHORT-TERM NCER
Short-term net carbon exchange rates (NCER) for a 37 to 42-day-old soybean canopy which consisted of 180 plants (LAI average of 6), with overhead lighting () and overhead combined with inner canopy irradiation (ICI) (). Error bars indicate +/- the standard error of the means of three replicates.
Increases in the rate of carbon assimilation
ranged from 23 to 87 percent between 1200 and 400 µmol m-2 s-1 of
overhead irradiation
CARBON
Carbon assimilation (mols) for soybean (cv. Secord) grown with (�) and without (ð ) supplemental inner canopy irradiation in closed loop sealed environment chambers .
30% increase in carbon accumulation at the end of 119 days of growth compared to only 11%
additional energy supplied by the inner
canopy lighting system
WATER
Water accumulation (l) from condensate recovery for soybean (cv. Secord) grown with () and without (à ) supplemental inner canopy irradiation in closed loop sealed environment chambers.
Net increase of 160% over control - water use efficiency (WUE) was lower in canopies with
inner canopy irradiation
ETHYLENE
Ethylene concentration normalized for daily cumulative ethylene loss due to leakage for soybean grown with () and without () supplemental inner canopy irradiation. Three distinct phases were noted, coinciding with observed vegetative growth (I), anthesis (II), and pod filling (III).
Ethylene levels reached as high as 160 ppb - the rate of production was
unaltered when normalized with carbon
accumulation
MORPHOLOGY
76 day-old soybean plants grown with (+ICI) and without (Control) supplemental inner canopy irradiation.
ICI plants had a more developed lower canopy
with higher leaf area, and more seeds and
pods
SUMMARYEnergy supplied to the inner canopy has the potential to not only
improve volumetric efficiency, but can also improve carbon
assimilation and the production of oxygen and water beyond what
would result from overhead lighting systems alone
OXYGENNet production was increased by 92% with supplemental ICI
chamberviewed
fromabove