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Effect of Light Quality on Production of Bioprotective Compounds in Red Leaf Lettuce
G.W. Stutte1*, I. Eraso1, P. Bisbee1, C. Ledeker2, and T. Skerritt3.
1Dynamac Corporation,, Kennedy Space Center, FL, USA, 2Dept of Animal and Food Science, University of Delaware,
3Dept Applied Science, Limerick Institute of Technology, Limerick, Ireland
2008 International Meeting on Controlled Environment AgricultureCocoa Beach, FL 8-12 March, 2008
Background
Exposure to ionizing radiation during long-duration space missions increases risk for short term illness and long-term risk for cancer.
@Mauricio Granado (www.mauriciogranados.com)
Background
Radiation induces free-radical formation.Anti-oxidant defense mechanisms are over-riddenDamage at membrane, enzyme and chromosome level occurs
@Mauricio Granado (www.mauriciogranados.com)
Background
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Increasing levels of anti-oxidants increases resistance to damage.Anthocyanins are pigments with anti-oxidative propertiesRed leaf lettuce is candidate salad crop and a relatively high source of anthocyanins.
Research Objective
To determine whether the production of bioprotective compounds in candidate salad crops can be increased by regulating the morphology, growth, and biochemistry of the plants with though spectral quality using light emitting diodes.
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Research Approach
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Lactuca sativa cv. Outredgeous seedlings were grown in Rockwool under in small (16 x 19 x 24 cm) chambers at 300 µmol m-2 s-1 PPF with 18/6 photoperiod.Environment conditions were 23oC, 65% RH and 1200 µmol mol CO2.Total anthocyanin production in leaves was determined using spectrophotometerAnti-oxidant potential determined using the ORAC methodology
LED arrays with multiple wavelengths were used to alter spectral quality
400 nm
440 nm
530 nm
640 nm
660 nm
730 nm
LED arrays designed and built by Orbitec using Norlux LED engines
Spectral Quality Established by Altering Power to the LED arrays.Light treatments are established using blue (440 nm), green (530 nm), red (640 nm), and far red (730 nm) LED’s. Spectral quality and quantity determined with using spectroradiometer.300 µmol m-2 s-1 PPF from triphosphor fluorescent lamps (TPF; Pentron T-5) was used as the control treatment.
-5
0
5
10
15
20
25
30
350 450 550 650 750 850 950 1050
Wavelength (nm)
Qua
nta
TPSRGBRBRRFr
Treat PARTPS 287RGB 284RB 276R 279RFr 294
Light quality affected plant morphology alter efficiency of light interception
RGB RB R RFr
0.00.20.40.60.81.01.21.4
RGB RB R RFr
Dry
Mas
s (g
)
Lactuca sativa cv Outredgeous Both blue (440 nm) and
Fr (730 nm) affect leaf morphology and plant
architecture
Light quality has significant effect on anthocyanin concentration in leaves.
RGB RB R RFr
0
1
2
3
4
5
RGB RB R RFr
Ant
hocy
anin
(ug/
g FM
)
Blue light (440 nm) is required to maintain
anthocyanin content in the leaves.
Lactuca sativa cv Outredgeous
Blue (440 nm) light increases total anthocyanin content of plant.
RGB RB R RFr
010203040506070
RGB RB R RFr
Ant
hocy
anin
(ug/
plan
t)
Additive effects of light quality on anthocyanin concentration and plant
biomass occurs.
Lactuca sativa cv Outredgeous
Blue (440 nm) light increases total anti-oxidant potential (ORAC) value of plant.
05
1015202530
RGB RB R RFr
OR
AC
(TE/
plan
t)
RGB RB R RFr
Lactuca sativa cv Outredgeous
Threshold for blue (440 nm) was <5% of total PAR for anthocyanin production
Control RedRed/Blue
Conclusions
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LED’s can be used optimize spectral quality in plant chambers for long duration missions in order to increase yields by increasing light interception and increased efficiency of light conversion.Photoregulation of secondary metabolisms has potential to significantly increase the bioprotectant and nutraceutical valuecandidate salad cropsA significant amount of research is required to understand the photo regulation of bioprotectant metabolism in plants.
Funding provided by NASA Kennedy Space Center CTC grant (LSS5-16F)
Acknowledgments
Student SupportChristie Ledeker (University of Delaware) supported though Dynamac Internship Program.Tony Skerritt (Limerick Institute of Technology) supported through FÁS, Irelands Training and Employment Authority.
Funding provided by NASA Kennedy Space Center CTC grant (LSS5-16F)
@Mauricio Granado (www.mauriciogranados.com) @Mauricio Granado (www.mauriciogranados.com)
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