# Presentation: 467706

## Growth Characteristics and Anthocyanin Content in Red  Lettuce under ISS Environmental Conditions

- Colleen Yunker
- PI: Jeff Richards
- SLSTP CBS Trainee

## Initial Description

- A space garden on long duration missions could have physiological and potential psychological benefits for the crew.  Space-grown plants must thrive under higher CO2 concentrations and lower lighting due to power and space limitations.  This project looked at these effects on growth characteristics and anthocyanin content in red-romaine lettuce.

## Introduction and Methods

- Three cultivars of red romaine-type lettuce, Outredgeous, Eruption, and Red Sails, were grown under three different lighting intensities, 8.6, 17.2, and 26 mol m-2 d-1.
-  Lettuce is a critical salad crop, but red lettuce contains anthocyanins, which create the red pigmentation and are also antioxidants, potentially combating cosmic radiation and adding more color to a space garden.
- The plants were grown hydroponically in a modified half-strength Hoagland’s solution and harvested on 7, 14, 21, and 28 days after planting.  At these times, fresh weight, dry weight, leaf area, and diameter was noted for an analysis of growth characteristics.

- At 28 days, the plants were also sampled for anthocyanin analysis.  The red pigment was extracted from the samples using acidified methanol and then quantified from a reading at 530 nm on the spectrophotometer.
- Figure 3:Anthocyanin extraction from leaf tissue by acidified methanol.  The sample was incubated overnight in the dark at 4°C.

- Figure 1: The hydroponic system of Grodan® Rockwool cubes in the 2” x 2” net cups resting in Hoagland’s solution

- Figure 2: Yunker harvesting 7 day old lettuce plants of the cultivar Outredgeous.

## Results and Acknowledgements

- This research was conducted as part of the 2004 Spaceflight and Life Sciences Training Program funded by the National Aeronautics and Space Administration.  The authors recognize the support of the Dynamac Corporation, the NASA Spaceflight and Life Sciences Training Program Academic Partner Alliance and the United States Department of Agriculture. Thank you to Jeff Richards, the Principal Investigator, for his support and guidance in the project.  Thank you to Joyce Smolik for her help in plant care and sample analysis.  Thank you to Adam Santone for  his advice and criticism on all of the work. Thank you to Sharon Edney, Nate Cranston, Matt Sisko, and Hope Jones for their assistance and training.

- Red Sails, the cultivar with the highest edible fresh weight, significantly increased its growth with each increasing light level.  Eruption and Outredgeous increased significantly from the lowest light level to the middle but had no difference from the middle to the highest lighting intensity.
-  Eruption and Outredgeous had an approximately equivalent anthocyanin content per gram of fresh weight at 8.6 PPF, with Red Sails being much lower.  However, from there Outredgeous increased steadily, having more red pigment with each higher lighting level.  Eruption leveled off and Red Sails increased slightly but at a three-fold lower anthocyanin level.

- Figure 4: Mean Edible Fresh Weight of each Cultivar at each Lighting Intensity at the 28 Day Harvest

- Figure 5: Anthocyanin Content per gram of Fresh Weight at each Lighting Intensity at the 28 Day Harvest