EVALUATING GROWTH CHARACTERISTICS AND TOTAL ANTHOCYANIN CONTENT IN THREE CULTIVARS OF RED ROMAEVE-TYPE LETTUCE (Lactuca sativa L.) IN RESPONSE TO THREE LIGHTING INTENSITIES

摘要

The ability to provide fresh food in the diet of a crew on long duration space missions can have significant physiological and psychological benefits. Providing a sufficient quantity and variety of fresh crops as well as providing colorful foods may further increase the benefit. Due to the power limitations and air filtration systems in a spacecraft, space-grown plants will likely be grown in an open systems sharing the same atmosphere as the crew, consisting of high CO_2 concentrations and low lighting levels. In this test, three cultivars of red romaine-type lettuce, "Outredgeous", "Eruption", and "Red Sails", were grown hydroponically under three different light intensities; 8.6, 17.2, and 26 mol m~(-2) d~(-1) to determine the yield characteristics. In addition, as a potential criteria for selection of a cultivar, total anthocyanin content (i.e. red coloration) of each cultivar was determined. Of the three cultivars, the one with the optimal growth characteristics and anthocyanin content under the spaceflight environmental conditions will be selected as a possible candidate crop to be grown on the International Space Station (ISS), a Mars transit vehicle, or Martian and lunar bases. Results indicated that "Red Sails" had the highest edible fresh weight at all light intensities, but its stature may not be conducive for the limited volume of a plant growing unit or as part of mixed crop production system. Both "Eruption" and "Outredgeous" had similar anthocyanin contents among all light intensities and were nearly three-fold higher than "Red Sails". However, "Outredgeous" had greater yield than "Eruption" and therefore may be the best suited cultivar for the use in a space application.