Effects of elevated and super-elevated carbon dioxide on salad crops for space

Abstract

Space habitats typically have elevated CO2 and NASA is considering growing leafy greens in space to supplement astronauts’ diets. Dragoon’ and ‘Outredgeous’ lettuce, ‘Amara’ mustard, ‘Extra Dwarf’ pak choi, shungiku, ‘Red Russian’ kale, ‘Toscano’ kale, and ‘Barese’ Swiss chard were grown for 4 weeks at 400, 1500, 3000, and 6000 ppm CO2. Shoot fresh mass at 28 days was greater for one of more elevated CO2 levels for all species/cultivars except ‘Toscano’ kale. Fresh mass varied by species/cultivar, with pak choi and ‘Dragoon’ lettuce showing the greatest yields. Super-elevated CO2 (6000 ppm) reduced shoot mass for both lettuce cvs. compared to 3000 ppm. Elevated CO2 increased K levels for most species/cultivars but decreased Mg for some species/cultivars. CO2 affected Vitamin B1 and Vitamin C content but had no effect on Vitamin K. ‘Toscano’ and ‘Red Russian’ kale, and Amara mustard had the highest mineral and vitamin content.