S06 - Session P16 - Regolith simulant and green compost as substrates for plant cultivation in Mars space colonies

Authors: Stefania De Pascale *, Greta Liuzzi, Roberta Paradiso, Antonio Caporale, Paola Adamo

Human exploration beyond Low Earth Orbit (LEO) will require specific technologies to regenerate resources, while recycling the crew waste, and to exploit the in situ resources, to overcome the need of continuous resupply from Earth and to prevent extra-terrestrial bodies pollution. Plant cultivation will be fundamental for self-sustenance of planetary colonies, as plants represent an optimal tool to regenerate air through photosynthesis, to recover purified water through transpiration, and to recycle waste products through mineral nutrition, while providing fresh food, and health and psychological benefits to the astronauts. However, the configuration of a fertile substrate for plant cultivation based on extraterrestrial soil represents one of the main challenges in space research. Potato ( Solanum tuberosum L.) is a tuberous plant typically grown under open-field conditions, and is a candidate crop for cultivation in Space, based on technical and dietary criteria. The aim of our experiment was to evaluate plant adaptability to cultivation in pot in greenhouse, on different substrates including a Mars regolith simulant. Specifically, the Mojave Mars Simulant (MMS-1), alone and in mixture with a commercial green compost (70:30, v:v), was compared to a fluvial sand, with or without compost at the same rate, and to two terrestrial soils, a red sub-alkaline clay soil from Sicily (Italy), characterised by a high iron content and cation exchange capacity (CEC), and a volcanic sub-alkaline sandy-loam soil from Campania (Italy), with a non-negligible content of carbonates. All substrates were characterised for physico-chemical and hydraulic properties before and after plant cultivation. Plant growth and photosynthetic process (net photosynthesis and chlorophyll a fluorescence) were monitored throughout the different phenological phases (vegetative phase and tuberization), and edible production was determined as number of tubers and tuber fresh weight. Tuber quality was evaluated in terms of both nutritional value and content of anti-nutritional compounds.