Lunar regolith simulant for cultivation of plants: seed germination and early growth study of plant vitality

Abstract Bioregenerative life support systems (BLSS) designed to produce food crops in future crewed missions to the Moon or Mars consider in-situ resource utilisation (ISRU). Lunar regolith is, therefore, in focus for future technologies of farming on lunar bases. We tested germination and early growth of broccoli plants ( Brassica oleracea var. botrytis italica ) in Murashige-Skoog liquid medium with addition of leachate from a lunar regolith simulant. As the additions to growth, differently diluted water and acidic leachates were used. Physiological status of the germinating plants was evaluated by chlorophyll fluorescence parameters related to plant vitality (relative fluorescence decline – Rfd) and photosynthetic performance of photosystem II (1) potential (F V /F M ) and (2) effective quantum yield of PSII (Φ PSII ), photochemical quenching referring to number of open PSII reaction centres. Both water and acidic leachates inhibited plant growth, however, the extent of growth limitation was dilution-dependent. Full inhibition of germination was apparent when undiluted acidic leachate was added. However, 50% dilution (and higher) resulted in seed germination and the early growth. No negative effects of the water dilutions on F V /F M as well as Φ PSII , were apparent in 15 days old plants, their cotyledonary and the first primary leaves, in particular. Similarly, qP and Rfd showed no sign of either water or acidic leachate addition effect. Although photosystem II-related parameters exhibited no negative effect of the leachates addition, a growth of plants was found dilution-dependent: higher degree of dilution resulted in a more pronounced reduction in plant projection area. In spite of the growth rate reduction (compared to untreated control), properly diluted water and acidic leachates from lunar regolith and/or its simulants might be used in follow up studies focused on plant species prospective for future cultivation in Moon-based stations with temporary or permanent crew.