Antarctic regolith as prospective substrate for cultivation of plants in space analog habitat greenhouses: Seed germination and early growth study of broccoli in aqueous and acidic dilutions

Food prouction for the needs of space mission crews has posed one of the leading concerns of recent space research. One of the arguably best terrestrial analogs of extraterrestrial habitats are the polar research stations, such as those found in Antarctica. Plants cultivation, offering a valulable source of fresh food, have been a prominent research topic not only for their significance for space analog experiments, but also for the needs of the scientists working at these stations. One of the approaches is the In Situ Resource Utilization (ISRU), which in this case can be adopted by cultivating crops directly in the local soil. Our study aims to evaluate early growth phase and photosynthetic performance of Brassica oleracea var. botrytis italica in Antarctic regolith collected at foothill of the Berry Hill mesa, James Ross Island, Antarctica. Fine grained regolith consisting primarily of hyaloclastic breccias was collected and transported to the laboratories in the Czech Republic. For germination and growth of the experimental plants, leachates were prepared from the regolith using deionized water and 0.11 M acetic acid. Individuals of B. oleracea were cultivated from seeds in a Murashige-Skoog (MS) liquid solution under controlled conditions (T = 21°C, PAR = 120 µmol m-2 s-1) either without addition of regolith leachates (control) or with addition of leachates done by using demineralized water and weak acetic acid. Growth rate, and photosynthetic activity of the experimental plants were measured by chlorophyll fluorescence in 1 day intervals for 21 days. We measured (1) FV/FM (potential yield of photochemical photosynthetic processes), and (2) ФPSII (effective quantum yield of photosystem II). It was showed that acidic leachate either fully inhibited germination or had a strong inhibitory effect on B. oleracea. Water leachates added to the MS medium had moderately strong inhibitory effects on FV/FM and ФPSII. The experimental plants showed decreased but still satisfactory growth rate. The results are promising for follow-up studies aimed to understand and expand the experimental plant growth in Antarctic regolith and its potential association with ISRU purposes.