Martian soil toxicity and environmental conditions prevent terrestrial plant growth
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Five peer-reviewed sources and reference items discuss plant growth, agriculture, and environmental constraints related to Martian soil and regolith simulants.
Development of sustainable agriculture on Mars is a critical step towards its colonisation. However, Martian regolith is coarse-grained, and its mineral profile differs significantly from that of terrestrial arable soil, resulting in poor seed germination success and stunted plant development. This study investigates whether germination success and plant growth can be improved by exposing seeds and plants to water enriched with either i) biochemically active reactive oxygen and nitrogen species generated by atmospheric pressure plasma (PAW) or (ii) nano-/micro-bubbles and minerals such as potassium and calcium extracted from Aquapulse<sup>®</sup> feldspar (APW), a type of rock that is readily available on Mars, at different stages of the crop lifecycle. As a crop model, microgreen crops of <i>B. oleracea</i> and <i>M. sativa</i> are chosen for their short growth cycle, low resource requirements, and high nutritional value. For <i>B. oleracea</i> crops, soaking of seeds in PAW followed by irrigation with APW led to an increase in germination by ~566.7%, in biomass by 412.4%, and in chlorophyll content by 17.7% compared to crops grown using normal water for seed soaking and irrigation. For <i>M. sativa</i> crops, the use of APW for soaking and irrigation yielded an increase of 41.7% in seed germination and 45.2% in crop biomass, whereas the use of PAW for both soaking and irrigation resulted in the greatest improvement in seed germination, 41.7%, when compared to control. These results suggest that, with further optimisation, a regiment of treatment with PAW and APW in place of normal water can be used to address stage-specific challenges of the crop lifecycle in Martian regolith. As amending Martian regolith with a minimum of 1% organic matter is required to promote healthy plant development, further studies should investigate the use of plasma-mediated reforming of biowaste for in situ production of e.g., biochar.
Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( https://creativecommons.org/licenses/by/4.0/ ). Abstract Development of sustainable agriculture on Mars is a critical step towards its colonisation. However, Martian regolith is coarse-grained, and its mineral profile differs significantly from that of terrestrial arable soil, resulting in poor seed germination success and stunted plant development.
However, as a growth substrate, Martian regolith lacks organic matter and essential nutrients such as nitrogen and phosphorus [ 7 ] required for plant growth [ 8 ], while at the same time containing increased levels of germination- and growth-retarding compounds, and its water holding capacity is only around 30% of that of terrestrial soils [ 9 ]. The combination of unsuitable nutrient profile and poor water transport in unconditioned Martian regolith leads to difficulties in seed germination, root system development, and plant growth [ 7 ]. To overcome these challenges, there are several strategies currently being considered.
Results and Discussion This study investigates changes in germination success and plant growth in response to changes in the physico-chemical properties of water used for seed pre-soaking and plant irrigation for crops grown in soil based on simulated Martian regolith. As previously noted, the chemical profile of Martian regolith differs significantly from that of the terrestrial soil, with previous studies reporting poor seed germination success and stunted plant development [ 29 ].
In terrestrial agriculture practices, poor soils are often augmented with additives that e.g., improve their physical properties to ensure an appropriate level of movement of water and air, provide macro- and micro-nutrients that support plant development and growth, or deliver biochemically active substances e.g., signalling molecules capable of inducing a specific biological response in plants. The selection of these additives and methods for their delivery is typically constrained by their cost and energy budget, their abundance, and the environmental impact associated with their production and deployment, to name a few.
oleracea , suggesting the important role the optimisation of soaking and irrigation regimens may play in optimising the performance of crops that may have different growth needs. Figure 1 Comparative beneficial effects of seed soaking + irrigation regimens on biomass and photosynthetic performance in ( a ) M. sativa and ( b ) B. oleracea grown in a soil based on simulated Martian regolith. The arrows in the figure represent sequence of application and representative plant response.
In this work, the selection of plant species was informed by their relatively high tolerance to such environmental conditions as high salinity, different nutrient requirements, and their suitability to be grown as microgreens with high nutritional value and a diverse flavour profile [ 59 , 60 , 61 , 62 , 63 ]. Briefly, M. sativa is a highly adaptable perennial legume known for its exceptional agronomic and nutritional value which can be grown productively in arid and semi-arid conditions, with a preference for deep, well-drained, neutral-pH soils [ 64 ]. The nitrogen-fixing quality of M.
( b ) Preparation of PAW. Water is treated with an atmospheric pressure nitrogen plasma jet
Water for Soaking and Irrigation In order to understand the effects of the physico-chemical properties of water on the development of plants grown on Martian-like soil, three types of water were used, referred to as NW, APW, and PAW. NW represents tap water that was used without further modification. APW water was prepared by immersing feldspar particles contained within a stainless steel cartridge into 1000 mL of tap water in a beaker, allowing for leaching of the minerals and nano-/micro-bubble generation to take place over a period of 7 days under ambient conditions ( Figure 8 a).
Gypsophytes are plants that thrive on gypsum soils on Earth. They possess some adaptive traits that could constitute pre-adaptations to the conditions for potential cultivation in a controlled habitat on Mars. Martian agriculture should utilize substrates obtained directly from the planet itself. However, the detection of perchlorates in the soil of Mars raises doubts about this possibility. These molecules are distributed globally and in concentrations toxic to both humans and plants. The polar winds may preserve some Martian gypsum outcrops from the effects of perchlorates. If so, using this Martian gypsum as a growing substrate for gypsophytes may be a viable option. In the medium term, implementing gypsophyte adaptations on staple crops would also be possible using CRISPR-Cas9 and/or other gene-editing technologies. According to the literature reviewed, Gypsophila struthium subsp. struthium shows a high degree of colonization capacity and high resistance to drought. This taxon serves as an ecological facilitator for other species, and its germination appears to be favored by the presence of gypsum. Several experimental results suggest it would be worthwhile to test the cultivation of this and other plants on reliable simulants or Martian gypsum through sample return missions or on a mission that would perform the cultivation on Mars itself.
Gypsophytes and the use of Martian Gypsum: A review of their potential for agriculture on Mars | DIGITAL.CSIC Skip navigation DIGITAL.CSIC Recursos Naturales Instituto Botánico de Barcelona (IBB) (IBB) Artículos Por favor, use este identificador para citar o enlazar a este item: http://hdl.handle.net/10261/414085 COMPARTIR / EXPORTAR : SHARE BASE Comparte tu historia de Acceso Abierto Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL | DATACITE Refman EndNote Bibtex RefWorks Excel CSV PDF DataCite Send via email Título : Gypsophytes and the use of Martian Gypsum: A review of their potential for agriculture on Mars Autor : de Luis, Miguel ; López-Pujol, Jordi CSIC ORCID ; Mota, Juan ; Merlo, M. Encarnación ; Álvarez-Jiménez, Julio ; Aparicio, Jose Ignacio ; Bartolomé, Carmen ; Ormö, Jens CSIC ORCID ; Parro, Laura M.
Financiadores : Ministerio de Ciencia e Innovación (España) Ministerio de Universidades (España) Junta de Andalucía Palabras clave : Gypsophytes Mars preadaptation Gypsum Martian agriculture Plant ecology Olympia undae Mars polar caps Fecha de publicación : 25-sep-2025 Editor : Elsevier BV Citación : Life Sciences in Space Research 48: 17- 25 (2025) Resumen : Gypsophytes are plants that thrive on gypsum soils on Earth. They possess some adaptive traits that could constitute pre-adaptations to the conditions for potential cultivation in a controlled habitat on Mars. Martian agriculture should utilize substrates obtained directly from the planet itself. However, the detection of perchlorates in the soil of Mars raises doubts about this possibility. These molecules are distributed globally and in concentrations toxic to both humans and plants. The polar winds may preserve some Martian gypsum outcrops from the effects of perchlorates. If so, using this Martian gypsum as a growing substrate for gypsophytes may be a viable option. In the medium term, implementing gypsophyte adaptations on staple crops would also be possible using CRISPR-Cas9 and/or other gene-editing technologies. According to the literature reviewed, Gypsophila struthium subsp. struthium shows a high degree of colonization capacity and high resistance to drought. This taxon serves as an ecological facilitator for other species, and its germination appears to be favored by the presence of gypsum. Several experimental results suggest it would be worthwhile to test the cultivation of this and other plants on reliable simulants or Martian gypsum through sample return missions or on a mission that would perform the cultivation on Mars itself.
A fundamental challenge in human missions to Mars is producing consumable foods efficiently with the in situ resources such as soil, water, nutrients and solar radiation available on Mars. The low nutrient content of martian soil and high salinity of water render them unfit for direct use for propagating food crops on Mars. It is therefore essential to develop strategies to enhance nutrient content in Mars soil and to desalinate briny water for long-term missions on Mars. We report simple and efficient strategies for treating basaltic regolith simulant soil and briny water simulant for suitabl
National Aeronautics and Space Administration, and is driving technology development to support such an endeavor. While the vision to sustain human activity on Mars is compelling, providing consumables to the crews is a fundamental challenge due to transport costs and need for continuous replenishment. Consequently, long-term human missions to Mars will rely on using martian resources available in situ to develop food production system. Yet, many resources such as soil, water, solar radiation, carbon and nitrogen found on the martian surface [ 1 ] cannot be directly exploited by plants for growth in the form which they are found.
A first step towards enabling habitation of Mars is the optimization of in situ resources as suitable resources for growing plants as part of a bioregenerative food system [ 18 ]. Consumable plants are an essential part of bioregenerative systems but also have secondary benefits such as contributing to generation of oxygen and organic waste recycling [ 19 , 20 ]. Although there is no location on Earth exactly reproducing martian environmental conditions, the harsh martian climate and geological features are comparable to some places on Earth [ 21 – 23 ].
The use of terrestrial analogues has therefore lead to the understanding of the physical, geochemical and environmental conditions that occur on Mars and help to resolve limitations to habitation relying on martian resources [ 8 , 24 – 33 ]. Microbes and higher plants have the potential to adapt to extreme terrestrial environments that simulate martian conditions [ 7 , 8 , 10 , 24 , 25 , 27 , 34 – 37 ]. Photosynthetic bacteria that are commonly employed in seawater biodesalination technologies allow cost and energy-efficient desalination [ 38 , 39 ]. Exploitation of such microbes in desalination of martian briny water may provide a usable water resource.
Plant growth experiments Turnip ( Brassica rapa ), radish ( Raphanus sativus ), lettuce ( Lactuca sativa ) or alfalfa ( Medicago sativa ) seeds were sown in pots containing basaltic regolith simulant soil or garden soil and germination was assessed after a week. Plants were grown in a growth chamber (Percival-Scientific) under controlled condition [16 h white soft light (650 μmol photons/m 2 /s) at 26°C and 8 h dark at 24°C] and watered once a week. Plant shoot height and root length were measured at 1 week interval.
The geochemical properties of martian basaltic regolith soil and briny water require strategies for treating these resources as suitable resources, that may lead to production of consumable plants [ 7 , 18 ]. In mineral composition, Mars regolith simulants are comparable to Earth soils [ 43 , 44 ] and they can be mimicked by using basalt [ 10 , 45 ]. Mars regolith analogs have been tested for growing plants and established that the capacity of specific regolith simulants supported plant growth only in short term without nutrient supplementation [ 10 , 18 , 28 , 31 , 32 , 45 – 47 ].
As all these properties of these crops are desirable for consumables during martian habitation, growth of these three plant species was evaluated in alfalfa (grown in bare simulant soil as first generation biological) treated basaltic regolith simulant soil watered with fresh water. The significant increase in growth and biomass of turnip, radish and lettuce plants in alfalfa treated simulant soil demonstrated that the alfalfa grown in bare simulant soil augment nutrients to the basaltic regolith simulant soil to sustain normal growth and productivity of the next generation crops.
On the other hand, the presence of perchlorate in martian regolith provides a significant challenge in its use as an agricultural substrate [ 50 ]. As we aimed to find a strategy to raise a nutrient resource (alfalfa) in the simulant itself, we did not test the effect of perchlorate on the growth of plants in the simulant soil. Our future research in this line could incorporate perchloride amendments in the simulant soil and before testing plant growth. In alfalfa treated simulant soil watered with briny water simulant, no turnip seeds germinated within 7 days of sowing, while 100% of the seeds germinated in 3 days when watered with fresh water.
Halobacteria from saline lakes (considered as analogues of ancient martian organisms) withstand low temperatures and high NaCl content similar to conditions in Mars [ 57 ]. Terrestrial microbes including fungus grow in densest brines such as those on Mars [ 16 , 17 ]. Considering the potential adaptation of terrestrial microbes to extreme salinity as found in Mars, we explored the use of microbes to desalinate the briny water simulant. Autotrophic cyanobacteria of marine origin can bloom in seawater with minimal nutrient
We report simple and efficient strategies for treating basaltic regolith soil and briny water simulants, and demonstrate that the treated simulants can sustain normal growth of food crops. Collectively, the efficient growth of the three plant species in the alfalfa augmented basaltic regolith simulant soil with Synechococcus sp. PCC 7002 mediated biodesalinated water supports, that in principle, it is possible to grow food crops in treated martian basaltic regolith soil watered with biodesalinated water. A next step would be to test growth of cereal and leguminous crops in the treated simulant soil. Alfalfa and Synechococcus sp.
The environmental conditions on present‑day Mars are far outside the range tolerated by known complex terrestrial life. Conceptual climate studies have suggested that, in hypothetical terraforming scenarios, artificially enhancing the greenhouse effect could restore Mars to more habitable surface conditions. Early colonizing terrestrial life on a warming Mars would plausibly consist of lichens and high‑alpine or high‑arctic plants. Here, we consider a later, more demanding step and investigate the thermal conditions under which the first tree could, in principle, grow on the Martian surface. B
Conceptual climate studies have suggested that, in hypothetical terraforming scenarios, artificially enhancing the greenhouse effect could restore Mars to more habitable surface conditions. Early colonizing terrestrial life on a warming Mars would plausibly consist of lichens and high‑alpine or high‑arctic plants. Here, we consider a later, more demanding step and investigate the thermal conditions under which the first tree could, in principle, grow on the Martian surface.
Lichen exposure experiments have shown that certain Antarctic species can physiologically adapt to simulated Martian surface conditions on relatively short timescales [ 27 ], suggesting that some extremophiles may tolerate aspects of the present day Martian environment. At the same time, research on higher plants in controlled environments and Mars analog substrates demonstrates that plant growth is possible but tightly constrained by factors such as substrate composition, atmospheric pressure, gas mixture, and radiation [ 28 – 30 ].
[ 31 ] experimentally tested the growth of Antarctic plant species on Martian and Lunar soil simulants under terrestrial atmospheric conditions, showing that at least some extremophile plants can germinate and develop on regolith analogs. These results support the idea that cold-adapted terrestrial flora could be promising candidates for early biological experiments and bioregenerative concepts in Mars and Moon exploration and, in a broader sense, for long‑term terraforming scenarios.
We assume that the necessary microbial community to support tree growth is part of the inoculum added to the soil with the seeds of the trees. The role of plants in terraforming Mars remains of interest; recently, [ 32 ] discussed utilizing algae as biocatalysts for making Mars habitable. In this paper, we use a high-resolution simulation of the Martian surface as it is warmed by the artificial enhancement of the greenhouse effect to determine when and where trees could grow on Mars.
In this study we use them strictly as proxy thermal limits for a representative high‑elevation conifer (Pinus sibirica/ cembra) and adopt their direct application to Mars as a simplifying assumption within a conceptual framework. In Martian conditions, the effective thresholds for growth might need to be shifted due to differences in atmospheric composition, radiation environment, gravity, and soil development, and our results should therefore be interpreted as indicative rather than as precise quantitative predictions for any particular species. The treeline‐based temperature thresholds adopted in this study should be understood as necessary but not sufficient conditions for tree growth.
Design studies of greenhouses on Mars and the Moon have motivated extensive experiments with growing plants, although not large trees, at reduced atmospheric pressure (as low as 100 hPa) and with a high fraction of CO₂ and reduced O₂ (e.g., [ 40 – 43 ]). More recent experimental and conceptual studies of controlled‑environment agriculture and bioregenerative life support for space missions further explore plant performance under reduced pressure and Martian‑analog conditions [ 28 – 30 ]. For plant growth at a total pressure of 100 hPa the optimal CO₂ level is ~ 1 [ 41 – 43 ] and levels above ~ 10 hPa would be toxic [ 44 , 45 ].
Laboratory and greenhouse studies indicate that for higher plants the optimal CO₂ partial pressure is of order ~1 hPa, with growth inhibition and toxicity becoming significant above ~10 hPa. Thus, the pure‑CO₂ atmospheres considered here are not directly compatible with these biological thresholds. In any realistic scenario where terrestrial trees could grow on Mars, most of the total pressure would instead have to be provided by an inert background gas such as N₂, with CO₂ restricted to the physiologically acceptable range and O₂ maintained near ~1 hPa for respiration.
Consequently, the “growth regions” identified here mark locations and parameter combinations where thermal pre‑conditions for tree growth, as inferred from terrestrial treeline studies, could in principle be satisfied, but they do not by themselves guarantee that trees could
Within this modelling structure, the maps and percentage values presented in this work should be interpreted strictly as indicating where and when thermal conditions alone would cease to be the dominant limitation for terrestrial tree growth. They identify spatio‑temporal thermal windows under simplified atmospheric assumptions, but they do not imply that these regions are fully habitable or that other key constraints – such as the availability and state of water, soil development, radiation shielding, or self‑consistent atmospheric composition – are automatically satisfied.
Taken together, our results therefore define a thermal pre‑condition – or “thermal window” – for potential tree growth on Mars, rather than a full habitability criterion, and should be viewed as a first step to be combined in future work with explicit treatments of hydrology, atmospheric composition, radiation, soils, and biology. In this study, we focused on the temperature increase due to higher CO₂ pressure plus additional artificial greenhouse warming. We assumed an atmosphere at the lowest pressure that plants have been shown to grow (100 hPa). For the purposes of the thermal calculation, we assumed pure CO₂.
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", for its orange-red appearance. Mars is a desert-like rocky planet with a tenuous atmosphere that is primarily carbon dioxide (CO2). At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from −153 to 20 °C (−243 to 68 °F), and cosmic radiation is high. Mars r
Mars is a terrestrial planet with a surface that consists of minerals containing silicon and oxygen, metals, and other elements that typically make up rock. The Martian surface is primarily composed of tholeiitic basalt, although parts are more silica-rich than typical basalt and may be similar to andesitic rocks on Earth, or silica glass. Regions of low albedo suggest concentrations of plagioclase feldspar, with northern low albedo regions displaying higher than normal concentrations of sheet silicates and high-silicon glass. Parts of the southern highlands include detectable amounts of high-calcium pyroxenes. Localized concentrations of hematite and olivine have been found. Much of the surface is deeply covered by finely grained iron(III) oxide dust.
The Phoenix lander returned data showing Martian soil to be slightly alkaline and containing elements such as magnesium, sodium, potassium and chlorine. These nutrients are found in soils on Earth, and are necessary for plant growth. Experiments performed by the lander showed that the Martian soil has a basic pH of 7.7, and contains 0.6% perchlorate by weight, concentrations that are toxic to humans.
Streaks are common across Mars and new ones appear frequently on steep slopes of craters, troughs, and valleys. The streaks are dark at first and get lighter with age. The streaks can start in a tiny area, then spread out for hundreds of metres. They have been seen to follow the edges of boulders and other obstacles in their path. The commonly accepted hypotheses include that they are dark underlying layers of soil revealed after avalanches of bright dust or dust devils. Several other explanations have been put forward, including those that involve water or even the growth of organisms.
Environmental radiation levels on the surface are on average 0.64 millisieverts of radiation per day, and significantly less than the radiation of 1.84 millisieverts per day or 22 millirads per day during the flight to and from Mars. For comparison the radiation levels in low Earth orbit, where Earth's space stations orbit, are around 0.5 millisieverts of radiation per day. Hellas Planitia has the lowest surface radiation at about…
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