An Oxygen Delivery Polymer Enhances Seed Germination in a Martian-like Environment.

John G Macdonald,Karien Rodriguez,Stephen Quirk

doi:10.1089/ast.2019.2056

Abstract

Critical to the success of establishing a sustainable human presence on Mars is the ability to economically grow crop plants. Several environmental factors make it difficult to fully rely on local resources for agriculture. These include nutrient sparse regolith, low and fluctuating temperatures, a high amount of ultraviolet radiation, and water trapped locally in the form of ice or metal oxides. While the 96% CO2 martian atmosphere is ideal to support photosynthesis, high CO2 concentrations inhibit germination. An added difficulty is the fact that a vast majority of crop plants require oxygen for germination. Here, we report the production of a polymer-based oxygen delivery system that supports the germination and growth of cress seeds (Lepidium sativum) in a martian regolith simulant under a martian atmosphere at 101 kPa. The oxygen-donating system is based on a low-density lightly cross-linked polyacrylate that is foamed and converted into a dry powder. It is lightweight, added in low amounts to regolith simulant, and efficiently donates enough oxygen throughout the volume of hydrated regolith simulant to fully support seed germination and plant growth. Germination rates, plant development, and plant mass are nearly identical for L. sativum grown in 100% CO2 in the presence of the oxygen-donating lightly cross-linked polyacrylate compared with plants grown in air. The polymer system also serves to protect root structures and better anchors plants in the regolith simulant.

Highlights

Successful long-term colonization of Mars is dependent on several factors
Foremost is the fact that martian surface soil is devoid of organic material and reactive nitrogen and contains high concentrations of magnesium, aluminum, and other salts that are refractory to plant growth (Foley et al, 2003); more recently, the Curiosity mission has detected the presence of reactive nitrogen in the form of nitrous oxide
Access to partial oxygen pressure during germination and embryo growth is absolutely required for the start of photosynthesis and continued plant growth (Morris et al, 2011) and is as important as access to water (Wang et al, 2015)

Summary

Introduction

Successful long-term colonization of Mars is dependent on several factors. One of the most important is the ability to sustainably grow plants for food or as part of a biological life support system (Murukesan et al, 2016). Foremost is the fact that martian surface soil (regolith) is devoid of organic material and reactive nitrogen and contains high concentrations of magnesium, aluminum, and other salts that are refractory to plant growth (Foley et al, 2003); more recently, the Curiosity mission has detected the presence of reactive nitrogen in the form of nitrous oxide. Martian regolith does contain nutrients needed to sustain plant growth (most notably phosphorous, iron, and potassium), but they are not in a form that can be immediately utilized to sustain plant growth (Arvidson et al, 2014), yet they could be utilized as plant growth resources as needed. Mars has a reduced gravity environment of 0.38 g, an atmospheric pressure of 0.7 kPa, a high ultraviolet flux, and relatively severe temperature fluctuations (de Vera et al, 2010; Cockell, 2014)

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Conclusion