Characterizing Hydroponic Dwarf Tomato Growth in Microbially Inoculated Lunar Regolith Simulant

Abstract

Plant-microorganism interactions in crop production represent a critical and under-researched aspect of controlled environment agriculture (CEA) and bioregenerative life support systems (BLSS). Beneficial microorganisms have been shown to enhance plant resistance to pathogens, response to abiotic stress, and ability to uptake nutrients through the roots. The objectives of the current research were: 1) to demonstrate hydroponic crop production with lunar regolith for in-situ resource utilization (ISRU) within BLSS; and 2) to investigate the utility of microorganisms in hydroponic and BLSS via inoculation of lunar regolith simulant in a Bato bucket system. Dwarf tomatoes (c.v. Red Robin) were grown in coco coir-amended lunar regolith simulant (LRS) over 6 weeks, excluding germination and emergence stages, in a 2-factor factorial design (substrate x inoculation). Data was analyzed using SAS procedure GLM (general linear model) with least squares means and Tukey’s Honestly Significant Difference (HSD). Dwarf tomato ripe fruit yield and total fruit yield from plants grown in LRS was not significantly different from those grown in the control substrate (perlite), indicating that lunar regolith might be viable for ISRU within hydroponic crop production in BLSS. However, dwarf tomato shoot biomass (both fresh and dry weight) was significantly lower in LRS compared to perlite, indicating a negative impact to vegetative plant growth in lunar regolith that requires further investigation. Interestingly, the Brix (soluble sugar content) of ripe fruit was not significantly different between treatment groups, indicating a lack of plant salinity stress from the LRS which was another positive result. Finally, microbial inoculation showed no significant impact, either positive or negative, on any response variable measured and no significant interactions were found. Numerical patterns indicate that extending the duration of this type of study may reveal positive effects of microbial inoculation on plant biomass in both LRS and perlite, warranting further investigation.